Structure elucidation and gene cluster characterization of the O-antigen of Escherichia coli O80

• Escherichia coli O80 is a HUS-associated serotype.
• Structure of the O-polysaccharide of E. coli O80 was elucidated.
• The hexasaccharide O-unit of the O80-polysaccharide includes two side-chain l-Fuc residues.
• The O-antigen gene cluster of E. coli O80 is consistent with the O-polysaccharide structure.

Mild alkaline degradation of the lipopolysaccharide of Escherichia coli O80 afforded a polysaccharide, which was studied by sugar analysis, selective cleavage of glycosidic linkages, and 1H and 13C NMR spectroscopy. Solvolysis of the polysaccharide with CF3CO2H cleaved the linkages of α-Fuc and β-linked GlcNAc and GalNAc residues to give two disaccharides. The following structure of the hexasaccharide repeating unit of the O-polysaccharide was established:Figure optionsDownload as PowerPoint slideThe polysaccharide repeat also contains a minor O-acetyl group but its position was not determined. The O-antigen gene cluster of E. coli O80 between the conserved galF and gnd genes was analyzed and found to be consistent with the O-polysaccharide structure established.

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