Structure of the O-polysaccharides of Escherichia coli O162 containing 4-deoxy-D-arabino-hexose and structurally related O-polysaccharides of E. coli O101

Abstract

Immunospecificity of gram-negative bacteria, including Escherichia coli, is defined by the fine structure of the O-specific polysaccharide chain of the lipopolysaccharide called O-antigen. Structures of the O-antigens have been established for the majority of about 200 known serotypes of E. coli but serotype O162 was among few that have not been studied in this respect yet. In the present work, it was found that bacteria of this serotype produce several O-polysaccharides differing in the main chains composed of N-acetylglucosamine and N-acetylgalactosamine residues as well as in the presence or absence of side-chain 4-deoxy-D-arabino-hexose residues. It was also shown that E. coli O101 produces two linear O-polysaccharides, which are structurally similar to the main chains of E. coli O162, whereas only one of them had been identified in these bacteria earlier.