Structure of the O polysaccharide and immunochemical relationships betweenthe lipopolysaccharides of Pseudomonas syringae pathovar tomato and pathovar maculicola

O polysaccharides (OPS) of the lipopolysaccharides (LPS) of Pseudomonas syr ingae pathovar tomato GSPB 483 and pathovar maculicola IMV 381 were studied by H-1-NMR and C-13-NMR spectroscopy, including two-dimensional COSY, rota ting-frame NOE spectroscopy (ROESY), and H-detected H-1, C-13 heteronuclear multiple-quantum coherence (HMQC) experiments. The OPS from both strains w ere shown to be chemically identical. Two structurally different types of r epeating units (O repeats 1 and 2) were elucidated in each OPS. The minor O repeat is a pentasaccharide having the structure 2. The same structure has been reported earlier for some other OPS of P. syringae. The major O repea t is a hexasaccharide with the novel structure 1 which is distinguished fro m 2 by the presence of the second lateral residue of 3-acetamido-3,6-dideox y-D-galactose (D-Fuc3NAc) and by a different position of substitution of on e of the L-rhamnose (Rha) residues in the backbone. [GRAPHICS] Structural and serological diversity of OPS of strains belonging to Ft syri ngae pv. tomato and pv. maculicola and phylogenetic relatedness of the stra ins are discussed.