Identification of three oligo-/polysaccharide-specific ligases in Yersinia enterocolitica

• Published in: Molecular microbiology 2012-01, Vol.83 (1), p.125-136
• Main Authors: Pinta, Elise, Li, Zhilin, Batzilla, Julia, Pajunen, Maria, Kasanen, Tiina, Rabsztyn, Kamila, Rakin, Alexander, Skurnik, Mikael
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Biosynthesis; Escherichia; Fundamental and applied biological sciences. Psychology; Gene expression; Genes; Gram-negative bacteria; Ligases - genetics; Ligases - metabolism; Lipids; Lipopolysaccharides - biosynthesis; Microbiology; Miscellaneous; Molecular Sequence Data; Mutation; Yersinia enterocolitica; Yersinia enterocolitica - enzymology; Yersinia enterocolitica - genetics; Yersinia enterocolitica - metabolism; Yersinia pestis
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2011.07918.x

Summary In lipopolysaccharide (LPS) biosynthesis of Gram‐negative bacteria the lipid A‐core oligosaccharide (LA‐core) and O‐polysaccharide (O‐PS) biosynthesis pathways proceed separately and converge in periplasmic space where the waaL‐encoded ligase joins O‐PS onto LA‐core. Enterobacterial common antigen (ECA) biosynthesis follows that of O‐PS except that ECA is usually ligated to phosphatidylglycerol (PG) and only rarely to LA‐core. In Yersinia enterocolitica serotype O:3 LPS is composed of LA‐inner core (IC) onto which a homopolymeric O‐PS, a hexasaccharide called outer core (OC), and/or ECA are ligated. We found that an individual O:3 LPS molecule carries either OC or O‐PS substitution but not both. Related to this, we identified three genes in Y. enterocolitica O:3 that all expressed O‐PS ligase activity in the Escherichia coliΔwaaL mutant. The LPS phenotypes of Y. enterocolitica O:3 single, double and triple ligase mutants indicated that two of ligases, named as WaaLos and WaaLps, had a preferred substrate specificity for OC and O‐PS, respectively, although with some promiscuity between the ligases; the third ligase named as WaaLxs was not involved in LPS or ECA biosynthesis. In Y. enterocolitica O:8 the WaaLos homologue (Ye1727) ligated a single pentasaccharide O‐unit to LA‐IC suggesting that in both Y. enterocolitica O:3 and O:8 WaaLos is an oligosaccharide (OS)‐specific ligase. Finally, Yersinia pestis and Y. pseudotuberculosis carry only the waaLps gene, while either waaLos or waaLxs or both are additionally present in other Yersinia species. This is the first report on the presence of three different oligo‐/polysaccharide‐specific ligases in a single bacterium.