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. By(1)H-and'3C-nuclear magne tic resonance spectroscopy, methylation analysis and Smith degradation, the polysaccharide was shown to be abackbonecomposed of 2,3)-alpha -L-Rhap(1-- >; 2)-alpha -L-Rhap(1-->; and 3)-alpha -L-Rhap(1--> residues with N-acetyl- fucosamine as a branch residue, primarily of the following structure: [GRAPHICS] An oligosaccharide of the following probable structure: [GRAPHICS] comprising 28% of the total carbohydrate was unexpectedly recovered from th e 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 p roposed serogrouping system.