The O-polysaccharide (O-antigen) was isolated from the lipopolysaccharide of Escherichia coli O137 and studied by sugar analysis and NMR spectroscopy. The following structure of the branched tetrasaccharide repeating unit was established: Formula: see text] Both structure and gene cluster of the E. coli O137 polysaccharide are related to those of the E. coli K40 polysaccharide (Amor et al., 1999), which lacks the side-chain glucosylation but contains serine that is amide-linked to GlcA. Functions of genes in the O137-antigen gene cluster were assigned by a comparison with those in K40 and sequences in the available databases. Particularly, predicted glycosyltransferases encoded in the gene cluster were assigned to the formation of three glycosidic linkages in the O-polysaccharide repeating unit.
Lipopolysaccharide, O-antigen, Escherichia coli, bacterial polysaccharide structure, O-antigen gene cluster
Publication DOI: 10.1016/j.carres.2016.01.002Journal NLM ID: 0043535Publisher: Elsevier
Correspondence: perepel@ioc.ac.ru
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, 300457, China, The Third Central Hospital of Tianjin, Hedong District, Tianjin 300170, China
Methods: 13C NMR, 1H NMR, NMR-2D, sugar analysis, acid hydrolysis, GLC, GPC, mild acid degradation, function analysis of gene clusters