Multiple protein-protein interactions within the DNA-PK complex are mediated by the C-terminus of Ku 80

Sara M. Bennett, Derek S. Woods, Katherine S. Pawelczak, John J. Turchi

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


DNA double strand breaks (DSB) are among the most lethal forms of DNA damage and, in humans, are repaired predominantly by the non-homologous end joining (NHEJ) pathway. NHEJ is initiated by the Ku70/80 het-erodimer binding free DNA termini and then recruiting the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to form the catalytically active DNA-PK holoenzyme. The extreme C-terminus of Ku80 (Ku80CTD) has been shown to be important for in vitro stimulation of DNA-PK activity and NHEJ in vivo. To better define the mechanism by which the Ku80CTD elicits these activities, we assessed its functional and physical interactions with DNA-PKcs and Ku70/80. The results demonstrate that DNA-PKcs activity could not be complemented by addition of a Ku80CTD suggesting that the physical connection of the C-terminus to the DNA binding domain of Ku70/80 is required for DNA-PKcs activation. Analysis of protein-protein interactions revealed a low but measurable binding of the Ku80CTD for Ku70/80ΔC and for DNA-PKcs while dimer formation and the formation of higher ordered structures of the Ku80CTD was readily apparent. Ku has been shown to tether DNA termini possibly due to protein/protein interactions. Results demonstrate that the presence of the Ku80CTD stimulates this activity possibly through Ku80CTD/Ku80CTD interactions.

Original languageEnglish (US)
Pages (from-to)36-45
Number of pages10
JournalInternational Journal of Biochemistry and Molecular Biology
Issue number1
StatePublished - Apr 18 2012


  • Chemical crosslinking
  • Dimerization
  • DNA repair
  • DNA-PK
  • Ku
  • NHEJ

ASJC Scopus subject areas

  • Molecular Biology
  • Biochemistry

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