Casein kinase 2-dependent phosphorylation of human Rad9 mediates the interaction between human Rad9-Hus1-Rad1 complex and TopBP1

Yukimasa Takeishi, Eiji Ohashi, Kaori Ogawa, Hisao Masai, Chikashi Obuse, Toshiki Tsurimoto

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

The checkpoint clamp Rad9-Hus1-Rad1 (9-1-1) is loaded by the Rad17-RFC complex onto chromatin after DNA damage and plays a key role in the ATR-dependent checkpoint activation. Here, we demonstrate that in vitro casein kinase 2 (CK2) specifically interacts with human 9-1-1 and phosphorylates serines 341 and 387 (Ser-341 and Ser-387) in the C-terminal tail of Rad9. Interestingly, phosphorylated Ser-387 has previously been reported to be required for interacting with a checkpoint mediator TopBP1. Indeed, 9-1-1 purified from Escherichia coli and phosphorylated in vitro by CK2 physically interacts with TopBP1. Further analyses showed that phosphorylation at both serine residues occurs in vivo and is required for the efficient interaction with TopBP1 in vitro. Furthermore, when over-expressed in HeLa cells, a mutant Rad9 harboring phospho-deficient substitutions at both Ser-341 and Ser-387 residues causes hypersensitivity to UV and methyl methane sulfonate (MMS). Our observations suggest that CK2 plays a crucial role in the ATR-dependent checkpoint pathway through its ability to phosphorylate Ser-341 and Ser-387 of the Rad9 subunit of the 9-1-1 complex.

Original languageEnglish
Pages (from-to)761-771
Number of pages11
JournalGenes to Cells
Volume15
Issue number7
DOIs
Publication statusPublished - Jun 2010

All Science Journal Classification (ASJC) codes

  • Genetics
  • Cell Biology

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