umu.sePublications
Change search
Refine search result
345678 251 - 300 of 360
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 251. Perdersen, Martin Nors
    et al.
    Fodera, Vito
    Horvath, Istvan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    van Maarschalkerweerd, Andreas
    Toft, Katrine Norgaard
    Weise, Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wittung-Stafshede, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Vestergaard, Bente
    Direct Correlation Between Ligand-Induced alpha-Synuclein Oligomers and Amyloid-like Fibril Growth2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 10422Article in journal (Refereed)
    Abstract [en]

    Aggregation of proteins into amyloid deposits is the hallmark of several neurodegenerative diseases such as Alzheimer's and Parkinson's disease. The suggestion that intermediate oligomeric species may be cytotoxic has led to intensified investigations of pre-fibrillar oligomers, which are complicated by their transient nature and low population. Here we investigate alpha-synuclein oligomers, enriched by a 2-pyridone molecule (FN075), and the conversion of oligomers into fibrils. As probed by leakage assays, the FN075 induced oligomers potently disrupt vesicles in vitro, suggesting a potential link to disease related degenerative activity. Fibrils formed in the presence and absence of FN075 are indistinguishable on microscopic and macroscopic levels. Using small angle X-ray scattering, we reveal that FN075 induced oligomers are similar, but not identical, to oligomers previously observed during alpha-synuclein fibrillation. Since the levels of FN075 induced oligomers correlate with the amounts of fibrils among different FN075: protein ratios, the oligomers appear to be on-pathway and modeling supports an 'oligomer stacking model' for alpha-synuclein fibril elongation.

  • 252.
    Persson, Helena
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Johansson Söderberg, Jenny
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Vindebro, Reine
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Johansson, Björn P
    von Pawel-Rammingen, Ulrich
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Proteolytic processing of the streptococcal IgG endopeptidase IdeS modulates the functional properties of the enzyme and results in reduced immunorecognition2015In: Molecular Immunology, ISSN 0161-5890, E-ISSN 1872-9142, Vol. 68, no 2, p. 176-184Article in journal (Refereed)
    Abstract [en]

    The important human gram positive bacterial pathogen Streptococcus pyogenes employs various virulence factors to promote inflammation and to facilitate invasive disease progression. In this study we explored the relation of the secreted streptococcal cysteine proteases IdeS and SpeB, and neutrophil (PMN) proteases. We found that SpeB is resistant to proteolytic attack in an inflammatory environment, emphasizing the importance of SpeB for streptococcal pathogenicity, while PMN enzymes and SpeB itself process the IgG degrading endopeptidase IdeS. Processing occurs as NH2-terminal cleavage of IdeS resulting in reduced immunorecognition of the protease by specific antibodies. While the endopeptidase retains IgG cleaving activity, its ability to suppress the generation of reactive oxygen species is abolished. We suggest that the cleavage of NH2-terminal peptides by SpeB and/or neutrophil proteases is a mechanism evolved to prevent early inactivation of this important streptococcal virulence factor, albeit at the cost of impaired functionality.

  • 253.
    Persson, Helena
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Vindebro, Reine
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    von Pawel-Rammingen, Ulrich
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    The streptococcal cysteine protease SpeB is not a natural immunoglobulin-cleaving enzyme2013In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 81, no 6, p. 2236-2241Article in journal (Refereed)
    Abstract [en]

    The human bacterial pathogen Streptococcus pyogenes has developed a broad variety of virulence mechanisms to evade the actions of the host immune defense. One of the best-characterized factors is the streptococcal cysteine protease SpeB, an important multifunctional protease that contributes to group A streptococcal pathogenesis in vivo. Among many suggested activities, SpeB has been described to degrade various human plasma proteins, including immunoglobulins (Igs). In this study, we show that SpeB has no Ig-cleaving activity under physiological conditions and that only Igs in a reduced state, i.e., semimonomeric molecules, are cleaved and degraded by SpeB. Since reducing conditions outside eukaryotic cells have to be considered nonphysiological and IgG in a reduced state lacks biological effector functions, we conclude that SpeB does not contribute to S. pyogenes virulence through the proteolytic degradation of Igs.

  • 254.
    Pinne, Marija
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Bunikis, Ignas
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Takade, Akemi
    Mizunoe, Yoshimitsu
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Structural characterization of Borrelia burgdorferi porins by electron crystallographyManuscript (Other academic)
  • 255. Plagens, Andre
    et al.
    Richter, Hagen
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Randau, Lennart
    DNA and RNA interference mechanisms by CRISPR-Cas surveillance complexes2015In: FEMS Microbiology Reviews, ISSN 0168-6445, E-ISSN 1574-6976, Vol. 39, no 3, p. 442-463Article, review/survey (Refereed)
    Abstract [en]

    The CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) adaptive immune systems use small guide RNAs, the CRISPR RNAs (crRNAs), to mark foreign genetic material, e.g. viral nucleic acids, for degradation. Archaea and bacteria encode a large variety of Cas proteins that bind crRNA molecules and build active ribonucleoprotein surveillance complexes. The evolution of CRISPR-Cas systems has resulted in a diversification of cas genes and a classification of the systems into three types and additional subtypes characterized by distinct surveillance and interfering complexes. Recent crystallographic and biochemical advances have revealed detailed insights into the assembly and DNA/RNA targeting mechanisms of the various complexes. Here, we review our knowledge on the molecular mechanism involved in the DNA and RNA interference stages of type I (Cascade: CRISPR-associated complex for antiviral defense), type II (Cas9) and type III (Csm, Cmr) CRISPR-Cas systems. We further highlight recently reported structural and mechanistic themes shared among these systems.

  • 256. Porrúa, Odil
    et al.
    García-González, Vicente
    Santero, Eduardo
    Shingler, Victoria
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Govantes, Fernando
    Activation and repression of a σN-dependent promoter naturally lacking upstream activation sequences2009In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 73, no 3, p. 419-433Article in journal (Refereed)
    Abstract [en]

    The Pseudomonas sp. strain ADP protein AtzR is a LysR-type transcriptional regulator required for activation of the atzDEF operon in response to nitrogen limitation and cyanuric acid. Transcription of atzR is directed by the σ(N)-dependent promoter PatzR, activated by NtrC and repressed by AtzR. Here we use in vivo and in vitro approaches to address the mechanisms of PatzR activation and repression. Activation by NtrC did not require any promoter sequences other than the sigma(N) recognition motif both in vivo and in vitro, suggesting that NtrC activates PatzR in an upstream activation sequences-independent fashion. Regarding AtzR-dependent autorepression, our in vitro transcription experiments show that the concentration of AtzR required for repression of the PatzR promoter in vitro correlates with AtzR affinity for its binding site. In addition, AtzR prevents transcription from PatzR when added to a preformed E-sigma(N)-PatzR closed complex, but isomerization to an open complex prevents repression. Gel mobility shift and DNase I footprint assays indicate that DNA-bound AtzR and E-σ(N) are mutually exclusive. Taken together, these results strongly support the notion that AtzR represses transcription from PatzR by competing with E-σ(N) for their overlapping binding sites. There are no previous reports of a similar mechanism for repression of σ(N)-dependent transcription.

  • 257.
    Putzova, Daniela
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defense, Hradec Králové, Czech Republic.
    Panda, Swarupa
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Härtlova, Anetta
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Stulík, Jirí
    Gekara, Nelson O.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Subversion of innate immune responses by Francisella involves the disruption of TRAF3 and TRAF6 signalling complexes2017In: Cellular Microbiology, ISSN 1462-5814, E-ISSN 1462-5822, Vol. 19, no 11, article id e12769Article in journal (Refereed)
    Abstract [en]

    The success of pathogens depends on their ability to circumvent immune defences. Francisella tularensis is one of the most infectious bacteria known. The remarkable virulence of Francisella is believed to be due to its capacity to evade or subvert the immune system, but how remains obscure. Here, we show that Francisella triggers but concomitantly inhibits the Toll-like receptor, RIG-I-like receptor, and cytoplasmic DNA pathways. Francisella subverts these pathways at least in part by inhibiting K63-linked polyubiquitination and assembly of TRAF6 and TRAF3 complexes that control the transcriptional responses of pattern recognition receptors. We show that this mode of inhibition requires a functional type VI secretion system and/or the presence of live bacteria in the cytoplasm. The ability of Francisella to enter the cytosol while simultaneously inhibiting multiple pattern recognition receptor pathways may account for the notable capacity of this bacterium to invade and proliferate in the host without evoking a self-limiting innate immune response.

  • 258. Quereda, Juan J.
    et al.
    Andersson, Christopher
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Cossart, Pascale
    Johansson, Jörgen
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Pizarro-Cerda, Javier
    Role in virulence of phospholipases, listeriolysin O and listeriolysin S from epidemic Listeria monocytogenes using the chicken embryo infection model2018In: Veterinary research (Print), ISSN 0928-4249, E-ISSN 1297-9716, Vol. 49, article id 13Article in journal (Refereed)
    Abstract [en]

    Most human listeriosis outbreaks are caused by Listeria monocytogenes evolutionary lineage I strains which possess four exotoxins: a phosphatidylinositol-specific phospholipase C (PlcA), a broad-range phospholipase C (PlcB), listeriolysin O (LLO) and listeriolysin S (LLS). The simultaneous contribution of these molecules to virulence has never been explored. Here, the importance of these four exotoxins of an epidemic lineage I L. monocytogenes strain (F2365) in virulence was assessed in chicken embryos infected in the allantoic cavity. We show that LLS does not play a role in virulence while LLO is required to infect and kill chicken embryos both in wild type transcriptional regulator of virulence PrfA -(PrfAWT) and constitutively active PrfA (PrfA*) backgrounds. We demonstrate that PlcA, a toxin previously considered as a minor virulence factor, played a major role in virulence in a PrfA* background. Interestingly, GFP transcriptional fusions show that the plcA promoter is less active than the hly promoter in vitro, explaining why the contribution of PlcA to virulence could be observed more importantly in a PrfA* background. Together, our results suggest that PlcA might play a more important role in the infectious lifecycle of L. monocytogenes than previously thought, explaining why all the strains of L. monocytogenes have conserved an intact copy of plcA in their genomes.

  • 259.
    Ramstedt, Madeleine
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nakao, Ryoma
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Nyunt Wai, Sun
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Boily, Jean-Francois
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Monitoring surface chemistry changes in the bacterial cell wall: multivariate analysis of Cryo-X-ray photoelectron spectroscopy data2011In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 286, no 14, p. 12389-12396Article in journal (Refereed)
    Abstract [en]

    Gram-negative bacteria can alter the composition of the Lipopolysaccharide (LPS) layer of the outer membrane as a response to different growth conditions and external stimuli. These alterations can, for example, promote attachment to surfaces and biofilm formation. The changes occur in the outermost layer of the cell and may consequently influence interactions between bacterial cells and surrounding host tissue, as well as other surfaces. Microscopic analyses, fractionation of bacterial cells or other traditional microbiological assays have previously been used to study these alterations. These methods can, however, be time consuming and do not always give detailed chemical information about the bacterial cell surface. We here present an analytical method that provides chemical information on the outermost portion of bacterial cells with respect to protein, peptidoglycan, lipid and polysaccharide content. The method involves cryo-X-ray Photoelectron Spectroscopy (XPS) analyses of the outermost portion (within ~10 nm of the surface) of intact bacterial cells, followed by a multivariate curve resolution analysis of carbon spectra. It can be used as a tool for characterizing and monitoring variations in the chemical composition of bacterial cell walls or of isolated outer membrane vesicles, variations that result from e.g. mutations or external stimuli. The method enabled us to accurately predict the alterations in polysaccharide content and surface chemistries of a set of well characterized Escherichia coli LPS mutants. The described approach may moreover be applied to monitor surface chemical composition of other biological samples.

  • 260.
    Rhen, Mikael
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
    Salmonella and Reactive Oxygen Species: A Love-Hate Relationship2019In: Journal of Innate Immunity, ISSN 1662-811X, E-ISSN 1662-8128, Vol. 11, no 3, p. 216-226Article, review/survey (Refereed)
    Abstract [en]

    Salmonella enterica represents an enterobacterial species including numerous serovars that cause infections at, or initiated at, the intestinal epithelium. Many serovars also act as facultative intracellular pathogens with a tropism for phagocytic cells. These bacteria not only survive in phagocytes but also undergo de facto replication therein. Phagocytes, through the activities of phagocyte NADPH-dependent oxidase and inducible nitric oxide synthase, are very proficient in converting molecular oxygen to reactive oxygen (ROS) and nitrogen species (RNS). These compounds represent highly efficient effectors of the innate immune defense. Salmonella is by no means resistant to these effectors, which may stand in contrast to the host niches chosen. To cope with this paradox, these bacteria rely on an array of detoxification and repair systems. Combination these systems allows for a high enough tolerance to ROS and RNS to enable establishment of infection. In addition, salmonella possesses protein factors that have the potential to dampen the infection-associated inflammation, which evidently results in a reduced exposure to ROS and RNS. This review attempts to summarize the activities and strategies by which salmonella tries to cope with ROS and RNS and how the bacterium can make use of these innate defense factors.

  • 261. Richter, Florian
    et al.
    Fonfara, Ines
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Max Planck Inst Infect Biol, D-10117 Berlin, Germany.
    Bouazza, Boris
    Schumacher, Charlotte Helene
    Bratovic, Majda
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Max Planck Inst Infect Biol, D-10117 Berlin, Germany.
    Moeglich, Andreas
    Engineering of temperature- and light-switchable Cas9 variants2016In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 44, no 20, p. 10003-10014Article in journal (Refereed)
    Abstract [en]

    Sensory photoreceptors have enabled non-invasive and spatiotemporal control of numerous biological processes. Photoreceptor engineering has expanded the repertoire beyond natural receptors, but to date no generally applicable strategy exists towards constructing light-regulated protein actuators of arbitrary function. We hence explored whether the homodimeric Rhodobacter sphaeroides light-oxygen-voltage (LOV) domain (RsLOV) that dissociates upon blue-light exposure can confer light sensitivity onto effector proteins, via amechanism of light-induced functional site release. We chose the RNA-guided programmable DNA endonuclease Cas9 as proof-of-principle effector, and constructed a comprehensive library of RsLOV inserted throughout the Cas9 protein. Screening with a high-throughput assay based on transcriptional repression in Es-cherichia coli yielded paRC9, a moderately light-activatable variant. As domain insertion can lead to protein destabilization, we also screened the library for temperature-sensitive variants and isolated tsRC9, a variant with robust activity at 29 degrees C but negligible activity at 37. C. Biochemical assays confirmed temperature-dependent DNA cleavage and binding for tsRC9, but indicated that the light sensitivity of paRC9 is specific to the cellular setting. Using tsRC9, the first temperature-sensitive Cas9 variant, we demonstrate temperature-dependent transcriptional control over ectopic and endogenous genetic loci. Taken together, RsLOV can confer light sensitivity onto an unrelated effector; unexpectedly, the same LOV domain can also impart strong temperature sensitivity.

  • 262. Richter, Florian
    et al.
    Fonfara, Ines
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Max Planck Institute for Infection Biology, 10117 Berlin, Germany.
    Gelfert, Renate
    Nack, Jennifer
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Max Planck Institute for Infection Biology, 10117 Berlin, Germany.
    Möglich, Andreas
    Switchable Cas92017In: Current Opinion in Biotechnology, ISSN 0958-1669, E-ISSN 1879-0429, Vol. 48, p. 119-126Article, review/survey (Refereed)
    Abstract [en]

    Ever since its discovery, Cas9 from Streptococcus pyogenes has revolutionized biology by enabling analysis and engineering of genomes with unprecedented precision and ease. To fine-tune on-target effects and to mitigate adverse effects caused by untimely and off-target action of Cas9, strategies have been developed to control its activity at the post-translational stage via external trigger signals. Control is either achieved by modifying the Cas9 protein itself or its programmable RNA molecules. To date, switchable Cas9 variants responding to small ligands, light or temperature have been engineered. With these variants in hand, the regulation and modification of genomes can be accomplished in graded and ever more precise manner.

  • 263.
    Romby, Pascale
    et al.
    Architecture et Re´activite´ de l’ARN, Universite´ de Strasbourg, Strasbourg, France.
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    An overview of RNAs with regulatory functions in gram-positive bacteria.2010In: Cellular and Molecular Life Sciences (CMLS), ISSN 1420-682X, E-ISSN 1420-9071, Vol. 67, no 2, p. 217-237Article in journal (Refereed)
    Abstract [en]

    During the last decade, RNA molecules with regulatory functions on gene expression have benefited from a renewed interest. In bacteria, recent high throughput computational and experimental approaches have led to the discovery that 10-20% of all genes code for RNAs with critical regulatory roles in metabolic, physiological and pathogenic processes. The trans-acting RNAs comprise the noncoding RNAs, RNAs with a short open reading frame and antisense RNAs. Many of these RNAs act through binding to their target mRNAs while others modulate protein activity or target DNA. The cis-acting RNAs include regulatory regions of mRNAs that can respond to various signals. These RNAs often provide the missing link between sensing changing conditions in the environment and fine-tuning the subsequent biological responses. Information on their various functions and modes of action has been well documented for gram-negative bacteria. Here, we summarize the current knowledge of regulatory RNAs in gram-positive bacteria.

  • 264.
    Rompikuntal, Pramod Kumar
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Thay, Bernard
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Khan, Muhammad Khanzeb
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Alanko, Jonna
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Penttinen, Anna-Maija
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Asikainen, Sirkka
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Oscarsson, Jan
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Perinuclear localization of internalized outer membrane vesicles carrying active cytolethal distending toxin (CDT) from aggregatibacter actinomycetemcomitans2012In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 80, no 1, p. 31-42Article in journal (Refereed)
    Abstract [en]

    Aggregatibacter actinomycetemcomitans is implicated in aggressive forms of periodontitis. Similar to several other Gram-negative species this organism produces and excretes a cytolethal distending toxin (CDT), a genotoxin associated with cell distention, G(2) cell cycle arrest and/or apoptosis in many mammalian cell types. In this study we have identified A. actinomycetemcomitans outer membrane vesicles (OMVs) as a vehicle for simultaneous delivery of multiple proteins, including CDT into human cells. The OMV proteins were internalized in both HeLa cells and human gingival fibroblasts (HGF) via a mechanism of OMV fusion with lipid rafts in the plasma membrane. The active toxin unit, CdtB was localized inside the nucleus of the intoxicated cells, whereas OmpA and proteins detected using an antibody specific to whole A. actinomycetemcomitans serotype a cells had a perinuclear distribution. In accordance with a tight association of CdtB with OMVs, vesicles isolated from A. actinomycetemcomitans strain D7SS (serotype a) in contrast to OMVs from a D7SS cdtABC mutant induced a cytolethal distending effect on HeLa and HGF cells, indicating that OMV-associated CDT was biologically active. Association of CDT with OMVs was also observed in A. actinomycetemcomitans isolates, belonging to serotypes b, and c, respectively, indicating that OMV-mediated release of CDT may be conserved in A. actinomycetemcomitans. Although, the role of A. actinomycetemcomitans OMVs in periodontal disease has not yet been elucidated, our present data suggest that OMVs could deliver biologically active CDT and additional virulence factors into susceptible cells of the periodontium.

  • 265.
    Ruhal, Rohit
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Antti, Henrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rzhepishevska, Olena
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boulanger, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Barbero, David R.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Ramstedt, Madeleine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A multivariate approach to correlate bacterial surface properties to biofilm formation by lipopolysaccharide mutants of Pseudomonas aeruginosa2015In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 127, no 0, p. 182-191Article in journal (Refereed)
    Abstract [en]

    Abstract Bacterial biofilms are involved in various medical infections and for this reason it is of great importance to better understand the process of biofilm formation in order to eradicate or mitigate it. It is a very complex process and a large range of variables have been suggested to influence biofilm formation. However, their internal importance is still not well understood. In the present study, a range of surface properties of Pseudomonas aeruginosa lipopolysaccharide mutants were studied in relation to biofilm formation measured in different kinds of multi-well plates and growth conditions in order to better understand the complexity of biofilm formation. Multivariate analysis was used to simultaneously evaluate the role of a range of physiochemical parameters under different conditions. Our results suggest the presence of serum inhibited biofilm formation due to changes in twitching motility. From the multivariate analysis it was observed that the most important parameters, positively correlated to biofilm formation on two types of plates, were high hydrophobicity, near neutral zeta potential and motility. Negative correlation was observed with cell aggregation, as well as formation of outer membrane vesicles and exopolysaccharides. This work shows that the complexity of biofilm formation can be better understood using a multivariate approach that can interpret and rank the importance of different factors being present simultaneously under several different environmental conditions, enabling a better understanding of this complex process.

  • 266. Rungelrath, Viktoria
    et al.
    Wohlsein, Jan Christian
    Siebert, Ursula
    Stott, Jeffrey
    Prenger-Berninghoff, Ellen
    von Pawel-Rammingen, Ulrich
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Valentin-Weigand, Peter
    Baums, Christoph G.
    Seele, Jana
    Identification of a novel host-specific IgG protease in Streptococcus phocae subsp phocae2017In: Veterinary Microbiology, ISSN 0378-1135, E-ISSN 1873-2542, Vol. 201, p. 42-48Article in journal (Refereed)
    Abstract [en]

    Streptococcus (S.) phocae subsp. phocae causes bronchopneumonia and septicemia in a variety of marine mammals. Especially in harbor seals infected with phocine distemper virus it plays an important role as an opportunistic pathogen. This study was initiated by the detection of IgG cleavage products in Western blot analysis after incubation of bacterial supernatant with harbor seal serum. Hence, the objectives of this study were the identification and characterization of a secreted IgG cleaving protease in S. phocae subsp. phocae isolated from marine mammals. To further identify the responsible factor of IgG cleavage a protease inhibitor profile was generated. Inhibition of the IgG cleaving activity by iodoacetamide and Z-LVG-CHN2 indicated that a cysteine protease is involved. Moreover, an anti-IdeS antibody directed against the IgG endopeptidase IdeS of S. pyogenes showed cross reactivity with the putative IgG protease of S. phocae subsp. phocae. The IgG cleaving factor of S. phocae subsp. phocae was identified through an inverse PCR approach and designated IdeP (Immunoglobulin G degrading enzyme of S. phocae subsp. phocae) in analogy to the cysteine protease IdeS. Notably, recombinant (r) IdeP is a host and substrate specific protease as it cleaves IgG from grey and harbor seals but not IgG from harbor porpoises or non-marine mammals. The identification of IdeP represents the first description of a protein in S. phocae subsp. phocae involved in immune evasion. Furthermore, the fact that IdeP cleaves solely IgG of certain marine mammals reflects functional adaption of S. phocae subsp. phocae to grey and harbor seals as its main hosts.

  • 267.
    Röhm, Marc
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Grimm, Melissa J.
    D'Auria, Anthony C.
    Almyroudis, Nikolaos G.
    Segal, Brahm H.
    Urban, Constantin F.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    NADPH Oxidase Promotes Neutrophil Extracellular Trap Formation in Pulmonary Aspergillosis2014In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 82, no 5, p. 1766-1777Article in journal (Refereed)
    Abstract [en]

    NADPH oxidase is a crucial enzyme in antimicrobial host defense and in regulating inflammation. Chronic granulomatous disease (CGD) is an inherited disorder of NADPH oxidase in which phagocytes are defective in generation of reactive oxidant intermediates. Aspergillus species are ubiquitous, filamentous fungi, which can cause invasive aspergillosis, a major cause of morbidity and mortality in CGD, reflecting the critical role for NADPH oxidase in antifungal host defense. Activation of NADPH oxidase in neutrophils can be coupled to the release of proteins and chromatin that comingle in neutrophil extracellular traps (NETs), which can augment extracellular antimicrobial host defense. NETosis can be driven by NADPH oxidase-dependent and -independent pathways. We therefore undertook an analysis of whether NADPH oxidase was required for NETosis in Aspergillus fumigatus pneumonia. Oropharyngeal instillation of live Aspergillus hyphae induced neutrophilic pneumonitis in both wildtype and NADPH oxidase-deficient (p47(phox-/-)) mice which had resolved in wild-type mice by day 5 but progressed in p47(phox-/-) mice. NETs, identified by immunostaining, were observed in lungs of wild-type mice but were absent in p47(phox-/-) mice. Using bona fide NETs and nuclear chromatin decondensation as an early NETosis marker, we found that NETosis required a functional NADPH oxidase in vivo and ex vivo. In addition, NADPH oxidase increased the proportion of apoptotic neutrophils. Together, our results show that NADPH oxidase is required for pulmonary clearance of Aspergillus hyphae and generation of NETs in vivo. We speculate that dual modulation of NETosis and apoptosis by NADPH oxidase enhances antifungal host defense and promotes resolution of inflammation upon infection clearance.

  • 268.
    Römling, U.
    et al.
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, S-17177 Stockholm, Sweden.
    Kjelleberg, S.
    Singapore Ctr Environm Life Sci Engn, Singapore, Singapore.
    Normark, S.
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, S-17177 Stockholm, Sweden.
    Nyman, L.
    Pfizer AB, Stockholm, Sweden.
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Åkerlund, B.
    Karolinska Univ Hosp, Dept Med Huddinge, Infect Dis Unit, Stockholm, Sweden.
    Microbial biofilm formation: a need to act2014In: Journal of Internal Medicine, ISSN 0954-6820, E-ISSN 1365-2796, Vol. 276, no 2, p. 98-110Article in journal (Refereed)
  • 269.
    Sabharwal, Dharmesh
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Johansson, Jörgen
    Wai, Sun Nyunt
    A new sRNA, VrrB, acts as a regulator for vafA, a gene involved in amino acid starvation survival of Vibrio choleraeManuscript (preprint) (Other academic)
  • 270.
    Sabharwal, Dharmesh
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Song, Tianyan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Papenfort, Kai
    University of Wurzburg.
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    The VrrA sRNA controls stationary phase survival factor Vrp of Vibrio cholerae2015In: RNA Biology, ISSN 1547-6286, E-ISSN 1555-8584, Vol. 12, no 2, p. 186-196Article in journal (Refereed)
    Abstract [en]

    Small non-coding RNAs (sRNAs) are emerging regulatory elements in bacteria. The Vibrio cholerae sRNA VrrA has previously been shown to down-regulate outer membrane proteins (OmpA and OmpT) and biofilmmatrix protein (RbmC) by base-pairing with the 50 region of the corresponding mRNAs. In this study, we present an additional target of VrrA in V. cholerae, the mRNA coding for the ribosome binding protein Vrp. Vrp is homologous to ribosome-associated inhibitor A (RaiA) of Escherichia coli which facilitates stationary phase survival through ribosome hibernation. We show that VrrA downregulates Vrp protein synthesis by base-pairing to the 50 region of vrp mRNA and that the regulation requires the RNA chaperone protein, Hfq. We further demonstrate that Vrp is highly expressed during stationary phase growth and associates with the ribosome of V. cholerae. The effect of the Vrp protein in starvation survival is synergistic with that of the VC2530 protein, a homolog of the E. coli hibernation promoting factor HPF, suggesting a combined role for these proteins in ribosome hibernation in V. cholerae. Vrp and VC2530 are important for V. cholerae starvation survival under nutrient deficient conditions. While VC2530 is down-regulated in cells lacking vrrA, mutation of vrp results in VC2530 activation. This is the first report indicating a regulatory role for an sRNA, modulating stationary factors involved in bacterial ribosome hibernation.

  • 271.
    Saleeb, Michael
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mojica, Sergio
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Eriksson, Anna U.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, C. David
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gylfe, Åsa
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Elofsson, Mikael
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Natural product inspired library synthesis – Identification of 2,3-diarylbenzofuran and 2,3-dihydrobenzofuran based inhibitors of Chlamydia trachomatis2018In: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 143, p. 1077-1089Article in journal (Refereed)
    Abstract [en]

    A natural product inspired library was synthesized based on 2,3-diarylbenzofuran and 2,3-diaryl-2,3-dihydrobenzofuran scaffolds. The library of forty-eight compounds was prepared by utilizing Pd-catalyzed one-pot multicomponent reactions and ruthenium-catalyzed intramolecular carbenoid C-H insertions. The compounds were evaluated for antibacterial activity in a panel of test systems including phenotypic, biochemical and image-based screening assays. We identified several potent inhibitors that block intracellular replication of pathogenic Chlamydia trachomatis with IC50 ≤ 3 μM. These new C. trachomatis inhibitors can serve as starting points for the development of specific treatments that reduces the global burden of C. trachomatis infections.

  • 272.
    Salomonsson, Emelie
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). CBRN Defence and Security, FOI Swedish Defence Research Agency, Cementvägen 20, 901 82 Umeå, Sweden.
    Forsberg, Åke
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). CBRN Defence and Security, FOI Swedish Defence Research Agency, Cementvägen 20, 901 82 Umeå, Sweden.
    Roos, Norbert
    Holz, Claudia
    Maier, Berenike
    Koomey, Michael
    Winther-Larsen, Hanne C
    Functional analyses of pilin-like proteins from Francisella tularensis: complementation of type IV pilus phenotypes in Neisseria gonorrhoeae2009In: Microbiology, ISSN 1350-0872, E-ISSN 1465-2080, Vol. 155, p. 2546-2559Article in journal (Refereed)
    Abstract [en]

    Accumulating evidence from a number of studies strongly suggests that proteins orthologous to those involved in type IV pili (Tfp) assembly and function are required for Francisella pathogenicity. However, the molecular mechanisms by which the components exert their influence on virulence remain poorly understood. Owing to the conservation and promiscuity of Tfp biogenesis machineries, expression of Tfp pilins in heterologous species has been used successfully to analyse organelle structure-function relationships. In this study we expressed a number of Francisella pilin genes in the Tfp-expressing pathogen Neisseria gonorrhoeae lacking its endogenous pilin subunit. Two gene products, the orthologous PiIA proteins from Francisella tularensis subspecies tularensis and novicida, were capable of restoring the expression of Tfp-like appendages that were shown to be dependent upon the neisserial Tfp biogenesis machinery for surface localization. Expression of Francisella PiIA pilins also partially restored competence for natural transformation in N. gonorrhoeae. This phenotype was not complemented by expression of the PuIG and XcpT proteins, which are equivalent components of the related type II protein secretion system. Taken together, these findings provide compelling, although indirect, evidence of the potential for Francisella PiIA proteins to express functional Tfp.

  • 273.
    Salomonsson, Emelie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Forslund, Anna-Lena
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Kuoppa, Kerstin
    CBRN Defence and Security, FOI Swedish Defence Research Agency, Sweden..
    Michell, Stephen
    School of Biosciences, University of Exeter, Devon, UK.
    Titball, Richard
    School of Biosciences, University of Exeter, Devon, UK.
    Oyston, Petra
    Defence Science and Technology Laboratory, Porton Down, UK..
    Noppa, Laila
    CBRN Defence and Security, FOI Swedish Defence Research Agency, Sweden..
    Forsberg, Åke
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Role of type IV pilin encoding genes in virulence of Francisella tularensis subspecies holarcticaManuscript (preprint) (Other academic)
    Abstract [en]

    The number of virulence factors identified in Francisella tularensis, the causative agent of tularemia, is so far relatively few. The F. tularensis genome contains some genes with homology to known virulence factors. One of these is the type IV pili system, which is known to have a key role in virulence of other bacterial species. When we compared different F. tularensis subspecies we could identify distinct differences in Type IV pilin genes between the highly virulent type A strains and the less pathogenic type B strains. In this work we addressed the role in virulence of the different pilin genes in a virulent type B strain. Of all the pilin genes only PilA and the pseudopilins FTT1621-1622 were proven to have a role in virulence. In addition we also verified that the gene encoding the PilT ATPase is non-functional due to a non-sense mutation and we also confirmed that the truncated pilT has no role in mouse virulence. Furthermore we also provide evidence that the F. tularensis pilins are posttranslationally modified presumably by glycosylation by a PilO dependent mechanism.

  • 274.
    Salomonsson, Emelie
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Kuoppa, Kerstin
    Totalförsvarets forskningsinstitut FOI.
    Forslund, Anna-Lena
    Zingmark, Carl
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Golovliov, Igor
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Noppa, Laila
    Totalförsvarets forskningsinstitut FOI.
    Forsberg, Åke
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Reintroduction of two deleted virulence loci restores full virulence to the live vaccine strain of Francisella tularensis2009In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 77, no 8, p. 3424-3431Article in journal (Refereed)
    Abstract [en]

    A disadvantage of several old vaccines is that the genetic events resulting in the attenuation are often largely unknown and reversion to virulence cannot be excluded. In the 1950s, a live vaccine strain, LVS, was developed from a type B strain of Francisella tularensis, the causative agent of tularemia. LVS, which is highly attenuated for humans but still virulent for mice by some infection routes, has been extensively studied and found to protect staff from laboratory-acquired tularemia. The efforts to improve biopreparedness have identified a demand for a vaccine against tularemia. Recently the rapid progress in genomics of different Francisella strains has led to identification of several regions of differences (RDs). Two genes carried within RDs, pilA, encoding a putative type IV pilin, and FTT0918, encoding an outer membrane protein, have been linked to virulence. Interestingly, LVS has lost these two genes via direct repeat-mediated deletions. Here we show that reintroduction of the two deleted regions restores virulence of LVS in a mouse infection model to a level indistinguishable from that of virulent type B strains. The identification of the two attenuating deletion events could facilitate the licensing of LVS for use in humans.

  • 275. Santos, Denys E. S.
    et al.
    Pol-Fachin, Laercio
    Lins, Roberto D.
    Soares, Thereza A.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Univ Fed Pernambuco, Dept Fundamental Chem, BR-50740560 Recife, PE, Brazil.
    Polymyxin Binding to the Bacterial Outer Membrane Reveals Cation Displacement and Increasing Membrane Curvature in Susceptible but Not in Resistant Lipopolysaccharide Chemotypes2017In: Journal of Chemical Information and Modeling, ISSN 1549-9596, E-ISSN 1549-960X, Vol. 57, no 9, p. 2181-2193Article in journal (Refereed)
    Abstract [en]

    Lipid-A is the causative agent of Gram-negative sepsis and is responsible for an increasingly high mortality rate among hospitalized patients. Compounds that bind Lipid-A can limit this inflammatory process. The cationic antimicrobial peptide polymyxin B (Pmx-B) is one of the simplest molecules capable of selectively binding to Lipid-A and may serve as a model for further development of Lipid-A binding agents. Gram-negative bacteria resistance to Pmx-B relies on the upregulation of a number of regulatory systems, which promote chemical modifications of the lipopolysaccharide (LPS) structure and leads to major changes in the physical chemical properties of the outer membrane. A detailed understanding of how the chemical structure of the LPS modulates macroscopic properties of the outer membrane is paramount for the design and optimization of novel drugs targeting clinically relevant strains. We have performed a systematic investigation of Pmx-B binding to outer membrane models composed of distinct LPS chemotypes experimentally shown to be either resistant or susceptible to the peptide. Molecular dynamics simulations were carried out for Pmx-B bound to the penta- and hexa-acylated forms of Lipid-A (more susceptible) and Lipid-A modified with 4-amino-4-deoxy-L-arabinose (resistant) as well as the penta-acylated form of LPS Re (less susceptible). The present simulations show that upon binding to the bacterial outer membrane surface, Pmx-B promotes cation displacement and structural changes in membrane curvature and integrity as a function of the LPS chemotype susceptibility or resistance to the antimicrobial peptide.

  • 276. Schwenteit, J. M.
    et al.
    Weber, Barbara
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Milton, Debra L.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Southern Research Institute, Birmingham, AL, USA.
    Bornscheuer, U. T.
    Gudmundsdottir, B. K.
    Construction of Aeromonas salmonicida subsp. achromogenes AsaP1-toxoid strains and study of their ability to induce immunity in Arctic char, Salvelinus alpinus L.2015In: Journal of Fish Diseases, ISSN 0140-7775, E-ISSN 1365-2761, Vol. 38, no 10, p. 891-900Article in journal (Refereed)
    Abstract [en]

    The metalloendopeptidase AsaP1 is one of the major extracellular virulence factors of A. salmonicida subsp. achromogenes, expressed as a 37-kDa pre-pro-peptide and processed to a 19-kDa active peptide. The aim of this study was to construct mutant strains secreting an AsaP1-toxoid instead of AsaP1-wt, to study virulence of these strains and to test the potency of the AsaP1-toxoid bacterin and the recombinant AsaP1-toxoids to induce protective immunity in Arctic char. Two A. salmonicida mutants were constructed that secrete either AsaP1(E294A) or AsaP1(Y309F). The secreted AsaP1(Y309F)-toxoid had weak caseinolytic activity and was processed to the 19-kDa peptide, whereas the AsaP1(E294A)-toxoid was found as a 37-kDa pre-pro-peptide suggesting that AsaP1 is auto-catalytically processed. The LD50 of the AsaP1(Y309F)-toxoid mutant in Arctic char was significantly higher than that of the corresponding wt strain, and LD50 of the AsaP1(E294A)-toxoid mutant was comparable with that of an AsaP1-deficient strain. Bacterin based on AsaP1(Y309F)-toxoid mutant provided significant protection, comparable with that induced by a commercial polyvalent furunculosis vaccine. Detoxification of AsaP1 is very hard, expensive and time consuming. Therefore, an AsaP1-toxoid-secreting mutant is more suitable than the respective wt strain for production of fish bacterins aimed to protect against atypical furunculosis.

  • 277.
    Seele, J.
    et al.
    University of Veterinary Medicine Hannover, Inst Microbiol, Hannover, Germany.
    Singpiel, A.
    University of Veterinary Medicine Hannover, Inst Microbiol, Hannover, Germany.
    Spoerry, Christian
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    von Pawel-Rammingen, Ulrich
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Valentin-Weigand, P.
    University of Veterinary Medicine Hannover, Inst Microbiol, Hannover, Germany.
    Baums, C. G.
    University of Veterinary Medicine Hannover, Inst Microbiol, Hannover, Germany.
    Identification of a novel host-specific IgM protease in Streptococcus suis2013In: International Journal of Medical Microbiology, ISSN 1438-4221, E-ISSN 1618-0607, Vol. 303, no Suppl. 1, MPP35, p. 58-58Article in journal (Other academic)
    Abstract [en]

    Streptococcus (S.) suis is an important invasive, extracellular pathogen in pigs, which causes meningitis, arthritis, serositis and other diseases. Furthermore, it is also an emerging zoonotic agent. This study was initiated by the finding that IgM degradation products are released after opsonization of S. suis with porcine serum. The objective of this work was to identify and characterize the factor responsible for IgM cleavage. The results showed that a protein of S. suis with high homology to the well characterized IgG endopeptidase of S. pyogenes IdeS (or Mac1) [1, 2], designated IdeSsuis, degrades immunoglobulins (Ig) of the isotype M, but not IgG, IgA or other proteins present in porcine cerebrospinal fluid, joint fluid or serum. Western Blot analysis revealed that IdeSsuis is host-specific as it exclusively cleaves porcine IgM but not IgM from six other species. Flow cytometry and immunofluorescence microscopy demonstrated that this protein modulates binding of IgM to the bacterial surface. Furthermore the isogenic ideSsuis deletion mutant is significantly attenuated in survival in porcine blood [3]. IdeSsuis is the first prokaryotic IgM-specific protease described indicating a novel host-pathogen interaction at an early stage of the host immune response. Furthermore cleavage of porcine IgM by IdeSsuis is the first identified phenotype reflecting functional adaptation of S. suis to pigs as the main host.

  • 278. Seele, Jana
    et al.
    Hillermann, Lena-Maria
    Beineke, Andreas
    Seitz, Maren
    von Pawel-Rammingen, Ulrich
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Valentin-Weigand, Peter
    Baums, Christoph G.
    The immunoglobulin M-degrading enzyme of Streptococcus suis, Ide(Ssuis), is a highly protective antigen against serotype 22015In: Vaccine, ISSN 0264-410X, E-ISSN 1873-2518, Vol. 33, no 19, p. 2207-2212Article in journal (Refereed)
    Abstract [en]

    Streptococcus suis (S. suis) is a major porcine pathogen causing meningitis, arthritis and several other pathologies. Recently, we identified a highly specific immunoglobulin M degrading enzyme of S. suis, designated IdeSsuis, which is expressed by various serotypes. The objective of this work was to access the immunogenicity and protective efficacy of a recombinant vaccine including IdeSsuis. Vaccination with rIdeSsuis elicited antibodies efficiently neutralizing the IgM protease activity. Importantly, 18 piglets vaccinated with rIdeSsuis alone or in combination with bacterin priming were completely protected against mortality and severe morbidity after S. suis serotype 2 challenge. In contrast, 12 of the 17 piglets either treated with the placebo or primed with the bacterin only, succumbed to S. suis disease. Immunity against Idessuis was associated with increased killing of S. suis wt in porcine blood ex vivo leading to a tenfold difference in the bacterial survival factor in blood of placebo-treated and rIdeSsuis-vaccinated piglets. In conclusion, the results of this study indicate that rIdeSsuis is a highly protective antigen in pigs.

  • 279. Seele, Jana
    et al.
    Singpiel, Alena
    Spoerry, Christian
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    von Pawel-Rammingen, Ulrich
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Valentin-Weigand, Peter
    Baums, Christoph G.
    Identification of a Novel Host-Specific IgM Protease in Streptococcus suis2013In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 195, no 5, p. 930-940Article in journal (Refereed)
    Abstract [en]

    Streptococcus suis serotype 2 is a highly invasive, extracellular pathogen in pigs with the capacity to cause severe infections in humans. This study was initiated by the finding that IgM degradation products are released after opsonization of S. suis. The objective of this work was to identify the bacterial factor responsible for IgM degradation. The results of this study showed that a member of the IdeS family, designated Ide(Ssuis) (Immunoglobulin M-degrading enzyme of S. suis), is responsible and sufficient for IgM cleavage. Recombinant Ide(Ssuis) was found to degrade only IgM but neither IgG nor IgA. Interestingly, Western blot analysis revealed that Ide(Ssuis) is host specific, as it exclusively cleaves porcine IgM but not IgM from six other species, including a closely related member of the Suidae family. As demonstrated by flow cytometry and immunofluorescence microscopy, Ide(Ssuis) modulates binding of IgM to the bacterial surface. Ide(Ssuis) is the first prokaryotic IgM-specific protease described, indicating that this enzyme is involved in a so-far-unknown mechanism of host-pathogen interaction at an early stage of the host immune response. Furthermore, cleavage of porcine IgM by Ide(Ssuis) is the first identified phenotype reflecting functional adaptation of S. suis to pigs as the main host.

  • 280.
    Sellstedt, Magnus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nyberg, Anders
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rosenbaum, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Engström, Patrik
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Wickström, Malin
    Department of Medicinal Sciences, Division of Clinical Pharmacology, Uppsala University Hospital, 75185 Uppsala, Sweden.
    Gullbo, Joachim
    Department of Medicinal Sciences, Division of Clinical Pharmacology, Uppsala University Hospital, 75185 Uppsala, Sweden.
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Johansson, Lennart B-Å
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis and characterization of a multi ring-fused 2-pyridone-based fluorescent scaffold2010In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 32, p. 6171-6178Article in journal (Refereed)
    Abstract [en]

    A series of compounds based on a novel fluorescent scaffold have been synthesized. Most of the compounds displayed high quantum yields of fluorescence and unusually long fluorescence lifetimes. HeLa cells were treated with one of the compounds and its use as a fluorescent dye was demonstrated with fluorescence confocal microscopy.

  • 281.
    Sellstedt, Magnus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Prasad, G Krishna
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Krishnan, K Syam
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Directed diversity-oriented synthesis. Ring-fused 5- to 10-membered rings from a common peptidomimetic 2-pyridone precursor.2012In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 53, no 45, p. 6022-6024Article in journal (Refereed)
    Abstract [en]

    A variety of ring-fused 2-pyridone-based central fragments were prepared using a strategy inspired by diversity-oriented synthesis. The produced compounds are diverse, yet focused, analogs of biologically active peptidomimetic 2-pyridones.

  • 282.
    Seper, Andrea
    et al.
    Institute of Molecular Biosciences, University of Graz, Graz, Austria.
    Hosseinzadeh, Ava
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Gorkiewicz, Gregor
    University of Graz, Graz, Austria.
    Lichtenegger, Sabine
    University of Graz, Graz, Austria.
    Roier, Sandro
    University of Graz, Graz, Austria.
    Leitner, Deborah R
    University of Graz, Graz, Austria.
    Röhm, Marc
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Grutsch, Andreas
    Institute of Molecular Biosciences, University of Graz, Graz, Austria.
    Reidl, Joachim
    University of Graz, Graz, Austria.
    Urban, Constantin F
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Schild, Stefan
    Institute of Molecular Biosciences, University of Graz, Graz, Austria.
    Vibrio cholerae evades neutrophil extracellular traps by the activity of two extracellular nucleases2013In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 9, no 9, article id e1003614Article in journal (Refereed)
    Abstract [en]

    The Gram negative bacterium Vibrio cholerae is the causative agent of the secretory diarrheal disease cholera, which has traditionally been classified as a noninflammatory disease. However, several recent reports suggest that a V. cholerae infection induces an inflammatory response in the gastrointestinal tract indicated by recruitment of innate immune cells and increase of inflammatory cytokines. In this study, we describe a colonization defect of a double extracellular nuclease V. cholerae mutant in immunocompetent mice, which is not evident in neutropenic mice. Intrigued by this observation, we investigated the impact of neutrophils, as a central part of the innate immune system, on the pathogen V. cholerae in more detail. Our results demonstrate that V. cholerae induces formation of neutrophil extracellular traps (NETs) upon contact with neutrophils, while V. cholerae in return induces the two extracellular nucleases upon presence of NETs. We show that the V. cholerae wild type rapidly degrades the DNA component of the NETs by the combined activity of the two extracellular nucleases Dns and Xds. In contrast, NETs exhibit prolonged stability in presence of the double nuclease mutant. Finally, we demonstrate that Dns and Xds mediate evasion of V. cholerae from NETs and lower the susceptibility for extracellular killing in the presence of NETs. This report provides a first comprehensive characterization of the interplay between neutrophils and V. cholerae along with new evidence that the innate immune response impacts the colonization of V. cholerae in vivo. A limitation of this study is an inability for technical and physiological reasons to visualize intact NETs in the intestinal lumen of infected mice, but we can hypothesize that extracellular nuclease production by V. cholerae may enhance survival fitness of the pathogen through NET degradation.

  • 283. Shaffer, Carrie L.
    et al.
    Good, James A. D.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Kumar, Santosh
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Krishnan, K. Syam
    Gaddy, Jennifer A.
    Loh, John T.
    Chappell, Joseph
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Cover, Timothy L.
    Hadjifrangiskou, Maria
    Peptidomimetic Small Molecules Disrupt Type IV Secretion System Activity in Diverse Bacterial Pathogens2016In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 7, no 2, article id e00221-16Article in journal (Refereed)
    Abstract [en]

    Bacteria utilize complex type IV secretion systems (T4SSs) to translocate diverse effector proteins or DNA into target cells. Despite the importance of T4SSs in bacterial pathogenesis, the mechanism by which these translocation machineries deliver cargo across the bacterial envelope remains poorly understood, and very few studies have investigated the use of synthetic molecules to disrupt T4SS-mediated transport. Here, we describe two synthetic small molecules (C10 and KSK85) that disrupt T4SS-dependent processes in multiple bacterial pathogens. Helicobacter pylori exploits a pilus appendage associated with the cag T4SS to inject an oncogenic effector protein (CagA) and peptidoglycan into gastric epithelial cells. In H. pylori, KSK85 impedes biogenesis of the pilus appendage associated with the cag T4SS, while C10 disrupts cag T4SS activity without perturbing pilus assembly. In addition to the effects in H. pylori, we demonstrate that these compounds disrupt interbacterial DNA transfer by conjugative T4SSs in Escherichia coli and impede vir T4SS-mediated DNA delivery by Agrobacterium tumefaciens in a plant model of infection. Of note, C10 effectively disarmed dissemination of a derepressed IncF plasmid into a recipient bacterial population, thus demonstrating the potential of these compounds in mitigating the spread of antibiotic resistance determinants driven by conjugation. To our knowledge, this study is the first report of synthetic small molecules that impair delivery of both effector protein and DNA cargos by diverse T4SSs. IMPORTANCE Many human and plant pathogens utilize complex nanomachines called type IV secretion systems (T4SSs) to transport proteins and DNA to target cells. In addition to delivery of harmful effector proteins into target cells, T4SSs can disseminate genetic determinants that confer antibiotic resistance among bacterial populations. In this study, we sought to identify compounds that disrupt T4SS-mediated processes. Using the human gastric pathogen H. pylori as a model system, we identified and characterized two small molecules that prevent transfer of an oncogenic effector protein to host cells. We discovered that these small molecules also prevented the spread of antibiotic resistance plasmids in E. coli populations and diminished the transfer of tumor-inducing DNA from the plant pathogen A. tumefaciens to target cells. Thus, these compounds are versatile molecular tools that can be used to study and disarm these important bacterial machines.

  • 284.
    Sharma, Atin
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Puhar, Andrea
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Gentamicin Protection Assay to Determine the Number of Intracellular Bacteria during Infection of Human TC7 Intestinal Epithelial Cells by Shigella flexneri2019In: BIO-PROTOCOL, ISSN 2331-8325, Vol. 9, no 13, article id UNSP e3292Article in journal (Refereed)
    Abstract [en]

    Shigella flexneri is an intracellular bacterial pathogen that gains access to the gut epithelium using a specialized Type III Secretion System (T3SS). Various determinants mediating this invasive infection have been experimentally verified using the classical gentamicin protection assay presented here. In this assay epithelial cell lines are infected by bacteria in vitro and the extracellular bacteria are killed by gentamicin. The internalized bacteria, which are protected from the bactericidal action of gentamicin, are recovered by lysing the epithelial cells and enumerated by determining the colonies formed on solid medium. Various techniques based on light microscopy, such as immunofluorescence and bacteria expressing fluorescent proteins, are also used for studying intracellular bacteria. However, these techniques are not only labor intensive and require sophisticated equipment, but mostly are also not quantitative. Despite being an easy quantitative method to study invasiveness of bacteria, the gentamicin protection assay cannot distinguish between the survival and multiplication of the internalized bacteria over longer incubation periods. To alleviate the complications created by multiplication and dissemination of internalized bacteria, complementary assays like plaque formation assays are required. This protocol presents an easy and cost-effective method to determine the invasiveness and the capacity to establish an infection of Shigella under different conditions.

  • 285.
    Sharma, Atin
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Puhar, Andrea
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Plaque Assay to Determine Invasion and Intercellular Dissemination of Shigella flexneri in TC7 Human Intestinal Epithelial Cells2019In: BIO-PROTOCOL, ISSN 2331-8325, Vol. 9, no 13, article id UNSP e3293Article in journal (Refereed)
    Abstract [en]

    Shigella flexneri invades the epithelial cells lining the gut lumen and replicates intracellularly. The specialized Type III Secretion System (T3SS) and its effector proteins, encoded on a large virulence plasmid, assist the bacterium to gain access to the cytosol. Thereafter Shigella disseminates to neighboring cells in an epithelial layer without further extracellular steps. Host cell lysis occurs when these bacteria have extensively replicated in the target cell cytosol. Here we describe a simple method to qualitatively as well as quantitatively study the capacity of Shigella to invade and disseminate within an epithelium by assessing the number and size of plaques representing the dead cells in a monolayer of TC7 cells. This classical protocol follows a simple approach of infecting the monolayers of epithelial cell lines with Shigella and visualizing the dead cells as plaques formed against a stained background.

  • 286. Siller, Maria
    et al.
    Janapatla, Rajendra P
    Pirzada, Zaid A
    Hassler, Christine
    Zinkl, Daniela
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Functional analysis of the group A streptococcal luxS/AI-2 system in metabolism, adaptation to stress and interaction with host cells2008In: BMC Microbiology, ISSN 1471-2180, E-ISSN 1471-2180, Vol. 8, p. 188-Article in journal (Refereed)
    Abstract [en]

    Background

    The luxS/AI-2 signaling pathway has been reported to interfere with important physiological and pathogenic functions in a variety of bacteria. In the present study, we investigated the functional role of the streptococcal luxS/AI-2 system in metabolism and diverse aspects of pathogenicity including the adaptation of the organism to stress conditions using two serotypes of Streptococcus pyogenes, M1 and M19.

    Results

    Exposing wild-type and isogenic luxS-deficient strains to sulfur-limited media suggested a limited role for luxS in streptococcal activated methyl cycle metabolism. Interestingly, loss of luxS led to an increased acid tolerance in both serotypes. Accordingly, luxS expression and AI-2 production were reduced at lower pH, thus linking the luxS/AI-2 system to stress adaptation in S. pyogenes. luxS expression and AI-2 production also decreased when cells were grown in RPMI medium supplemented with 10% serum, considered to be a host environment-mimicking medium. Furthermore, interaction analysis with epithelial cells and macrophages showed a clear advantage of the luxS-deficient mutants to be internalized and survive intracellularly in the host cells compared to the wild-type parents. In addition, our data revealed that luxS influences the expression of two virulence-associated factors, the fasX regulatory RNA and the virulence gene sibA (psp).

    Conclusion

    Here, we suggest that the group A streptococcal luxS/AI-2 system is not only involved in the regulation of virulence factor expression but in addition low level of luxS expression seems to provide an advantage for bacterial survival in conditions that can be encountered during infections.

  • 287. Simon, Sylvia
    et al.
    Schell, Ursula
    Heuer, Natalie
    Hager, Dominik
    Albers, Michael F
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Matthias, Jan
    Fahrnbauer, Felix
    Trauner, Dirk
    Eichinger, Ludwig
    Hedberg, Christian
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Department of Chemical Biology, Max-Planck-Institute of Molecular Physiology, Dortmund, Germany.
    Hilbi, Hubert
    Inter-kingdom Signaling by the Legionella Quorum Sensing Molecule LAI-1 Modulates Cell Migration through an IQGAP1-Cdc42-ARHGEF9-Dependent Pathway2015In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 11, no 12, article id e1005307Article in journal (Refereed)
    Abstract [en]

    Small molecule signaling promotes the communication between bacteria as well as between bacteria and eukaryotes. The opportunistic pathogenic bacterium Legionella pneumophila employs LAI-1 (3-hydroxypentadecane-4-one) for bacterial cell-cell communication. LAI-1 is produced and detected by the Lqs (Legionella quorum sensing) system, which regulates a variety of processes including natural competence for DNA uptake and pathogen-host cell interactions. In this study, we analyze the role of LAI-1 in inter-kingdom signaling. L. pneumophila lacking the autoinducer synthase LqsA no longer impeded the migration of infected cells, and the defect was complemented by plasmid-borne lqsA. Synthetic LAI-1 dose-dependently inhibited cell migration, without affecting bacterial uptake or cytotoxicity. The forward migration index but not the velocity of LAI-1-treated cells was reduced, and the cell cytoskeleton appeared destabilized. LAI-1-dependent inhibition of cell migration involved the scaffold protein IQGAP1, the small GTPase Cdc42 as well as the Cdc42-specific guanine nucleotide exchange factor ARHGEF9, but not other modulators of Cdc42, or RhoA, Rac1 or Ran GTPase. Upon treatment with LAI-1, Cdc42 was inactivated and IQGAP1 redistributed to the cell cortex regardless of whether Cdc42 was present or not. Furthermore, LAI-1 reversed the inhibition of cell migration by L. pneumophila, suggesting that the compound and the bacteria antagonistically target host signaling pathway(s). Collectively, the results indicate that the L. pneumophila quorum sensing compound LAI-1 modulates migration of eukaryotic cells through a signaling pathway involving IQGAP1, Cdc42 and ARHGEF9.

  • 288.
    Sixt, Barbara Susanne
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). INSERM U1138, Centre de Recherche des Cordeliers, Paris, France; Equipe 11 labellisée Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Université Paris Descartes, Paris, France; Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France.
    Núñez-Otero, Carlos
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Kepp, Oliver
    INSERM U1138, Centre de Recherche des Cordeliers; Equipe 11 labellisée Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers; Université Paris Descartes; Metabolomics and Cell Biology Platforms, Institut Gustave Roussy.
    Valdivia, Raphael H
    Duke University School of Medicine, Department of Molecular Genetics and Microbiology.
    Kroemer, Guido
    INSERM U1138, Centre de Recherche des Cordeliers; Equipe 11 labellisée Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers; Université Paris Descartes; Metabolomics and Cell Biology Platforms, Institut Gustave Roussy.
    Chlamydia trachomatis fails to protect its growth niche against pro-apoptotic insults2019In: Cell Death and Differentiation, ISSN 1350-9047, E-ISSN 1476-5403, Vol. 26, no 8, p. 1485-1500Article in journal (Refereed)
    Abstract [en]

    Chlamydia trachomatis is an obligate intracellular bacterial agent responsible for ocular infections and sexually transmitted diseases. It has been postulated that Chlamydia inhibits apoptosis in host cells to maintain an intact replicative niche until sufficient infectious progeny can be generated. Here we report that, while cells infected with C. trachomatis are protected from apoptosis at early and mid-stages of infection, they remain susceptible to the induction of other cell death modalities. By monitoring the fate of infected cells by time-lapse video microscopy and by analyzing host plasma membrane integrity and the activity of caspases, we determined that C. trachomatis-infected cells exposed to pro-apoptotic stimuli predominately died by a mechanism resembling necrosis. This necrotic death of infected cells occurred with kinetics similar to the induction of apoptosis in uninfected cells, indicating that C. trachomatis fails to considerably prolong the lifespan of its host cell when exposed to pro-apoptotic insults. Inhibitors of bacterial protein synthesis partially blocked necrotic death of infected cells, suggesting that the switch from apoptosis to necrosis relies on an active contribution of the bacteria. Tumor necrosis factor alpha (TNF-α)-mediated induction of necrosis in cells infected with C. trachomatis was not dependent on canonical regulators of necroptosis, such as RIPK1, RIPK3, or MLKL, yet was blocked by inhibition or depletion of CASP8. These results suggest that alternative signaling pathways regulate necrotic death in the context of C. trachomatis infections. Finally, consistent with the inability of C. trachomatis to preserve host cell viability, necrosis resulting from pro-apoptotic conditions significantly impaired production of infectious progeny. Taken together, our findings suggest that Chlamydia's anti-apoptotic activities are not sufficient to protect the pathogen's replicative niche.

  • 289.
    Sondén, Berit
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Kocíncová, Dana
    Deshayes, Caroline
    Euphrasie, Daniel
    Rhayat, Lamya
    Laval, Françoise
    Frehel, Claude
    Daffé, Mamadou
    Etienne, Gilles
    Reyrat, Jean-Marc
    Gap, a mycobacterial specific integral membrane protein, is required for glycolipid transport to the cell surface.2005In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 58, no 2, p. 426-440Article in journal (Refereed)
    Abstract [en]

    The cell envelope of mycobacteria is a complex multilaminar structure that protects the cell from stresses encountered in the environment, and plays an important role against the bactericidal activity of immune system cells. The outermost layer of the mycobacterial envelope typically contains species-specific glycolipids. Depending on the mycobacterial species, the major glycolipid localized at the surface can be either a phenolglycolipid or a peptidoglycolipid (GPL). Currently, the mechanism of how these glycolipids are addressed to the cell surface is not understood. In this study, by using a transposon library of Mycobacterium smegmatis and a simple dye assay, six genes involved in GPLs synthesis have been characterized. All of these genes are clustered in a single genomic region of approximately 60 kb. We show by biochemical analyses that two non-ribosomal peptide synthetases, a polyketide synthase, a methyltransferase and a member of the MmpL family are required for the biosynthesis of the GPLs backbone. Furthermore, we demonstrate that a small integral membrane protein of 272 amino acids named Gap (gap: GPL addressing protein) is specifically required for the transport of the GPLs to the cell surface. This protein is predicted to contain six transmembrane segments and possesses homologues across the mycobacterial genus, thus delineating a new protein family. This Gap family represents a new paradigm for the transport of small molecules across the mycobacterial envelope, a critical determinant of mycobacterial virulence.

  • 290.
    Song, Tianyan
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Mika, Franziska
    Lindmark, Barbro
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Liu, Zhi
    Schild, Stefan
    Bishop, Anne
    Zhu, Jun
    Camilli, Andrew
    Johansson, Jörgen
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Vogel, Jörg
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    A new Vibrio cholerae sRNA modulates colonization and affects release of outer membrane vesicles.2008In: Molecular microbiology, ISSN 1365-2958, Vol. 70, no 1, p. 100-11Article in journal (Refereed)
    Abstract [en]

    We discovered a new small non-coding RNA (sRNA) gene, vrrA of Vibrio cholerae O1 strain A1552. A vrrA mutant overproduces OmpA porin, and we demonstrate that the 140 nt VrrA RNA represses ompA translation by base-pairing with the 5' region of the mRNA. The RNA chaperone Hfq is not stringently required for VrrA action, but expression of the vrrA gene requires the membrane stress sigma factor, sigma(E), suggesting that VrrA acts on ompA in response to periplasmic protein folding stress. We also observed that OmpA levels inversely correlated with the number of outer membrane vesicles (OMVs), and that VrrA increased OMV production comparable to loss of OmpA. VrrA is the first sRNA known to control OMV formation. Moreover, a vrrA mutant showed a fivefold increased ability to colonize the intestines of infant mice as compared with the wild type. There was increased expression of the main colonization factor of V. cholerae, the toxin co-regulated pili, in the vrrA mutant as monitored by immunoblot detection of the TcpA protein. VrrA overproduction caused a distinct reduction in the TcpA protein level. Our findings suggest that VrrA contributes to bacterial fitness in certain stressful environments, and modulates infection of the host intestinal tract.

  • 291.
    Song, Tianyan
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Sabharwal, Dharmesh
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Gurung, Jyoti Mohan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Cheng, Andrew T.
    Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America.
    Sjöström, Annika E.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Yildiz, Fitnat H.
    Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America.
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Vibrio cholerae Utilizes Direct sRNA Regulation in Expression of a Biofilm Matrix Protein2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 7, article id e101280Article in journal (Refereed)
    Abstract [en]

    Vibrio cholerae biofilms contain exopolysaccharide and three matrix proteins RbmA, RbmC and Bap1. While much is known about exopolysaccharide regulation, little is known about the mechanisms by which the matrix protein components of biofilms are regulated. VrrA is a conserved, 140-nt sRNA of V. cholerae, whose expression is controlled by sigma factor sigma(E). In this study, we demonstrate that VrrA negatively regulates rbmC translation by pairing to the 5' untranslated region of the rbmC transcript and that this regulation is not stringently dependent on the RNA chaperone protein Hfq. These results point to VrrA as a molecular link between the sigma(E)-regulon and biofilm formation in V. cholerae. In addition, VrrA represents the first example of direct regulation of sRNA on biofilm matrix component, by-passing global master regulators.

  • 292.
    Song, Tianyan
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Sabharwal, Dharmesh
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    VrrA mediates Hfq-dependent regulation of OmpT synthesis in Vibrio cholerae2010In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 400, no 4, p. 682-688Article in journal (Refereed)
    Abstract [en]

    OmpT, an outer membrane porin of Vibrio cholerae, is tightly regulated by the organism in response to different environments. Two transcriptional regulators, cAMP receptor protein (CRP) and ToxR, compete at the ompT promoter region. CRP activates ompT transcription by a loop-forming mechanism, while ToxR functions as an antiactivator and repressor, depending on its interplay with CRP. VrrA, a 140-nt small noncoding RNA in V. cholerae, is controlled by the alternative sigma factor sigma(E). We have demonstrated previously that VrrA represses ompA translation by base-pairing with the 5’ region of the mRNA, thereby affecting the release of outer membrane vesicles and modulating the colonization ability of V. cholerae. In this study, we demonstrate that VrrA RNA represses ompT translation by base-pairing with the 5’ region of the mRNA and that regulation requires the RNA chaperone protein Hfq. These results add new insight into the regulation of OmpT. In addition to pH/temperature signals via the ToxR regulon and carbon source signals via the cAMP-CRP complex, OmpT is further regulated by signals received via the sigma(E) regulon through VrrA.

  • 293.
    Spjut, Sara
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Qian, Weixing
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Bauer, Johannes
    Storm, Rickard
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Frängsmyr, Lars
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Stehle, Thilo
    Arnberg, Niklas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Elofsson, Mikael
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    A Potent Trivalent Sialic Acid Inhibitor of Adenovirus Type 37 Infection of Human Corneal Cells2011In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, no 29, p. 6519-6521Article in journal (Refereed)
  • 294.
    Spoerry, Christian
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Streptococcal immunoglobulin degrading enzymes of the IdeS and IgdE family2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bacteria of the genus Streptococcus are common asymptomatic colonisers of humans and animals. As opportunistic pathogens they can however, depending on their host’s immune status and other circumstances, cause mild to very severe infections. Streptococci are highly intertwined with specific host species, but can also cause zoonosis or anthroponosis in more uncommon hosts. Prolonged and reoccurring infections require immune evasion strategies to circumvent detection and eradication by the host’s immune defence. A substantial part of the immune defence against bacterial pathogens is mediated by immunoglobulins. This thesis is based on work to identify and characterise immunoglobulin degrading enzymes secreted by different Streptococcus species as a means to sabotage and evade antibody-mediated immune responses.

    Stoichiometric and kinetic analysis of the IgG degrading enzyme IdeS from the important human pathogen S. pyogenes revealed that IdeS cleaves IgG, opposed to previous publications, as a monomer following classical Michaelis-Menten kinetics.

    The IdeS homologue of S. suis, IdeSsuis, did however not cleave IgG, but was highly specific fo rporcine IgM. S. suis was found to possess yet another protease, IgdE, capable of cleaving porcine IgG. Both of these proteases were shown to promote increased bacterial survival in porcine blood during certain conditions.

    IgdE is the founding member of a novel cysteine protease family (C113). Novel streptococcal members of this protease family were shown to specifically degrade certain IgG subtypes of the respective Streptococcus species’ main host. The observed substrate specificity of IgdE family proteases reflects the host tropism of these Streptococcus species, thereby giving insights into host-pathogen co-evolution.

    The abundance of immunoglobulin degrading enzymes among Streptococcus species indicates the importance of evasion from the antibody mediated immune responses for streptococci. These novel identified immunoglobulin degrading enzymes of the IdeS and IgdE protease families are potential valid vaccine targets and could also be of biotechnological use.

  • 295.
    Spoerry, Christian
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Seele, Jana
    Valentin-Weigand, Peter
    Baums, Christoph G.
    von Pawel-Rammingen, Ulrich
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Identification and Characterization of IgdE, a Novel IgG-degrading Protease of Streptococcus suis with Unique Specificity for Porcine IgG.2016In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 291, no 15, p. 7915-7925Article in journal (Refereed)
    Abstract [en]

    Streptococcus suis is a major endemic pathogen of pigs causing meningitis, arthritis, and other diseases. Zoonotic S. suis infections are emerging in humans causing similar pathologies as well as severe conditions such as toxic shock-like syndrome. Recently, we discovered an IdeS family protease of S. suis that exclusively cleaves porcine IgM and represents the first virulence factor described, linking S. suis to pigs as their natural host. Here we report the identification and characterization of a novel, unrelated protease of S. suis that exclusively targets porcine IgG. This enzyme, designated IgdE for immunoglobulin G-degrading enzyme of S. suis, is a cysteine protease distinct from previous characterized streptococcal immunoglobulin degrading proteases of the IdeS family and mediates efficient cleavage of the hinge region of porcine IgG with a high degree of specificity. The findings that all S. suis strains investigated possess the IgG proteolytic activity and that piglet serum samples contain specific antibodies against IgdE strongly indicate that the protease is expressed in vivo during infection and represents a novel and putative important bacterial virulence/colonization determinant, and a thus potential therapeutic target.

  • 296.
    Strand, Mårten
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Islam, Koushikul
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Edlund, Karin
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Öberg, Christopher T
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Allard, Annika
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Bergström, Tomas
    Univ Gothenburg, Sahlgrenska Acad, Dept Virol, Gothenburg, Sweden.
    Mei, Ya-Fang
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Elofsson, Mikael
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Wadell, Göran
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    2-[4,5-Difluoro-2-(2-fluorobenzoylamino)-benzoylamino]benzoic acid, an antiviral compound with activity against acyclovir-resistant isolates of herpes simplex virus type 1 and 22012In: Antimicrobial Agents and Chemotherapy, ISSN 0066-4804, E-ISSN 1098-6596, Vol. 56, no 11, p. 5735-5743Article in journal (Refereed)
    Abstract [en]

    Herpes simplex viruses (HSV-1 and HSV-2) are responsible for life-long latent infections in humans, with periods of viral reactivation associated with recurring ulcerations in the orofacial and genital tract. In immunosuppressed patients and neonates, HSV infections are associated with severe morbidity, and in some cases even mortality. Today, acyclovir is the standard therapy for management of HSV infections. However, the need for novel antiviral agents is apparent since HSV isolates resistant to acyclovir therapy are frequently isolated in immunosuppressed patients. In this study, we assessed the anti-HSV activity of the anti-adenoviral compounds 2-[2-(2-benzoylamino)-benzoylamino]benzoic acid, (Benzavir-1) and 2-[4,5-difluoro-2-(2-fluorobenzoylamino)-benzoylamino]benzoic acid, (Benzavir-2) on HSV-1 and HSV-2. Both compounds were active against both viruses. Importantly, Benzavir-2 had similar potency to acyclovir against both HSV types and it was active against clinical acyclovir-resistant HSV isolates.

  • 297.
    Stylianou, Marios
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Clinical Microbiology, Umeå Univeristy.
    Pharmaceutical And Immunollogical Challenge Of Fungal Pathogens2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Incidences of fungal infections are on the rise in immunosuppressed people. Predominant causative agents for these mycoses are species of the genus Candida, including Candida albicans, Candida glabrata and Candida dublieniensis. Despite a wide range of emerging pathogens, C. albicans remains the leading cause. According to recent epidemiological studies, blood stream infections with C. albicans cause annually ~55% mortality in approximately 300,000 patients from intensive care units worldwide. Furthermore, the percentage of morbidity linked to oral, esophageal and vulvovaginal mycoses cause by C. albicans reach up to 90%. Reasons for these medical concerns are the lack of efficient diagnostics and antifungal therapy.

    Here, we therefore sought to find novel antifungal strategies inspired by innate immune cells, such as neutrophils. These phagocytes are able to block the fungal pathogenicity. Neutrophils are bloodstream leukocytes serving as the first line of defense against pathogenic microbes. It has been shown that neutrophils have a strong antifungal activity by impairing the conversion of the dimorphic C. albicans from yeast to hyphal form (Y-H). Consequently, we raised the question whether other immune cells, such as mast cells, with less phagocytic cabapilities may have similar activity to neutrophils.

    Mast cells are tissue-dwelling cells. Mucosal tissue is rich in mast cells and usually constitutes the entry ports for fungal pathogens into the human body. A contribution of mast cells in antifungal defense is, thus, very likely. We human explored mast cell functions upon encounter with fungal pathogens. Interestingly, human mast cells show a transient potential to impair fungal viability. To understand the mechanism behind this impairment we analyzed the human mast cell functions in more detail. We found that human mast cells challenged with C. albicans, immediately degranulate and secrete distinct cytokines and chemokines in an orchestrated manner. The chemokines secreted attract neutrophils. Mast cells moreover are able to internalize fungal cells and to ‘commit suicide’ by releasing extracellular DNA traps that ensnare the pathogen.

     

    The effectiveness of future antifungals is depended on targeting the pathogen virulence with more efficiency.

    The dimorphism of C. albicans is proven to be essential its virulence. Blockage of this switching ability could render the pathogen avirulent. Consequently, we screened for compounds that mimic the neutrophils anti-dimorphic activity by screening small chemical molecule libraries that block Y-H transition. The screening of big chemical libraries requires a reliable, reproducible and rapid high-throughput screening assay (HTS). We developed an HTS assay based on automated microscopy and image analysis, thereby allowing to distinguish between yeast and filamentous forms. In order to find the ideal Y-H blocker, we also evaluated the cell viability via the count of ATP levels when challenged with the respective small chemical molecules.

     

    Drug development is an elaborate and expensive process. We therefore applied our screening setup to identify antidimorphic/antifungal activity in compounds from two different chemical libraries including FDA-approved drugs. The study disclosed 7 off-patent antifungal drugs that have potent antimycotic activity, including 4 neoplastic agents, 2 antipsychotic drugs and 1 antianemic medication.

    In a nutshell, we aimed to mimic the anti-dimorphic/antifungal activity of neutrophils with small chemical molecules. Furthermore, we elucidated how immune cells contribute to antifungal defense to exploit these mechanisms for the development of novel antifungal therapies. Thus, this thesis provides novel tools for the discovery of more efficient compounds, identifies previously unknown antifungal aspect of off-patent FDA-approved drugs and highlights the interplay of mast cells with pathogenic fungi with the aim to define new screening strategies.

  • 298.
    Stylianou, Marios
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Uvell, Hanna
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lopes, Jose Pedro
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Enquist, Per-Anders
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Elofsson, Mikael
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Urban, Constantin F
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Novel High-Throughput Screening Method for Identification of Fungal Dimorphism Blockers2015In: Journal of Biomolecular Screening, ISSN 1087-0571, E-ISSN 1552-454X, Vol. 20, no 2, p. 285-91Article in journal (Refereed)
    Abstract [en]

    Invasive mycoses have been increasing worldwide, with Candida spp. being the most prevalent fungal pathogen causing high morbidity and mortality in immunocompromised individuals. Only few antimycotics exist, often with severe side effects. Therefore, new antifungal drugs are urgently needed. Because the identification of antifungal compounds depends on fast and reliable assays, we present a new approach based on high-throughput image analysis to define cell morphology. Candida albicans and other fungi of the Candida clade switch between different growth morphologies, from budding yeast to filamentous hyphae. Yeasts are considered proliferative, whereas hyphae are required for invasion and dissemination. Thus, morphotype switching in many Candida spp. is connected to virulence and pathogenesis. It is, consequently, reasonable to presume that morphotype blockers interfere with the virulence, thereby preventing hazardous colonization. Our method efficiently differentiates yeast from hyphal cells using a combination of automated microscopy and image analysis. We selected the parameters length/width ratio and mean object shape to quantitatively discriminate yeasts and hyphae. Notably, Z' factor calculations for these parameters confirmed the suitability of our method for high-throughput screening. As a second stage, we determined cell viability to discriminate morphotype-switching inhibitors from those that are fungicidal. Thus, our method serves as a basis for the identification of candidates for next-generation antimycotics.

  • 299. Sundin, Charlotta
    et al.
    Elofsson, Mikael
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Wolf-Watz, Hans
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Rosell, Sune
    Virulensblockerande antibiotika: Antibakteriella medel med helt ny verkningsmekanism2009In: Läkartidningen, Vol. 106, no 40, p. 2543-2545Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Antibiotics are probably the most successful drugs ever. Despite this success bacterial diseases continue to plague mankind and an ever increasing number of bacteria become resistant to antibiotics in use today. There is an obvious need to turn the tide by development of novel antibacterial drugs. Such drugs should be based on new chemical scaffolds and target bacterial functions not yet explored in the clinic. Our knowledge on how bacteria cause disease has increased dramatically during the last decade. Highly sophisticated virulence systems enable the bacteria to evade host immune responses and establish infection. Virulence systems are pathogen specific and therefore constitute attractive targets for drug development. Small molecules that target virulence in several Gram-negative bacteria have been identified. These molecules, virulence blocking antibiotics, can be used against resistant bacteria and their specificity for the pathogen will spare the endogenous micro flora and thus reduce selection for resistance.

  • 300.
    Sunduru, Naresh
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Salin, Olli
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Gylfe, Åsa
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Elofsson, Mikael
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Design, synthesis and evaluation of novel polypharmacological antichlamydial agents2015In: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 101, p. 595-603Article in journal (Refereed)
    Abstract [en]

    Discovery of new polypharmacological antibacterial agents with multiple modes of actions can be an alternative to combination therapy and also a possibility to slow development of antibiotic resistance. In support to this hypothesis, we synthesized 16 compounds by combining the pharmacophores of Chlamydia trachomatis inhibitors and inhibitors of type III secretion (T3S) in gram-negative bacteria. In this study we have developed salicylidene acylhydrazide sulfonamides (11c & 11d) as new antichlamydial agents that also inhibit T3S in Yersinia pseudotuberculosis.