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Protein kinase CK2 interacts with Chk2 and phosphorylates Mre11 on serine 649

Seong-Tae Kim1

  • 1Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, 300 Chunchundong, Jangangu, Suwon, Kyonggido 440-746, Republic of Korea. stkim@med.skku.ac.kr

Biochemical and Biophysical Research Communications
|April 23, 2005
PubMed

Insights

Protein kinase CK2 phosphorylates the Mre11-Rad50-Nbs1 complex component Mre11 at serine 649. This phosphorylation, occurring both in vitro and in vivo, suggests CK2 is an upstream regulator of DNA double-strand break repair.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Cellular Biology

Background:

  • The Mre11-Rad50-Nbs1 (MRN) complex is crucial for DNA double-strand break (DSB) repair.
  • Mre11 phosphorylation increases after ionizing radiation, indicating a regulatory role.

Purpose of the Study:

  • To identify the kinase responsible for Mre11 phosphorylation.
  • To elucidate the regulatory mechanism of the MRN complex in DNA repair.

Main Methods:

  • Immunoprecipitation and kinase assays using Chk2 and HeLa nuclear extracts.
  • Protein purification via tandem affinity tagging and chromatography.
  • In vitro kinase assays with truncated Mre11 and site-directed mutagenesis.
  • In vivo labeling and phosphopeptide mapping.

Main Results:

  • Protein kinase CK2 was identified as the Mre11-phosphorylating kinase.
  • CK2 phosphorylates Mre11 in vitro, primarily at serine 649.
  • This serine 649 phosphorylation was confirmed to occur in vivo.

Conclusions:

  • Protein kinase CK2 acts as an upstream regulator of Mre11 function.
  • CK2-mediated phosphorylation of Mre11 is a key event in DNA damage response pathways.
  • Further research into CK2's role in DSB repair is warranted.

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