%0 Journal Article %A Borralho, L. M. %A Malamud, D. R. %A Panek, A. D. %A Tenan, M. N. %A Oliveira, D. E. %A Mattoon, J. R. %T Parallel Changes in Catabolite Repression of Haem Biosynthesis and Cytochromes in Repression-resistant Mutants of Saccharomyces cerevisiae %D 1989 %J Microbiology, %V 135 %N 5 %P 1217-1227 %@ 1465-2080 %R https://doi.org/10.1099/00221287-135-5-1217 %I Microbiology Society, %X Effects of three mutant genes, CAT1-2d, cat2-1 and hex2-3, on catabolite repression of mitochondrial cytochromes and the first two enzymes of haem biosynthesis were compared. The CAT1-2d mutation gave no resistance to glucose, whereas cat2-1 endowed both cytochromes and 5-aminolaevulinate dehydratase with resistance, but did not alter the effect of glucose on 5-aminolaevulinate synthase. The hex2-3 mutation caused repression resistance of cytochromes and of the two haem biosynthetic enzymes. hex2-3 strains also accumulated intracellular 5-aminolaevulinate. Co-inheritance of the latter traits, sensitivity to maltose inhibition and ability to grow on raffinose in the presence of 2-deoxyglucose, demonstrated that the pleiotropic phenotype is a function of the single gene hex2-3. Revertants which grew on maltose regained sensitivity to deoxyglucose and exhibited normal sensitivity of cytochromes and haem biosynthesis enzymes to repression. Addition of the hex1-18 mutation, which renders cytochromes resistant to repression, to a cat2-1 strain did not produce the same effect on 5-aminolaevulinate synthase as hex2-3. It is concluded that repression patterns of haem and cytochrome biosynthesis are substantially affected by hex2-3 and cat2-1 but not by CAT1-2d . %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-135-5-1217