Structure of the Lipopolysaccharide Side-chain of Pseudomonas syringae pv. tomato Strain CFBP 2545 in Relation to O-serotype

The side-chain from the lipopolysaccharide (LPS) of Pseudomonas syringae pv. tomato strain CFBP 2545 contained L-rhamnose. By1H-and13C-nuclear magnetic resonance spectroscopy, methylation analysis and Smith degradation, the polysaccharide was shown to be a backbone composed of 2,3)±a±L±Rhap(14; 2)±a±L± Rhap(14; and 3)±a±L±Rhap(14 residues with N-acetyl- fucosamine as a branch residue, primarily of the fol- lowing structure: 3)±a±L±Rhap(143)±a±L± Rhap(142)±a±L±Rhap(142)±a±L±Rhap(14 3) " a±D±Fuc3NAc(1 An oligosaccharide of the following probable structure: a±L±Rhap(143)±a±L± Rhap(142)±a±L±Rhap(143)±a±L±Rha 3) " a±D±Fuc3NAc(1 comprising 28% of the total carbohydrate was unex- pectedly recovered from the side-chain during the course of Smith degradation. The polysaccharide dif- fered from the side-chains of LPSs from P. syringae pv. tomato strains 140(R) and GSPB 483. The side-chain structure is correlated with a previously proposed sero- grouping system