Document Type
Article
Publication Date
3-2017
Abstract
Type VI secretion systems (T6SS) enable bacteria to engage neighboring cells in contact-dependent competition. In Vibrio cholerae, three chromosomal clusters each encode a pair of effector and immunity genes downstream of those encoding the T6SS structural machinery for effector delivery. Different combinations of effector-immunity proteins lead to competition between strains of V. cholerae, which are thought to be protected only from the toxicity of their own effectors. Screening of all publically available V. cholerae genomes showed that numerous strains possess long arrays of orphan immunity genes encoded in the 3' region of their T6SS clusters. Phylogenetic analysis reveals that these genes are highly similar to those found in the effector-immunity pairs of other strains, indicating acquisition by horizontal gene transfer. Extensive genomic comparisons also suggest that successive addition of effector-immunity gene pairs replaces ancestral effectors, yet retains the cognate immunity genes. The retention of old immunity genes perhaps provides protection against nearby kin bacteria in which the old effector was not replaced. This mechanism, combined with frequent homologous recombination, is likely responsible for the high diversity of T6SS effector-immunity gene profiles observed for V. cholerae and closely related species.
Recommended Citation
Kirchberger, Paul C., Daniel Unterweger, Daniele Provenzano, Stefan Pukatzki, and Yan Boucher. "Sequential displacement of type VI secretion system effector genes leads to evolution of diverse immunity gene arrays in Vibrio cholerae." Scientific reports 7, no. 1 (2017): 45133. https://doi.org/10.1038/srep45133
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Publication Title
Scientific Reports
DOI
https://doi.org/10.1038/srep45133
Comments
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