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  • 351.
    Zakrisson, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Wiklund, Krister
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    The shaft of the type 1 fimbriae regulates an externalforce to match the FimH catch bond2013Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 104, nr 10, s. 2137-2148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Type 1 fimbriae mediate adhesion of uropathogenic Escherichia coli to host cells. It has been hypothesized that due to their ability to uncoil under exposure to force, fimbriae can reduce fluid shear stress on the adhesin-receptor interaction by which the bacterium adheres to the surface. In this work, we develop a model that describes how the force on the adhesin-receptor interaction of a type 1 fimbria varies as a bacterium is affected by a time-dependent fluid flow mimicking in vivo conditions. The model combines in vivo hydrodynamic conditions with previously assessed biomechanical properties of the fimbriae. Numerical methods are used to solve for the motion and adhesion force under the presence of time-dependent fluid profiles. It is found that a bacterium tethered with a type 1 pilus will experience significantly reduced shear stress for moderate to high flow velocities and that the maximum stress the adhesin will experience is limited to ∼120 pN, which is sufficient to activate the conformational change of the FimH adhesin into its stronger state but also lower than the force required for breaking it under rapid loading. Our model thus supports the assumption that the type 1 fimbria shaft and the FimH adhesin-receptor interaction are optimized to each other, and that they give piliated bacteria significant advantages in rapidly changing fluidic environments.

  • 352.
    Zakrisson, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wiklund, Krister
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Servin, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Lacoursiere, Claude
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Rigid multibody simulation of a helix-like structure: the dynamics of bacterial adhesion pili2015Ingår i: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 44, nr 5, s. 291-300Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a coarse-grained rigid multibody model of a subunit assembled helix-like polymer, e.g., adhesion pili expressed by bacteria, that is capable of describing the polymer's force-extension response. With building blocks representing individual subunits, the model appropriately describes the complex behavior of pili expressed by the gram-negative uropathogenic Escherichia coli bacteria under the action of an external force. Numerical simulations show that the dynamics of the model, which include the effects of both unwinding and rewinding, are in good quantitative agreement with the characteristic force-extension response as observed experimentally for type 1 and P pili. By tuning the model, it is also possible to reproduce the force-extension response in the presence of anti-shaft antibodies, which dramatically changes the mechanical properties. Thus, the model and results in this work give enhanced understanding of how a pilus unwinds under the action of external forces and provide a new perspective of the complex bacterial adhesion processes.

  • 353.
    Zetterström, Caroline E.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Hasselgren, Jenny
    Creative Antibiotics Sweden AB, Umeå, Sweden .
    Salin, Olli
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Davis, Rohan A.
    Eskitis Institute, Griffith University, Brisbane, Australia.
    Quinn, Ronald J.
    Eskitis Institute, Griffith University, Brisbane, Australia.
    Sundin, Charlotta
    Creative Antibiotics Sweden AB, Umeå, Sweden .
    Elofsson, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    The Resveratrol Tetramer (-)-Hopeaphenol Inhibits Type III Secretion in the Gram-Negative Pathogens Yersinia pseudotuberculosis and Pseudomonas aeruginosa2013Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 12, artikel-id e81969Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Society faces huge challenges, as a large number of bacteria have developed resistance towards many or all of the antibiotics currently available. Novel strategies that can help solve this problem are urgently needed. One such strategy is to target bacterial virulence, the ability to cause disease e.g., by inhibition of type III secretion systems (T3SSs) utilized by many clinically relevant gram-negative pathogens. Many of the antibiotics used today originate from natural sources. In contrast, most virulence-blocking compounds towards the T3SS identified so far are small organic molecules. A recent high-throughput screening of a prefractionated natural product library identified the resveratrol tetramer (-)-hopeaphenol as an inhibitor of the T3SS in Yersinia pseudotuberculosis. In this study we have investigated the virulence blocking properties of (-)-hopeaphenol in three different gram-negative bacteria. (-)- Hopeaphenol was found to have micromolar activity towards the T3SSs in Yersinia pseudotuberculosis and Pseudomonas aeruginosa in cell-based infection models. In addition (-)-hopeaphenol reduced cell entry and subsequent intracellular growth of Chlamydia trachomatis.

  • 354.
    Zetterström, Caroline E.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Uusitalo, Pia
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Qian, Weixing
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Hinch, Shannon
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Caraballo, Remi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Grundström, Christin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Elofsson, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Screening for Inhibitors of Acetaldehyde Dehydrogenase (AdhE) from Enterohemorrhagic Escherichia coli (EHEC)2018Ingår i: SLAS Discovery, ISSN 2472-5552, Vol. 23, nr 8, s. 815-822Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Acetaldehyde dehydrogenase (AdhE) is a bifunctional acetaldehyde-coenzyme A (CoA) dehydrogenase and alcohol dehydrogenase involved in anaerobic metabolism in gram-negative bacteria. This enzyme was recently found to be a key regulator of the type three secretion (T3S) system in Escherichia coli. AdhE inhibitors can be used as tools to study bacterial virulence and a starting point for discovery of novel antibacterial agents. We developed a robust enzymatic assay, based on the acetaldehyde-CoA dehydrogenase activity of AdhE using both absorption and fluorescence detection models (Z' > 0.7). This assay was used to screen similar to 11,000 small molecules in 384-well format that resulted in three hits that were confirmed by resynthesis and validation. All three compounds are noncompetitive with respect to acetaldehyde and display a clear dose-response effect with hill slopes of 1-2. These new inhibitors will be used as chemical tools to study the interplay between metabolism and virulence and the role of AdhE in T3S regulation in gram-negative bacteria, and as starting points for the development of novel antibacterial agents.

  • 355.
    Zhang, Hanqing
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Stangner, Tim
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wiklund, Krister
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Object plane detection and phase retrieval from single-shot holograms using multi-wavelength in-line holographyManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Phase retrieval and the twin-image problem in digital in-line holographic microscopy can be resolvedby iterative reconstruction routines. However, recovering the phase properties of an object in a hologramneeds an object plane to be chosen correctly for reconstruction. In this work, we present a novelmulti-wavelength Gerchberg-Saxton algorithm to determine the object plane using single-shot hologramsrecorded with multiple wavelengths in an in-line holographic microscope. For micro-sized objects, weverify the object positioning capabilities of the method for various shapes and derive the phase informationusing synthetic and experimental data. Experimentally, we built a compact digital in-line holographicmicroscopy setup around a standard optical microscope with a regular RGB-CCD camera andacquire holograms of micro-spheres, E. coli and red blood cells, that are illuminated using three lasersoperating at 491nm, 532nm and 633nm, respectively. We demonstrate that our method provides accurateobject plane detection and phase retrieval under noisy conditions, e.g., using low-contrast hologramswithout background normalization. This method allows for automatic positioning and phase retrievalsuitable for holographic particle velocimetry, and object tracking in biophysical or colloidal research.

  • 356. Zhou, Yizhou
    et al.
    Smith, Daniel
    Leong, Bryan J
    Brännström, Kristoffer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Chapman, Matthew R
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Promiscuous cross-seeding between bacterial amyloids promotes interspecies biofilms2012Ingår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 287, nr 42, s. 35092-35103Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Amyloids are highly aggregated proteinaceous fibers historically associated with neurodegenerative conditions including Alzheimer's, Parkinson's and prion-based encephalopathies. Polymerization of amyloidogenic proteins into ordered fibers can be accelerated by preformed amyloid aggregates derived from the same protein in a process called seeding. Seeding of disease-associated amyloids and prions is highly specific and cross-seeding is usually limited or prevented. Here we describe the first study on the cross-seeding potential of bacterial functional amyloids. Curli are produced on the surface of many Gram-negative bacteria where they facilitate surface attachment and biofilm development. Curli fibers are composed of the major subunit CsgA and the nucleator CsgB, which templates CsgA into fibers. Our results showed that curli subunit homologs from Escherichia coli, Salmonella typhimurium LT2 and Citrobacter koseri were able to cross-seed in vitro. The polymerization of E. coli CsgA was also accelerated by fibers derived from a distant homolog in Shewanella oneidensis that shares less than 30% identity in primary sequence. Cross-seeding of curli proteins was also observed in mixed colony biofilms with E. coli and S. typhimurium. CsgA secreted from E. coli csgB- mutants assembled into fibers on adjacent S. typhimurium that presented CsgB on its surfaces. Similarly, CsgA secreted by S. typhimurium csgB- mutants formed curli on CsgB-presenting E. coli. This interspecies curli assembly enhanced bacterial attachment to agar surfaces and supported pellicle biofilm formation. Collectively, this work suggests that the seeding specificity among curli homologs is relaxed and that heterogeneous curli fibers can facilitate multispecies biofilm development.

  • 357.
    Zlatkov, Nikola
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Absence of Global Stress Regulation in Escherichia coli Promotes Pathoadaptation and Novel c-di-GMP-dependent Metabolic Capability2019Ingår i: Scientific Reports, ISSN 2045-2322, Vol. 9, artikel-id 2600Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    athoadaptive mutations linked to c-di-GMP signalling were investigated in neonatal meningitis-causing Escherichia coli (NMEC). The results indicated that NMEC strains deficient in RpoS (the global stress regulator) maintained remarkably low levels of c-di-GMP, a major bacterial sessility-motility switch. Deletion of ycgG2, shown here to encode a YcgG allozyme with c-di-GMP phosphodiesterase activity, and the restoration of RpoS led to a decrease in S-fimbriae, robustly produced in artificial urine, hinting that the urinary tract could serve as a habitat for NMEC. We showed that NMEC were skilled in aerobic citrate utilization in the presence of glucose, a property that normally does not exist in E. coli. Our data suggest that this metabolic novelty is a property of extraintestinal pathogenic E. coli since we reconstituted this ability in E. coli UTI89 (a cystitis isolate) via deactivation rpoS; additionally, a set of pyelonephritis E. coli isolates were shown here to aerobically use citrate in the presence of glucose. We found that the main reason for this metabolic capability is RpoS inactivation leading to the production of the citrate transporter CitT, exploited by NMEC for ferric citrate uptake dependent on YcgG2 (an allozyme with c-di-GMP phosphodiesterase activity).

  • 358.
    Zlatkov, Nikola
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    C-di-GMP-mediated Morphotypic Pathoadaptability of Neonatal Meningitis Escherichia coliManuskript (preprint) (Övrigt vetenskapligt)
  • 359.
    Zwack, Erin
    et al.
    University of Pennsylvania, USA.
    Snyder, Annelise
    University of Pennsylvania, USA.
    Wynosky-Dolfi, Meghan
    University of Pennsylvania, USA.
    Ruthel, Gordon
    University of Pennsylvania, USA.
    Philip, Naomi
    University of Pennsylvania, USA.
    Marketon, Melanie
    Indiana University, USA.
    Francis, Matthew
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Bliska, James
    SUNY Stony Brook, USA.
    Brodsky, Igor
    University of Pennsylvania, USA.
    Inflammasome activation in response to the Yersinia type III secretion system requires hyperinjection of translocon proteins YopB and YopD2015Ingår i: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 6, nr 1, artikel-id e02095-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Type III secretion systems (T3SS) translocate effector proteins into target cells in order to disrupt or modulate host cell signaling pathways and establish replicative niches. However, recognition of T3SS activity by cytosolic pattern recognition receptors (PRRs) of the nucleotide-binding domain leucine rich repeat (NLR) family, either through detection of translocated products or membrane disruption, induces assembly of multiprotein complexes known as inflammasomes. Macrophages infected with Yersinia pseudotuberculosis strains lacking all known effectors or lacking the translocation regulator YopK induce rapid activation of both the canonical NLRP3 and noncanonical caspase-11 inflammasomes. While this inflammasome activation requires a functional T3SS, the precise signal that triggers inflammasome activation in response to Yersinia T3SS activity remains unclear. Effectorless strains of Yersinia as well as ΔyopK strains translocate elevated levels of T3SS substrates into infected cells. To dissect the contribution of pore formation and translocation to inflammasome activation, we took advantage of variants of YopD and LcrH that separate these functions of the T3SS. Notably, YopD variants that abrogated translocation but not pore-forming activity failed to induce inflammasome activation. Furthermore, analysis of individual infected cells revealed that inflammasome activation at the single-cell level correlated with translocated levels of YopB and YopD themselves. Intriguingly, LcrH mutants that are fully competent for effector translocation but produce and translocate lower levels of YopB and YopD also fail to trigger inflammasome activation. Our findings therefore suggest that hypertranslocation of YopD and YopB is linked to inflammasome activation in response to the Yersinia T3SS.

  • 360.
    Öberg, Christopher T
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Strand, Mårten
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Andersson, Emma K
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Edlund, Karin
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Tran, Nam Phuong Nguyen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Mei, Ya-Fang
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Wadell, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Elofsson, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Synthesis, biological evaluation, and structure-activity relationships of 2-[2-(benzoylamino)benzoylamino]benzoic acid analogues as inhibitors of adenovirus replication2012Ingår i: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 55, nr 7, s. 3170-3181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    2-[2-Benzoylamino)benzoylamino]benzoic acid (1) was previously identified as a potent and nontoxic antiadenoviral compound ( Antimicrob. Agents Chemother. 2010 , 54 , 3871 ). Here, the potency of 1 was improved over three generations of compounds. We found that the ortho, ortho substituent pattern and the presence of the carboxylic acid of 1 are favorable for this class of compounds and that the direction of the amide bonds (as in 1) is obligatory. Some variability in the N-terminal moiety was tolerated, but benzamides appear to be preferred. The substituents on the middle and C-terminal rings were varied, resulting in two potent inhibitors, 35g and 35j, with EC(50) = 0.6 μM and low cell toxicity.

  • 361.
    Österberg, Sofia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Skärfstad, Eleonore
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Shingler, Victoria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    The σ-factor FliA, ppGpp and DksA coordinate transcriptional control of the aer2 gene of Pseudomonas putida2010Ingår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 12, nr 6, s. 1439-1451Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Here the σ-factor requirement for transcription of three similar, but differentially regulated, aer genes of Pseudomonas putida KT2440 is investigated. Previous work has shown that the three Aer proteins, like chemoreceptors, colocalize to a single pole in a CheA-dependent manner. Lack of Aer2 - the most abundant of these three proteins - mediates defects in metabolism-dependent taxis and aerotaxis, while lack of Aer1 or Aer3 has no apparent phenotype. We show, using wild-type and mutant P. putida derivatives combined with P. putida reconstituted FliA- (σ28) and σ70-dependent in vitro transcription assays, that transcription of aer2 is coupled to motility through the flagella σ-factor FliA, while σ70 is responsible for transcription of aer1 and aer3. By comparing activities of the wild-type and mutant forms of the aer2 promoter, we present evidence (i) that transcription from FliA-dependent Paer2 is enhanced by changes towards the Escherichia coli consensus for FliA promoters rather than towards that of P. putida, (ii) that the nature of the AT-rich upstream region is important for both output and σ70 discrimination of this promoter, and (iii) that Paer2 output is directly stimulated by the bacterial alarmone ppGpp and its cofactor DksA.

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