title: A similarity in the O-acetylation pattern of the O-antigens of Shigellaflexneri types 1a, 1b, and 2a.
abstract: Shigella flexneri type 2a is the first, and type 1b is the second, most prevalent isolates from patients with shigellosis in Russia. The O-specific polysaccharides (OPSs, O-antigens) of S. flexneri types 1-5 possess a common -->2)-alpha-l-RhapIII-(1-->2)-alpha-l-RhapII-(1-->3)-alpha-l-RhapI-(1-->3)-beta-d-GlcpNAc-(1--> backbone and differ from each other in its glucosylation or/and O-acetylation at various positions, the modifications being responsible for various O-factors. It was suggested that O-factor 6 expressed by type 1b is associated with O-acetylation of RhaI at position 2 but more than one O-acetyl group has been detected in the type 1b OPS [Kenne, L. et al. Eur. J. Biochem.1978, 91, 279-284]. In this work, O-acetylation of RhapI in the type 1b OPS was confirmed by NMR spectroscopy and location of an additional O-acetyl group at position either 3 (major) or 4 (minor) of RhapIII was determined. Type 1a differs from type 1b in the lack of O-acetylation of RhapI only. In type 2a, in addition to two reported major O-acetyl groups at position 6 of GlcNAc and position 3 of RhapIII [Kubler-Kielb, J. et al. Carbohydr. Res.2007, 342, 643-647], a minor O-acetyl group was found at position 4 of RhaIII. Therefore, RhapIII is O-acetylated in the same manner in all three S. flexneri serotypes studied.
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation. perepel@ioc.ac.ru
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Perepelov
authors.forename: Vyacheslav L
authors.initials: VL
authors.lastname: L'vov
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Sof'ya N
authors.initials: SN
authors.lastname: Senchenkova
authors.forename: Mariya E
authors.initials: ME
authors.lastname: Shekht
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Shashkov
authors.forename: Lu
authors.initials: L
authors.lastname: Feng
authors.forename: Petr G
authors.initials: PG
authors.lastname: Aparin
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Yuriy A
authors.initials: YA
authors.lastname: Knirel
mesh_terms: D000107:Acetylation; D009682:Magnetic Resonance Spectroscopy; D019081:O Antigens / Q000737:chemistry*; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012763:Shigella flexneri / Q000737:chemistry*
chemical_list: D019081:O Antigens; D011135:Polysaccharides, Bacterial