Bacterial Secretion: Vibrio Cholerae Beats the Competition

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Bacterial secretion Vibrio cholerae beats the competition

actin crosslinking domain (ACD) of the V. cholerae T6SS protein The Vibrio VgrG1. Given that E. coli pos cholerae sesses the actin homologue MreB, the authors analysed the effects type VI on E. coli of a V. cholerae str. V52 secretion mutant in which the ACD had been system can deleted from VgrG1. The mutant, target both which had previously been shown to be harmless to eukaryotic cells, eukaryotic and retained full virulence against E. coli, bacterial cells. indicating that MreB is unlikely to be the target. This suggests that the V. cholerae T6SS might kill eukaryo tic and bacterial cells by different mechanisms. T6SSencoding genes are wide spread among V. cholerae strains. Several bacterial systems have been str. V52 can also kill a range of Hence, the T6SS could be used by described that secrete effector pro Gramnegative bacteria, including these organisms to outcompete teins into the extracellular milieu or Escherichia coli, Salmonella enterica other bacteria and evade predation directly into host cells. The type VI subsp. enterica serovar Typhimurium by phagocytic cells in both the host secretion system (T6SS) was recently and Citrobacter rodentium. This gut and the aquatic environment. discovered, and its main role is still effect was shown to be dependent However, the pandemic serogroups unclear, as only some T6SSs seem on a functional T6SS, as it was of V. cholerae do not show toxicity to contribute to pathogenesis. Now, abolished in a T6SSdefective mutant against E. coli or D. discoideum under MacIntyre and colleagues report that of V. cholerae str. V52. Moreover, the laboratory conditions, which suggests the T6SS of Vibrio cholerae can kill authors demonstrated that cell–cell that the T6SS might be tightly regu both eukaryotic and bacterial cells contact was required, as killing was lated in these strains. Future work on contact. abrogated by placing a 0.22 μm filter will determine whether this secretion Previous research had shown (which would allow the diffusion of system has a role in the pathogenesis that the T6SS of V. cholerae str. V52, any secreted substances) between or transmission of cholera. which is in the O37 serogroup, predator and prey. Interestingly, Cesar Sanchez conferred virulence against the Grampositive bacteria and other oriGinal researcH PaPer MacIntyre, D. L., phagocytic amoeba Dictyostelium serogroups of V. cholerae were Miyata, S. T., Kitaoka, M. & Pukatzki, S. The Vibrio discoideum and against mouse macro unharmed by V. cholerae str. V52. cholerae type VI secretion system displays phages. MacIntyre and colleagues T6SSdependent killing of antimicrobial properties. Proc. Natl Acad. Sci. USA 107, 19520–19524 (2010) found that wildtype V. cholerae eukaryotic cells is mediated by the