Structural determination of the O-antigenic polysaccharide from Escherichia coli O35 and cross-reactivity to Salmonella arizonae O62.

The structure of the O-antigenic polysaccharide from Escherichia coli O35 has been investigated with the aid of NMR spectroscopy, sugar and methylation analyses. The sequence of the sugar residues could be determined by NOESY and heteronuclear-multiple-bond-connectivity NMR experiments. The polysaccharide is composed of hexasaccharide repeating units with the following structure, where Rha and GalNAcAN represent rhamnose and 2-acetamido-2-deoxy-galacturonamide, respectively: carbohydrate sequence [see text]. The O-antigen of Escherichia coli O35 is similar to the O-specific polysaccharide from Salmonella arizonae O62, which instead has a terminal 2-acetamido-2-deoxy-alpha-D-galacturonic acid residue. Immunochemical analyses using a rabbit antiserum specific for the Salmonella arizonae O62 O-antigen showed an identical reactivity with both lipopolysaccharides.