- Analysis of the Dual Promoters and the H 2 O 2 -responsive Element of the catA Gene Encoding Catalase A in Streptomyces coelicolor
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You-Hee Cho , Ji-Sook Hahn , Jung-Hye Roe
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J. Microbiol. 2000;38(4):239-244.
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 Abstract
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The catA gene encodes the major catalase in Streptomyces coelicolor, whose production increases upon H_2O_2 treatment. Besides the previously identified primary promoter (catAp1), a minor promoter (catAp2) was newly assigned by S1 nuclease mapping. The catAp2 transcript was observed transiently upon entry into the stationary phase in liquid culture and upon differentiation on solid plates, whereas the level of catAp1 transcription did not change significantly during this growth transition. The catAp1 promoter was transcribed by the major vegetative RNA polymerase holoenzyme containing [sigma]^HrdB , whereas the catAp2 was transcribed in vitro by the holoenzyme containing [sigma]^R that is activated under oxidative conditions. The cis-element regulating the H_2 O_2 -inducibility of catAp1 was identified within the 23 bp inverted repeat sequence located between -65 and -43 of the catAp1 promoter. We named this sequence HRE (H_2O_2 -responsive element). The distal half of the inverted repeat was more crucial for H_2 O_2 ?pendent induction of the catAp1 transcript than the proximal half. HRE most likely serves as a binding site for the H_2 O_2 -responsive repressor CatR.
- Isolation of the Regulator Gene Responsible for Overproduction of Catalase A in H 2 O 2 -resistant Mutant of Streptomyces coelicolor
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Ji-Sook Hahn , So-Young Oh , Keith F. Chater , Jung-Hye Roe
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J. Microbiol. 2000;38(1):18-23.
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Abstract
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Streptomyces coelicolor produces three kinds of catalases to cope with oxidative stress and to allow nor-mal differentiation. Catalase A is the major vegetative catalase which functions in removing hydrogen peroxide generated during the process of aerobic metabolism. To understand the regulatory mechanism of response against oxidative stress, hydrogen peroxide-resistant mutant (HR40) was isolated from S. coelicolor J1501 following UV mutagenesis. The mutant overproduced catalase A more than 50-fold compared with the wild type. The mutation locus catR1 was mapped closed to the mthB2 locus by genetic crossings. An ordered cosmid library of S. coelicolor encompassing the mthB2 locus was used to isolate the regulator gene (catR) which represses catalase overproduction when introduced into HR40. A candidate catR gene was found to encode a Fur-like protein of 138 amino acids (15319 Da).
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