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

Sci Rep. 2016 Nov 15:6:36891. 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Clustered Regularly Interspaced Short Palindromic Repeats
  • Genomic Islands*
  • Multigene Family
  • Sequence Analysis, DNA
  • Type VI Secretion Systems / genetics
  • Vibrio cholerae O139 / genetics*
  • Vibrio cholerae O139 / pathogenicity
  • Vibrio cholerae non-O1 / genetics*
  • Vibrio cholerae non-O1 / pathogenicity
  • Virulence Factors / genetics*

Substances

  • Bacterial Proteins
  • Type VI Secretion Systems
  • Virulence Factors