DBF2, a cell cycle-regulated protein kinase, is physically and functionally associated with the CCR4 transcriptional regulatory complex.

CCR4, a general transcriptional regulator affecting the expression of a number of genes in yeast, forms a multi-subunit complex in vivo. Using the yeast two-hybrid screen, we have identified DBF2, a cell cycle-regulated protein kinase, as a CCR4-associated protein. DBF2 is required for cell cycle progression at the telophase to G1 cell cycle transition. DBF2 co-immunoprecipitated with CCR4 and CAF1/POP2, a CCR4-associated factor, and co-purified with the CCR4 complex. Moreover, a dbf2 disruption resulted in phenotypes and transcriptional defects similar to those observed in strains deficient for CCR4 or CAF1. ccr4 and caf1 mutations, on the other hand, were found to affect cell cycle progression in a manner similar to that observed for dbf2 defects. These data indicate that DBF2 is involved in the control of gene expression and suggest that the CCR4 complex regulates transcription during the late mitotic part of the cell cycle.