Stimulation of the DNA-dependent protein kinase by poly(ADP-ribose) polymerase

Tracy Ruscetti, Bruce E. Lehnert, James Halbrook, Hai Le Trong, Merl F. Hoekstra, David J. Chen, Scott R. Peterson

Research output: Contribution to journalArticlepeer-review

216 Scopus citations


The DNA-dependent protein kinase (DNA-PK) is a heterotrimeric enzyme that binds to double-stranded DNA and is required for the rejoining of double-stranded DNA breaks in mammalian cells. It has been proposed that DNA- PK functions in this DNA repair pathway by binding to the ends of broken DNA molecules and phosphorylating proteins that bind to the damaged DNA ends. Another enzyme that binds to DNA strand breaks and may also function in the cellular response to DNA damage is the poly(ADP-ribose) polymerase (PARP). Here, we show that PARP can be phosphorylated by purified DNA-PK, and the catalytic subunit of DNA-PK is ADP-ribosylated by PARP. The protein kinase activity of DNA-PK can be stimulated by PARP in the presence of NAD+ in a reaction that is blocked by the PARP inhibitor 1,5-dihydroxyisoquinoline. The stimulation of DNA-PK by PARP-mediated protein ADP-ribosylation occurs independent of the Ku70/80 complex. Taken together, these results show that PARP can modify the activity of DNA-PK in vitro and suggest that these enzymes may function coordinately in vivo in response to DNA damage.

Original languageEnglish (US)
Pages (from-to)14461-14467
Number of pages7
JournalJournal of Biological Chemistry
Issue number23
StatePublished - Jun 5 1998

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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