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The structure of the O-antigenic polysaccharide from Escherichia coli O167:H5 has been investigated. Sugar and methylation analyses, fast-atom-bombardment mass spectrometry and 1H- and 13C NMR spectroscopy were the main methods used. The structure of the repeating unit of the polysaccharide was found to be: [formula in text]. Oligosaccharide derivatives of the polysaccharide were obtained by HF solvolysis and by a Smith degradation. Furthermore, base treatment of the polysaccharide led to a degraded polymeric material. For the methylated polysaccharide the amide linkage between alanine and the galacturonic acid residue was reductively cleaved with LiBD4 in ethanol, to give, among other things, a 3-O-methyl galactose derivative.

Lipopolysaccharide, NMR, LPS, structure, structural, polysaccharide, O-antigen, O antigen, Escherichia, Escherichia coli, polysaccharides, structural studies, galactofuranose, galacturonic acid, amide, L-alanine

NCBI PubMed ID: 9208951
Publication DOI: 10.1111/j.1432-1033.1997.00565.x
Journal NLM ID: 0107600
Publisher: Oxford, UK: Blackwell Science Ltd. on behalf of the Federation of European Biochemical Societies
Institutions: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Sweden, Swedish Insitute of Infectious Disease Control (SMI), Stockholm, Sweden
Methods: methylation, NMR-2D, FAB-MS, partial acid hydrolysis, NMR, sugar analysis, Smith degradation

Escherichia coli is usually a non-pathogenic member of the human colonic flora. However, certain strains have acquired virulence factors and may cause a variety of infections in humans and in animals. There are three clinical syndromes caused by E. coli: (i) sepsis/meningitis; (ii) urinary tract infection and (iii) diarrhoea. Furthermore the E. coli causing diarrhoea is divided into different 'pathotypes' depending on the type of disease, i.e. (i) enterotoxigenic; (ii) enteropathogenic; (iii) enteroinvasive; (iv) enterohaemorrhagic; (v) enteroaggregative and (vi) diffusely adherent. The serotyping of E. coli based on the somatic (O), flagellar (H) and capsular polysaccharide antigens (K) is used in epidemiology. The different antigens may be unique for a particular serogroup or antigenic determinants may be shared, resulting in cross-reactions with other serogroups of E. coli or even with other members of the family Enterobacteriacea. To establish the uniqueness of a particular serogroup or to identify the presence of common epitopes, a database of the structures of O-antigenic polysaccharides has been created. The E. coli database (ECODAB) contains structures, nuclear magnetic resonance chemical shifts and to some extent cross-reactivity relationships. All fields are searchable. A ranking is produced based on similarity, which facilitates rapid identification of strains that are difficult to serotype (if known) based on classical agglutinating methods. In addition, results pertinent to the biosynthesis of the repeating units of O-antigens are discussed. The ECODAB is accessible to the scientific community at http://www.casper.organ.su.se/ECODAB/

NMR, structure, serotype, O-antigen, Enterobacteriacea, database

NCBI PubMed ID: 16594963
Publication DOI: 10.1111/j.1574-6976.2006.00016.x
Journal NLM ID: 8902526
Publisher: Oxford University Press
Correspondence: andrej.weintraub@ki.se
Institutions: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden

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