Parallel changes in catabolite repression of haem biosynthesis and cytochromes in repression-resistant mutants of Saccharomyces cerevisiae

J Gen Microbiol. 1989 May;135(5):1217-27. doi: 10.1099/00221287-135-5-1217.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 5-Aminolevulinate Synthetase / biosynthesis
  • Aerobiosis
  • Cytochromes / biosynthesis*
  • Deoxyglucose / pharmacology
  • Enzyme Induction / drug effects
  • Feedback
  • Fungal Proteins / biosynthesis*
  • Gene Expression Regulation, Fungal / drug effects*
  • Genes, Fungal
  • Glucose / pharmacology
  • Heme / biosynthesis*
  • Maltose / pharmacology
  • Porphobilinogen Synthase / biosynthesis
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / genetics*


  • Cytochromes
  • Fungal Proteins
  • Heme
  • Maltose
  • Deoxyglucose
  • 5-Aminolevulinate Synthetase
  • Porphobilinogen Synthase
  • Glucose