title: Structural studies of the O-antigenic polysaccharides from the enteroaggregative Escherichia coli strain 94/D4 and the international type strain Escherichia coli O82.
abstract: The structure of the O-antigen polysaccharides (PS) from the enteroaggregative Escherichia coli strain 94/D4 and the international type strain E. coli O82 have been determined. Component analysis and (1)H, (13)C, and (31)P NMR spectroscopy experiments were employed to elucidate the structure. Inter-residue correlations were determined by (1)H, (13)C-heteronuclear multiple-bond correlation, and (1)H, (1)H-NOESY experiments. D-GroA as a substituent is linked via its O-2 in a phosphodiester-linkage to O-6 of the alpha-D-Glcp residue. The PS is composed of tetrasaccharide repeating units with the following structure: -->4)-alpha-D-Glcp6-(P-2-D-GroA)-(1-->4)-beta-D-Galp-(1-->4)-beta-D-Glcp-(1-->3)-beta-D-GlcpNAc-(1--> Cross-peaks of low intensity from an alpha-D-Glcp residue were present in the NMR spectra and spectral analysis indicates that they originate from the terminal residue of the polysaccharide. Consequently, the biological repeating unit has a 3-substituted N-acetyl-D-glucosamine residue at its reducing end. Enzyme immunoassay using specific anti-E. coli O82 rabbit sera showed identical reactivity to the LPS of the two strains, in agreement with the structural analysis of their O-antigen polysaccharides.
authors.affiliation: Department of Microbiology, Faculty of Medical Sciences, National Autonomous University of Nicaragua León, Nicaragua.
authors.forename: Samuel
authors.initials: S
authors.lastname: Vilchez
authors.forename: Magnus
authors.initials: M
authors.lastname: Lundborg
authors.forename: Felipe
authors.initials: F
authors.lastname: Urbina
authors.forename: Andrej
authors.initials: A
authors.lastname: Weintraub
authors.forename: Göran
authors.initials: G
authors.lastname: Widmalm
mesh_terms: D000117:Acetylglucosamine; D000942:Antigens, Bacterial / Q000737:chemistry; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D004926:Escherichia coli / Q000737:chemistry* / Q000276:immunology; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000276:immunology; D009682:Magnetic Resonance Spectroscopy; D019081:O Antigens
chemical_list: D000942:Antigens, Bacterial; D008070:Lipopolysaccharides; D019081:O Antigens; D000117:Acetylglucosamine