Simon R. Haseley

Structure of the putative O10 antigen from Acinetobacter baumannii

A polysaccharide containing L-rhamnose, 2-acetamido-2-deoxy-D-glucose, and 2-acetamido-2-deoxy-D-mannose was obtained from an aqueous phenol extract of isolated cell walls from the reference strain for Acinetobacter baumannii serogroup O10. By means of NMR studies and chemical degradations, the repeating unit of the polymer (the putative O10 antigen) was identified as a branched pentasaccharide of the structure shown.

Structure of a surface polysaccharide from Acinetobacter baumannii strain 214

A polysaccharide containing D-galactose, D-glucose, and 2-acetamido-2-deoxy-D-galactose was obtained from an aqueous phenol extract of isolated cell walls from Acinetobacter baumannii strain 214. By means of NMR studies and chemical degradations, the repeating unit of the polymer was identified as a branched trisaccharide of the structure shown. [formula: see text]

Structure of the O-7 antigen from Acinetobacter baumannii

The polymeric O-antigen was isolated from the lipopolysaccharide of the reference of the reference strain for Acinetobacter baumannii serogroup O-7. Both the lipopolysaccharide and the isolated polymer reacted with the homologous antiserum. Monosaccharide analyses and NMR spectra showed that the polymer had a hexasaccharide repeating unit constructed from residues of L-rhamnose (4) and N-acetyl-D-glucosamine (2). The following structure for the repeating unit was established by means of detailed interpretation of the NMR spectra, methylation analysis, and chemical degradations. The tetrasaccharide backbone is identical to that for the O-10 antigen of A. baumannii, which has alpha-D-ManpNAc as the lateral substituent in place of the disaccharide present in the O-7 antigen. [formula: see text]