Structures of lipopolysaccharides from Klebsiella pneumoniae: Elucidation of the structure of the linkage region between core and polysaccharide O chain and identification of the residues at the non-reducing termini of the O chains

Abstract

Deamination of LPSs from Klebsiella pneumoniae released O-chain polysaccharides together with a fragment of the core oligosaccharide. The structures of the products from serotypes O1, O2a, O2a,c, O3, O4, O5, and O12 were determined by NMR spectroscopy and chemical methods, identifying the linkage region between the O antigens and the core as well as novel residues at the non-reducing ends of the polysaccharides. All serotypes had an identical linkage between the O chain and core. [polysaccharide]-(1-3)-β-GlcNAc-(1-5)-α-Kdo-(2)-[rest of core] α-Hep-(1-4)] STRUCTURE I where L-glycero-D-manno-heptose is non-stoichiometric. Analysis of the LPSs from a waaL (O-polysaccharide ligase-deficient) mutant showed that the β-GlcNAc in the linkage region is derived from the O-chain biosynthesis pathway, and the α-3-deoxy-D-manno-octulosonic acid represents the core residue to which the O chain is ligated. Consistent with the common ligation site, the WaaL proteins from these serotypes are essentially identical. Polysaccharides from serotypes O1, O2a, and O2a,c contain no special groups at the non-reducing end, whereas polysaccharides from serotypes O3, O4, O5, and O12 have residues at the non-reducing end that are not found in the polymer repeating units.