Mild acid degradation of the lipopolysaccharide of Escherichia coli O96 afforded a mixture of two polysaccharides. The following structure of the pentasaccharide repeating unit of the major polymer was established by sugar analysis, Smith degradation, and (1)H and (13)C NMR spectroscopy: [Formula: see text]. The O-antigen gene cluster of E. coli O96 between conserved galF and gnd genes was found to be consistent with this structure, and hence, the major polysaccharide represents the O96-antigen. The O96-antigen structure and gene cluster are similar to those of E. coli O170, and two proteins encoded in the gene clusters of both bacteria were putatively assigned a function of galactofuranosyltransferases. The minor polymer has the same structure as a peptidoglycan-related polysaccharide reported earlier in Providencia alcalifeciens O45 and several other O-serogoups of this species (Ovchinnikova OG, Liu B, Kocharova NA, Shashkov AS, Kondakova AN, Siwinska M, Feng L, Rozalski A, Wang L, Knirel YA. Biochemistry (Moscow) 2012;77:609-15) →4)-β-D-GlcpNAc-(1→4)-β-D-GlcpNAc3(Rlac-lAla)-(1→ where Rlac-lAla indicates (R)-1-[(S)-1-carboxyethylaminocarbonyl]ethyl.
O-antigen, Escherichia coli, O-polysaccharide, bacterial polysaccharide structure, O-antigen gene cluster, Peptidoglycan-related polysaccharide
NCBI PubMed ID: 26706815Publication DOI: 10.1016/j.carres.2015.11.005Journal NLM ID: 0043535Publisher: Elsevier
Correspondence: perepel@ioc.ac.ru
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
Methods: 13C NMR, 1H NMR, NMR-2D, sugar analysis, ESI-MS, acid hydrolysis, GLC, Smith degradation, GPC, mild acid degradation, function analysis of gene clusters