Location of the O-methyl groups in the O polysaccharide of Pseudomonas syringae pv. phaseolicola Original Research Article

The O-methylation pattern of the O polysaccharide (OPS) of the lipopolysaccharide of Pseudomonas syringae pv. phaseolicola GSPB 1552 was revealed by methylation (CD3I) analysis, Smith degradation, and NMR spectroscopy. Together with the major O repeats consisting of d-rhamnopyranose (d-Rhap) and d-fucofuranose (d-Fucf), there are minor repeats (∼30%) containing 3-O-methyl-d-rhamnose (d-acofriose), which is 2-substituted in the interior repeats and occupies the terminal non-reducing end of the OPS. It was suggested that the methylated O repeats are linked to each other nearby the non-reducing end of the OPS and that the ‘biologica