Molecular Cell
Volume 64, Issue 1, 6 October 2016, Pages 189-198
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Short Article
VCP/p97 Extracts Sterically Trapped Ku70/80 Rings from DNA in Double-Strand Break Repair

https://doi.org/10.1016/j.molcel.2016.08.037Get rights and content
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Highlights

  • VCP/p97 extracts sterically trapped Ku80 after NHEJ

  • VCP/p97 targets Ku modified with K48-linked ubiquitin chains

  • VCP/p97 is also essential for DNA repair pathway choice

Summary

During DNA double-strand break (DSB) repair, the ring-shaped Ku70/80 complex becomes trapped on DNA and needs to be actively extracted, but it has remained unclear what provides the required energy. By means of reconstitution of DSB repair on beads, we demonstrate here that DNA-locked Ku rings are released by the AAA-ATPase p97. To achieve this, p97 requires ATP hydrolysis, cooperates with the Ufd1-Npl4 ubiquitin-adaptor complex, and specifically targets Ku80 that is modified by K48-linked ubiquitin chains. In U2OS cells, chemical inhibition of p97 or siRNA-mediated depletion of p97 or its adapters impairs Ku80 removal after non-homologous end joining of DSBs. Moreover, this inhibition attenuates early steps in homologous recombination, consistent with p97-driven Ku release also affecting repair pathway choice. Thus, our data answer a central question regarding regulation of Ku in DSB repair and illustrate the ability of p97 to segregate even tightly bound protein complexes for release from DNA.

Keywords

DNA repair
Ku
Ku80
NHEJ
p97
VCP
double strand break
chromatin
homologous recombination

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