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Visualization of a DNA-PK/PARP1 complex

Lookup NU author(s): Dr Jody Barbeau, Professor Nicola CurtinORCiD

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Abstract

The DNA-dependent protein kinase (DNA-PK) and Poly(ADP-ribose) polymerase-1 (PARP1) are critical enzymes that reduce genomic damage caused by DNA lesions. They are both activated by DNA strand breaks generated by physiological and environmental factors, and they have been shown to interact. Here, we report in vivo evidence that DNA-PK and PARP1 are equally necessary for rapid repair. We purified a DNA-PK/PARP1 complex loaded on DNA and performed electron microscopy and single particle analysis on its tetrameric and dimer-of-tetramers forms. By comparison with the DNA-PK holoenzyme and fitting crystallographic structures, we see that the PARP1 density is in close contact with the Ku subunit. Crucially, PARP1 binding elicits substantial conformational changes in the DNA-PK synaptic dimer assembly. Taken together, our data support a functional, in-pathway role for DNA-PK and PARP1 in double-strand break (DSB) repair. We also propose a NHEJ model where protein-protein interactions alter substantially the architecture of DNA-PK dimers at DSBs, to trigger subsequent interactions or enzymatic reactions.

Publication metadata

Author(s): Spagnolo L, Barbeau J, Curtin NJ, Morris EP, Pearl LH

Publication type: Article

Publication status: Published

Journal: Nucleic Acids Research

Year: 2012

Volume: 40

Issue: 9

Pages: 4168-4177

Print publication date: 05/01/2012

Date deposited: 12/10/2012

ISSN (print): 0305-1048

ISSN (electronic): 1362-4962

Publisher: Oxford University Press

URL: http://dx.doi.org/10.1093/nar/gkr1231

DOI: 10.1093/nar/gkr1231

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