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Role of LPS in vesicle mediated export of Vibrio cholerae PrtV protease
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). (Sun Nyunt Wai)
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). (Sun Nyunt Wai)
Institut für Molekulare Biowissenschaften, Karl-Franzens-Universität Graz, 8010 Graz, Austria.
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). (Sun Nyunt Wai)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Gram negative bacteria produce outer membrane vesicles (OMVs) during normal bacterial growth. Recent studies have shown that OMVs can transport biologically active toxins and enzymes to the environment and into the host. We have initiated analysis of OMV associated proteins in V. cholerae. In this study, V. cholerae wild type strain P27459 and the O-antigen ligase mutant waaL, which lacks the O-antigen of the LPS were analyzed for the OMV associated release of the secreted protease PrtV. OMVs from the waaL mutant showed a higher amount of associated secreted PrtV protein than the OMVs from wild type V. cholerae indicating that LPS might be involved in vesicle association of the PrtV protein. We showed that the OMV associated PrtV protein is biologically active.

National Category
Cell and Molecular Biology
Research subject
Molecular Biology
Identifiers
URN: urn:nbn:se:umu:diva-30256OAI: oai:DiVA.org:umu-30256DiVA: diva2:281249
Available from: 2009-12-15 Created: 2009-12-15 Last updated: 2009-12-22Bibliographically approved
In thesis
1. Modulators of Vibrio cholerae predator interaction and virulence
Open this publication in new window or tab >>Modulators of Vibrio cholerae predator interaction and virulence
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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 the CT gene through lysogenic conversion with CTXΦ, a filamentous phage that encodes CT and uses TCP as a receptor.  V. cholerae is a Gram-negative bacterium and a natural inhabitant of estuarine and coastal waters throughout both temperate and tropical regions of the world. In the aquatic environment, V. cholerae encounters several environmental stresses, such as change in salinity, UV stress, nutrient limitation, temperature fluctuations, viral infections and protozoan predation. To fully understand the pathogenic and virulence potential of V. cholerae, knowledge is required of its interactions with, not only human, but also environmental factors. By using the nematode Caenorhabditis elegans as host model, we were able to identify a previously uncharacterised protein, the extracellular protease PrtV. PrtV was shown to be required for the killing of. elegans and also necessary for survival from grazing by the ciliate Tetrahymena pyriformis and the flagellate Cafeteria roenbergensis. The PrtV protein, which belongs to a M6 family of metallopeptidases was cloned and purified for further characterisations. The purified PrtV was cytotoxic against the human intestinal cell line HCT8. By using human blood plasma, fibrinogen, fibronectin and plasminogen were identified as candidate substrates for the PrtV protease.

Outer membrane vesicles (OMVs) are released to the surroundings by most Gram-negative bacteria through “bulging and pinching” of the outer membrane.  OMVs have been shown to contain many virulence factors important in pathogenesis. Therefore, we investigated the association of PrtV with OMVs. PrtV was not associated with OMVs from the wild type O1 strain. In contrast, in an LPS mutant lacking two sugar chains in the core oligosaccharide PrtV was found to be associated with the OMVs. The OMV-associated PrtV was shown to be proteolytically and cytotoxically active.

V. cholerae strains are grouped into >200 serogroups. Only the O1 and O139 serogroups have been associated with pandemic cholera, a severe diarrhoeal disease.  All other serogroups are collectively referred to as non-O1 non-O139 V. cholerae. Non-O1 non-O139 V. cholerae can cause gastroenteritis and extraintestinal infections, but unlike O1 and O139 strains of V. cholerae, little is known about the virulence gene content and their potential to become human pathogens. We analysed clinical and environmental non-O1 non-O139 isolates for their putative virulence traits. None of them carry the genes encoding CT or the TCP, but other putative virulence factors were present in these isolates. The incidence of serum resistance was found to vary considerably and was independent of encapsulation. Three strains were strongly serum-resistant, and these same strains could also kill C. elegans.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2009. 64 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1312
Keyword
Vibrio cholerae, Caenorhabditis elegans, PrtV, outer membrane vesicles, non-O1 non-O139, serum resistance
National Category
Cell and Molecular Biology
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-30211 (URN)978-91-7264-918-7 (ISBN)
Public defence
2010-01-22, Major Groove, Försörjningsvägen byggnad 6L, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2009-12-22 Created: 2009-12-14 Last updated: 2009-12-22Bibliographically approved

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Lindmark, BarbroRompikuntal, PramodWai, Sun

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