title: A second galacturonic acid transferase is required for core lipopolysaccharide biosynthesis and complete capsule association with the cell surface in Klebsiella pneumoniae.
abstract: The core lipopolysaccharide (LPS) of Klebsiella pneumoniae contains two galacturonic acid (GalA) residues, but only one GalA transferase (WabG) has been identified. Data from chemical and structural analysis of LPS isolated from a wabO mutant show the absence of the inner core beta-GalA residue linked to L-glycero-D-manno-heptose III (L,D-Hep III). An in vitro assay demonstrates that the purified WabO is able to catalyze the transfer of GalA from UDP-GalA to the acceptor LPS isolated from the wabO mutant, but not to LPS isolated from waaQ mutant (deficient in l,d-Hep III). The absence of this inner core beta-GalA residue results in a decrease in virulence in a capsule-dependent experimental mouse pneumonia model. In addition, this mutation leads to a strong reduction in cell-bound capsule. Interestingly, a K66 Klebsiella strain (natural isolate) without a functional wabO gene shows reduced levels of cell-bound capsule in comparison to those of other K66 strains. Thus, the WabO enzyme plays an important role in core LPS biosynthesis and determines the level of cell-bound capsule in Klebsiella pneumoniae.
authors.affiliation: Departamento de Microbiología, Facultad de Biologia, Universidad de Barcelona, Diagonal 645, 08071 Barcelona, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Fresno
authors.forename: Natalia
authors.initials: N
authors.lastname: Jiménez
authors.forename: Rocío
authors.initials: R
authors.lastname: Canals
authors.forename: Susana
authors.initials: S
authors.lastname: Merino
authors.forename: Maria Michela
authors.initials: MM
authors.lastname: Corsaro
authors.forename: Rosa
authors.initials: R
authors.lastname: Lanzetta
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Parrilli
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Pieretti
authors.forename: Miguel
authors.initials: M
authors.lastname: Regué
authors.forename: Juan M
authors.initials: JM
authors.lastname: Tomás
mesh_terms: D000818:Animals; D016667:Bacterial Capsules / Q000378:metabolism* / Q000648:ultrastructure; D002240:Carbohydrate Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D005798:Genes, Bacterial; D016695:Glycosyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006603:Hexuronic Acids / Q000737:chemistry / Q000378:metabolism*; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D008070:Lipopolysaccharides / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014774:Virulence / Q000235:genetics
chemical_list: D006603:Hexuronic Acids; D008070:Lipopolysaccharides; C007819:galacturonic acid; D016695:Glycosyltransferases