Translational control of catalase synthesis by hemin in the yeast Saccharomyces cerevisiae

Abstract

mRNA-dependent cell-free protein synthesis systems were prepared from a heme-deficient ole3 mutant of the yeast Saccharomyces cerevisiae grown either in the absence or in the presence of the heme precursor delta-aminolevulinate. When supplemented with total yeast mRNA, the two systems-from heme-deficient and from heme-containing cells-translate most mRNAs with comparable efficiencies. mRNAs coding for the hemoproteins catalase T and catalase A, however, are translated at a low rate by the system from heme-deficient cells whereas their translation in the system from heme-containing cells is comparable to that observed in a heterologous in vitro system from wheat germ. Addition of 10 muM hemin to the system from heme-deficient cells stimulates translation of catalase mRNAs significantly. Control experiments showed that the results obtained cannot be explained by specific proteinase or nuclease action. Together with previous findings indicating lack of translation of catalase T mRNA in heme-deficient cells in vivo, the results demonstrate that specific control of yeast catalase formation occurs at the level of translation.