Effect of cyclic AMP on invertase activity in Neurospora crassa HERNAN

Invertase activity in wild-type and several mutant strains of Neurospora crassa, was significantly enhanced by supplementing the culture medium with cyclic AMP (5.0 mM). Cyclic AMP stimulated invertase by (i) increasing overall enzyme production and (ii) substituting for natural carbohydrate inducers (i.e. galactose or raffinose) as a requirement for maximal enzyme production. The effect of cAMP was specific for the nucleotide and was sensitive to glucose repression. The effect of exogenous cAMP was also studied in mycelial and cell-wall-less derivatives of a ‘slime’ strain. It was observed that cAMP stimulated invertase production in the mycelial phenotype of ‘slime’, while its cell-wall-less derivative was totally refractory to the effect of the nucleotide. These findings indicate that the effect of cAMP on N. crassa invertase production could be mediated with the participation of cell surface elements.