CLONING AND PHENOTYPIC CHARACTERIZATION OF A GENE ENHANCING RESISTANCE AGAINST OXIDATIVE STRESS IN SACCHAROMYCES-CEREVISIAE

A DNA fragment enhancing resistance against oxidative stress caused by several peroxides was cloned from the yeast Saccharomyces cerevisiae, and the corresponding gene was designated OSR; oxidative stress-resistant gene. By amplification of the OSR gene in the yeast cell, the transformant became resistant to tert-butyl hydroperoxide, linoleic acid hydroperoxide and hydrogen peroxide, whereas it became hypersensitive to cumene hydroperoxide. Thus, the dosage of the OSR gene in the yeast cell seemed to affect the behaviour of the transformant against peroxides. The resistance of the transformant was suppressed by the addition of buthionine sulfoximine, a potent inhibitor of glutathione biosynthesis, into a medium containing lipid hydroperoxide; thus a glutathione-dependent resistance mechanism was suggested to be concerned with the phenotype of the transformant.