Cell Cycle Regulation of the Saccharomyces cerevisiae Polo-Like Kinase Cdc5p

ABSTRACT

Progression through and completion of mitosis require the actions of the evolutionarily conserved Polo kinase. We have determined that the levels of Cdc5p, a Saccharomyces cerevisiae member of the Polo family of mitotic kinases, are cell cycle regulated. Cdc5p accumulates in the nuclei of G₂/M-phase cells, and its levels decline dramatically as cells progress through anaphase and begin telophase. We report that Cdc5p levels are sensitive to mutations in key components of the anaphase-promoting complex (APC). We have determined that Cdc5p-associated kinase activity is restricted to G₂/M and that this activity is posttranslationally regulated. These results further link the actions of the APC to the completion of mitosis and suggest possible roles for Cdc5p during progression through and completion of mitosis.

ACKNOWLEDGMENTS

We thank L. Hartwell, K. Nasmyth, J. Cooper, D. Lew, O. Cohen-Fix, D. Koshland, and M. Rout for strains and plasmids; S. Dowdy and lab for excellent help with FACS; S. Wente for reading the manuscript; H. Piwnica-Worms for helpful discussions; J. A. Cooper and T. Karpova for the use of their Olympus; T. Collyer and T. Zonca for technical support in the early stages of the project; and J. Kilmartin for the SPC-42 strain.

This work was supported by grants RPG-97-162-01-CCG from ACS and GM5678801 from NIH to C.F.J.H.