title: A minor catalase/peroxidase from Burkholderia cenocepacia is required for normal aconitase activity.
abstract: The opportunistic bacterium Burkholderia cenocepacia C5424 contains two catalase/peroxidase genes, katA and katB. To investigate the functions of these genes, katA and katB mutants were generated by targeted integration of suicide plasmids into the katA and katB genes. The catalase/peroxidase activity of the katA mutant was not affected as compared with that of the parental strain, while no catalase/peroxidase activity was detected in the katB mutant. However, the katA mutant displayed reduced resistance to hydrogen peroxide under iron limitation, while the katB mutant showed hypersensitivity to hydrogen peroxide, and reduced growth under all conditions tested. The katA mutant displayed reduced growth only in the presence of carbon sources that are metabolized through the tricarboxylic acid (TCA) cycle, as the growth defect was abrogated in cultures supplemented with glucose or glycerol. This phenotype was also correlated with a marked reduction in aconitase activity. In contrast, aconitase activity was not reduced in the katB mutant and parental strains. The authors conclude that the KatA protein is a specialized catalase/peroxidase that has a novel function by contributing to maintain the normal activity of the TCA cycle, while KatB is a classical catalase/peroxidase that plays a global role in cellular protection against oxidative stress.
authors.affiliation: Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1.
authors.forename: Mathew D
authors.initials: MD
authors.lastname: Lefebre
authors.affiliation: Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1.
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Flannagan
authors.affiliation: Department of Medicine, University of Western Ontario, London, Ontario, Canada N6A 5C1.|Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Valvano
mesh_terms: D000154:Aconitate Hydratase / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism*; D019117:Burkholderia / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D002952:Citric Acid Cycle / Q000502:physiology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D023061:Gene Order; D005798:Genes, Bacterial; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010544:Peroxidases / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D006861:Hydrogen Peroxide; D010544:Peroxidases; C081610:catalase-peroxidase, bacteria; D000154:Aconitate Hydratase; D005947:Glucose; D005990:Glycerol