Lipophilic O-antigens in Rhodospirillum tenue

The structure of the polysaccharide moiety of Rhodopseudomonas sphaeroides ATCC 17023 lipopolysaccharide

The chemical structure of the polysaccharide moiety of the lipopolysaccharide Rhodopseudomonas sphaeroides ATCC 17023 was established. Mild acetic acid hydrolysis of isolated lipopolysaccharide, followed by preparative high-voltage paper electrophoresis afforded three oligosaccharides. They were characterized by chemical and physicochemical studies to be: GlcA(alpha 1----4)dOclA8P, Thr(6') GlcA(alpha 1----4)GlcA and GlcA(alpha 1----4)dOclA, where GlcA is D-glucuronic acid and dOc1A is 3-deoxy-D-manno-octulosonic acid. Carboxyl-reduction of the lipopolysaccharide followed by acid hydrolysis gave a trisaccharide: GlcA(alpha 1----4)Glc(alpha 1----4)Glc, showing the presence of three residues of glucuronic acids in the O-specific chain and indicating that only two of them are reducible by NaBH4. The linkage between the polysaccharide and lipid A was shown to be through a single 1,4-linked residue of dOc1A attached by a 2,6'-linkage to the lipid A moiety.

Structure of the heptose region of lipopolysaccharies from Rhodospirillum tenue

There is a common structure (core region) in the lipopolysaccharides of Rhodospirillum tenue. It is composed of a branched trisaccharide of L-glycero-D-mannoheptose (and of 2-keto-3-deoxyoctonate), as revealed by methylation analyses of degraded polysaccharides of four different R. tenue strains. The structure is similar or might even be identical to the inner core of enterobacterial O antigens. In addition, each of the four R. tenue lipopolysaccharides contains a strain-specific region that consists of heptose(s) (L-glycero-D-mannoheptose or D-glycero-D-mannoheptose or both) or hexoses. There is a partial substitution of the core region and the strain-specific region by phosphorus, showing microheterogeneity.

Fatty acids and neutral sugars present in lipopolysaccharides isolated from Fusobacterium species

Lipopolysaccharides (LPS) extracted from cells of Fusobacterium necrophorum, F. mortiferum, F. Gonidiaformans. varium and single strains of F. naviforme and F. russi were analysed for sugars and fatty acids. All preparations contained a monosaccharide tentatively identified as L-glycero-D-mannoheptose, but showed variation with respect to the presence of glucose, galactose, rhamnose and another heptose isomer, tentatively identified as L-glycero-D-mannoheptose. L-glycero-D-mannoheptose was a monosaccharide of great abundance in all LPS examined. 2-keto-3-deoxy-octonate and glucosamine were present in all LPS preparations. The fatty acids present were 3-hydroxy-tetradecanoic acid as the main component, and n-tetradecanoic acid. Some LPS contained n-hexadecanoic acid. All the strains of F. nucleatum contained 3-hydroxy-hexadecanoic acid as a group-specific LPS constituent.

Isolation and characterization of the lipopolysaccharide of Thiocapsa roseopersicina

The lipopolysaccharide from Thiocapsa roseopersicina was isolated by phenol/water, being found in the water phase. It is cleaved into a polysaccharide moiety (degraded polysaccharide) and lipid A by hydrolysis with 10% acetic acid (100 degree C, 3 h). D-Mannose, L-rhamnose, 3-amino-3, 6-dideoxy-D-galactose and D-glucose are the major constituents of the degraded polysaccharide. 2-O-Methyl-L-rhamnose, 3-O-methyl-D-mannose, D-galactose, glucosamine and quinovosamine are minor constituents. D-Glycer-D-manno-heptose (tentatively identified) and 3-deoxy-D-manno-octulosonic acid were detected in only small amounts. Conspicuously, lipid A from T. roseopersicina contains a neutral sugar, D-mannose, in addition to D-glucosamine, as had been observed with lipid A from Chromatium vinosum D. Major fatty acids are beta-hydroxymyristic and lauric acids. Only trace amounts of phosphorus were found indicating this lipid A to be free of phosphate. The lipopolysaccharide of T. roseopersicina represents the O-antigen of the strain. It reacts with antisera prepared against living or heat-killed cells in passive hemagglutination.

Structural studies on the D-arabinose-containing lipid A from Rhodospirillum tenue 2761

Structural studies carried out on the isolated free lipid A of Rhodospirillum tenue 2761 revealed a new type of structure for this lipid. The lipid A backbone of 1',6-linked glucosamine disaccharide (central disaccharide) is substituted by three different sugar residues: the non-reducing end of the disaccharide by 4-amino-4-deoxy-L-arabinose 1-phosphate and its reducing end glycosidically by D-arabinofuranose 1-phosphate; further, the reducing glucosamine of the disaccharide is branched to a third glucosamine residue by a 1'',4-glycosidic linkage. The amino and the hydroxyl groups of the central disaccharide are acylated by 3-hydroxydecanoic acid (amide-linked) and palmitic and myristic acids (ester-linked). Neither amino nor hydroxyl groups of the three external sugar residues are acylated. The results suggest the following chemical structure for the lipid A of R. tenue 2761: (formula: see text).

Chemotypes of Fusobacterium nucleatum lipopolysaccharides

Lipopolysaccharides (LPS) were isolated from 20 strains of Fusobacterium nucleatum and examined by paper chromatography, gas liquid chromatography and colorimetric methods for the presence of neutral sugars, amino sugars and 2-keto-3-dexoxy-octonate (KDO). The LPS had in common glucosamine, L-glycero-D-manno-heptose, glucose and KDO. The KDO content was low. Galatose, rhamnose and D-glycero-D-manno-heptose were found in some strains. Based on the sugar composition of the LPS, the F. nucleatum strains could be classified into six chemotypes.