title: Catalase-peroxidase activity is decreased in a Caulobacter crescentus rho mutant.
abstract: A Caulobacter crescentus rho::Tn5 mutant strain presenting a partially functional transcription termination factor Rho is highly sensitive to hydrogen peroxide in both exponential and stationary phases. The mutant was shown to be permanently under oxidative stress, based on fluorophore oxidation, and also to be sensitive to tert-butyl hydroperoxide and paraquat. However, the results showed that the activities of superoxide dismutases CuZnSOD and FeSOD and the alkylhydroperoxide reductase ahpC mRNA levels in the rho mutant were comparable to the wild-type control in the exponential and stationary phases. In contrast, the KatG catalase activity of the rho mutant strain was drastically decreased and did not show the expected increase in the stationary phase compared with the exponential phase. Transcription of the katG gene was increased in the rho mutant and the levels of the immunoreactive KatG protein do not differ considerably compared with the wild type in the stationary phase, suggesting that KatG activity is affected in a translational or a post-translational step.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Valéria C S
authors.initials: VC
authors.lastname: Italiani
authors.forename: Vânia S
authors.initials: VS
authors.lastname: Braz
authors.forename: Huifang
authors.initials: H
authors.lastname: Xiao
authors.forename: Howard M
authors.initials: HM
authors.lastname: Steinman
authors.forename: Marilis V
authors.initials: MV
authors.lastname: Marques
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis*; D016935:Caulobacter crescentus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D004251:DNA Transposable Elements; D020869:Gene Expression Profiling; D006861:Hydrogen Peroxide / Q000633:toxicity; D050296:Microbial Viability / Q000187:drug effects; D016254:Mutagenesis, Insertional; D016877:Oxidants / Q000633:toxicity; D018384:Oxidative Stress; D010269:Paraquat / Q000633:toxicity; D010544:Peroxidases / Q000096:biosynthesis*; D054464:Peroxiredoxins / Q000096:biosynthesis; D012234:Rho Factor / Q000172:deficiency*; D013482:Superoxide Dismutase / Q000096:biosynthesis; D020122:tert-Butylhydroperoxide / Q000633:toxicity
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D016877:Oxidants; D012234:Rho Factor; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D010544:Peroxidases; C081610:catalase-peroxidase, bacteria; D054464:Peroxiredoxins; D013482:Superoxide Dismutase; D010269:Paraquat