STRUCTURE OF THE CORE OLIGOSACCHARIDE IN THE SEROTYPE O8 LIPOPOLYSACCHARIDE FROM KLEBSIELLA-PNEUMONIAE

Two classes of mutants with O-antigen-deficient lipopolysaccharides we re isolated from the serotype O8 reference strain, belonging to Klebsi ella pneumoniae subspecies ozaenae. These mutants were selected by res istance to bacteriophage KO1-2, which recognizes and lyses strains wit h lipopolysaccharide molecules containing the D-galactan II O antigen. Strain RFK-11 contains a defect in O-antigen synthesis and has a comp lete core, including the attachment site for O antigen. This mutation is complemented by a plasmid carrying the rfb (O-antigen biosynthesis) gene cluster from the related K. pneumoniae serotype O1. In sodium do decyl sulfate-polyacrylamide gel electrophoresis, the lipopolysacchari de from strain RFK-9 has a mobility typical of deep-rough lipopolysacc haride. RFK-9 lipopolysaccharide lacks the attachment site for O antig en. Lipopolysaccharides from strains RFK-9 and RFK-11 were isolated, a nd their structures were determined by methylation analyses, nuclear m agnetic resonance spectroscopy, and mass spectroscopy. The deduced O8 core oligosaccharide includes the partial core structure reported for the K. pneumoniae subspecies pneumoniae serotype O1 lipopolysaccharide (M. Susskind, S. Muller-Leonnies, W. Nimmich, H. Brade, and O. Hoist, Carbohydr. Res. 269:C1-C7, 1995), consistent with the possibility of a conserved core structure within the species. The core oligosaccharid e differs from those of the genera Salmonella and Escherichia by the a bsence of a hexose-containing outer core, the lack of phosphate residu es in the inner core, and the presence of galacturonic acid residues.