title: Alteration of O-specific polysaccharide structure of symbiotically defective Mesorhizobium loti mutant 2213.1 derived from strain NZP2213.
abstract: Mesorhizobium loti mutant 2213.1 derived from the wild-type strain NZP2213 by Tn5 mutagenesis showed impaired effectiveness of symbiosis with the host plant Lotus corniculatus (Turska-Szewczuk et al., 2007 Microbiol Res, in press). The inability of lipopolysaccharide (LPS) isolated from the mutant 2213.1 strain or de-O-acetylated LPS of the parental cells to inactivate phage A1 particles implicated alterations in the LPS structure. The O-specific polysaccharide of the mutant was studied by chemical analyses along with (1)H and (13)C NMR spectroscopy, which clearly confirmed alterations in the O-chain structure. 2D NMR data showed that the mutant O-polysaccharide consists of a tetrasaccharide repeating unit containing non-substituted as well as O-acetylated or O-methylated 6-deoxytalopyranose residues. Additionally, an immunogold assay revealed a reduced number of gold particles on the mutant bacteroid cell surface, which could result from both a diminished amount of an O-antigenic determinant in mutant LPS and modifications of structural epitopes caused by alterations in O-acetylation or O-methylation of sugar residues. Western immunoblot assay of alkaline de-O-acetylated lipophilic M. loti NZP2213 LPS showed no reactivity with homologous serum indicating a role of O-acetyl groups in its O-specificity.
authors.affiliation: Department of General Microbiology, Maria Curie-Sklodowska University, Lublin, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Turska-Szewczuk
authors.forename: Hubert
authors.initials: H
authors.lastname: Pietras
authors.forename: Wojciech
authors.initials: W
authors.lastname: Borucki
authors.forename: Ryszard
authors.initials: R
authors.lastname: Russa
mesh_terms: D000215:Acylation; D000941:Antigens / Q000737:chemistry; D001671:Biochemistry / Q000379:methods; D015153:Blotting, Western; D002241:Carbohydrates / Q000737:chemistry; D003837:Deoxy Sugars / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000737:chemistry; D006601:Hexoses / Q000737:chemistry; D007150:Immunohistochemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008956:Models, Chemical; D009154:Mutation; D011134:Polysaccharides / Q000737:chemistry*; D012231:Rhizobium / Q000235:genetics*; D013379:Substrate Specificity
chemical_list: D000941:Antigens; D002241:Carbohydrates; D003837:Deoxy Sugars; D000939:Epitopes; D006601:Hexoses; D011134:Polysaccharides; C011754:6-deoxytalose