R- and S-Pyruvate-Containing Polysaccharide from the Cell Wall of Rathayibacter sp. VKM Ac-2927

The structures of two cell wall glycopolymers from the strain <i>Rathayibacter</i> sp. VKM Ac-2927 (family Microbacteriaceae, class Actinomycetes), isolated from the leaves of a linden affected by leaf miner, were established using chemical and NMR spectroscopy methods. The first polymer, rhamnomannan, is a heterogeneous chain polymer composed of regularly alternating α-D-rhamnose and α-D-mannose residues linked by (1→3)- and (1→2)-glycosidic bonds and contains a minor amount of lateral β-D-xylopyranose residues (structure is presented in the text). The second polymer, acetalized with <i>R</i>- and <i>S</i>-pyruvic acid, consists of branched tetrasaccharide units, →3)-α-D-Gal<i>p</i>4,6-(<i>R-</i>Pyr)-(1→3)-β-D-Glc<i>p</i>-(1→6)-[β-D-Gal<i>p</i>3,4-(<i>S</i>-Pyr)-(1→4)]-α-D-Man<i>p</i>-(1→. Structure of this polysaccharide is new for the representatives of the genus <i>Rathayibacter</i> and prokaryotes in general. The results of present study indicate structural diversity of microbial glycopolymers and are consistent with the previously obtained data on specificity of their composition for the species of the <i>Rathayibacter</i> genus.