Role of cAMP in the mediation of glucose catabolite repression of glucoamylase synthesis in Aspergillus awamori.

Exogenous cAMP was shown to mimic glucose in its effect on the synthesis of glucoamylase in Aspergillus awamori. cAMP (4 mM) when added to the starch medium blocked the derepression of glucoamylase by inhibiting its protein synthesis by about twofold. The repressive effect of cAMP on the glucoamylase synthesis was found to be due to twofold reduction in the glucoamylase specific mRNA levels. This cAMP related repression of the glucoamylase mRNA levels was most likely brought about at the level of gene transcription as cAMP had no apparent effect on the processing or stability of glucoamylase mRNA.