Chemical and biological properties of lipopolysaccharide from Selenomonas sputigena ATCC 33150

Abstract

Chemical and biological studies were performed on lipopolysaccharide isolated from Selenomonas sputigena ATCC 33150T, a possible causative agent of periodontal diseases. The sugar components of the lipopolysaccharide of S. sputigena were mannose, galactose, glucose, L-glycero-D-mannoheptose (heptose), 2-keto-3-deoxy-octonic acid, glucosamine and galactosamine in a molar ratio of 0.3:1.0:1.0:1.0:0.2:3.0:3.2 (mol/mol heptose). Sephadex G-50 chromatography of the polysaccharide portion of the lipopolysaccharide obtained by partial hydrolysis yielded three fractions: the O-polysaccharide chain attached to the core oligosaccharide, the core oligosaccharide and monosaccharides. Compositional analysis of these fractions revealed that lipopolysaccharide of S. sputigena carries a short O-polysaccharide chain consisting of galactose and glucosamine and that the core oligosaccharide consisted of glucose, heptose, glucosamine and 2-keto-3-deoxyoctonic acid. It is of particular interest that galactosamine was detected as a component sugar of the lipid A moiety in addition to glucosamine, which is a usual component sugar of the lipid A of most gram-negative bacteria. Thus, the lipid A of S. sputigena might have a unique backbone that differs from that of the lipid A of other gram-negative bacteria. Lipid A of S. sputigena consisted mainly of fatty acids such as undecanoic, tridecanoic, tridecenoic, 3-hydroxytridecanoic and 3-hydroxytetradecanoic acid in a molar ratio of 0.4:1.0:0.3:4.0:0.5 (mol/mol tridecanoic acid). Lipopolysaccharide and lipid A from S. sputigena both exhibited biological activity in activating the clotting enzyme of Limulus amebocytes, the Schwartzman reaction, mitogenicity for murine lymphocytes and in inducing interleukin-1 alpha and interleukin-6 production in murine macrophages to the same extent as those observed for lipopolysaccharide of the Salmonella serovar typhimurium used as a positive control. The results suggested that the lipopolysaccharide of S. sputigena is a virulent factor in human periodontal diseases.