Structure and genetics of the O-antigen of Enterobacter cloacae G3054 containing di-N-acetylpseudaminic acid

• E. cloacae is a pathogen causing respiratory, urinary, and surgical site infections.
• The OPS structure of E. cloacae G3054 was established.
• The gene cluster of E. cloacae G3054 has been sequenced and genes were annotated.

Mild acid degradation of the lipopolysaccharide of Enterobacter cloacae G3054 resulted in the cleavage of the O-polysaccharide at the linkage of residues of 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid (di-N-acetylpseudaminic acid, Pse5Ac7Ac) in the main chain. The resultant oligosaccharide and an alkali-treated lipopolysaccharide were studied by sugar analysis along with 1H and 13C NMR spectroscopy, and the following structure of the branched pentasaccharide O-unit of the O-polysaccharide was established:Figure optionsDownload as PowerPoint slideThe O-antigen gene cluster of E. cloacae G3054 between conserved genes galF and gnd was sequenced. Most genes necessary for the O-antigen synthesis were found in the cluster and their functions were tentatively assigned by comparison with sequences in the available databases.

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