Abstract

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).

• Keywords: catA; hydrogen peroxide-resistant mutant; Fur homologue; repressor gene; Streptomyces coeli-color