Characterization and functional analysis of a cAMP-dependent protein kinase A catalytic subunit gene (pka1) in Sclerotinia sclerotiorum

Increased cAMP levels inhibit sclerotial development and raise oxalate production in Sclerotinia sclerotiorum. These effects were hypothesized to be mediated by protein kinase A (PKA). To test this hypothesis, a pka1 catalytic subunit gene was cloned and disrupted. Southern hybridization confirmed disruption, and northern analysis revealed loss of a wild-type pka1 transcript. Mutant strains were cAMP-responsive, pathogenic, and had wild-type levels of PKA activity. Phylogenetic analyses of pka1 with other fungal pka genes and encoded peptides suggest that filamentous fungi possess two pka paralogs. Multiple lines of evidence presented in this work suggest that a second pka catalytic subunit gene, pka2, exists and contributes the majority of PKA activity in S. sclerotiorum. (C) 2004 Elsevier Ltd. All rights reserved.