A genomic island in Vibrio cholerae with VPI-1 site-specific recombination characteristics contains CRISPR-Cas and type VI secretion modules

Labbate, Maurizio, Orata, Fabini D., Petty, Nicola K., Jayatilleke, Nathasha D., King, William L., Kirchberger, Paul C., Allen, Chris, Mann, Gulay, Mutreja, Ankur, Thomson, Nicholas R., Boucher, Yan and Charles, Ian G. (2016) A genomic island in Vibrio cholerae with VPI-1 site-specific recombination characteristics contains CRISPR-Cas and type VI secretion modules. Scientific Reports, 6, [36891]. (doi:10.1038/srep36891).

Abstract

Cholera is a devastating diarrhoeal disease caused by certain strains of serogroup O1/O139 Vibrio cholerae. Mobile genetic elements such as genomic islands (GIs) have been pivotal in the evolution of O1/O139 V. cholerae. Perhaps the most important GI involved in cholera disease is the V. cholerae pathogenicity island 1 (VPI-1). This GI contains the toxin-coregulated pilus (TCP) gene cluster that is necessary for colonization of the human intestine as well as being the receptor for infection by the cholera-toxin bearing CTX phage. In this study, we report a GI (designated GIVchS12) from a non-O1/O139 strain of V. cholerae that is present in the same chromosomal location as VPI-1, contains an integrase gene with 94% nucleotide and 100% protein identity to the VPI-1 integrase, and attachment (att) sites 100% identical to those found in VPI-1. However, instead of TCP and the other accessory genes present in VPI-1, GIVchS12 contains a CRISPR-Cas element and a type VI secretion system (T6SS). GIs similar to GIVchS12 were identified in other V. cholerae genomes, also containing CRISPR-Cas elements and/or T6SS's. This study highlights the diversity of GIs circulating in natural V. cholerae populations and identifies GIs with VPI-1 recombination characteristics as a propagator of CRISPR-Cas and T6SS modules.

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Contributors

Author: William L. King

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