title: Elucidation of the full O-polysaccharide structure and identification of the core type of the lipopolysaccharide of Providencia alcalifaciens O9.
abstract: Opportunistic human pathogens of the genus Providencia from the family Enterobacteriaceae are serotyped by their O-antigens, which represent the O-polysaccharide chains of the lipopolysaccharides (LPSs) on the cell surface. In this work, the O-polysaccharide of Providencia alcalifaciens O9 was obtained by mild acid degradation of a long-chain S-form LPS. The structure of the hexasaccharide repeat (O-unit) of the O-polysaccharide containing one D-Gal, two D-Glc, and three D-GalNAc residues was established by sugar and methylation analyses along with one- and two-dimensional (1)H and (13)C NMR spectroscopy. Another degradation product was derived from a short-chain SR-form LPS and found to consist of a core oligosaccharide bearing one O-unit. Its studies by NMR spectroscopy and electrospray ionization mass spectrometry enabled identification of one of the GalNAc residues as the first monosaccharide of the O-unit, whose glycosidic linkage links the O-units to each other and the first O-unit to the core. The core is distinguished by the occurrence of two glycoforms differing in the nature of a lateral monosaccharide, which is either D-Glc or D-GlcNAc. Although composed of common monosaccharides, the O-polysaccharide of P. alcalifaciens O9 has a unique structure among bacterial polysaccharides, whereas the oligosaccharide region belongs to one of several core types recognized in the LPSs of Providencia.
authors.affiliation: N D Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation. olga.ovchinnikova@gmail.com
authors.forename: Olga G
authors.initials: OG
authors.lastname: Ovchinnikova
authors.forename: Nina A
authors.initials: NA
authors.lastname: Kocharova
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Shashkov
authors.forename: Nikolay P
authors.initials: NP
authors.lastname: Arbatsky
authors.forename: Antoni
authors.initials: A
authors.lastname: Rozalski
authors.forename: Yuriy A
authors.initials: YA
authors.lastname: Knirel
mesh_terms: D002240:Carbohydrate Sequence; D008070:Lipopolysaccharides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011532:Providencia / Q000737:chemistry*
chemical_list: D008070:Lipopolysaccharides