Integrating conjugative elements of the SXT/R391 family trigger the excision and drive the mobilization of a new class of Vibrio genomic islands

Mol Microbiol. 2010 Nov;78(3):576-88. doi: 10.1111/j.1365-2958.2010.07364.x. Epub 2010 Sep 28.


In vibrios and enterobacteria lateral gene transfer is often facilitated by integrating conjugative elements (ICEs) of the SXT/R391 family. SXT/R391 ICEs integrate by site-specific recombination into prfC and transfer by conjugation, a process that is initiated at a specific locus called the origin of transfer (oriT(SXT) ). We identified genomic islands (GIs) harbouring a sequence that shares >63% identity with oriT(SXT) in three species of Vibrio. Unlike SXT/R391 ICEs, these GIs are integrated into a gene coding for a putative stress-induced protein and do not appear to carry any gene coding for a conjugative machinery or for mobilization proteins. Our results show that SXT/R391 ICEs trigger the excision and mediate the conjugative transfer in trans of the three Vibrio GIs at high frequency. GIs' excision is independent of the ICE-encoded recombinase and is controlled by the ICE-encoded transcriptional activator SetCD, which is expressed during the host SOS response. Both mobI and traI, two ICE-borne genes involved in oriT recognition, are essential for GIs' transfer. We also found that SXT/R391 ICEs mobilize in trans over 1 Mb of chromosomal DNA located 5' of the GIs' integration site. Together these results support a novel mechanism of mobilization of GIs by ICEs of the SXT/R391 family.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics*
  • Base Sequence
  • Conjugation, Genetic*
  • DNA Transposable Elements*
  • Genomic Islands*
  • Molecular Sequence Data
  • Multigene Family
  • Recombinases / genetics
  • Recombination, Genetic
  • Vibrio / enzymology
  • Vibrio / genetics*


  • Bacterial Proteins
  • DNA Transposable Elements
  • Recombinases