Cyclic AMP Can Decrease Expression of Genes Subject to Catabolite Repression in Saccharomyces cerevisiae

External cyclic AMP (cAMP) hindered the derepression of gluconeogenic enzymes in a pde2 mutant of Saccharomyces cerevisiae, but it did not prevent invertase derepression. cAMP reduced nearly 20-fold the transcription driven by upstream activation sequence (UAS1(FBP1)) from FBP1, encoding fructose-1,6-bisphosphatase; it decreased 2-fold the activation of transcription by UAS2(FBP1). Nuclear extracts from cells derepressed in the presence of cAMP were impaired in the formation of specific UAS(FBP1)-protein complexes in band shift experiments. cAMP does not appear to act through the repressing protein Mig1. Control of FBP1 transcription through cAMP is redundant with other regulatory mechanisms.