Journal Article

Visualization of a DNA-PK/PARP1 complex

Laura Spagnolo, Jody Barbeau, Nicola J. Curtin, Edward P. Morris and Laurence H. Pearl

in Nucleic Acids Research

Volume 40, issue 9, pages 4168-4177
Published in print May 2012 | ISSN: 0305-1048
Published online January 2012 | e-ISSN: 1362-4962 | DOI: https://dx.doi.org/10.1093/nar/gkr1231

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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.

Journal Article.  5514 words.  Illustrated.

Subjects: Chemistry ; Biochemistry ; Bioinformatics and Computational Biology ; Genetics and Genomics ; Molecular and Cell Biology

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