tailieunhanh - Báo cáo khoa học: NMR and MS evidences for a random assembled O-specific chain structure in the LPS of the bacterium Xanthomonas campestris pv. Vitians A case of unsystematic biosynthetic polymerization

Xanthomonas is a Gram-negative plant-associated bacterium that acts as causative agent of bacterial leaf spot and headrot in lettuce. The lipopolysac-charide of this bacterium is suspected to be an important molecule for adhesion to and infection of the plants. The lipopolysaccharide has been isolated from the phenol phase and the O-specific chain characterized by compositional analysis, high fieldNMRandMALDI-TOFMS. | Eur. J. Biochem. 269 4185-4193 2002 FEBS 2002 doi NMR and MS evidences for a random assembled O-specific chain structure in the LPS of the bacterium Xanthomonas campestris pv. Vitians A case of unsystematic biosynthetic polymerization Antonio Molinaro1 Cristina De Castro1 Rosa Lanzetta1 Michelangelo Parrilli1 Bent O. Petersen2 B Anders Broberg2 and Jens 0 Duus2 1 Dipartimento di Chimica Organica e Biochimica Universita di Napoli Federico II Napoli Italy department of Chemistry Carlsberg Laboratory Copenhagen Denmark Xanthomonas campestris pv. vitians is a Gram-negative plant-associated bacterium that acts as causative agent of bacterial leaf spot and headrot in lettuce. The lipopolysaccharide of this bacterium is suspected to be an important molecule for adhesion to and infection of the plants. The lipopolysaccharide has been isolated from the phenol phase and the O-specific chain characterized by compositional analysis high field NMR and MALDI-TOF MS. It consists of a nonrepetitive branched polysaccharide with a rhamnan backbone to which Fuc3NAc is linked. The NMR and MS approach led to the characterization of the fine structure of the polymer which is randomly assembled. The rhamnan backbone is built up of b-Rhap and a-Rhap this last is present in one two or three adjacent units and branched by an a-Fucp3NAc unit. This is a real case of a random constituted O-specific chain therefore biosynthetic studies towards the comprehension of this irregular biosynthesis are needed. Keywords Xanthomonas campestris lipopolysaccharide phytopathogen O-specific chain random polymerization. Until recently structural data on lipopolysaccharides LPSs of phytopathogenic bacteria have been rather limited but the interest in their structure is increasing especially in the structural analysis of O-specific polysaccharides OPSs 1 . The main purposes of these investigations are to establish a chemotaxonomic relationship among strains and species of the .