Comparative Characterization of G Protein α Subunits in .

Trimeric G proteins play a central role in the G protein signaling in filamentous fungi and Gα subunits are the major component of trimeric G proteins. In this study, we characterize three Gα subunits in the human pathogen . While the deletion of and led to reduced colony growth, the growth of the Δ strain was increased in minimal media. The germination rate, conidiation, and mRNA expression of key asexual development regulators were significantly decreased by the loss of . In contrast, the deletion of resulted in increased conidiation and mRNA expression levels of key asexual regulators. The deletion of caused a reduction in conidial tolerance against HO, but not in paraquat (PQ). Moreover, the Δ mutant showed enhanced susceptibility against membrane targeting azole antifungal drugs and reduced production of gliotoxin (GT). The protein kinase A (PKA) activity of the Δ strain was severely decreased and protein kinase C (PKC) activity was detected all strains at similar levels, indicating that all G protein α subunits of . may be a component of the cAMP/PKA signaling pathway and appear to possess the PKC signaling pathway as an alternative backup pathway to compensate for PKA depletion. Collectively, the three Gα subunits regulate growth, germination, asexual development, resistance to oxidative stress, and GT production differently the PKA or PKC signaling pathway. The function of GanA of . was elucidated for the first time.