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This review summarizes data on the composition and structure of the O-antigens, the polysaccharide chains of the outer-membrane lipopolysaccharides (LPS) of Gram-negative bacteria defining the immunospecificity of these microbial cells. Special reference is given to some structural features of the O-antigens, such as the presence of unique monosaccharides and noncarbohydrate components, masked regularity, and the occurrence in one microorganism of LPS with structurally different polysaccharide chains. Antigenic relationships between microorganisms belonging to different taxonomic groups are discussed.

structure, O-antigen, chemical composition, bacterial lipopolysaccharides, Salmonella livingstone C1

NCBI PubMed ID: 7533007
Journal NLM ID: 0376536
Publisher: Nauka/Interperiodica
Institutions: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia

The structure of the O-polysaccharide component of the lipopolysaccharide produced by Escherichia coli 0119 was determined by the use of methylation analysis, periodate oxidation, 1D and 2D nuclear magnetic resonance spectroscopy, and mass spectrometric methods. The O-polysaccharide was found to be a high molecular weight polymer of a repeating pentasaccharide unit composed of D-mannose, D-galactose, L-rhamnose, 2-acetamido-2-deoxy-D-glucose, and 2-acetamido-2,3-dideoxy-3-formamido-D-rhamnose residues (1:1:1:1:1) and had the structure: [formula: see text].

NMR, Escherichia coli, O-polysaccharide

NCBI PubMed ID: 1284112
Publication DOI: 10.1016/S0008-6215(92)84247-P
Journal NLM ID: 0043535
Publisher: Elsevier
Institutions: Institute of Biological Sciences, National Research Council of Canada, Ottawa, Ontario
Methods: 13C NMR, 1H NMR, methylation, GLC-MS, NMR-2D, FAB-MS, 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