Fck1, a C-type cyclin-dependent kinase, interacts with Fcc1 to regulate development and secondary metabolism in Fusarium verticillioides

In Fusarium verticillioides, the C-type cyclin Fcc1 is a global regulator of gene expression. In Saccharomyces cerevisiae and other organisms, C-type cyclins regulate the activity of specific cyclin-dependent kinases through physical association. We identified FCK1, a gene encoding a cyclin-dependent kinase in F. verticillioides. The Fck1 protein is predicted to contain a cyclin-binding motif and a serine-threonine protein kinase domain homologous to previously described cyclin-dependent kinases. Disruption of FCK1 resulted in pleiotropic morphological defects including reduced growth, conidiation, fumonisin B1 (FB1) production, and enhanced pigmentation. Two-hybrid analysis indicated a strong physical interaction between Fcc1 and Fck1. This study presents the first description of the interaction between a C-type cyclin and a cyclin-dependent kinase in a filamentous fungus and provides new insight regarding a molecular mechanism that regulates aspects of maize kernel colonization by F. verticillioides.