Cell‐Wall Lipopolysaccharide of the ‘Shigella‐like’Escherichia coli 058

Abstract

Two lipopolysaccharide preparations were obtained from E. coli O58 by extraction with 45% aqueous phenol and fractional precipitation with cetyltrimethyl ammonium bromide (Cetavlon). Chemical analysis and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate showed that the 2 preparations differed only in the extent of the O-specific polysaccharide moiety. The O-specific polysaccharide was characterized with PMR and IR spectroscopy, optical rotation and paper electrophoresis. GLC and ion-exchange chromatography showed that it contained D-mannose [Man], 2-acetamido-2-deoxy-D-glucose, 3-O-(R-1''-carboxyethyl)-L-rhamnose (rhamnolactylic acid) and O-acetyl [Ac] groups in the molar ratios of 2:1:1:1. The polysaccharide and oligosaccharides obtained from it were subjected to methylation and chromic acid oxidation. The results obtained indicated that the polysaccharide consists of tetrasaccharide repeating units in which the trisaccharide .beta.-Glc[glucosamine]NAc1 .sbd. 4.alpha.Man-1 .sbd. 4(2/3-O-Ac)-Man is substituted at C-3 of the non-acetylated mannose with rhamnolactylic acid. The repeating units are joined through .alpha.-mannosyl-1 .sbd. 3-glucosamine bonds. This structure is identical with that of the cell wall polysaccharide of S. dysenteriae type 5. [This study has relevance to the pathogenicity of these 2 bacteria].