Upon mild acid degradation of the lipopolysaccharide of Escherichia coli O165, the O-polysaccharide chain was cleaved at the glycosidic linkage of 5-N-acetyl-7-N-[(R)-3-hydroxybutanoyl]pseudaminic acid (Pse5Hb7Ac). Analysis of the resulting linear tetrasaccharide and alkali-treated lipopolysaccharide by 1H/13C 1D and 2D NMR spectroscopy enabled elucidation of the following structure of the O-polysaccharide:→8)-α-Psep5Hb7Ac-(2→6)-β-d-Galp-(1→4)-β-d-Glcp-(1→3)-α-d-GlcpNAc-(1→The β-d-Galp-(1→4)-β-d-Glcp-(1→3)-d-GlcpNAc structural element is also present in the O-polysaccharide of E. coli O82. The content of the O-antigen gene cluster of E. coli O165 was found to be consistent with the O-polysaccharide structure established. Functions of proteins encoded in the gene cluster, including enzymes involved in the Pse5Hb7Ac biosynthesis and glycosyltransferases, were putatively assigned by comparison with sequences in available databases.
Lipopolysaccharide, Escherichia coli, bacterial polysaccharide structure, O-antigen gene cluster
NCBI PubMed ID: 26582605Publication DOI: 10.1093/glycob/cwv106Journal NLM ID: 9104124Publisher: IRL Press at Oxford University Press
Correspondence: goran.widmalm@su.se
Institutions: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
Methods: 13C NMR, 1H NMR, NMR-2D, GLC, mild acid hydrolysis, composition analysis, mild alkaline degradation, NMR-1D, GPC, bioinformatic analysis
Found