Rad3-dependent phosphorylation of the checkpoint clamp regulates repair-pathway choice

Mihoko Kai, Kanji Furuya, Francesca Paderi, Antony M. Carr, Teresa S.F. Wang

Research output: Contribution to journalArticlepeer-review


When replication forks collapse, Rad3 phosphorylates the checkpoint-clamp protein Rad9 in a manner that depends on Thr 225, a residue within the PCNA-like domain. The physiological function of Thr 225-dependent Rad9 phosphorylation, however, remains elusive. Here, we show that Thr 225-dependent Rad9 phosphorylation by Rad3 regulates DNA repair pathways. A rad9T225C mutant induces a translesion synthesis (TLS)-dependent high spontaneous mutation rate and a hyper-recombination phenotype. Consistent with this, Rad9 coprecipitates with the post-replication repair protein Mms2. This interaction is dependent on Rad9 Thr 225 and is enhanced by DNA damage. Genetic analyses indicate that Thr 225-dependent Rad9 phosphorylation prevents inappropriate Rhp51-dependent recombination, potentially by redirecting the repair through a Pli1-mediated sumoylation pathway into the error-free branch of the Rhp6 repair pathway. Our findings reveal a new mechanism by which phosphorylation of Rad9 at Thr 225 regulates the choice of repair pathways for maintaining genomic integrity during the cell cycle.

Original languageEnglish (US)
Pages (from-to)691-697
Number of pages7
JournalNature cell biology
Issue number6
StatePublished - Jun 1 2007
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology

Fingerprint Dive into the research topics of 'Rad3-dependent phosphorylation of the checkpoint clamp regulates repair-pathway choice'. Together they form a unique fingerprint.

Cite this