Revision of the O-polysaccharide structure of Yersinia pseudotuberculosis O:1a; confirmation of the function of WbyM as paratosyltransferase.

An O-polysaccharide was isolated by mild acid degradation at pH 4.5 of the long-chain lipopolysaccharide of Yersinia pseudotuberculosis PB1 (serotype O:1a) and studied using 2D NMR spectroscopy. It was found to contain two uncommon monosaccharides: paratose (3,6-dideoxy-d-ribo-hexose, Par) in the furanose form and 6-deoxy-d-manno-heptose (d-6dmanHep). The following structure of a branched tetrasaccharide repeat (O-unit) with a disaccharide side chain was established: This structure is at variance with the O-polysaccharide structure of Y. pseudotuberculosis O:1a reported earlier (Komandrova, N. A.; Gorshkova, R. P.; Isakov, V. V.; Ovodov, Y. S. Bioorg. Khim.1984, 10, 232-237). A comparative study by high-resolution ESI MS of the short-chain lipopolysaccharides from strain PB1 and a wbyM mutant thereof confirmed the function of wbyM as the paratosyltransferase gene.