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A phosphorylated O-specific polysaccharide was obtained by mild acidic degradation of the lipopolysaccharide from the enteric bacterium Escherichia coli O130 and characterized by the methods of chemical analysis, including dephosphorylation and 1H and 13C NMR spectroscopy. The polysaccharide was shown to be composed of branched tetrasaccharide repeating units containing two N-acetyl-D-galactosamine residues,D-galactose, D-glucose,and glycerophosphate residues (one of each). The polysaccharide has the following structure, which is unique among the known bacterial polysaccharides:

Escherichia coli, O-specific polysaccharide, teichoic acid, glycerophosphate, structure; NMR spectroscopy

Publication DOI: 10.1134/S1068162007010062
Journal NLM ID: 9420101
Publisher: Springer Science and Business Media
Correspondence: knirel@ioc.ac.ru
Institutions: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia,TEDA School of Biological Sciences and Biotechnology, Nankai University, TEDA, China Tyan-jin Key Laboratory for Microbial Functional Genomics, TEDA College, Nankai University, TEDA, Tyan-jin, China
Methods: 13C NMR, 1H NMR, NMR-2D, HF solvolysis, sugar analysis, 31P NMR, GLC, mild acid hydrolysis, NMR-1D

Gene clusters for biosynthesis of 24 of 34 basic O-antigen forms of Shigella spp. are identical or similar to those of the genetically closely related bacterium Escherichia coli. For 18 of these relatedness was confirmed chemically by elucidation of the O-antigen (O-polysaccharide) structures. In this work, structures of the six remaining O-antigens of E. coli O32, O53, O79, O105, O183 (all related to S. boydii serotypes), and O38 (related to S. dysenteriae type 8) were established using (1)H and (13)C NMR spectroscopy. They were found to be identical to the Shigella counterparts, except for the O32- and O38-polysaccharides, which differ in the presence of O-acetyl groups. The structure of the E. coli O105-related O-polysaccharide of S. boydii type 11 proposed earlier is revised. The contents of the O-antigen gene clusters of the related strains of E. coli and Shigella spp. and different mechanisms of O-antigen diversification in these bacteria are discussed in view of the O-polysaccharide structures established. These data illustrate the value of the O-antigen chemistry and genetics for elucidation of evolutionary relationships of bacteria.

Escherichia coli, Shigella dysenteriae, Shigella boydii, O-antigen gene cluster, O-Polysaccharide structure

NCBI PubMed ID: 27301288
Publication DOI: 10.1134/S0006297916060067
Journal NLM ID: 0376536
Publisher: Nauka/Interperiodica
Correspondence: yknirel@gmail.com
Institutions: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Nankai University, TEDA Institute of Biological Sciences and Biotechnology, Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 300457 Tianjin, China
Methods: 13C NMR, 1H NMR, NMR-2D, sugar analysis, acid hydrolysis, de-O-acetylation, GPC, mild acid degradation, function analysis of gene clusters

Escherichia coli includes clonal groups of both commensal and pathogenic strains, with some of the latter causing serious infectious diseases. O antigen variation is current standard in defining strains for taxonomy and epidemiology, providing the basis for many serotyping schemes for Gram-negative bacteria. This review covers the diversity in E. coli O antigen structures and gene clusters, and the genetic basis for the structural diversity. Of the 187 formally defined O antigens, six (O31, O47, O67, O72, O94 and O122) have since been removed and four (O14, O34, O89 and O144) strains do not produce any O antigen. Therefore, structures are presented for 176 of the 181 E. coli O antigens, some of which include subgroups. Most (93%) of these O antigens are synthesized via the Wzx/Wzy pathway, 11 via the ABC transporter pathway, with O20, O57 and O60 still uncharacterized due to failure to find their O antigen gene clusters. Biosynthetic pathways are given for 38 of the 49 sugars found in E. coli O antigens, and several pairs or groups of the E. coli antigens that have related structures show close relationships of the O antigen gene clusters within clades, thereby highlighting the genetic basis of the evolution of diversity.

structure, O antigen, Escherichia coli, gene cluster, serogroup, diversity

NCBI PubMed ID: 31778182
Publication DOI: 10.1093/femsre/fuz028
Journal NLM ID: 8902526
Publisher: Oxford University Press
Correspondence: G. Widmalm ; Lei Wang
Institutions: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China, The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, China, School of Molecular and Microbial Bioscience (G08), University of Sydney, Sydney, Australia, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China, Department of Immunology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China