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XRCC1 is phosphorylated by DNA-dependent protein kinase in response to DNA damage

Nicolas Lévy1, Adeline Martz, Anne Bresson

  • 1Département Intégrité du génome de l'UMR 7175, CNRS, Ecole Supérieure de Biotechnologie de Strasbourg, Boulevard S. Brant, BP 10413, F-67412 Illkirch Cedex, France.

Nucleic Acids Research
|January 7, 2006
PubMed

Insights

The XRCC1 protein

Area of Science:

  • Molecular Biology
  • DNA Repair Mechanisms
  • Cellular Response to DNA Damage

Background:

  • XRCC1 protein's BRCT domains mediate interactions in DNA repair pathways.
  • BRCT1 domain is crucial for recruiting XRCC1 to DNA breaks, essential for survival.
  • Understanding XRCC1's role in DNA end processing requires identifying associated proteins.

Purpose of the Study:

  • To identify proteins interacting with the BRCT1 domain of XRCC1.
  • To investigate the interaction between XRCC1 and DNA-PK in response to DNA damage.
  • To elucidate the functional consequences of XRCC1 phosphorylation by DNA-PK.

Main Methods:

  • Mass spectrometry was used to identify proteins pulled down by GST-BRCT1 from HeLa cell extracts.
  • Interaction and phosphorylation assays were performed using ionizing irradiation (IR).
  • Site-directed mutagenesis was used to create XRCC1 mutants (S371D, S371L) and analyze their function.

Main Results:

  • DNA-PK, a double-strand break (DSB) repair complex, interacts with XRCC1's BRCT1 domain.
  • DNA-PK phosphorylates XRCC1 at serine 371 upon ionizing irradiation, causing XRCC1 dimer dissociation.
  • XRCC1 stimulates DNA-PK-mediated phosphorylation of p53-Ser15; specific mutants reveal functional roles in DSB repair.

Conclusions:

  • XRCC1 and DNA-PK functionally associate in a common DNA double-strand break repair pathway.
  • Phosphorylation of XRCC1 by DNA-PK at Ser371 is a key regulatory event in DNA damage response.
  • This interaction highlights a novel mechanism in the cellular response to ionizing radiation.

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