Structure of O-Specific Side Chains of Lipopolysaccharides from Yersinia pseudotuberculosis

Abstract

Lipopolysaccharide prepared from cells of Yersinia ( Pasteurella ) pseudotuberculosis of serogroups I, II, III, IV, and V is known to contain the 3,6-dideoxyhexose (DDH) paratose, abequose, paratose, tyvelose, and ascarylose in its respective O-specific side chains. Lipopolysaccharides or lipid-free polysaccharides of all of the 10 known serogroups and subgroups were subjected to methylation analysis and determined as alditol acetates by gas-liquid chromatography and mass spectrometry. The results indicated that the O-specific side chains of nine serotypes are composed of oligosaccharide repeating units in the form of four alternative general structures in which a terminal DDH may vary. These structures are DDH [Formula: see text] 6-deoxy- d - manno -heptose [Formula: see text] d -galactose (serogroups IA, IIA, and IVB), DDH [Formula: see text] d -mannose [Formula: see text] l -fucose (serogroups IB and IIB), and two configurations similar to the latter except that the 4-position of l -fucose was either linked to the d -mannose residue (serogroups VA and VB) or to the DDH residue (serogroups III and IVA). In contrast, O-groups in lipopolysaccharide of the newly discovered serogroup VI contained the DDH colitose and 2-acetamido-2-deoxy- d -galactose. Accordingly, all five known types of DDH have now been detected in lipopolysaccharides of Y. pseudotuberculosis . The sugar 6-deoxy- d - manno -heptose, present in O-specific side chains of serogroups IA, IIA, and IVB, has not yet been reported to occur elsewhere in nature.