Increasing outer membrane complexity: the case of the lipopolysaccharide lipid A from marine Cellulophaga pacifica.

Gram-negative bacteria living in marine waters have evolved peculiar adaptation strategies to deal with the numerous stress conditions that characterize aquatic environments. Among the multiple mechanisms for efficient adaptation, these bacteria typically exhibit chemical modifications in the structure of the lipopolysaccharide (LPS), which is a fundamental component of their outer membrane. In particular, the glycolipid anchor to the membrane of marine bacteria LPSs, i.e. the lipid A, frequently shows unusual chemical structures, which are reflected in equally singular immunological properties with potential applications as immune adjuvants or anti-sepsis drugs. In this work, we determined the chemical structure of the lipid A from Cellulophaga pacifica KMM 3664T isolated from the Sea of Japan. This bacterium showed to produce a heterogeneous mixture of lipid A molecules that mainly display five acyl chains and carry a single phosphate and a D-mannose disaccharide on the glucosamine backbone. Furthermore, we proved that C. pacifica KMM 3664T LPS acts as a weaker activator of Toll-like receptor 4 (TLR4) compared to the prototypical enterobacterial Salmonella typhimurium LPS. Our results are relevant to the future development of novel vaccine adjuvants and immunomodulators inspired by marine LPS chemistry.

Structure and in vitro antiproliferative activity against breast cancer cells of the cell-wall polysaccharide from the marine bacterium Kangiella japonica KMM 3899T.

Kangiella japonica KMM 3899T is a Gram-negative bacterium isolated from a sandy sediment sample collected from the Sea of Japan. Here the results of the structure and the biological activity against breast cancer cells of the cell-wall polysaccharide from K. japonica KMM 3899T have been described. The structure of the repeating unit of the polysaccharide was elucidated using chemical analysis and NMR spectroscopy: →4)-α-L-GalpNAc3AcA-(1 â†’ 3)-α-D-GlcpNAc-(1 â†’ 4)-ß-D-GlcpNAc3NAcAN-(1→. The cell-wall polysaccharide had an antiproliferative effect against T-47D cells. Flow cytometric and Western blot analysis revealed that the polysaccharide induced S phase arrest and mitochondrial-dependent apoptosis.

Lipopolysaccharides of Herbaspirillum species and their relevance for bacterium-host interactions.

The lipopolysaccharides of Herbaspirillum lusitanum P6-12T (HlP6-12T) and H. frisingense GSF30T (HfGSF30T) was isolated by phenol-water extraction from bacterial cells and was characterized using chemical analysis and SDS-PAGE. It was shown that these bacteria produce LPSs that differ in their physicochemical properties and macromolecular organization. In this paper, the lipid A structure of the HlP6-12T LPS, was characterized through chemical analyses and matrix-assisted laser desorption ionization (MALDI) mass spectrometry. To prove the effect of the size of micelles on their bioavailability, we examined the activity of both LPSs toward the morphology of wheat seedlings. Analysis of the HlP6-12T and HfGSF30T genomes showed no significant differences between the operons that encode proteins involved in the biosynthesis of the lipids A and core oligosaccharides. The difference may be due to the composition of the O-antigen operon. HfGSF30T has two copies of the rfb operon, with the main one divided into two fragments. In contrast, the HlP6-12T genome contains only a single rfb-containing operon, and the other O-antigen operons are not comparable at all. The integrity of O-antigen-related genes may also affect LPS variability of. Specifically, we have observed a hairpin structure in the middle of the O-antigen glycosyltransferase gene, which led to the division of the gene into two fragments, resulting in incorrect protein synthesis and potential abnormalities in O-antigen production.

Structure of the O-polysaccharide from the moderately halophilic bacterium Halomonas fontilapidosi KR26.

Lipopolysaccharide was obtained from the aerobic moderately halophilic bacterium Halomonas fontilapidosi KR26. The O-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide and was examined by chemical methods and by 1H and 13C NMR spectroscopy, including 1H,1H COSY, TOCSY, ROESY, and 1H,13C HSQC, and HMBC experiments. The following structure of the linear tetrasaccharide repeating unit was deduced. →2)-α-l-Rhap-(1→2)-α-l-Rhap-(1→3)-α-l-Rhap-(1→3)-ß-d-Galp-(1→.