The O-specific polysaccharide structure and gene cluster of serotype O:12 of the Yersinia pseudotuberculosis complex, and the identification of a novel L-quinovose biosynthesis gene.

A major virulence factor for Yersinia pseudotuberculosis is lipopolysaccharide, including O-polysaccharide (OPS). Currently, the OPS based serotyping scheme for Y. pseudotuberculosis includes 21 known O-serotypes, with genetic and structural data available for 17 of them. The completion of the OPS structures and genetics of this species will enable the visualization of relationships between O-serotypes and allow for analysis of the evolutionary processes within the species that give rise to new serotypes. Here we present the OPS structure and gene cluster of serotype O:12, thus adding one more to the set of completed serotypes, and show that this serotype is present in both Y. pseudotuberculosis and the newly identified Y. similis species. The O:12 structure is shown to include two rares ugars: 4-C[(R)-1-hydroxyethyl]-3,6-dideoxy-D-xylo-hexose(D-yersiniose) and 6-deoxy-L-glucopyranose (L-quinovose).We have identified a novel putative guanine diphosphate(GDP)-L-fucose 4-epimerase gene and propose a pathway for the synthesis of GDP-L-quinovose, which extends the known GDP-L-fucose pathway.