Structure and gene cluster of the O-antigen of Escherichia coli O76

The O-polysaccharide (O-antigen) of Escherichia coli O76 was studied by sugar analysis along with 1D and 2D 1H,13C NMR spectroscopies. The following structure of the linear tetrasaccharide repeating unit was established:The degree of O-acetylation of 4-substituted β-GalNAc residue is ∼70%. The O-antigen gene cluster of E. coli O76 was sequenced. The functions of genes in the O-antigen gene cluster were tentatively assigned by comparison with sequences in the available databases and found to be in full agreement with the E. coli O76 O-antigen structure.