Genetic and physiological analysis of the major OxyR-regulated katA from Xanthomonas campestris pv. phaseoli.
katA encodes the major catalase that accounts for 90 % of the total catalase activity present in Xanthomonas campestris pv. phaseoli. katA is located upstream of an ORF designated ankA encoding a cytoplasmic membrane protein homologous to eukaryotic ankyrin. Transcriptional analysis of katA and ankA identified two katA transcripts: a major monocistronic katA transcript and a minor bicistronic katA-ankA transcript. KatA expression was induced in the presence of various oxidants including H2O2, organic hydroperoxides and the superoxide-generating agent menadione, in an OxyR-dependent manner. Analysis of the katA promoter region showed a putative OxyR binding site located upstream of an Escherichia coli-like sigma70 -35 region that is likely to be responsible for transcription activation in response to oxidant treatment. Gel mobility shift experiments confirmed that purified OxyR specifically binds to the katA promoter. A katA mutant was highly sensitive to H2O2 during both the exponential and stationary phases of growth. This phenotype could be complemented by functional katA, confirming the essential role of the gene in protecting X. campestris from H2O2 toxicity. Unexpectedly, inactivation of ankA also significantly reduced resistance to H2O2 and the phenotype could be complemented by plasmid-borne expression of ankA. Physiological analyses showed that katA plays an important role in, but is not solely responsible for, both the adaptive and menadione-induced cross-protective responses to H2O2 killing in X. campestris.
Chauvatcharin
Nopmanee
N
Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.|Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.
Atichartpongkul
Sopapan
S
Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.
Utamapongchai
Supa
S
Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.
Whangsuk
Wirongrong
W
Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.
Vattanaviboon
Paiboon
P
Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.
Mongkolsuk
Skorn
S
Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.|Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.
D017487:Ankyrins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002374:Catalase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D024483:Vitamin K 3 / Q000494:pharmacology; D016959:Xanthomonas campestris / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
D017487:Ankyrins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D024483:Vitamin K 3; D006861:Hydrogen Peroxide; D002374:Catalase