The structure of the phosphorylated carbohydrate backbone of the lipopolysaccharide of the phytopathogen bacterium Pseudomonas tolaasii Original Research Article

A novel core-lipid A backbone oligosaccharide was isolated and identified from the lipopolysaccharide fraction of the mushrooms pathogen bacterium Pseudomonas tolaasii. The oligosaccharide was obtained by alkaline treatment of the lipopolysaccharide fraction. Since the repeating unit of the O-antigen contained one residue of → 4)-α-l-GulpNAcAN, the hydrolysis was accompanied by β-elimination on this residue and following depolymerization, producing a mixture of oligosaccharides. The complete structural elucidation showed the presence of a single core glycoform and was achieved by chemical analysis and by 1H, 31P, and 13C NMR spectroscopy applying various 1D and 2D experiments.All sugars are α-d-pyranoses, if not stated otherwise. Hep is l-glycero-d-manno-heptose, Kdo is 3-deoxy-d-manno-oct-2-ulosonic acid, P is phosphate. QuiN and ΔGulNA are present in nonstoichiometric amount.