Structure of the O-polysaccharide of Pseudomonas syringae pv. delphinii NCPPB 1879T Having Side Chains of 3-Acetamido-3,6-dideoxy-D-galactose Residues

The O-polysaccharide (OPS) was obtained from the lipopolysaccharide of Pseudomonas syringae pv. delphinii NCPPB 1879T and studied by sugar and methylation analyses, Smith degradation, and 1H- and 13C-NMR spectroscopy. The OPS was found to contain residues of L-rhamnose (L-Rha) and 3-acetamido-3,6-dideoxy-D-galactose (D-Fuc3NAc), and the following structure of the major (n = 2) and minor (n = 3) heptasaccharide repeating units of the OPS was established: $$\begin{gathered} {\alpha} - {D} - {Fuc}p3{NAc} - (1 \to 2) - {\alpha} - {D} - {Fuc}p3{NAc} - (1 \to 2) - {\alpha} - {D} - {Fuc}p3{Nac} \hfill \\ { 1} \hfill \\ { } \downarrow \hfill \\ { 4} \hfill \\ { } \to {2} - {\alpha} - {L} - {Rha}p - (1 \to 3) - {\alpha} - {L} - {Rha}p - (1 \to 3) - {\alpha} - {L} - {Rha}p(1 \to n) - {\alpha} - {L} - {Rha}p - (1 \to \hfill \\ \hfill \\ \end{gathered}$$ The OPS is distinguished by the presence of oligosaccharide side chains consisting of three D-Fuc3NAc residues that are connected to each other by the (α1→2)-linkage. The OPS is characterized by a structural heterogeneity due to a different position of substitution of one of the four L-rhamnose residues in the main chain of the repeating unit as well as to the presence of oligosaccharide units with an incomplete side chain.