Identification and overexpression of genes encoding cAMP-dependent protein kinase catalytic subunits in homobasidiomycete Schizophyllum commune

This report describes the first cloning and overexpression experiments on genes encoding cAMP-dependent protein kinase catalytic subunits in homobasidiomycete Schizophyllum commune. We used a degenerate PCR approach to identify two novel genes (ScPKAC1 and ScPKAC2) that are very similar to the catalytic subunits in many eukaryotes. The morphological phenotypes of ScPKAC1 and ScPKAC2 overexpressing clones were compared with those of constitutively active ScGP-A overexpressing clones to determine whether ScPKAC1 and ScPKAC2 are located downstream of heterotrimeric G-protein alpha subunit ScGP-A. Overexpression of constitutively active ScGP-A increased intracellular cAMP levels and suppressed aerial mycelium formation. In contrast, overexpressing ScPKAC1 and ScPKAC2 did not affect the intracellular cAMP levels, though aerial mycelium formation was strongly suppressed. These observations suggest that ScPKAC1 and ScPKAC2 proteins are located downstream of the G-protein alpha subunit ScGP-A in the cAMP signaling pathway.