Relatedness of the O-polysaccharide structures of Escherichia coli O123 and Salmonella enterica O58, both containing 4,6-dideoxy-4-{N-[(S)-3-hydroxybutanoyl]-D-alanyl}amino-D-glucose; revision of the E. coli O123 O-polysaccharide structure

摘要

O-Polysaccharides were isolated by mild acid degradation of the lipopolysaccharides of Escherichia coil O123 and Salmonella enterica 058 and studied by chemical methods and 2D H-1 and C-13 NMR spectroscopy, including experiments in a H2O/D2O mixture, which enabled observation of correlations for nitrogen-linked protons. The following structure of the O-polysaccharide of E. coil O123 was established: similar to 30% OAC - 6 -> 3)-beta-DQuip4NalaHb-(1 -> 6)-alpha-D-GlcpNAc-(1 -> 3)-alpha-L-QuipNAc-(1 -> 3)-alpha-D-GlcpNAc-(1 -> where L-QuipNAc stands for 2-acetamido-2,6-dideoxy-L-glucose and D-Qui4NAlaHb for 4-(N[(S)-3-hydroxybutanoy1]-n-alanyl)amino-4,6-dideoxy-D-glucose. The latter was isolated as an ethylene glycol glycoside by three sequential Smith degradations of the O-deacetylated O-polysaccharide. The structure established in this work is at variance with the E. coli O123-polysaccharide structure reported earlier [Clark, C. G.; Kropinski, A. M.; Parolis, H.; Grant, C. C.; Trout-Yakel, K. M.; Franklin, K.; Ng, L. K.; Paramonov, N. A.; Parolis, L. A.; Rahn, K.; Tabor, H.]. Med. Microbiol. 2009, 58, 884-894]. In accordance with the genetic data, the O-polysaccharide of S. enterica 058 has the same structure, except for it lacks the O-acetylation.