Composition, Acquisition, and Distribution of the Vi Exopolysaccharide-Encoding Salmonella enterica Pathogenicity Island SPI-7

Pickard, Derek, Wain, John, Baker, Stephen, Line, Alexandra, Chohan, Sonia, Fookes, Maria, Barron, Andrew, O Gaora, Peadar, Chabalgoity, José A., Thanky, Niren, Scholes, Christoph, Thomson, Nicholas, Quail, Michael, Parkhill, Julian and Dougan, Gordon (2003) Composition, Acquisition, and Distribution of the Vi Exopolysaccharide-Encoding Salmonella enterica Pathogenicity Island SPI-7. Journal of Bacteriology, 185 (17). pp. 5055-5065. ISSN 0021-9193

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Abstract

Vi capsular polysaccharide production is encoded by the viaB locus, which has a limited distribution in Salmonella enterica serovars. In S. enterica serovar Typhi, viaB is encoded on a 134-kb pathogenicity island known as SPI-7 that is located between partially duplicated tRNApheU sites. Functional and bioinformatic analysis suggests that SPI-7 has a mosaic structure and may have evolved as a consequence of several independent insertion events. Analysis of viaB-associated DNA in Vi-positive S. enterica serovar Paratyphi C and S. enterica serovar Dublin isolates revealed the presence of similar SPI-7 islands. In S. enterica serovars Paratyphi C and Dublin, the SopE bacteriophage and a 15-kb fragment adjacent to the intact tRNApheU site were absent. In S. enterica serovar Paratyphi C only, a region encoding a type IV pilus involved in the adherence of S. enterica serovar Typhi to host cells was missing. The remainder of the SPI-7 islands investigated exhibited over 99% DNA sequence identity in the three serovars. Of 30 other Salmonella serovars examined, 24 contained no insertions at the equivalent tRNApheU site, 2 had a 3.7-kb insertion, and 4 showed sequence variation at the tRNApheU-phoN junction, which was not analyzed further. Sequence analysis of the SPI-7 region from S. enterica serovar Typhi strain CT18 revealed significant synteny with clusters of genes from a variety of saprophytic bacteria and phytobacteria, including Pseudomonas aeruginosa and Xanthomonas axonopodis pv. citri. This analysis suggested that SPI-7 may be a mobile element, such as a conjugative transposon or an integrated plasmid remnant.

Item Type: Article
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Rhiannon Harvey
Date Deposited: 13 Jul 2011 10:38
Last Modified: 07 May 2019 16:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/33566
DOI: 10.1128/JB.185.17.5055-5065.2003

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