umu.sePublications
Change search
Refine search result
345678 251 - 300 of 385
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.
    Nygård Skalman, Lars
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Holst, Mikkel R.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Larsson, Elin
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Lundmark, Richard
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Plasma membrane damage caused by listeriolysin O is not repaired through endocytosis of the membrane pore2018In: Biology Open, ISSN 2046-6390, Vol. 7, no 10Article in journal (Refereed)
    Abstract [en]

    Endocytic mechanisms have been suggested to be important for plasma membrane repair in response to pore-forming toxins such as listeriolysin O (LLO), which form membrane pores that disrupt cellular homeostasis. Yet, little is known about the specific role of distinct endocytic machineries in this process. Here, we have addressed the importance of key endocytic pathways and developed reporter systems for real-time imaging of the endocytic response to LLO pore formation. We found that loss of clathrin-independent endocytic pathways negatively influenced the efficiency of membrane repair. However, we did not detect any increased activity of these pathways, or co-localisation with the toxin or markers of membrane repair, suggesting that they were not directly involved in removal of LLO pores from the plasma membrane. In fact, markers of clathrin-independent carriers (CLICs) were rapidly disassembled in the acute phase of membrane damage due to Ca2+ influx, followed by a reassembly about 2 min after pore formation. We propose that these endocytic mechanisms might influence membrane repair by regulating the plasma membrane composition and tension, but not via direct internalisation of LLO pores.

  • 252. Obanda, Vincent
    et al.
    Michuki, George
    Jowers, Michael J.
    Rumberia, Cecilia
    Mutinda, Mathew
    Lwande, Olivia Wesula
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Wangoru, Kihara
    Kasiiti-Orengo, Jacquiline
    Yongo, Moses
    Angelone-Alasaad, Samer
    COMPLETE GENOMIC SEQUENCE OF VIRULENT PIGEON PARAMYXOVIRUS IN LAUGHING DOVES (STREPTOPELIA SENEGALENSIS) IN KENYA2016In: Journal of Wildlife Diseases, ISSN 0090-3558, E-ISSN 1943-3700, Vol. 52, no 3, p. 599-608Article in journal (Refereed)
    Abstract [en]

    Following mass deaths of Laughing Doves (Streptopelia senegalensis) in different localities throughout Kenya, internal organs obtained during necropsy of two moribund birds were sampled and analyzed by next generation sequencing. We isolated the virulent strain of pigeon paramyxovirus type-1 (PPMV-1), PPMV1/Laughing Dove/Kenya/Isiolo/B2/2012, which had a characteristic fusion gene motif (110)GGRRQKRF(117). We obtained a partial full genome of 15,114 nucleotides. The phylogenetic relationship based on the fusion gene and genomic sequence grouped our isolate as class II genotype VI, a group of viruses commonly isolated from wild birds but potentially lethal to Chickens (Gallus gallus domesticus). The fusion gene isolate clustered with PPMV-I strains from pigeons (Columbidae) in Nigeria. The complete genome showed a basal and highly divergent lineage to American, European, and Asian strains, indicating a divergent evolutionary pathway. The isolated strain is highly virulent and apparently species-specific to Laughing Doves in Kenya. Risk of transmission of such a strain to poultry is potentially high whereas the cyclic epizootic in doves is a threat to conservation of wild Columbidae in Kenya.

  • 253.
    Obi, Ikenna
    et al.
    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).
    Francis, Matthew
    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).
    Demarcating SurA activities required for outer membrane targeting of Yersinia pseudotuberculosis adhesins2013In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 81, no 7, p. 2296-2308Article in journal (Refereed)
    Abstract [en]

    SurA is a periplasmic protein folding factor involved in chaperoning and trafficking of outer membrane proteins across the Gram-negative bacterial periplasm. In addition, SurA also possesses peptidyl-prolyl cis/trans isomerase activity. In enteropathogenic Yersinia pseudotuberculosis, we have previously reported that SurA is needed for bacterial virulence and envelope integrity. In this study, we investigated the role of SurA in the assembly of important Yersinia adhesins. Using genetic mutation, biochemical characterization and an in vitro-based bacterial host cell association assay, we confirmed that surface localization of the invasin adhesin is dependent on SurA. As a surA deletion also has some impact on the levels of individual components of the BAM complex in the Yersinia outer membrane, abolished invasin surface assembly could reflect both a direct loss of SurA-dependent periplasmic targeting as well as a potentially compromised BAM complex assembly platform in the outer membrane. To varying degrees, the assembly of two other adhesins, Ail and the pH 6 antigen fibrillum PsaA also depend on SurA. Consequently, loss of SurA leads to a dramatic reduction in Yersinia attachment to eukaryotic host cells. Genetic complementation of surA deletion mutants indicated a prominent role for SurA chaperone function in outer membrane protein assembly. Significantly, the N-terminus of SurA contributed most of this SurA chaperone function. Despite a dominant chaperoning role, it was also evident that SurA isomerization activity did make a modest contribution to this assembly process.

  • 254.
    Obi, Ikenna
    et al.
    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).
    Nordfelth, Roland
    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).
    Francis, Matthew
    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).
    Varying dependency of periplasmic peptidylprolyl cis-trans isomerases in promoting Yersinia pseudotuberculosis stress tolerance and pathogenicity2011In: Biochemical Journal, ISSN 0264-6021, E-ISSN 1470-8728, Vol. 439, no 2, p. 321-332Article in journal (Refereed)
    Abstract [en]

    Periplasmic PPIases (peptidylprolyl cis-trans isomerases) catalyse the cis-trans isomerization of peptidyl-prolyl bonds, which is a rate-limiting step during protein folding. We demonstrate that the surA, ppiA, ppiD, fkpA and fklB alleles each encode a periplasmic PPIase in the bacterial pathogen Yersinia pseudotuberculosis. Of these, four were purified to homogeneity. Purified SurA, FkpA and FklB, but not PpiD, displayed detectable PPIase activity in vitro. Significantly, only Y. pseudotuberculosis lacking surA caused drastic alterations to the outer membrane protein profile and FA (fatty acid) composition. They also exhibited aberrant cellular morphology, leaking LPS (lipopolysaccharide) into the extracellular environment. The SurA PPIase is therefore most critical for maintaining Y. pseudotuberculosis envelope integrity during routine culturing. On the other hand, bacteria lacking either surA or all of the genes ppiA, ppiD, fkpA and fklB were sensitive to hydrogen peroxide and were attenuated in mice infections. Thus Y. pseudotuberculosis exhibits both SurA-dependent and -independent requirements for periplasmic PPIase activity to ensure in vivo survival and a full virulence effect in a mammalian host.

  • 255.
    Ochtrop, Philipp
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Swart, Leonie
    Simon, Sylvia
    Janning, Petra
    Dickhut, Clarissa
    Zahedi, Rene, P.
    Hilbi, Hubert
    Hedberg, Christian
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Identification of cellular protein targets for the Legionella pneumophila phosphocholinating effector AnkXManuscript (preprint) (Other academic)
  • 256. O'Donoghue, Beth
    et al.
    NicAogain, Kerrie
    Bennett, Claire
    Conneely, Alan
    Tiensuu, Teresa
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Johansson, Jörgen
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    O'Byrne, Conor
    Blue-Light Inhibition of Listeria monocytogenes Growth Is Mediated by Reactive Oxygen Species and Is Influenced by sigma(B) and the Blue-Light Sensor Lmo07992016In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 82, no 13, p. 4017-4027Article in journal (Refereed)
    Abstract [en]

    Listeria monocytogenes senses blue light via the flavin mononucleotide-containing sensory protein Lmo0799, leading to activation of the general stress response sigma factor SigB (sigma(B)). In this study, we investigated the physiological response of this foodborne pathogen to blue light. We show that blue light (460 to 470 nm) doses of 1.5 to 2 mW cm(-2) cause inhibition of growth on agar-based and liquid culture media. The inhibitory effects are dependent on cell density, with reduced effects evident when high cell numbers are present. The addition of 20 mM dimethylthiourea, a scavenger of reactive oxygen species, or catalase to the medium reverses the inhibitory effects of blue light, suggesting that growth inhibition is mediated by the formation of reactive oxygen species. A mutant strain lacking sigma(B) (Delta sigB) was found to be less inhibited by blue light than the wild type, likely indicating the energetic cost of deploying the general stress response. When a lethal dose of light (8 mW cm(-2)) was applied to cells, the Delta sigB mutant displayed a marked increase in sensitivity to light compared to the wild type. To investigate the role of the blue-light sensor Lmo0799, mutants were constructed that either had a deletion of the gene (Delta lmo0799) or alteration in a conserved cysteine residue at position 56, which is predicted to play a pivotal role in the photocycle of the protein (lmo0799 C56A). Both mutants displayed phenotypes similar to the Delta sigB mutant in the presence of blue light, providing genetic evidence that residue 56 is critical for light sensing in L. monocytogenes. Taken together, these results demonstrate that L. monocytogenes is inhibited by blue light in a manner that depends on reactive oxygen species, and they demonstrate clear light-dependent phenotypes associated with sigma(B) and the blue-light sensor Lmo0799.

  • 257.
    Okumura, Cheryl
    et al.
    University of California.
    Anderson, Ericka L
    University of California.
    Döhrmann, Simon
    Tran, Dan N
    University of California.
    Olson, Joshua
    University of California.
    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).
    Nizet, Victor
    University of California.
    IgG protease Mac/IdeS is not essential for phagocyte resistance or mouse virulence of M1T1 group A Streptococcus2013In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 4, no 4, p. e00499-e00513Article in journal (Refereed)
    Abstract [en]

    The Mac/IdeS protein of group A Streptococcus (GAS) is a secreted cysteine protease with cleavage specificity for IgG and is highly expressed in the GAS serotype M1T1 clone, which is the serotype most frequently isolated from patients with life-threatening invasive infections. While studies of Mac/IdeS with recombinant protein have shown that the protein can potentially prevent opsonophagocytosis of GAS by neutrophils, the role of the protein in immune evasion as physiologically produced by the living organism has not been studied. Here we examined the contribution of Mac/IdeS to invasive GAS disease by generating a mutant lacking Mac/IdeS in the hyperinvasive M1T1 background. While Mac/IdeS was highly expressed and proteolytically active in the hyperinvasive strain, elimination of the bacterial protease did not significantly influence GAS phagocytic uptake, oxidative-burst induction, cathelicidin sensitivity, resistance to neutrophil or macrophage killing, or pathogenicity in pre- or postimmune mouse infectious challenges. We conclude that in the highly virulent M1T1 background, Mac/IdeS is not essential for either phagocyte resistance or virulence. Given the conservation of Mac/IdeS and homologues across GAS strains, it is possible that Mac/IdeS serves another important function in GAS ecology or contributes to virulence in other strain backgrounds.

    IMPORTANCE Group A Streptococcus (GAS) causes human infections ranging from strep throat to life-threatening conditions such as flesh-eating disease and toxic shock syndrome. Common disease-associated clones of GAS can cause both mild and severe infections because of a characteristic mutation and subsequent change in the expression of several genes that develops under host immune selection. One of these genes encodes Mac/IdeS, a protease that has been shown to cleave antibodies important to the immune defense system. In this study, we found that while Mac/IdeS is highly expressed in hypervirulent GAS, it does not significantly contribute to the ability of the bacteria to survive white blood cell killing or produce invasive infection in the mouse. These data underscore the importance of correlating studies on virulence factor function with physiologic expression levels and the complexity of streptococcal pathogenesis and contribute to our overall understanding of how GAS causes disease.

  • 258.
    Olofsson, Annelie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Nygård Skalman, Lars
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Obi, Ikenna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Lundmark, Richard
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Uptake of Helicobacter pylori vesicles is facilitated by clathrin-dependent and clathrin-independent endocytic pathways2014In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 5, no 3, p. e00979-14-Article in journal (Refereed)
    Abstract [en]

    UNLABELLED: Bacteria shed a diverse set of outer membrane vesicles that function as transport vehicles to deliver effector molecules and virulence factors to host cells. Helicobacter pylori is a gastric pathogen that infects half of the world's population, and in some individuals the infection progresses into peptic ulcer disease or gastric cancer. Here we report that intact vesicles from H. pylori are internalized by clathrin-dependent endocytosis and further dynamin-dependent processes, as well as in a cholesterol-sensitive manner. We analyzed the uptake of H. pylori vesicles by gastric epithelial cells using a method that we refer to as quantification of internalized substances (qIS). The qIS assay is based on a near-infrared dye with a cleavable linker that enables the specific quantification of internalized substances after exposure to reducing conditions. Both chemical inhibition and RNA interference in combination with the qIS assay showed that H. pylori vesicles enter gastric epithelial cells via both clathrin-mediated endocytosis and additional endocytic processes that are dependent on dynamin. Confocal microscopy revealed that H. pylori vesicles colocalized with clathrin and dynamin II and with markers of subsequent endosomal and lysosomal trafficking. Interestingly, however, knockdown of components required for caveolae had no significant effect on internalization and knockdown of components required for clathrin-independent carrier (CLIC) endocytosis increased internalization of H. pylori vesicles. Furthermore, uptake of vesicles by both clathrin-dependent and -independent pathways was sensitive to depletion, but not sequestering, of cholesterol in the host cell membrane suggesting that membrane fluidity influences the efficiency of H. pylori vesicle uptake.

    IMPORTANCE: Bacterial vesicles act as long-distance tools to deliver toxins and effector molecules to host cells. Vesicles can cause a variety of host cell responses via cell surface-induced cell signaling or internalization. Vesicles of diverse bacterial species enter host cells via different endocytic pathways or via membrane fusion. With the combination of a fluorescence-based quantification assay that quantifies internalized vesicles in a large number of cells and either chemical inhibition or RNA interference, we show that clathrin-mediated endocytosis is the major pathway for uptake of Helicobacter pylori vesicles and that lipid microdomains of the host cell membrane affect uptake of vesicles via clathrin-independent pathways. Our results provide important insights about membrane fluidity and its important role in the complex process that directs the H. pylori vesicle to a specific endocytic pathway. Understanding the mechanisms that operate in vesicle-host interactions is important to fully recognize the impact of vesicles in pathogenesis.

  • 259.
    Olofsson, Martin
    et al.
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Lamela, Teresa
    Necton SA, Olhao, Portugal.
    Nilsson, Emmelie
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Bergé, Jean-Pascal
    IFREMER, Nantes, France.
    del Pino, Victória
    Necton SA, Olhao, Portugal.
    Uronen, Pauliina
    Neste Oil, Ctr Technol, Porvoo, Finland.
    Legrand, Catherine
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata 2014In: Marine Drugs, ISSN 1660-3397, E-ISSN 1660-3397, Vol. 12, no 4, p. 1891-1910Article in journal (Refereed)
    Abstract [en]

    Instead of sole nutrient starvation to boost algal lipid production, we addressed nutrient limitation at two different seasons (autumn and spring) during outdoor cultivation in flat panel photobioreactors. Lipid accumulation, biomass and lipid productivity and changes in fatty acid composition of Nannochloropsis oculata were investigated under nitrogen (N) limitation (nitrate:phosphate N:P 5, N:P 2.5 molar ratio). N. oculata was able to maintain a high biomass productivity under N-limitation compared to N-sufficiency (N:P 20) at both seasons, which in spring resulted in nearly double lipid productivity under N-limited conditions (0.21 g L−1 day−1) compared to N-sufficiency (0.11 g L−1 day−1). Saturated and monounsaturated fatty acids increased from 76% to nearly 90% of total fatty acids in N-limited cultures. Higher biomass and lipid productivity in spring could, partly, be explained by higher irradiance, partly by greater harvesting rate (~30%). Our results indicate the potential for the production of algal high value products (i.e., polyunsaturated fatty acids) during both N-sufficiency and N-limitation. To meet the sustainability challenges of algal biomass production, we propose a dual-system process: Closed photobioreactors producing biomass for high value products and inoculum for larger raceway ponds recycling waste/exhaust streams to produce bulk chemicals for fuel, feed and industrial material.

  • 260.
    Olofsson, Martin
    et al.
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Lindehoff, Elin
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Frick, Brage
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Svensson, Fredrik
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Legrand, Catherine
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Baltic Sea microalgae transform cement flue gas into valuable biomass2015In: Algal Research, ISSN 2211-9264, Vol. 11, p. 227-233Article in journal (Refereed)
    Abstract [en]

    We show high feasibility of using cement industrial flue gas as CO2 source for microalgal cultivation. The toxicity of cement flue gas (12-15% CO2) on algal biomass production and composition (lipids, proteins, carbohydrates) was tested using monocultures (Tetraselmis sp., green algae, Skeletonema marinoi, diatom) and natural brackish communities. The performance of a natural microalgal community dominated by spring diatoms was compared to a highly productive diatom monoculture S. marinoi fed with flue gas or air-CO2 mixture. Flue gas was not toxic to any of the microalgae tested. Instead we show high quality of microalgal biomass (lipids 20-30% DW, proteins 20-28% DW, carbohydrates 15-30% DW) and high production when cultivated with flue gas addition compared to CO2-air. Brackish Baltic Sea microalgal communities performed equally or better in terms of biomass quality and production than documented monocultures of diatom and green algae, often used in algal research and development. Hence, we conclude that microalgae should be included in biological solutions to transform waste into renewable resources in coastal waters. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

  • 261. Ormonde, P.
    et al.
    Hörstedt, P.
    O'Toole, R.
    Milton, Debra L
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Role of motility in adherence to and invasion of a fish cell line by Vibrio anguillarum2000In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 182, no 8, p. 2326-2328Article in journal (Refereed)
    Abstract [en]

    To understand further the role of the flagellum of Vibrio anguillarum in virulence, invasive and adhesive properties of isogenic motility mutants were analyzed by using a chinook salmon embryo cell line. Adhesion was unaffected but invasion of the cell line was significantly decreased in nonmotile or partially motile mutants, and the chemotactic mutant was hyperinvasive. These results suggest that active motility aids invasion by V. anguillarum, both in vivo and in vitro.

  • 262.
    Osorio, Hector
    et al.
    Center for Bioinformatics and Genome Biology, Fundacion Ciencia y Vida, Santiago and Depto. Ciencias Biologicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile.
    Mangold, Stefanie
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Denis, Yann
    CNRS and Aix-Marseille Université, IMM, Plateforme Transcriptome, 13009 Marseille, France.
    Nancucheo, Ivan
    College of Natural Sciences, Bangor University, Bangor LL57 2UW, U.K..
    Johnson, D. Barrie
    College of Natural Sciences, Bangor University, Bangor LL57 2UW, U.K.
    Bonnefoy, Violaine
    CNRS and Aix-Marseille Université, IMM, Laboratoire de Chimie Bactérienne UMR7283, 13009 Marseille, France.
    Dopson, Mark
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Holmes, David S.
    Center for Bioinformatics and Genome Biology, Fundacion Ciencia y Vida, Santiago and Depto. Ciencias Biologicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile.
    Anaerobic Sulfur Metabolism Coupled to Dissimilatory Iron Reduction in the Extremophile Acidithiobacillus ferrooxidans2013In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 79, no 7, p. 2172-2181Article in journal (Refereed)
    Abstract [en]

    Gene transcription (microarrays) and protein levels (proteomics) were compared in cultures of the acidophilic chemolithotroph Acidithiobacillus ferrooxidans grown on elemental sulfur as the electron donor under aerobic and anaerobic conditions, using either molecular oxygen or ferric iron as the electron acceptor, respectively. No evidence supporting the role of either tetrathionate hydrolase or arsenic reductase in mediating the transfer of electrons to ferric iron (as suggested by previous studies) was obtained. In addition, no novel ferric iron reductase was identified. However, data suggested that sulfur was disproportionated under anaerobic conditions, forming hydrogen sulfide via sulfur reductase and sulfate via heterodisulfide reductase and ATP sulfurylase. Supporting physiological evidence for H2S production came from the observation that soluble Cu2+ included in anaerobically incubated cultures was precipitated (seemingly as CuS). Since H2S reduces ferric iron to ferrous in acidic medium, its production under anaerobic conditions indicates that anaerobic iron reduction is mediated, at least in part, by an indirect mechanism. Evidence was obtained for an alternative model implicating the transfer of electrons from S-0 to Fe3+ via a respiratory chain that includes a bc(1) complex and a cytochrome c. Central carbon pathways were upregulated under aerobic conditions, correlating with higher growth rates, while many Calvin-Benson-Bassham cycle components were upregulated during anaerobic growth, probably as a result of more limited access to carbon dioxide. These results are important for understanding the role of A. ferrooxidans in environmental biogeochemical metal cycling and in industrial bioleaching operations.

  • 263. O'Toole, R
    et al.
    Milton, Debra L
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Hörstedt, P
    Wolf-Watz, H
    RpoN of the fish pathogen Vibrio (Listonella) anguillarum is essential for flagellum production and virulence by the water-borne but not intraperitoneal route of inoculation.1997In: Microbiology, ISSN 1350-0872, E-ISSN 1465-2080, Vol. 143 ( Pt 12)Article in journal (Refereed)
    Abstract [en]

    To investigate the involvement of RpoN in flagellum production and pathogenicity of Vibrio (Listonella) anguillarum, the rpoN gene was cloned and sequenced. The deduced product of the rpoN gene displayed strong homology to the alternative sigma 54 factor (RpoN) of numerous species of bacteria. In addition, partial sequencing of rpoN-linked ORFs revealed a marked resemblance to similarly located ORFs in other bacterial species. A polar insertion or an in-frame deletion in the coding region of rpoN abolished expression of the flagellin subunits and resulted in loss of motility. Introduction of the rpoN gene of V. anguillarum or Pseudomonas putida into the rpoN mutants restored flagellation and motility. The rpoN mutants were proficient in the expression of other proposed virulence determinants of V. anguillarum, such as ability to grow under low available iron conditions, and expression of the LPS O-antigen and of haemolytic and proteolytic extracellular products. The infectivity of the rpoN mutants with respect to the wild-type strain was unaffected following intraperitoneal injection of fish but was reduced significantly when fish were immersed in bacteria-containing water. Thus, RpoN does not appear to regulate any factors required for virulence subsequent to penetration of the fish epithelium, but is important in the infection of fish by water-borne V. anguillarum.

  • 264. O'Toole, R
    et al.
    Milton, Debra L
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Wolf-Watz, H
    Chemotactic motility is required for invasion of the host by the fish pathogen Vibrio anguillarum.1996In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 19, no 3, p. 625-637Article in journal (Refereed)
    Abstract [en]

    The role of the flagellum and motility in the virulence of the marine fish pathogen Vibrio anguillarum was examined. Non-motile mutants were generated by transposon mutagenesis. Infectivity studies revealed that disruption of the flagellum and subsequent loss of motility correlated with an approximate 500-fold decrease in virulence when fish were inoculated by immersion in bacteria-containing water. However, the flagellar filament and motility were not required for pathogenicity following intraperitoneal injection of fish. The transposon-insertion site for six mutants was determined by cloning and sequencing of the Vibrio DNA flanking the transposon. V. anguillarum genes whose products showed strong homology to proteins with an established role in flagellum biosynthesis were identified. One of the aflagellate mutants had a transposon insertion in the rpoN gene of V. anguillarum. This rpoN mutant failed to grow at low concentrations of available iron and was avirulent by both the immersion and intraperitoneal modes of inoculation. A chemotaxis gene, cheR, was located upstream of one transposon insertion and an in-frame deletion was constructed in the coding region of this gene. The resulting non-chemotactic mutant exhibited wild-type pathogenicity when injected intra-peritoneally into fish but showed a decrease in virulence similar to that seen for the non-motile aflagellate mutants following immersion infection. Hence, chemotactic motility is a required function of the flagellum for the virulence of V. anguillarum.

  • 265.
    Pajarillo, Edward Alain B.
    et al.
    Dankook University.
    Kim, Sang Hoon
    Dankook University.
    Valeriano, Valerie Diane
    Department of Animal Resources Science, Dankook University, Cheonan, South Korea.
    Lee, Ji Yoon
    Seoul National University.
    Kang, Dae-Kyung
    Dankook University.
    Proteomic View of the Crosstalk between Lactobacillus mucosae and Intestinal Epithelial Cells in Co-culture Revealed by Q Exactive-Based Quantitative Proteomics2017In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 8, article id 2459Article in journal (Refereed)
    Abstract [en]

    Lactobacilli are bacteria that are beneficial to host health, but information on communication between Lactobacilli and host cells in the intestine is lacking. In this study, we examined the proteomes of the Lactobacillus mucosae strain LM1, as a model of beneficial bacteria, and the intestinal porcine epithelial cell line (IPEC-J2) after co-culture. Label-free proteomics demonstrated the high-throughput capability of the technique, and robust characterization of the functional profiles and changes in the bacteria and intestinal cells was achieved in pure and mixed cultures. After co-culture, we identified totals of 376 and 653 differentially expressed proteins in the LM1 and IPEC-J2 proteomes, respectively. The major proteomic changes in the LM1 strain occurred in the functional categories of transcription, general function, and translation, whereas those in IPEC-J2 cells involved metabolic and cellular processes, and cellular component organization/biogenesis. Among them, elongation factor Tu, glyceraldehyde 3-phosphate dehydrogenase, and phosphocarrier protein HPr, which are known to be involved in bacterial adhesion, were upregulated in LM1. In contrast, proteins involved in tight junction assembly, actin organization, and genetic information processing (i.e., histones and signaling pathways) were significantly upregulated in IPEC-J2 cells. Furthermore, we identified functional pathways that are possibly involved in host–microbe crosstalk and response. These findings will provide novel insights into host–bacteria communication and the molecular mechanism of probiotic establishment in the intestine.

  • 266.
    Panigrahi, Satya
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Indira Gandhi Centre for Atomic Research.
    Nydahl, Anna
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Anton, Peter
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Wikner, Johan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Strong seasonal effect of moderate experimental warming on plankton respiration in a temperate estuarine plankton community2013In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 136, p. 269-279Article in journal (Refereed)
    Abstract [en]

    Climate change projections forecast a 1.1-6.4 °C global increase in surface water temperature and a 3 °C increase for the Baltic Sea. This study examined the short-term interactive effects of a realistic future temperature increase (3 °C) on pelagic respiration and bacterioplankton growth and phytoplanktonphotosynthesis in situ. This study was undertaken throughout a full seasonal cycle in the northern Baltic Sea. We found marked positive short-term effects of temperature on plankton respiration but no significant effect on bacterioplankton growth or phytoplankton photosynthesis. Absolute respiration rates remained similar to other comparable environments at the in situ temperature. With the 3 °C temperature increase, respiration rates in situ increased up to 5-fold during the winter and 2-fold during the summer. A maximum seasonal Q10 value of 332 was observed for respiration during the cold winter months (twater z 0 C), and summer Q10 values were comparatively high (9.1). Q10 values exhibited a significant inverse relationship to water temperature during winter. Our results thereby suggest that plankton respiration in this coastal zone is more temperature sensitive than previously reported. In addition, field data indicated that plankton respiration switched from being temperature limited to being limited by dissolved organic carbon (DOC) after the simulated temperature increase. Assuming that our observations are relevant over longer time scales, climate change may worsen hypoxia, increase CO2 emissions and create a more heterotrophic food web in coastal zones with a high load of riverine DOC.

  • 267.
    Pettersson, Jonas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Holmström, Anna
    Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-901 82 Umeå, Sweden.
    Hill, Jim
    Biomedical Sciences Department, Defence Evaluation and Research Agency, Porton Down, Salisbury, Wiltshire SP4 OJQ, UK.
    Leary, Sophie
    Biomedical Sciences Department, Defence Evaluation and Research Agency, Porton Down, Salisbury, Wiltshire SP4 OJQ, UK.
    Frithz-Lindsten, Elisabet
    Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-901 82 Umeå, Sweden.
    von Euler-Matell, Anne
    Microbiology and Tumor Biology Center, Karolinska Institute, S-171 77 Stockholm, Sweden.
    Carlsson, Eva
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Titball, Richard
    Biomedical Sciences Department, Defence Evaluation and Research Agency, Porton Down, Salisbury, Wiltshire SP4 OJQ, UK.
    Forsberg, Åke
    Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-901 82 Umeå, Sweden.
    Wolf-Watz, Hans
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    The V-antigen of Yersinia is surface exposed before target cell contact and involved in virulence protein translocation:  1999In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 32, no 5, p. 961-976Article in journal (Refereed)
    Abstract [en]

    Type III-mediated translocation of Yop effectors is an essential virulence mechanism of pathogenic Yersinia. LcrV is the only protein secreted by the type III secretion system that induces protective immunity. LcrV also plays a significant role in the regulation of Yop expression and secretion. The role of LcrV in the virulence process has, however, remained elusive on account of its pleiotropic effects. Here, we show that anti-LcrV antibodies can block the delivery of Yop effectors into the target cell cytosol. This argues strongly for a critical role of LcrV in the Yop translocation process. Additional evidence supporting this role was obtained by genetic analysis. LcrV was found to be present on the bacterial surface before the establishment of bacteria target cell contact. These findings suggest that LcrV serves an important role in the initiation of the translocation process and provides one possible explanation for the mechanism of LcrV-induced protective immunity.

  • 268.
    Pinhassi, Jarone
    et al.
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    DeLong, Edward F.
    Univ Hawaii, USA ; MIT, USA.
    Béjà, Oded
    Technion Israel Inst Technol, Israel.
    González, José M.
    Univ La Laguna, Spain.
    Pedrós-Alió, Carlos
    CSIC, Spain.
    Marine bacterial and archaeal ion-pumping rhodopsins: genetic diversity, physiology, and ecology2016In: Microbiology and molecular biology reviews, ISSN 1092-2172, E-ISSN 1098-5557, Vol. 80, no 4, p. 929-954Article, review/survey (Refereed)
    Abstract [en]

    The recognition of a new family of rhodopsins in marine planktonic bacteria, proton-pumping proteorhodopsin, expanded the known phylogenetic range, environmental distribution, and sequence diversity of retinylidene photoproteins. At the time of this discovery, microbial ion-pumping rhodopsins were known solely in haloarchaea inhabiting extreme hypersaline environments. Shortly thereafter, proteorhodopsins and other light-activated energy-generating rhodopsins were recognized to be widespread among marine bacteria. The ubiquity of marine rhodopsin photosystems now challenges prior understanding of the nature and contributions of "heterotrophic" bacteria to biogeochemical carbon cycling and energy fluxes. Subsequent investigations have focused on the biophysics and biochemistry of these novel microbial rhodopsins, their distribution across the tree of life, evolutionary trajectories, and functional expression in nature. Later discoveries included the identification of proteorhodopsin genes in all three domains of life, the spectral tuning of rhodopsin variants to wavelengths prevailing in the sea, variable light-activated ion-pumping specificities among bacterial rhodopsin variants, and the widespread lateral gene transfer of biosynthetic genes for bacterial rhodopsins and their associated photopigments. Heterologous expression experiments with marine rhodopsin genes (and associated retinal chromophore genes) provided early evidence that light energy harvested by rhodopsins could be harnessed to provide biochemical energy. Importantly, some studies with native marine bacteria show that rhodopsin-containing bacteria use light to enhance growth or promote survival during starvation. We infer from the distribution of rhodopsin genes in diverse genomic contexts that different marine bacteria probably use rhodopsins to support lightdependent fitness strategies somewhere between these two extremes.

  • 269. Pons, Benoît J
    et al.
    Bezine, Elisabeth
    Hanique, Mélissa
    Guillet, Valérie
    Mourey, Lionel
    Chicher, Johana
    Frisan, Teresa
    Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden.
    Vignard, Julien
    Mirey, Gladys
    Cell transfection of purified cytolethal distending toxin B subunits allows comparing their nuclease activity while plasmid degradation assay does not2019In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 14, no 3, article id e0214313Article in journal (Refereed)
    Abstract [en]

    The Cytolethal Distending Toxin (CDT) is produced by many pathogenic bacteria. CDT is known to induce genomic DNA damage to host eukaryotic cells through its catalytic subunit, CdtB. CdtB is structurally homologous to DNase I and has a nuclease activity, dependent on several key residues. Yet some differences between various CdtB subunit activities, and discrepancies between biochemical and cellular data, have been observed. To better characterise the role of CdtB in the induction of DNA damage, we affinity-purified wild-type and mutants of CdtB, issued from E. coli and H. ducreyi, under native and denaturing conditions. We then compared their nuclease activity by a classic in vitro assay using plasmid DNA, and two different eukaryotic assays-the first assay where host cells were transfected with a plasmid encoding CdtB, the second assay where host cells were directly transfected with purified CdtB. We show here that in vitro nuclease activities are difficult to quantify, whereas CdtB activities in host cells can be easily interpreted and confirmed the loss of function of the catalytic mutant. Our results highlight the importance of performing multiple assays while studying the effects of bacterial genotoxins, and indicate that the classic in vitro assay should be complemented with cellular assays.

  • 270. Porrúa, Odil
    et al.
    López-Sánchez, Aroa
    Platero, Ana I
    Santero, Eduardo
    Shingler, Victoria
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Govantes, Fernando
    An A-tract at the AtzR binding site assists DNA binding, inducer-dependent repositioning and transcriptional activation of the PatzDEF promoter2013In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 90, no 1, p. 72-87Article in journal (Refereed)
    Abstract [en]

    The LysR-type regulator AtzR activates the Pseudomonas sp. ADP atzDEF operon in response to nitrogen limitation and cyanuric acid. Activation involves repositioning of the AtzR tetramer on the PatzDEF promoter and relaxation of an AtzR-induced DNA bend. Here we examine the in vivo and in vitro contribution of an A5 -tract present at the PatzDEF promoter region to AtzR binding and transcriptional activation. Substitution of the A-tract for the sequence ACTCA prevented PatzDEF activation and high-affinity AtzR binding, impaired AtzR contacts with the activator binding site and shifted the position of the AtzR-induced DNA bend. Analysis of a collection of mutants bearing different alterations in the A-tract sequence showed that the extent of AtzR-dependent activation does not correlate with the magnitude or orientation of the spontaneous DNA bend generated at this site. Our results support the notion that indirect readout of the A-tract-associated narrow minor groove is essential for the AtzR-DNA complex to achieve a conformation competent for activation of the PatzDEF promoter. Conservation of this motif in several binding sites of LysR-type regulators suggests that this mechanism may be shared by other proteins in this family.

  • 271.
    Puhar, Andrea
    et al.
    Dipartimento di Scienze Biomediche Sperimentali, Università di Padova, Padova, Italy,.
    Dal Molin, Federica
    Horvath, Stéphanie
    Ladant, Daniel
    Ladants, Daniel
    Montecucco, Cesare
    Anthrax edema toxin modulates PKA- and CREB-dependent signaling in two phases2008In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 3, no 10, article id e3564Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Anthrax edema toxin (EdTx) is an adenylate cyclase which operates in the perinuclear region of host cells. However, the action of EdTx is poorly understood, especially at molecular level. The ability of EdTx to modulate cAMP-dependent signaling was studied in Jurkat T cells and was compared with that of other cAMP-rising agents: Bordetella pertussis adenylate cyclase toxin, cholera toxin and forskolin.

    METHODOLOGY/PRINCIPAL FINDINGS: EdTx caused a prolonged increase of the intracellular cAMP concentration. This led to nuclear translocation of the cAMP-dependent protein kinase (PKA) catalytic subunit, phosphorylation of cAMP response element binding protein (CREB) and expression of a reporter gene under control of the cAMP response element. Neither p90 ribosomal S6 kinase nor mitogen- and stress-activated kinase, which mediate CREB phosphorylation during T cell activation, were involved. The duration of phospho-CREB binding to chromatin correlated with the spatio-temporal rise of cAMP levels. Strikingly, EdTx pre-treated T cells were unresponsive to other stimuli involving CREB phosphorylation such as addition of forskolin or T cell receptor cross-linking.

    CONCLUSIONS/SIGNIFICANCE: We concluded that, in a first intoxication phase, EdTx induces PKA-dependent signaling, which culminates in CREB phosphorylation and activation of gene transcription. Subsequently CREB phosphorylation is impaired and therefore T cells are not able to respond to cues involving CREB. The present data functionally link the perinuclear localization of EdTx to its intoxication mechanism, indicating that this is a specific feature of its intoxication mechanism.

  • 272.
    Puhar, Andrea
    et al.
    Dipartimento di Scienze Biomediche Sperimentali, Università di Padova, I-35121 Padua, Italy.
    Johnson, E A
    Rossetto, O
    Montecucco, C
    Comparison of the pH-induced conformational change of different clostridial neurotoxins2004In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 319, no 1, p. 66-71Article in journal (Refereed)
    Abstract [en]

    Clostridial neurotoxins are internalized inside acidic compartments, wherefrom the catalytic chain translocates across the membrane into the cytosol in a low pH-driven process, reaching its proteolytic substrates. The pH range in which the structural rearrangement of clostridial neurotoxins takes place was determined by 8-anilinonaphthalene-1-sulfonate and tryptophan fluorescence measurements. Half conformational change was attained at pH 4.55, 4.50, 4.40, 4.60, 4.40, and 4.40 for tetanus neurotoxin and botulinum neurotoxin serotypes /A, /B, /C, /E, and /F, respectively. This similarity indicates the key residues for the conformation transition are strongly conserved. Acidic liposomes support the conformational rearrangement shifting the effect versus higher pH values, whereas zwitterionic liposomes do not. The disulfide bridge linking the light and the heavy chains together needs to be oxidized to allow toxin membrane insertion, indicating that in vivo its reduction follows exposure to the cytosol after penetration of the endosomal membrane.

  • 273.
    Puhar, Andrea
    et al.
    Dipartimento di Scienze Biomediche Sperimentali, Università di Padova, viale G. Colombo 3, I-35121 Padua, Italy.
    Montecucco, Cesare
    Where and how do anthrax toxins exit endosomes to intoxicate host cells?2007In: Trends in Microbiology, ISSN 0966-842X, E-ISSN 1878-4380, Vol. 15, no 11, p. 477-482Article in journal (Refereed)
    Abstract [en]

    The role of Bacillus anthracis virulence factors in its pathogenesis has been subjected to intense investigation with the aim of finding novel preventive and therapeutic protocols. Toxins that are endocytosed and act in the cytosol of host cells have a central role in B. anthracis infection. Understanding of anthrax toxin cell entry has increased during the past few years and a composite picture is emerging. Nevertheless, unanswered and controversial questions remain, particularly concerning the site and mode of anthrax toxin cell entry, the role of anthrax toxin receptors in the process and the possible involvement of cytosolic chaperones, which might affect entry efficiency. Here, the current model of anthrax toxin cell entry, an alternative model and experimental approaches for clarifying unanswered questions will be discussed.

  • 274.
    Puhar, Andrea
    et al.
    Inserm U786 and Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, Paris, France.
    Sansonetti, Philippe J.
    Microbiologie et Maladies Infectieuses, Collège de France, Paris, France.
    Induction of Connexin-hemichannel Opening2014In: Bio-Protocol, ISSN 2331-8325, Vol. 4, no 17, article id e1220Article in journal (Refereed)
    Abstract [en]

    [Abstract] Connexins (Cxs) are integral membrane proteins of vertebrates that associate to form hexameric transmembrane channels, named hemichannels. Twenty-one Cx types have been described, which are named according to their molecular weight. Cxs are expressed in many cell types, e.g. epithelial cells, astrocytes and immune cells. Hemichannels allow the passage of molecules of up to 1-2 kDa along the concentration gradient. When surface-exposed, hemichannels mediate the exchange of molecules between the cytosol and the extracellular space. Hemichannels are closed by default, but several cues inducing their opening have been described, e.g. a drop in the extracellular Ca2+ concentration (Evans et al., 2006) or infection with enteric pathogens (Puhar et al., 2013; Tran Van Nhieu et al., 2003). This protocol was used with epithelial cells, in particular with polarized and non-polarized intestinal epithelial TC7 cells and with Hela cells that were stably transfected with Cx26 or Cx43 (Paemeleire et al., 2000). Nevertheless, it could likely be used with other Cx-expressing cell types. Whether hemichannels are open can be determined by electrophysiology or by measuring the release into the extracellular medium of a hemichannel permeable molecule (for example, ATP) or the uptake of a hemichannel-permeable, plasma membrane-impermeant molecule [for example, the fluorescent dye ethidium bromide-see associated protocol “Dye-uptake Experiment through Connexin Hemichannels” (Puhar and Sansonetti, 2014)].

  • 275.
    Puhar, Andrea
    et al.
    Inserm U768 and Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris Cedex 15, France..
    Sansonetti, Philippe J
    Inserm U768 and Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris Cedex 15, France.
    Type III secretion system2014In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 24, no 17, p. R784-R791Article in journal (Refereed)
    Abstract [en]

    The type III secretion system (T3SS) is a membrane-embedded nanomachine found in several Gram-negative bacteria. Upon contact between bacteria and host cells, the syringe-like T3SS (Figure 1) transfers proteins termed effectors from the bacterial cytosol to the cytoplasm or the plasma membrane of a single target cell. This is a major difference from secretion systems that merely release molecules into the extracellular milieu, where they act on potentially distant target cells expressing the relevant surface receptors. The syringe architecture is conserved at the structural and functional level and supports injection into a great variety of hosts and tissues. However, the pool of effectors is species specific and determines the outcome of the interaction, via modulation of target-cell function.

  • 276.
    Puhar, Andrea
    et al.
    Inserm U786, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris Cedex 15, France; Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris Cedex 15, France.
    Tronchère, Hélène
    Payrastre, Bernard
    Nhieu, Guy Tran Van
    Sansonetti, Philippe J
    A Shigella effector dampens inflammation by regulating epithelial release of danger signal ATP through production of the lipid mediator PtdIns5P2013In: Immunity, ISSN 1074-7613, E-ISSN 1097-4180, Vol. 39, no 6, p. 1121-1131Article in journal (Refereed)
    Abstract [en]

    Upon infection with Shigella flexneri, epithelial cells release ATP through connexin hemichannels. However, the pathophysiological consequence and the regulation of this process are unclear. Here we showed that in intestinal epithelial cell ATP release was an early alert response to infection with enteric pathogens that eventually promoted inflammation of the gut. Shigella evolved to escape this inflammatory reaction by its type III secretion effector IpgD, which blocked hemichannels via the production of the lipid PtdIns5P. Infection with an ipgD mutant resulted in rapid hemichannel-dependent accumulation of extracellular ATP in vitro and in vivo, which preceded the onset of inflammation. At later stages of infection, ipgD-deficient Shigella caused strong intestinal inflammation owing to extracellular ATP. We therefore describe a new paradigm of host-pathogen interaction based on endogenous danger signaling and identify extracellular ATP as key regulator of mucosal inflammation during infection. Our data provide new angles of attack for the development of anti-inflammatory molecules.

  • 277. Ramirez, Kelly S.
    et al.
    Knight, Christopher G.
    de Hollander, Mattias
    Brearley, Francis Q.
    Constantinides, Bede
    Cotton, Anne
    Creer, Si
    Crowther, Thomas W.
    Davison, John
    Delgado-Baquerizo, Manuel
    Dorrepaal, Ellen
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Elliott, David R.
    Fox, Graeme
    Griffiths, Robert I.
    Hale, Chris
    Hartman, Kyle
    Houlden, Ashley
    Jones, David L.
    Krab, Eveline J.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Maestre, Fernando T.
    McGuire, Krista L.
    Monteux, Sylvain
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Orr, Caroline H.
    van der Putten, Wim H.
    Roberts, Ian S.
    Robinson, David A.
    Rocca, Jennifer D.
    Rowntree, Jennifer
    Schlaeppi, Klaus
    Shepherd, Matthew
    Singh, Brajesh K.
    Straathof, Angela L.
    Bhatnagar, Jennifer M.
    Thion, Cecile
    van der Heijden, Marcel G. A.
    de Vries, Franciska T.
    Detecting macroecological patterns in bacterial communities across independent studies of global soils2018In: Nature Microbiology, E-ISSN 2058-5276, Vol. 3, no 2, p. 189-196Article in journal (Refereed)
    Abstract [en]

    The emergence of high-throughput DNA sequencing methods provides unprecedented opportunities to further unravel bacterial biodiversity and its worldwide role from human health to ecosystem functioning. However, despite the abundance of sequencing studies, combining data from multiple individual studies to address macroecological questions of bacterial diversity remains methodically challenging and plagued with biases. Here, using a machine-learning approach that accounts for differences among studies and complex interactions among taxa, we merge 30 independent bacterial data sets comprising 1,998 soil samples from 21 countries. Whereas previous meta-analysis efforts have focused on bacterial diversity measures or abundances of major taxa, we show that disparate amplicon sequence data can be combined at the taxonomy-based level to assess bacterial community structure. We find that rarer taxa are more important for structuring soil communities than abundant taxa, and that these rarer taxa are better predictors of community structure than environmental factors, which are often confounded across studies. We conclude that combining data from independent studies can be used to explore bacterial community dynamics, identify potential 'indicator' taxa with an important role in structuring communities, and propose hypotheses on the factors that shape bacterial biogeography that have been overlooked in the past.

  • 278. Randriamanana, Tendry R.
    et al.
    Nissinen, Katri
    Ovaskainen, Anu
    Lavola, Anu
    Peltola, Heli
    Albrectsen, Benedicte Riber
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Julkunen-Tiitto, Riitta
    Does fungal endophyte inoculation affect the responses of aspen seedlings to carbon dioxide enrichment?2018In: Fungal ecology, ISSN 1754-5048, E-ISSN 1878-0083, Vol. 33, p. 24-31Article in journal (Refereed)
    Abstract [en]

    Endophytes are microorganisms that live inside plants without causing visible symptoms, at least during some parts of their life cycle. We studied, for the first time, the combined effects of CO2 enrichment (700 ppm) and fungal endophyte inoculation on the growth, the concentrations of low-molecular weight phenolics, and condensed tannins of aspen (Populus tremula) seedlings. As expected, we found that the endophyte strain we inoculated was neutral to plant growth and was able to bypass major plant defences. In addition, CO2 enrichment alone boosted plant growth, but had only minor effects on plant phenolics. Neither did it affect the plant-endophyte relationship. Based on our findings, we suggest that the successful and asymptomatic colonization of endophytes that we found in aspen might be due to the endophytes' special attributes enabling them to thrive inside plant tissues and to avoid or counteract the plant's chemical defences.

  • 279. Ravanal, María Cristina
    et al.
    Pezoa-Conte, Ricardo
    von Schoultz, Sebastian
    Hemming, Jarl
    Salazar, Oriana
    Anugwom, Ikenna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jogunola, Olatunde
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mäki-Arvela, Päivi
    Willför, Stefan
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo/Turku, Finland.
    Lienqueo, María Elena
    Comparison of different types of pretreatment and enzymatic saccharification of Macrocystis pyrifera for the production of biofuel2016In: Algal Research, ISSN 2211-9264, Vol. 13, p. 141-147Article in journal (Refereed)
    Abstract [en]

    In this work, the brown algae Macrocystis pyrifera were pretreated with dilute sulfuric acid, water and three different types of ionic liquids (ILs): 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), 1,5-diazabicyclo[4.3.0]non-5-ene acetate ([DBNH][OAc]) and 1,8-diazabicyclo-[5.4.0]–undec-7-ene–sulfurdioxide–monoethanolamine (DBU–MEA–SO2–SIL), to disassemble the complex polysaccharide structure. After each pretreatment procedure, enzymatic saccharification was performed to release the monosaccharides. The main building blocks of M. pyrifera were processed by derivatization via acid methanolysis and subjected to gas chromatographic analysis. It was found that the main constituents were alginate (60.6 wt.%) and cellulose (22.6 wt.%) of total carbohydrate content. The degradation of alginate requires the action of alginate lyase and oligoalginate lyase, which hydrolyze the main chain in a synergistic mechanism releasing uronic acid (unsaturated uronate). Upon saccharification of cellulose, cellulases and β-glucosidase were used allowing the release of glucose. It was found that the best pretreatment strategy for M. pyrifera consisted of a pretreatment with 2 vol.% sulfuric acid, followed by saccharification of cellulose with a mixture of cellulases at pH 5.2 for 4 h at 50 °C or by saccharification of alginate with the enzyme lyase/oligoalginate lyase at pH 7.5 for 2 h at 37 °C. The process resulted in a release of 68.4 wt.% of glucose (55.74 ± 0.05 mg glucose/g algae) whereas in the case of alginate 85.8 wt.% of uronic acid (193.7 ± 10.6 mg uronic acid/g algae) was released. To the best of our knowledge this is the first time that saccharification of both cellulose and alginate from brown algae is reported.

  • 280. Raychaudhuri, Saumya
    et al.
    Jain, Vibhu
    Dongre, Mitesh
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Identification of a constitutively active variant of LuxO that affects production of HA/protease and biofilm development in a non-O1, non-O139 Vibrio cholerae O110.2006In: Gene, ISSN 0378-1119, E-ISSN 1879-0038, Vol. 369, p. 126-33Article in journal (Refereed)
    Abstract [en]

    Pathogenesis of Vibrio cholerae depends on the concerted action of numerous virulence factors that includes a secreted hemagglutinin (HA) protease. Recent studies have evidenced that the expression of these virulence factors as well as the genes responsible for biofilm development is subject to control by quorum sensing in this organism. At low cell density, LuxO, the pivotal regulator of quorum-sensing circuit, has been shown to be phosphorylated at aspartate-47. Working in concert with sigma-54, LuxO-P activates the downstream repressor, which turned out to be four sRNAs [Lenz, D.H., Mok, K.C., Lilley, B.N., Kulkarni, R.V., Wingreen, N.S., Bassler, B.L., 2004. The small RNA chaperone Hfq and multiple small RNAs control quorum sensing in Vibrio harveyi and Vibrio cholerae. Cell 118, 69-82]. Subsequently, these sRNAs form complex with sRNA chaperone, Hfq. The Hfq-sRNA complex causes the destabilization of hapR mRNA transcript. HapR is a positive regulator of hapA that encodes HA/protease. At high cell density, dephosphorylation of LuxO impairs its function to activate the expression of sRNA, which in turn promotes HapR expression and causes protease production. It has been demonstrated that conversion of aspartate to glutamate (D47E) renders the LuxO molecule active without being phosphorylated. This variant of LuxO is referred as constitutively active LuxO or con-LuxO [Freeman, J.A., Bassler, B.L., 1999. A genetic analysis of the function of LuxO, a two-component response regulator involved in quorum sensing in Vibrio harveyi. Mol Microbiol 31, 665-677]. Other than D47E, mutation at L104Q also develops con-LuxO [Vance, R.E., Zhu, J., Mekalanos, J.J., 2003. A constitutively active variant of the quorum-sensing regulator LuxO affects protease production and biofilm formation in Vibrio cholerae. Infect. Immun. 71, 2571-2576]. The purpose of this study was to investigate the cause of protease negative phenotype of a non-O1, non-O139 strain of V. cholerae O110. In the process of exploring the nature of the phenotype, a constitutively active variant of LuxO molecule was characterized which represses protease production and enhances biofilm formation by this strain. Unlike luxU, disruption of luxO restored the protease production, which showed the constitutively active nature of LuxO protein in this strain.

  • 281. Rezelj, Veronica V
    et al.
    Överby, Anna K
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Elliott, Richard M
    Generation of mutant Uukuniemi viruses lacking the nonstructural protein NSs by reverse genetics indicates that NSs is a weak interferon antagonist.2015In: Journal of Virology, ISSN 0022-538X, E-ISSN 1098-5514, Vol. 89, no 9, p. 4849-4856Article in journal (Refereed)
    Abstract [en]

    Uukuniemi virus (UUKV) is a tick-borne member of the Phlebovirus genus (family Bunyaviridae) and has been widely used as a safe laboratory model to study aspects of bunyavirus replication. Recently, a number of new tick-borne phleboviruses have been discovered, some of which, like severe fever with thrombocytopenia syndrome virus and Heartland virus, are highly pathogenic in man. UUKV could now serve as a useful comparator to understand the molecular basis for the different pathogenicities of these related viruses. We established a reverse genetics system to recover UUKV entirely from cDNA clones. We generated two recombinant viruses, one in which the nonstructural protein NSs open reading frame was deleted from the S segment and one in which the NSs gene was replaced with GFP, allowing convenient visualization of viral infection. We show that the UUKV NSs protein acts as a weak interferon antagonist in human cells, but it is unable to completely counteract the interferon response, which could serve as an explanation for its inability to cause disease in man.

    IMPORTANCE: Uukuniemi virus (UUKV) is a tick-borne phlebovirus that is apathogenic for man and has been used as a convenient model to investigate aspects of phlebovirus replication. Recently new tick-borne phleboviruses have emerged, such as severe fever with thrombocytopenia syndrome virus in China and Heartland virus in the US, that are highly pathogenic, and UUKV will now serve as a comparison to aid understanding of the molecular basis for the virulence of these new viruses. To help such investigations, we have developed a reverse genetics system for UUKV that permits manipulation of the viral genome. We generated viruses lacking the nonstructural protein NSs and show that UUKV NSs is a weak interferon antagonist. In addition, we created a virus that expresses GFP and thus allows convenient monitoring of virus replication. These new tools represent a significant advance in the study of tick-borne phleboviruses.

  • 282. Ricroch, Agnes
    et al.
    Harwood, Wendy
    Svobodova, Zdenka
    Sagi, Laszlo
    Hundleby, Penelope
    Badea, Elena Marcela
    Rosca, Ioan
    Cruz, Gabriela
    Salema Fevereiro, Manuel Pedro
    Marfa Riera, Victoria
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Morandini, Piero
    Bojinov, Bojin
    Cetiner, Selim
    Custers, Rene
    Schrader, Uwe
    Jacobsen, Hans-Joerg
    Martin-Laffon, Jacqueline
    Boisron, Audrey
    Kuntz, Marcel
    Challenges facing European agriculture and possible biotechnological solutions2016In: Critical reviews in biotechnology, ISSN 0738-8551, E-ISSN 1549-7801, Vol. 36, no 5, p. 875-883Article, review/survey (Refereed)
    Abstract [en]

    Agriculture faces many challenges to maximize yields while it is required to operate in an environmentally sustainable manner. In the present study, we analyze the major agricultural challenges identified by European farmers (primarily related to biotic stresses) in 13 countries, namely Belgium, Bulgaria, the Czech Republic, France, Germany, Hungary, Italy, Portugal, Romania, Spain, Sweden, UK and Turkey, for nine major crops (barley, beet, grapevine, maize, oilseed rape, olive, potato, sunflower and wheat). Most biotic stresses (BSs) are related to fungi or insects, but viral diseases, bacterial diseases and even parasitic plants have an important impact on yield and harvest quality. We examine how these challenges have been addressed by public and private research sectors, using either conventional breeding, marker-assisted selection, transgenesis, cisgenesis, RNAi technology or mutagenesis. Both national surveys and scientific literature analysis followed by text mining were employed to evaluate genetic engineering (GE) and non-GE approaches. This is the first report of text mining of the scientific literature on plant breeding and agricultural biotechnology research. For the nine major crops in Europe, 128 BS challenges were identified with 40% of these addressed neither in the scientific literature nor in recent European public research programs. We found evidence that the private sector was addressing only a few of these neglected challenges. Consequently, there are considerable gaps between farmer's needs and current breeding and biotechnology research. We also provide evidence that the current political situation in certain European countries is an impediment to GE research in order to address these agricultural challenges in the future. This study should also contribute to the decision-making process on future pertinent international consortia to fill the identified research gaps.

  • 283. Rivera, L.
    et al.
    Lopez-Patino, M. A.
    Milton, Debra L.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Nieto, T. P.
    Farto, R.
    Effective qPCR methodology to quantify the expression of virulence genes in Aeromonas salmonicida subsp salmonicida2015In: Journal of Applied Microbiology, ISSN 1364-5072, E-ISSN 1365-2672, Vol. 118, no 4, p. 792-802Article in journal (Refereed)
    Abstract [en]

    Aims This study aimed to select and validate different methodological strategies to quantify the expression of the virulence genes ascC and ascV by qPCR in Aeromonas salmonicida subsp. salmonicida (Aer. salmonicida). Methods and Results Using the geNorm, Normfinder and BestKeeper algorithms, reference genes for the qPCR were selected based on their in vitro expression stabilities in three Aer. salmonicida strains. Gene amplification efficiency was calculated by Real-time PCR Miner and LinReg PCR programmes, which have not been used previously in the analysis of bacterial gene expression. The expression of the ascC and ascV virulence genes in a virulent Aer. salmonicida strain was evaluated by three quantification models, including single (least or most stable) or three most stable reference genes, combined with constant or specific gene amplification efficiency. The most stable reference genes were gyrB, proC and rpoC, while rpoD and fabD were the least stable. Quantification models showed different expression patterns. Conclusions The optimal strategy to quantify mRNA expression was to use a combination of the three algorithms and the quantification model including the three most stable reference genes. Real-time PCR Miner or LinReg PCR were valuable tools to estimate amplification efficiency. Significance and Impact of the Study The methods used in this study gave more reliable expression data using qPCR than previously published methods. The quantification and expression dynamics of virulence genes will contribute to a better understanding of how Aer. salmonicida interacts with its host and the environment, and therefore to the prevention of epizootics due to this pathogen.

  • 284. Rodríguez, Juanjo
    et al.
    Gallampois, Christine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Timonen, Sari
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Sinkko, Hanna
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Berglund, Åsa M. M.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ripszam, Matyas
    Figueroa, Daniela
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rowe, Owen
    Effects of Organic Pollutants on Bacterial Communities Under Future Climate Change Scenarios2018In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, article id 2926Article in journal (Refereed)
    Abstract [en]

    Coastal ecosystems are highly dynamic and can be strongly influenced by climate change, anthropogenic activities (e.g. pollution) and a combination of the two pressures. As a result of climate change, the northern hemisphere is predicted to undergo an increased precipitation regime, leading in turn to higher terrestrial runoff and increased river inflow. This increased runoff will transfer terrestrial dissolved organic matter (tDOM) and anthropogenic contaminants to coastal waters. Such changes can directly influence the resident biology, particularly at the base of the food web, and can influence the partitioning of contaminants and thus their potential impact on the food web. Bacteria have been shown to respond to high tDOM concentration and organic pollutants loads, and could represent the entry of some pollutants into coastal food webs. We carried out a mesocosm experiment to determine the effects of: 1) increased tDOM concentration, 2) organic pollutant exposure, and 3) the combined effect of these two factors, on pelagic bacterial communities. This study showed significant responses in bacterial community composition under the three environmental perturbations tested. The addition of tDOM increased bacterial activity and diversity, while the addition of organic pollutants led to an overall reduction of these parameters, particularly under concurrent elevated tDOM concentration. Furthermore, we identified 33 bacterial taxa contributing to the significant differences observed in community composition, as well as 35 bacterial taxa which responded differently to extended exposure to organic pollutants. These findings point to the potential impact of organic pollutants under future climate change conditions on the basal coastal ecosystem, as well as to the potential utility of natural bacterial communities as efficient indicators of environmental disturbance.

  • 285. Rolén, Ulrika
    et al.
    Freda, Elio
    Xie, Jianjun
    Pfirrmann, Thorsten
    Frisan, Teresa
    Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.
    Masucci, Maria G
    The ubiquitin C-terminal hydrolase UCH-L1 regulates B-cell proliferation and integrin activation2009In: Journal of Cellular and Molecular Medicine (Print), ISSN 1582-1838, E-ISSN 1582-4934, Vol. 13, no 8b, p. 1666-1678Article in journal (Refereed)
    Abstract [en]

    The ubiquitin C-terminal hydrolase-L1 (UCH-L1) is a deubiquitinating enzyme that catalyses the hydrolysis of polyubiquitin precursors and small ubiquitin adducts. UCH-L1 has been detected in a variety of malignant and metastatic tumours but its biological function in these cells is unknown. We have previously shown that UCH-L1 is highly expressed in Burkitt's lymphoma (BL) and is up-regulated upon infection of B lymphocytes with Epstein-Barr virus (EBV). Here we show that knockdown of UCH-L1 by RNAi inhibits the proliferation of BL cells in suspension and semisolid agar and activates strong LFA-1-dependent homotypic adhesion. Induction of cell adhesion correlated with cation-induced binding to ICAM-1, clustering of LFA-1 into lipid rafts and constitutive activation of the Rap1 and Rac1 GTPases. Expression of a catalytically active UCH-L1 promoted the proliferation of a UCH-L1-negative EBV transformed lymphoblastoid cell line (LCL) and inhibited cell adhesion, whereas a catalytic mutant had no effect, confirming the requirement of UCH-L1 enzymatic activity for the regulation of these phenotypes. Our results identify UCH-L1 as a new player in the signalling pathways that promote the proliferation and invasive capacity of malignant B cells.

  • 286. 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.

  • 287.
    Rzhepishevska, Olena
    Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology).
    Physiology and Genetics of Acidithiobacillus species: Applications for Biomining2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bacteria from the genus Acidithiobacillus are often associated with biominingand acid mine drainage. Biomining utilises acidophilic, sulphur and ironoxidising microorganisms for recovery of metals from sulphidic low grade oresand concentrates. Acid mine drainage results in acidification and contaminationwith metals of soil and water emanating from the dissolution of metal sulphidesfrom deposits and mine waste storage. Acidophilic microorganisms play acentral role in these processes by catalysing aerobic oxidation of sulphides.Acceleration of mineral solubilisation is a positive aspect in biomining whereas,in acid mine drainage it is undesirable and accordingly, microbial iron andsulphur oxidation is promoted in the first case and measures are taken to inhibitit in the second case. In this thesis, several approaches were taken in order tounderstand and increase oxidation efficiency in biomining and to gain an insightinto the biochemical reactions taking place in these environments. A laboratoryscale bioreactor was designed and tested allowing simulation of bioleaching inheaps of mine tailings at different aeration, irrigation and particle size conditions(Paper I). A new psychrotolerant strain of Acidithiobacillus ferrooxidans wascharacterised that has an application in boreal heap bioleaching. Iron, reducedinorganic sulphur compound oxidation and bioleaching of various ores by thisstrain was studied as well as gene expression during oxidation of tetrathionateand/or ferrous iron (Papers III & IV). Expression and regulation of atetrathionate hydrolase from Acidithiobacillus caldus, a key enzyme in reducedinorganic sulphur compound metabolism of this bacterium was investigated andthe presence of this enzyme in a bioleaching mixed culture was shown. The genecluster that harbours the gene coding for tetrathionate hydrolase (tetH) wasdescribed for the first time (Paper II).

  • 288. Saffari, Fereshteh
    et al.
    Widerström, Micael
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Gurram, Bharat Kumar
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Edebro, Helen
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Hojabri, Zoya
    Monsen, Tor
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Molecular and Phenotypic Characterization of Multidrug-Resistant Clones of Staphylococcus epidermidis in Iranian Hospitals: Clonal Relatedness to Healthcare-Associated Methicillin-Resistant Isolates in Northern Europe2016In: Microbial Drug Resistance, ISSN 1076-6294, E-ISSN 1931-8448, Vol. 22, no 7, p. 570-577Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to investigate the molecular epidemiology of Staphylococcus epidermidis in Iranian hospitals and to compare the genotypes with a previously characterized collection of >1,300 S. epidermidis isolates of nosocomial and community origin from Northern Europe, Australia, and USA. In total, 82 clinical S. epidermidis isolates from three Iranian hospitals were examined by multilocus sequence typing, pulsed-field gel electrophoresis (PFGE) and staphylococcal cassette chromosome mec (SCCmec) typing. In addition, antimicrobial susceptibility, the presence of the ica operon, and the predilection to biofilm formation were assessed. Three predominant PFGE clones were found. The PFGE patterns of the most common sequence type (PFGE type 040-ST2) showed 80% similarity to multidrug-resistant S. epidermidis (MDRSE) clinical isolates from eight hospitals in Northern Europe. The second most common (PFGE 024-ST22) showed an unique PFGE pattern, whereas the third most predominant genotype (PFGE 011-ST5) proved indistinguishable to the PFGE Co-ST5 identified in five hospitals in Northern Europe. In conclusion, the study documented the dissemination of three MDRSE clones within and between hospitals in Iran and revealed an intercontinental spread of two clonal multidrug-resistant lineages (ST2 and ST5) in the hospital environment. Isolates of the predominant clones were significantly more frequently associated with multidrug-resistance and biofilm formation compared to nonclonal isolates. Further studies are needed to explore and characterize the genetic traits that enable these successful MDRSE clones to persist and disseminate worldwide in the healthcare settings.

  • 289.
    Sarand, Inga
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Österberg, Sofia
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Holmqvist, Sofie
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Holmfeldt, Per
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Skärfstad, Eleonore
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Parales, Rebecca E
    Section of Microbiology, 226 Briggs Hall, 1 Shields Ave., University of California, Davis, CA 95616, USA.
    Shingler, Victoria
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Metabolism-dependent taxis towards (methyl)phenols is coupled through the most abundant of three polar localized Aer-like proteins of Pseudomonas putida2008In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 10, no 5, p. 1320-1334Article in journal (Refereed)
    Abstract [en]

    Comparatively little is known about directed motility of environmental bacteria to common aromatic pollutants. Here, by expressing different parts of a (methyl)phenol-degradative pathway and the use of specific mutants, we show that taxis of Pseudomonas putida towards (methyl)phenols is dictated by its ability to catabolize the aromatic compound. Thus, in contrast to previously described chemoreceptor-mediated chemotaxis mechanisms towards benzoate, naphthalene and toluene, taxis in response to (methyl)phenols is mediated by metabolism-dependent behaviour. Here we show that P. putida differentially expresses three Aer-like receptors that are all polar-localized through interactions with CheA, and that inactivation of the most abundant Aer2 protein significantly decreases taxis towards phenolics. In addition, the participation of a sensory signal transduction protein composed of a PAS, a GGDEF and an EAL domain in motility towards these compounds is demonstrated. The results are discussed in the context of the versatility of metabolism-dependent coupling and the necessity for P. putida to integrate diverse metabolic signals from its native heterogeneous soil and water environments.

  • 290. Sarmento, Hugo
    et al.
    Romera-Castillo, Cristina
    Lindh, Markus V.
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Pinhassi, Jarone
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Sala, M. Montserrat
    Gasol, Josep M.
    Marrase, Celia
    Taylor, Gordon T.
    Phytoplankton species-specific release of dissolved free amino acids and their selective consumption by bacteria2013In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 58, no 3, p. 1123-1135Article in journal (Refereed)
    Abstract [en]

    Despite representing only a small fraction of the ocean's dissolved organic matter pool, dissolved free amino acids (DFAA) have high turnover rates and are major nitrogen and carbon sources for bacterioplankton. Both phytoplankton and bacterioplankton assimilate and release DFAA, but their consumption and production are difficult to quantify in nature due to their short residence times (min) as dissolved monomers. We segregated DFAA production by phytoplankton and bacterial consumption by measuring individual DFAA concentrations in four axenic phytoplankton cultures during the exponential growth phase, and also after 4 d incubations in the presence of a natural bacterioplankton community. The amounts and composition of the DFAA pool varied widely among phytoplankton species. The proportion of dissolved organic carbon attributed to DFAA varied among cultures. The picoeukaryotic prasinophyte, Micromonas pusilla, released higher amounts of DFAA than the other species tested (diatoms and dinoflagellate), especially alanine, which has been reported as the dominant individual DFAA in some oligotrophic environments. Community structure of heterotrophic prokaryotes responded to differences in the quality of organic matter released among microalgal species, with Roseobacter-related bacteria responding strongly to exudate composition. Our results demonstrate the specificity of DFAA extracellular release among several algal species and their preferential uptake by members of bacterial communities.

  • 291. Schell, Ursula
    et al.
    Simon, Sylvia
    Sahr, Tobias
    Hager, Dominik
    Albers, Michael F
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kessler, Aline
    Fahrnbauer, Felix
    Trauner, Dirk
    Hedberg, Christian
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Buchrieser, Carmen
    Hilbi, Hubert
    The α-hydroxyketone LAI-1 regulates motility, Lqs-dependent phosphorylation signaling and gene expression of Legionella pneumophila2016In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 99, no 4, p. 778-793Article in journal (Refereed)
    Abstract [en]

    The causative agent of Legionnaires' disease, Legionella pneumophila, employs the autoinducer compound LAI-1 (3-hydroxypentadecane-4-one) for cell–cell communication. LAI-1 is produced and detected by the Lqs (Legionella quorum sensing) system, comprising the autoinducer synthase LqsA, the sensor kinases LqsS and LqsT, as well as the response regulator LqsR. Lqs-regulated processes include pathogen–host interactions, production of extracellular filaments and natural competence for DNA uptake. Here we show that synthetic LAI-1 promotes the motility of L. pneumophila by signalling through LqsS/LqsT and LqsR. Upon addition of LAI-1, autophosphorylation of LqsS/LqsT by [γ-32P]-ATP was inhibited in a dose-dependent manner. In contrast, the Vibrio cholerae autoinducer CAI-1 (3-hydroxytridecane-4-one) promoted the phosphorylation of LqsS (but not LqsT). LAI-1 did neither affect the stability of phospho-LqsS or phospho-LqsT, nor the dephosphorylation by LqsR. Transcriptome analysis of L. pneumophila treated with LAI-1 revealed that the compound positively regulates a number of genes, including the non-coding RNAs rsmY and rsmZ, and negatively regulates the RNA-binding global regulator crsA. Accordingly, LAI-1 controls the switch from the replicative to the transmissive growth phase of L. pneumophila. In summary, the findings indicate that LAI-1 regulates motility and the biphasic life style of L. pneumophila through LqsS- and LqsT-dependent phosphorylation signalling.

  • 292.
    Schmid, Martin R
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Anderl, Ines
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Valanne, S
    Vo, H
    Yang, Hairu
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Kronhamn, J
    Rusten, TE
    Hultmark, Dan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Genetic screen in Drosophila larvae links ird1 function to Toll signaling in the fat body and hemocyte motilityManuscript (preprint) (Other academic)
  • 293.
    Schmid, Martin Rudolf
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Anderl, Ines
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Institute of Biomedical Technology (BioMediTech), University of Tampere, Tampere, Finland.
    Vesala, L
    Vanha-aho, L-M
    Deng, Xiao-Juan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). College of Animal Science, South China Agricultural University, Guangzhou, China.
    Rämet, M
    Hultmark, Dan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Institute of Biomedical Technology (BioMediTech), University of Tampere, Tampere, Finland.
    Control of Drosophila blood cell activation via toll signaling in the fat body2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 8, article id e102568Article in journal (Refereed)
    Abstract [en]

    The Toll signaling pathway, first discovered in Drosophila, has a well-established role in immune responses in insects as well as in mammals. In Drosophila, the Toll-dependent induction of antimicrobial peptide production has been intensely studied as a model for innate immune responses in general. Besides this humoral immune response, Toll signaling is also known to activate blood cells in a reaction that is similar to the cellular immune response to parasite infections, but the mechanisms of this response are poorly understood. Here we have studied this response in detail, and found that Toll signaling in several different tissues can activate a cellular immune defense, and that this response does not require Toll signaling in the blood cells themselves. Like in the humoral immune response, we show that Toll signaling in the fat body (analogous to the liver in vertebrates) is of major importance in the Toll-dependent activation of blood cells. However, this Toll-dependent mechanism of blood cell activation contributes very little to the immune response against the parasitoid wasp, Leptopilina boulardi, probably because the wasp is able to suppress Toll induction. Other redundant pathways may be more important in the defense against this pathogen.

  • 294.
    Schröder, Björn
    Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, Bruna Stråket 16, University of Gothenburg, SE 413 45 Gothenburg, Sweden.
    Fight them or feed them: how the intestinal mucus layer manages the gut microbiota2019In: Gastroenterology Report, ISSN 2052-0034, Vol. 7, no 1, p. 3-12Article in journal (Refereed)
    Abstract [en]

    The intestinal tract is inhabited by a tremendous number of microorganisms, termed the gut microbiota. These microorganisms live in a mutualistic relationship with their host and assist in the degradation of complex carbohydrates. Although the gut microbiota is generally considered beneficial, the vast number of microbial cells also form a permanent threat to the host. Thus, the intestinal epithelium is covered with a dense layer of mucus to prevent translocation of the gut microbiota into underlying tissues. Intestinal mucus is an organized glycoprotein network with a host-specific glycan structure. While the mucus layer has long been considered a passive, host-designed barrier, recent studies showed that maturation and function of the mucus layer are strongly influenced by the gut microbiota. In return, the glycan repertoire of mucins can select for distinct mucosa-associated bacteria that are able to bind or degrade specific mucin glycans as a nutrient source. Because the intestinal mucus layer is at the crucial interface between host and microbes, its breakdown leads to gut bacterial encroachment that can eventually cause inflammation and infection. Accordingly, a dysfunctional mucus layer has been observed in colitis in mice and humans. Moreover, the increased consumption of a low-fiber Western-style diet in our modern society has recently been demonstrated to cause bacteria-mediated defects of the intestinal mucus layer. Here, I will review current knowledge on the interaction between gut bacteria and the intestinal mucus layer in health and disease. Understanding the molecular details of this host-microbe interaction may contribute to the development of novel treatment options for diseases involving a dysfunctional mucus layer, such as ulcerative colitis.

  • 295.
    Schröder, Björn
    et al.
    Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.
    Birchenough, George M H
    Ståhlman, Marcus
    Arike, Liisa
    Johansson, Malin E V
    Hansson, Gunnar C
    Bäckhed, Fredrik
    Bifidobacteria or Fiber Protects against Diet-Induced Microbiota-Mediated Colonic Mucus Deterioration2018In: Cell Host and Microbe, ISSN 1931-3128, E-ISSN 1934-6069, Vol. 23, no 1, p. 27-40.e7Article in journal (Refereed)
    Abstract [en]

    Diet strongly affects gut microbiota composition, and gut bacteria can influence the colonic mucus layer, a physical barrier that separates trillions of gut bacteria from the host. However, the interplay between a Western style diet (WSD), gut microbiota composition, and the intestinal mucus layer is less clear. Here we show that mice fed a WSD have an altered colonic microbiota composition that causes increased penetrability and a reduced growth rate of the inner mucus layer. Both barrier defects can be prevented by transplanting microbiota from chow-fed mice. In addition, we found that administration of Bifidobacterium longum was sufficient to restore mucus growth, whereas administration of the fiber inulin prevented increased mucus penetrability in WSD-fed mice. We hypothesize that the presence of distinct bacteria is crucial for proper mucus function. If confirmed in humans, these findings may help to better understand diseases with an affected mucus layer, such as ulcerative colitis.

  • 296.
    Schröder, Björn
    et al.
    Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.
    Bäckhed, Fredrik
    Signals from the gut microbiota to distant organs in physiology and disease2016In: Nature Medicine, ISSN 1078-8956, E-ISSN 1546-170X, Vol. 22, no 10, p. 1079-1089Article in journal (Refereed)
    Abstract [en]

    The ecosystem of the human gut consists of trillions of bacteria forming a bioreactor that is fueled by dietary macronutrients to produce bioactive compounds. These microbiota-derived metabolites signal to distant organs in the body, which enables the gut bacteria to connect to the immune and hormone system, to the brain (the gut-brain axis) and to host metabolism, as well as other functions of the host. This microbe-host communication is essential to maintain vital functions of the healthy host. Recently, however, the gut microbiota has been associated with a number of diseases, ranging from obesity and inflammatory diseases to behavioral and physiological abnormalities associated with neurodevelopmental disorders. In this Review, we will discuss microbiota-host cross-talk and intestinal microbiome signaling to extraintestinal organs. We will review mechanisms of how this communication might contribute to host physiology and discuss how misconfigured signaling might contribute to different diseases.

  • 297.
    Schröder, Björn
    et al.
    Dr Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany; University of Tuebingen, Tuebingen, Germany; Department of Microbiology and Immunology, School of Medicine, University of California, Davis, California, USA; Present address: Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden.
    Ehmann, D.
    Precht, J. C.
    Castillo, P. A.
    Küchler, R.
    Berger, J.
    Schaller, M.
    Stange, E. F.
    Wehkamp, J.
    Paneth cell α-defensin 6 (HD-6) is an antimicrobial peptide2015In: Mucosal Immunology, ISSN 1933-0219, E-ISSN 1935-3456, Vol. 8, no 3, p. 661-671Article in journal (Refereed)
    Abstract [en]

    Defensins protect human barriers from commensal and pathogenic microorganisms. Human α-defensin 6 (HD-6) is produced exclusively by small intestinal Paneth cells but, in contrast to other antimicrobial peptides (AMPs) for HD-6, no direct antibacterial killing activity has been detected so far. Herein, we systematically tested how environmental factors, like pH and reducing conditions, affect antimicrobial activity of different defensins against anaerobic bacteria of the human intestinal microbiota. Remarkably, by mimicking the intestinal milieu we detected for the first time antibacterial activity of HD-6. Activity was observed against anaerobic gut commensals but not against some pathogenic strains. Antibiotic activity was attributable to the reduced peptide and independent of free cysteines or a conserved histidine residue. Furthermore, the oxidoreductase thioredoxin, which is also expressed in Paneth cells, is able to reduce a truncated physiological variant of HD-6. Ultrastructural analyses revealed that reduced HD-6 causes disintegration of cytoplasmic structures and alterations in the bacterial cell envelope, while maintaining extracellular net-like structures. We conclude that HD-6 is an antimicrobial peptide. Our data suggest two distinct antimicrobial mechanisms by one peptide: HD-6 kills specific microbes depending on the local environmental conditions, whereas known microbial trapping by extracellular net structures is independent of the reducing milieu.

  • 298.
    Schröder, Björn O.
    et al.
    Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology; Stuttgart and University of Tübingen; Tübingen, Germany.
    Stange, Eduard F.
    Wehkamp, Jan
    Waking the wimp: Redox-modulation activates human beta-defensin 12011In: Gut microbes, ISSN 1949-0976, E-ISSN 1949-0984, Vol. 2, no 4, p. 262-266Article in journal (Refereed)
    Abstract [en]

    Antimicrobial peptides are key players of the innate immune system and form a primary barrier against infection by microorganisms. In humans, several classes of antimicrobial peptides are produced, including the defensins. These small, cationic peptides show broad spectrum antimicrobial activity against bacteria, some fungi and some viruses. Defensins are characterized by six conserved cysteine residues which are connected via three disulphide bridges. Depending on the pattern of connectivity, human defensins are either classified as α- or β-defensins. Human β-defensin 1 (hBD-1) is constitutively expressed by epithelia, but in comparison with other antimicrobial peptides the antimicrobial activity of hBD-1 was comparably low. We recently found that after reduction of hBD-1's three disulphide bonds its antimicrobial activity is strongly enhanced. Reduction can be either performed by a reducing environment, as it is present in parts of the human intestine, the oral cavity and other locations, or enzymatically by the thioredoxin-system, which is one of the major redox regulators. Reduced hBD-1 is able to kill Gram-positive anaerobic bacteria of the human normal flora as well as an opportunistic pathogenic fungus, whereas the oxidized peptide does not show activity against these microorganisms. Herein we provide additional data about reduced hBD-1 and discuss the biological context of our findings.

  • 299. Schröder, Björn
    et al.
    Stange, E F
    Wehkamp, J
    Human beta-defensin 1: from defence to offence2012In: Zeitschrift für Gastroenterologie - German Journal of Gastroenterology, ISSN 0044-2771, E-ISSN 1439-7803, Vol. 50, no 11, p. 1171-5Article in journal (Refereed)
    Abstract [de]

    The human gut is colonised by about one kilogram of commensal bacteria. These microorganisms are a potential threat, thus an efficient defence system is crucial in preventing bacterial translocation and infection. Besides other mechanisms of protection humans produce antimicrobial peptides (AMPs) that are able to kill a broad range of microorganisms. The human beta-defensin 1 (hBD-1) plays a major role because it is produced constitutively by all human epithelia and some immune cells. In contrast to other AMPs, however, the biological function of hBD-1 has remained unclear since the antibiotic activity of hBD-1 in vitro was only marginal. But still, several diseases have been associated with genetic polymorphisms in the hBD-1 encoding gene. Herein we discuss why the biological role of hBD-1 has been overlooked and how hBD-1 can be activated by chemical reduction. We elaborate on the biological significance of this activation and its importance for inflammatory bowel disease.

  • 300. Seiwert, Nina
    et al.
    Neitzel, Carina
    Stroh, Svenja
    Frisan, Teresa
    Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden.
    Audebert, Marc
    Toulany, Mahmoud
    Kaina, Bernd
    Fahrer, Jörg
    AKT2 suppresses pro-survival autophagy triggered by DNA double-strand breaks in colorectal cancer cells2017In: Cell Death and Disease, ISSN 2041-4889, E-ISSN 2041-4889, Vol. 8, no 8, article id e3019Article in journal (Refereed)
    Abstract [en]

    DNA double-strand breaks (DSBs) are critical DNA lesions, which threaten genome stability and cell survival. DSBs are directly induced by ionizing radiation (IR) and radiomimetic agents, including the cytolethal distending toxin (CDT). This bacterial genotoxin harbors a unique DNase-I-like endonuclease activity. Here we studied the role of DSBs induced by CDT and IR as a trigger of autophagy, which is a cellular degradation process involved in cell homeostasis, genome protection and cancer. The regulatory mechanisms of DSB-induced autophagy were analyzed, focusing on the ATM-p53-mediated DNA damage response and AKT signaling in colorectal cancer cells. We show that treatment of cells with CDT or IR increased the levels of the autophagy marker LC3B-II. Consistently, an enhanced formation of autophagosomes and a decrease of the autophagy substrate p62 were observed. Both CDT and IR concomitantly suppressed mTOR signaling and stimulated the autophagic flux. DSBs were demonstrated as the primary trigger of autophagy using a DNase I-defective CDT mutant, which neither induced DSBs nor autophagy. Genetic abrogation of p53 and inhibition of ATM signaling impaired the autophagic flux as revealed by LC3B-II accumulation and reduced formation of autophagic vesicles. Blocking of DSB-induced apoptotic cell death by the pan-caspase inhibitor Z-VAD stimulated autophagy. In line with this, pharmacological inhibition of autophagy increased cell death, while ATG5 knockdown did not affect cell death after DSB induction. Interestingly, both IR and CDT caused AKT activation, which repressed DSB-triggered autophagy independent of the cellular DNA-PK status. Further knockdown and pharmacological inhibitor experiments provided evidence that the negative autophagy regulation was largely attributable to AKT2. Finally, we show that upregulation of CDT-induced autophagy upon AKT inhibition resulted in lower apoptosis and increased cell viability. Collectively, the findings demonstrate that DSBs trigger pro-survival autophagy in an ATM- and p53-dependent manner, which is curtailed by AKT2 signaling.

345678 251 - 300 of 385
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