title: Structure of the neutral O-polysaccharide and biological activities of the lipopolysaccharide of Proteus mirabilis O20.
abstract: Mild acid degradation of the lipopolysaccharide (LPS) of Proteus mirabilis O20 resulted in depolymerisation of the O-polysaccharide to give a repeating-unit pentasaccharide. A polysaccharide was obtained by O-deacylation of the LPS followed by nitrous acid deamination. The derived pentasaccharide and polysaccharide were studied by NMR spectroscopy, including 2D 1H,1H COSY, TOCSY, ROESY, 1H,13C HMQC and HMQC-TOSCY experiments, along with chemical methods, and the following structure of the repeating unit of the O-polysaccharide was established: [Carbohydrate structure: see text]. As opposite to most other P. mirabilis O-polysaccharides studied, that of P. mirabilis O20 is neutral. A week serological cross-reactivity was observed between anti-P. mirabilis O20 serum and LPS of a number of Proteus serogroups with known O-polysaccharide structure. The ability of LPS of P. mirabilis O20 to activate the serine protease cascade was tested in Limulus amoebocyte lysate and in human blood plasma and compared with that of P. mirabilis O14a,14c having an acidic O-polysaccharide. The LPS of P. mirabilis O20 was found to be less active in both assays than the LPS of P. mirabilis O14a,14c and, therefore, the structurally variable O-polysaccharide may influenced the biological activity of the conserved lipid A moiety of the LPS.
authors.affiliation: ND Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia.
authors.forename: Anna N
authors.initials: AN
authors.lastname: Kondakova
authors.forename: Rafal
authors.initials: R
authors.lastname: Fudala
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Bednarska
authors.forename: Sof'ya N
authors.initials: SN
authors.lastname: Senchenkova
authors.forename: Yuriy A
authors.initials: YA
authors.lastname: Knirel
authors.forename: Wieslaw
authors.initials: W
authors.lastname: Kaca
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002457:Cell Extracts; D006737:Horseshoe Crabs / Q000201:enzymology; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007124:Immunoenzyme Techniques; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D019081:O Antigens / Q000737:chemistry* / Q000276:immunology / Q000494:pharmacology*; D011513:Proteus mirabilis / Q000737:chemistry* / Q000145:classification; D011817:Rabbits; D012697:Serine Endopeptidases / Q000097:blood / Q000378:metabolism
chemical_list: D002457:Cell Extracts; D007106:Immune Sera; D019081:O Antigens; D012697:Serine Endopeptidases