Structural characterization of an O-linked tetrasaccharide from Pseudomonas syringae pv. tabaci flagellin.

Abstract The flagellin of Pseudomonas syringae pv. tabaci is a glycoprotein that contains O-linked oligosaccharides composed of rhamnosyl and 4,6-dideoxy-4-(3-hydroxybutanamido)-2- O -methylglucosyl residues. These O-linked glycans are released by hydrazinolysis and then labeled at their reducing ends with 2-aminopyridine (PA). A PA-labeled trisaccharide and a PA-labeled tetrasaccharide are isolated by normal-phase high-performance liquid chromatography. These oligosaccharides are structurally characterized using mass spectrometry and NMR spectroscopy. Our data show that P. syringae pv. tabaci flagellin is glycosylated with a tetrasaccharide, 4,6-dideoxy-4-(3-hydroxybutanamido)-2- O -methyl-Glc p -(1→3)-α- l -Rha p -(1→2)-α- l -Rha p -(1→2)-α- l -Rha-(1→, as well a trisaccharide, 4,6-dideoxy-4-(3-hydroxybutanamido)-2- O -methyl-Glc p -(1→3)-α- l -Rha p- (1→2)-α- l -Rha-(1→, which was identified in a previous study.