An O-specific polysaccharide (O-antigen) was isolated by mild acid degradation of the lipopolysaccharide of Escherichia coli O50 followed by gel chromatography on Sephadex G-50. The following structure of the tetrasaccharide repeat was established by sugar analysis and 1D and 2D 1H and 13C NMR spectroscopy: →3)-α-l-Rhap-(1→2)-α-l-Rhap-(1→3)-β-l-Rhap-(1→4)-β-d-GlcpNAc-(1→. The linear O50 polysaccharide has the same structure as the main chain of the branched O polysaccharide of E. coli O2 studied earlier [Jansson et al., Carbohydr. Res. 161 (1987) 273-279], which differs in the presence of a side-chain α-d-Fucp3NAc residue. In spite of the difference between the O-polysaccharides, the corresponding genes in the O2- and O50-antigen gene cluster are 99-100% identical. The genetic basis for the lack of d-Fucp3NAc from the O50 polysaccharide is evidently a point mutation in the aminotransferase gene fdtB of the d-Fucp3NAc synthesis pathway resulting in a single amino acid change from histidine in O2 to arginine in O50.
Lipopolysaccharide, O-antigen, Escherichia coli, O-specific polysaccharide, bacterial polysaccharide structure, O-antigen gene cluster
NCBI PubMed ID: 29787897Publication DOI: 10.1016/j.carres.2018.05.001Journal NLM ID: 0043535Publisher: Elsevier
Correspondence: andreivperepelov@gmail.com
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China, Higher Chemical College of the Russian Academy of Sciences, D.I. Mendeleev University of Chemical Technology of Russia, Moscow, Russia
Methods: 13C NMR, 1H NMR, NMR-2D, sugar analysis, acid hydrolysis, GLC, GPC, delipidation, function analysis of gene clusters
Found