Cyclic AMP may not be involved in catabolite repression in Saccharomyces cerevisiae: Evidence from mutants unable to synthesize it

Abstract

Yeast cells with a nonsense adenylate cyclase mutation, cyrl-3, required cyclic AMP for growth. This phenotype was suppressed by the byc1 mutation; however, cyrl-3 bcy1 cells produced no detectable level of adenylate cyclase or cyclic AMP. On induction, the bcy1 and cyr1-3 bcy1 mutant cells produced the same levels of galactokinase and α-D-glucosidase as did the wild-type cells and fourfold higher levels of invertase. Since galactokinase synthesis was severely repressed by glucose in the constitutive GAL81 mutants, irrespective of the cyr1-3 bcyl genotype, cyclic AMP may not be involved in catabolite repression.