Cell wall galactofuranan and pyruvate-containing galactomannan in the cell walls of Clavibacter strains.

The cell wall glycopolymer structures of plant-associated strains Clavibacter sp. VKM Ac-1371, Clavibacter sp. VKM Ac-1372 and Clavibacter sp. VKM Ac-1374, members of three putative new species (family Microbacteriaceae, class Actinobacteria) were studied. Each strain was found to contain two glycopolymers, neutral and acidic ones. The main chain of neutral polymer, identical in all three strains, is (1 â†’ 6)-linked ß-d-galactofuranan with every second galactofuranose residue substituted at position 2 by side disaccharide, α-d-Manp-(1 â†’ 2)-α-d-Ribf-(1 â†’ . The second, acidic polymer, is pyruvate-containing galactomannan with the repeating unit, →3)-α-d-Galp-(1 â†’ 3)-α-d-[4,6-S-Pyr]-Manp-(1 â†’ 3)-α-d-Manp-(1 â†’ . Reducing mannopyranose residues of the acidic polysaccharides repeating unit from strains VKM Ac-1372 and VKM Ac-1374 bear O-acetyl residues additionally. The cell wall glycopolymer structures were established by chemical and NMR spectroscopic methods with using one- and two-dimensional techniques 1H,1H COSY, TOCSY, ROESY and 1H,13C HSQC, HMBC. The results obtained provide new data on diversity of the bacterial cell wall glycopolymers and may prove valuable for microbial taxonomy and insight into the molecular mechanisms of interactions between bacteria and plants and also of bacterial adaptation to survival in desert systems.

Novel galactofuranan and pyruvylated galactomannan in the cell wall of Clavibacter michiganensis subsp. michiganensis VKM Ac-1403T.

The cell wall of Clavibacter michiganensis subsp. michiganensis VKM Ас-1403Т (family Microbacteriaceae, class Actinobacteria) contains two polysaccharides. The first one is neutral (1 â†’ 6) linked galactofuranan in which every second galactofuranose residue in the main chain substituted at position 3 by side trisaccharide, ß-D-GlcpNAc-(1 â†’ 3)-α-L-Rhap-(1 â†’ 2)-α-D-Fucp-(1 â†’. The second polymer is pyruvylated galactomannan with the repeating unit, →3)-α-D-Galp-(1 â†’ 3)-α-D-[4,6-S-Pyr]-Manp-(1 â†’ 3)-α-D-Manp-(1 â†’. The cell wall glycopolymer structures were established by chemical and NMR spectroscopic methods. The obtained results provide new data on the cell wall composition of plant pathogenic species of the genus Clavibacter and can promote understanding the molecular mechanisms involved in colonization and infection of plants.