PMID:22438866

Citation	Kim, JS and Holmes, RK (2012) Characterization of OxyR as a negative transcriptional regulator that represses catalase production in Corynebacterium diphtheriae. PLoS ONE 7:e31709
Abstract	Corynebacterium diphtheriae and Corynebacterium glutamicum each have one gene (cat) encoding catalase. In-frame Δcat mutants of C. diphtheriae and C. glutamicum were hyper-sensitive to growth inhibition and killing by H(2)O(2). In C. diphtheriae C7(β), both catalase activity and cat transcription decreased ~2-fold during transition from exponential growth to early stationary phase. Prototypic OxyR in Escherichia coli senses oxidative stress and it activates katG transcription and catalase production in response to H(2)O(2). In contrast, exposure of C. diphtheriae C7(β) to H(2)O(2) did not stimulate transcription of cat. OxyR from C. diphtheriae and C. glutamicum have 52% similarity with E. coli OxyR and contain homologs of the two cysteine residues involved in H(2)O(2) sensing by E. coli OxyR. In-frame ΔoxyR deletion mutants of C. diphtheriae C7(β), C. diphtheriae NCTC13129, and C. glutamicum were much more resistant than their parental wild type strains to growth inhibition by H(2)O(2). In the C. diphtheriae C7(β) ΔoxyR mutant, cat transcripts were about 8-fold more abundant and catalase activity was about 20-fold greater than in the C7(β) wild type strain. The oxyR gene from C. diphtheriae or C. glutamicum, but not from E. coli, complemented the defect in ΔoxyR mutants of C. diphtheriae and C. glutamicum and decreased their H(2)O(2) resistance to the level of their parental strains. Gel-mobility shift, DNaseI footprint, and primer extension assays showed that purified OxyR from C. diphtheriae C7(β) bound, in the presence or absence of DTT, to a sequence in the cat promoter region that extends from nucleotide position -55 to -10 with respect to the +1 nucleotide in the cat ORF. These results demonstrate that OxyR from C. diphtheriae or C. glutamicum functions as a transcriptional repressor of the cat gene by a mechanism that is independent of oxidative stress induced by H(2)O(2).
Links	PubMed PMC3306370 Online version:10.1371/journal.pone.0031709
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Base Sequence; Catalase/biosynthesis; Catalase/genetics; Corynebacterium diphtheriae/drug effects; Corynebacterium diphtheriae/genetics; Corynebacterium diphtheriae/metabolism; Corynebacterium glutamicum/drug effects; Corynebacterium glutamicum/genetics; Corynebacterium glutamicum/metabolism; DNA, Bacterial/genetics; Escherichia coli/drug effects; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Genes, Bacterial; Genetic Complementation Test; Hydrogen Peroxide/pharmacology; Mutation; Oxidative Stress; Promoter Regions, Genetic; Recombinant Proteins/genetics; Recombinant Proteins/metabolism; Repressor Proteins/genetics; Repressor Proteins/metabolism; Species Specificity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
CORDI:H2GUE0		GO:0045892: negative regulation of transcription, DNA-templated	IMP: Inferred from Mutant Phenotype:	P	Seeded From UniProt	complete
CORDI:Q6NJW2		GO:0004096: catalase activity	ECO:0000315:		F		figure 1A and 1B demonstrated that C7(beta) needed the cat gene in order for survival. The mutant strains was not able to survive after deletion of the cat gene, they were not able to detoxifiy when hydrogen peroxide added, complete loss of viability was shown.	complete CACAO 4869
CORDI:H2H804		GO:0010629 : negative regulation of gene expression	IDA: Inferred from Direct Assay:	P	figure 4 and figure 5 demonstrated how oxyR downregulate the transcription of cat gene, this is shown by the doing a quantitative RT-PCR assays on catalase activty and comparing wild-type strains and mutant strains with deletion of oxyR mutants	complete CACAO 4871

References

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