Catalase-peroxidase activity is decreased in a Caulobacter crescentus rho mutant

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...

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Bibliographic Details
Published in:	FEMS microbiology letters 2010-02, Vol.303 (1), p.48-54
Main Authors:	Italiani, Valéria C.S, Braz, Vânia S, Xiao, Huifang, Steinman, Howard M, Marques, Marilis V
Format:	Article
Language:	eng
Subjects:	Bacterial Proteins - biosynthesis Bacteriology Biological and medical sciences Butyl hydroperoxide Catalase catalase activity Caulobacter crescentus Caulobacter crescentus - drug effects Caulobacter crescentus - enzymology Caulobacter crescentus - genetics DNA Transposable Elements Fundamental and applied biological sciences. Psychology Gene Expression Profiling Hydrogen peroxide Hydrogen Peroxide - toxicity KatG gene KatG protein Microbial Viability - drug effects Microbiology Miscellaneous Mutagenesis, Insertional Oxidants - toxicity Oxidation Oxidative Stress Paraquat Paraquat - toxicity Peroxidase Peroxidases - biosynthesis Peroxiredoxins - biosynthesis Post-translation Reductase Reductases Rho Factor - deficiency rho mutant Stationary phase Superoxide Superoxide Dismutase - biosynthesis tert-Butylhydroperoxide - toxicity Transcription termination Transcription termination factor RHO Translation
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Summary:	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.
ISSN:	0378-1097 1574-6968