Structure and gene cluster of the O-antigen of Enterobacter cloacae G3421

Abstract

The O-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide of Enterobacter cloacae G3421 and studied by sugar analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy. In addition, partial solvolysis with anhydrous trifluoroacetic acid was applied, which cleaved selectively the α-l-rhamnopyranosidic linkages. The following structure of the branched hexasaccharide repeating unit was established. The O-polysaccharide studied shares the β-l-Rhap-(1→4)-α-l-Rhap-(1→2)-α-l-Rhap trisaccharide fragment with the O-polysaccharide of Shigella boydii type 18. The O-antigen gene cluster of E. cloacae G3421 was sequenced. Functions of genes in the cluster, including those for glycosyltransferases, were tentatively assigned by a comparison with sequences in the available databases and found to be consistent with the O-polysaccharide structure.

Genetic Characterization of the O-Antigen and Development of a Molecular Serotyping Scheme for Enterobacter cloacae

“…The O-AGC of E. cloacae has been reported to be located between two housekeeping genes, galF and gnd, and shows perfect correlations with each O-antigen structure in several isolates (Filatov et al, 2014;Perepelov et al, 2014Perepelov et al, , 2015Perepelov et al, , 2016Perepelov et al, , 2017Han et al, 2017). These previous studies shed clear genetic and evolutionary information regarding O-AGC of E. cloacae.…”