Replication Checkpoint Kinase Cds1 Regulates Recombinational Repair Protein Rad60

Abstract

Genome integrity is protected by Cds1 (Chk2), a checkpoint kinase that stabilizes arrested replication forks. How Cds1 accomplishes this task is unknown. We report that Cds1 interacts with Rad60, a protein required for recombinational repair in fission yeast. Cds1 activation triggers Rad60 phosphorylation and nuclear delocalization. A Rad60 mutant that inhibits regulation by Cds1 renders cells specifically sensitive to replication fork arrest. Genetic and biochemical studies indicate that Rad60 functions codependently with Smc5 and Smc6, subunits of an SMC (structural maintenance of chromosomes) complex required for recombinational repair. These studies indicate that regulation of Rad60 is an important part of the replication checkpoint response controlled by Cds1. We propose that control of Rad60 regulates recombination events at stalled forks.

ACKNOWLEDGMENTS

We thank C. McGowan for comments on the manuscript and members of the Scripps Cell Cycle Groups for encouragement.

M.N.B. is a Research Special Fellow of the Leukemia & Lymphoma Society. W.H.M was supported by MERK-MGRI-241. E.N. was supported by the Human Frontiers Science Program. J.R.Y. was supported by RO1 EY1328801, MERK-MGRI-241, and CA81665 RR11823. This work was funded by NIH grants awarded to P.R.