title: Structural elucidation of the O-antigenic polysaccharide from Escherichia coli O175.
abstract: The structure of the O-antigen polysaccharide (PS) from Escherichia coli O175 has been elucidated. Component analysis together with (1)H and (13)C NMR spectroscopy experiments were used to determine the structure. Inter-residue correlations were determined by (1)H,(1)H-NOESY, and (1)H,(13)C-heteronuclear multiple-bond correlation experiments. The PS is composed of pentasaccharide repeating units with the following structure: →2)-α-D-Glcp-(1→4)-α-D-GlcpA-(1→3)-α-D-Manp-(1→2)-α-D-Manp-(1→3)-β-D-GalpNAc-(1→ Cross-peaks of low intensity from an α-linked glucopyranosyl residue were present in the (1)H,(1)H-TOCSY NMR spectra. The α-D-Glcp residue is suggested to originate from the terminal part of the polysaccharide and consequently the biological repeating unit has a 3-substituted N-acetyl-D-galactosamine residue at its reducing end. The repeating unit of the E. coli O175 O-antigen is similar to those from E. coli O22 and O83, both of which carry an α-D-Glcp-(1→4)-D-GlcpA structural element, thereby explaining the reported cross-reactivities between the strains.
authors.affiliation: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Sweden.
authors.forename: Mona V
authors.initials: MV
authors.lastname: Svensson
authors.forename: Andrej
authors.initials: A
authors.lastname: Weintraub
authors.forename: Göran
authors.initials: G
authors.lastname: Widmalm
mesh_terms: D002473:Cell Wall / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D019081:O Antigens / Q000737:chemistry*
chemical_list: D019081:O Antigens