Escherichia albertii EA046 (O9) harbors two polysaccharide gene clusters for synthesis of the O-antigen by the Wzx/Wzy-dependent pathway and a mannan shared by Escherichia coli O8 by the Wzm/Wzt-dependent pathway

• Published in: International journal of biological macromolecules 2020-01, Vol.142, p.609-614
• Main Authors: Naumenko, Olesya I., Zheng, Han, Shashkov, Alexander S., Sun, Yong, Senchenkova, Sof'ya N., Bai, Li, Wang, Jianping, Wang, Hong, Li, Qun, Knirel, Yuriy A., Xiong, Yanwen
• Format: Article
• Language: English
• Subjects: Escherichia albertii; Lipopolysaccharide; O-antigen
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2019.09.135

•The lipopolysaccharide of Escherichia albertii O9 contains two polysaccharides.•One is composed of tetrasaccharide repeating units.•The other is identified as a mannan.•Two polysaccharide gene clusters flanked by galF gene and the histidine synthesis operon. O antigen is a polysaccharide chain of a lipopolysaccharide on the outer membrane of Gram-negative bacteria. O-antigen-based serotyping and molecular typing are widely used for epidemiological and surveillance purposes. Two polysaccharides were isolated by Sephadex G-50 gel-permeation chromatography following mild acid degradation of the lipopolysaccharide of Escherichia albertii EA046 assigned to serotype O9. The polysaccharide eluted first was considered as the O-antigen. It was composed of tetrasaccharide repeating units containing two residues of d-Man and one residue each of d-Gal and d-GlcNAc as well as glycerol phosphate. It had the following unique structure which was established by NMR spectroscopy applied to the initial and dephosphorylated polysaccharides: ▪ The polysaccharide eluted from the gel second was identified as a mannan with a → 3)-β-d-Manp-(1 → 2)-α-d-Manp-(1 → 2)-α-d-Manp-(1 → trisaccharide repeating unit. In E. albertii EA046, two polysaccharide gene clusters were found at a chromosomal locus flanked by the conserved galF gene and the histidine synthesis operon (his). They were suggested to drive the biosynthesis of the O-antigen by the Wzy/Wzy-dependent pathway and the mannan by the Wzm/Wzt-dependent pathway. The mannan shares the structure and gene cluster with a polysaccharide isolated earlier from the lipopolysaccharide of Escherichia coli O8.