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Berlin Brandenburg

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  • 1
    Language: English
    In: Journal of Shellfish Research, 2012, Vol.31(1), pp.87-92
    Description: Vibrio cholerae may cause diarrheal diseases and wound infections, both of which have the potential to be fatal. Transmission to humans is often linked to consumption of contaminated shellfish/drinking water or dermal exposure to water (e.g. when swimming). In this study, we investigated whether different...
    Keywords: Natural Sciences ; Biological Sciences ; Naturvetenskap ; Biologiska Vetenskaper ; Mussel ; Mytilus Edulis ; Vibrio Cholerae ; Pathogenic ; Depuration ; Hemocytes ; Natural Sciences ; Naturvetenskap ; Mytilus Mulls ; Mikrobiologi Inom Det Medicinska Området ; Microbiology In The Medical Area
    ISSN: 0730-8000
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  • 2
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 2006, Vol.103(24), pp.9280-9285
    Description: Vibrio cholerae is the causal bacterium of the diarrheal disease cholera, and its growth and survival are thought to be curtailed by bacteriovorous predators, e.g., ciliates and flagellates. We explored Caenorhabditis elegans as a test organism after finding that V. cholerae can cause lethal infection...
    Keywords: Natural Sciences ; Naturvetenskap ; Animals ; Bacterial Proteins/Genetics/Metabolism ; Biofilms ; Caenorhabditis Elegans/Cytology/Microbiology/Physiology ; Cell Communication ; Cell Line; Tumor ; Cholera Toxin/Metabolism ; Feeding Behavior ; Fimbriae; Bacterial/Metabolism ; Humans ; Interleukin-8/Secretion ; Intestines/Cytology/Microbiology ; Peptide Hydrolases/Genetics/Metabolism ; Predatory Behavior ; Repressor Proteins/Genetics/Metabolism ; Survival Rate ; Trans-Activators/Genetics/Metabolism ; Transcription Factors/Genetics/Metabolism ; Vibrio Cholerae/Enzymology/Genetics/Pathogenicity
    ISSN: 0027-8424
    E-ISSN: 10916490
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  • 3
    Language: English
    In: PLoS ONE, 2009, Vol. 4(8)
    Description: BACKGROUND: The type VI secretion system (T6SS) has emerged as a protein secretion system important to several gram-negative bacterial species. One of the common components of the system is Hcp, initially described as a hemolysin co-regulated protein in a serotype O17 strain of Vibrio cholerae. Homologs to V. cholerae hcp genes have been found in all characterized type VI secretion systems and they are present also in the serotype O1 strains of V. cholerae that are the cause of cholera diseases but seemed to have non-functional T6SS.METHODOLOGY/PRINCIPAL FINDINGS: The serotype O1 V. cholerae strain A1552 was shown to express detectable levels of Hcp as determined by immunoblot analyses using polyclonal anti-Hcp antiserum. We found that the expression of Hcp was growth phase dependent. The levels of Hcp in quorum sensing deficient mutants of V. cholerae were compared with the levels in wild type V. cholerae O1 strain A1552. The expression of Hcp was positively and negatively regulated by the quorum sensing regulators HapR and LuxO, respectively. In addition, we observed that expression of Hcp was dependent on the cAMP-CRP global transcriptional regulatory complex and required the RpoN sigma factor.CONCLUSION/SIGNIFICANCE: Our results show that serotype O1 strains of V. cholerae do express Hcp which is regarded as one of the important T6SS components and is one of the secreted substrates in non-O1 non-O139 V. cholerae isolates. We found that expression of Hcp was strictly regulated by the quorum sensing system in the V. cholerae O1 strain. In addition, the expression of Hcp required the alternative sigma factor RpoN and the cAMP-CRP global regulatory complex. Interestingly, the environmental isolates of V. cholerae O1 strains that showed higher levels of the HapR quorum sensing regulator in comparison with our laboratory standard serotype O1 strain A1552 where also expressing higher levels of Hcp.
    Keywords: Natural Sciences ; Biological Sciences ; Microbiology ; Naturvetenskap ; Biologiska Vetenskaper ; Mikrobiologi
    ISSN: 1932-6203
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  • 4
    Language: English
    In: PLoS ONE, 2009, Vol. 4(11)
    Description: We suggest that VCC is capable of causing an inflammatory response characterized by increased permeability and production of IL-8 and TNF-alpha in tight monolayers. Pure VCC at a concentration of 160 ng/ml caused an inflammatory response that reached the magnitude of that caused by Vibrio-secreted factors, while higher concentrations caused epithelial cell death. The inflammatory response was totally abolished by treatment with PrtV. The findings suggest that low doses of VCC initiate a local immune defense reaction while high doses lead to intestinal epithelial lesions. Furthermore, VCC is indeed a substrate for PrtV and PrtV seems to execute an environment-dependent modulation of the activity of VCC that may be the cause of V. cholerae reactogenicity.
    Keywords: Medical And Health Sciences ; Basic Medicine ; Immunology In The Medical Area ; Medicin Och Hälsovetenskap ; Medicinska Och Farmaceutiska Grundvetenskaper ; Immunologi Inom Det Medicinska Området
    ISSN: 1932-6203
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  • 5
    Language: English
    In: Cell, 2003, Vol.115(1), pp.25-35
    Description: The ClyA protein is a pore-forming cytotoxin expressed by Escherichia coli and some other enterobacteria. It confers cytotoxic activity toward mammalian cells, but it has remained unknown how ClyA is surface exposed and exported from bacterial cells. Outer-membrane vesicles (OMVs) released from the bacteria were shown to contain ClyA protein. ClyA formed oligomeric pore assemblies in the OMVs, and the cytotoxic activity toward mammalian cells was considerably higher than that of ClyA protein purified from the bacterial periplasm. The redox status of ClyA correlated with its ability to form the oligomeric pore assemblies. In bacterial cells with a defective periplasmic disulphide oxidoreductase system, the ClyA protein was phenotypically expressed in a constitutive manner. The results define a vesicle-mediated transport mechanism in bacteria, and our findings show that the localization of proteins to OMVs directly may contribute to the activation and delivery of pathogenic effector proteins.
    Keywords: Biology
    ISSN: 0092-8674
    E-ISSN: 1097-4172
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  • 6
    Language: English
    In: Umeå University medical dissertations, 2009
    Description: Vibrio cholerae, the causal agent of cholera typically encodes two critical virulence factors: cholera toxin (CT), which is primarily responsible for the diarrhoeal purge, and toxin-co-regulated pilus (TCP), an essential colonisation factor. Nontoxigenic strains expressing TCP can efficiently acquire...
    Keywords: Medical And Health Sciences ; Basic Medicine ; Cell And Molecular Biology ; Medicin Och Hälsovetenskap ; Medicinska Och Farmaceutiska Grundvetenskaper ; Cell- Och Molekylärbiologi ; Vibrio Cholerae ; Caenorhabditis Elegans ; Prtv ; Outer Membrane Vesicles ; Non-O1 Non-O139 ; Serum Resistance ; Medicine ; Dermatology And Venerology,Clinical Genetics, Internal Medicine ; Clinical Genetics ; Molecular Biology ; Medicin ; Dermatologi Och Venerologi, Klinisk Genetik, Invärtesmedicin ; Klinisk Genetik ; Molekylärbiologi ; Molekylärbiologi ; Molecular Biology
    ISBN: 9789172649187
    ISSN: 0346-6612
    Source: SwePub (National Library of Sweden)
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  • 7
    Language: English
    In: BMC Microbiology, Oct 16, 2009, Vol.9, p.220
    Description: Background Background: Cytolethal distending toxin (CDT) is one of the well-characterized virulence factors of Campylobacter jejuni, but it is unknown how CDT becomes surface-exposed or is released from the bacterium to the surrounding environment. Results Our data suggest that CDT is secreted to the bacterial culture supernatant via outer membrane vesicles (OMVs) released from the bacteria. All three subunits (the CdtA, CdtB, and CdtC proteins) were detected by immunogold labeling and electron microscopy of OMVs. Subcellular fractionation of the bacteria indicated that, apart from the majority of CDT detected in the cytoplasmic compartment, appreciable amounts (20-50%) of the cellular pool of CDT proteins were present in the periplasmic compartment. In the bacterial culture supernatant, we found that a majority of the extracellular CDT was tightly associated with the OMVs. Isolated OMVs could exert the cell distending effects typical of CDT on a human intestinal cell line, indicating that CDT is present there in a biologically active form. Conclusion Our results strongly suggest that the release of outer membrane vesicles is functioning as a route of C. jejuni to deliver all the subunits of CDT toxin (CdtA, CdtB, and CdtC) to the surrounding environment, including infected host tissue.
    Keywords: Bacterial Toxins -- Health Aspects ; Bacterial Toxins -- Research ; Campylobacter -- Health Aspects ; Campylobacter -- Research ; Cell Membranes -- Physiological Aspects ; Cell Membranes -- Research ; Electron Microscopy -- Usage
    ISSN: 1471-2180
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: BMC Microbiology, Oct 16, 2009, Vol.9, p.220
    Description: Background Background: Cytolethal distending toxin (CDT) is one of the well-characterized virulence factors of Campylobacter jejuni, but it is unknown how CDT becomes surface-exposed or is released from the bacterium to the surrounding environment. Results Our data suggest that CDT is secreted to the bacterial culture supernatant via outer membrane vesicles (OMVs) released from the bacteria. All three subunits (the CdtA, CdtB, and CdtC proteins) were detected by immunogold labeling and electron microscopy of OMVs. Subcellular fractionation of the bacteria indicated that, apart from the majority of CDT detected in the cytoplasmic compartment, appreciable amounts (20-50%) of the cellular pool of CDT proteins were present in the periplasmic compartment. In the bacterial culture supernatant, we found that a majority of the extracellular CDT was tightly associated with the OMVs. Isolated OMVs could exert the cell distending effects typical of CDT on a human intestinal cell line, indicating that CDT is present there in a biologically active form. Conclusion Our results strongly suggest that the release of outer membrane vesicles is functioning as a route of C. jejuni to deliver all the subunits of CDT toxin (CdtA, CdtB, and CdtC) to the surrounding environment, including infected host tissue.
    Keywords: Bacterial Toxins -- Health Aspects ; Bacterial Toxins -- Research ; Campylobacter -- Health Aspects ; Campylobacter -- Research ; Cell Membranes -- Physiological Aspects ; Cell Membranes -- Research ; Electron Microscopy -- Usage
    ISSN: 1471-2180
    Source: Cengage Learning, Inc.
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  • 9
    In: Molecular Microbiology, October 2008, Vol.70(1), pp.100-111
    Description: We discovered a new small non‐coding RNA (sRNA) gene, of O1 strain A1552. A mutant overproduces OmpA porin, and we demonstrate that the 140 nt VrrA RNA represses translation by base‐pairing with the 5′ region of the mRNA. The RNA chaperone Hfq is not stringently required for VrrA action, but expression of the gene requires the membrane stress sigma factor, σ, suggesting that VrrA acts on in response to periplasmic protein folding stress. We also observed that OmpA levels inversely correlated with the number of outer membrane vesicles (OMVs), and that VrrA increased OMV production comparable to loss of OmpA. VrrA is the first sRNA known to control OMV formation. Moreover, a mutant showed a fivefold increased ability to colonize the intestines of infant mice as compared with the wild type. There was increased expression of the main colonization factor of , the toxin co‐regulated pili, in the mutant as monitored by immunoblot detection of the TcpA protein. VrrA overproduction caused a distinct reduction in the TcpA protein level. Our findings suggest that VrrA contributes to bacterial fitness in certain stressful environments, and modulates infection of the host intestinal tract.
    Keywords: Cholera ; Ribonucleic Acid–RNA ; Bacteria ; Membranes ; Mutation ; Gene Expression ; Proteins ; Microbiology;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
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  • 10
    Language: English
    In: BMC Microbiology, 01 October 2009, Vol.9(1), p.220
    Description: Abstract Background Background: Cytolethal distending toxin (CDT) is one of the well-characterized virulence factors of Campylobacter jejuni, but it is unknown how CDT becomes surface-exposed or is released from the bacterium to the surrounding environment. Results Our data suggest that CDT is secreted to the bacterial culture supernatant via outer membrane vesicles (OMVs) released from the bacteria. All three subunits (the CdtA, CdtB, and CdtC proteins) were detected by immunogold labeling and electron microscopy of OMVs. Subcellular fractionation of the bacteria indicated that, apart from the majority of CDT detected in the cytoplasmic compartment, appreciable amounts (20-50%) of the cellular pool of CDT proteins were present in the periplasmic compartment. In the bacterial culture supernatant, we found that a majority of the extracellular CDT was tightly associated with the OMVs. Isolated OMVs could exert the cell distending effects typical of CDT on a human intestinal cell line, indicating that CDT is present there in a biologically active form. Conclusion Our results strongly suggest that the release of outer membrane vesicles is functioning as a route of C. jejuni to deliver all the subunits of CDT toxin (CdtA, CdtB, and CdtC) to the surrounding environment, including infected host tissue.
    Keywords: Biology
    ISSN: 1471-2180
    E-ISSN: 1471-2180
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