Heterotrimeric G protein mediated regulation of proteinase production in Aspergillus nidulans

Extracellular proteinase production induced by carbon starvation was studied in a series of heterotrimeric G protein signaling pathway mutants of Aspergillus nidulans. All the mutants tested - including Delta fadA (G alpha), Delta sfaD (G beta), Delta gpgA (G gamma) and Delta sfgA (regulator of FadA signaling) - showed an elevated proteinase production after glucose depletion. Our results strongly support the view that during growth, FadA/SfaD/GpgA G protein signaling inhibits proteinase production via both Ga and G beta gamma subunits, and all conditions, which are not sufficient to support vegetative growth and, hence, inhibit this type of G protein signaling, elevate extracellular proteinase activities.