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PAXX binding to the NHEJ machinery explains functional redundancy with XLF

Nonhomologous end joining is a critical mechanism that repairs DNA double-strand breaks in human cells. In this work, we address the structural and functional role of the accessory protein PAXX [paralog of x-ray repair cross-complementing protein 4 (XRCC4) and XRCC4-like factor (XLF)] in this mechan...

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Detalles Bibliográficos
Autores principales: Seif-El-Dahan, Murielle, Kefala-Stavridi, Antonia, Frit, Philippe, Hardwick, Steven W., Chirgadze, Dima Y., Maia De Oliviera, Taiana, Britton, Sébastien, Barboule, Nadia, Bossaert, Madeleine, Pandurangan, Arun Prasad, Meek, Katheryn, Blundell, Tom L., Ropars, Virginie, Calsou, Patrick, Charbonnier, Jean-Baptiste, Chaplin, Amanda K.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Association for the Advancement of Science 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10413649/
https://www.ncbi.nlm.nih.gov/pubmed/37256950
http://dx.doi.org/10.1126/sciadv.adg2834
Descripción
Sumario:Nonhomologous end joining is a critical mechanism that repairs DNA double-strand breaks in human cells. In this work, we address the structural and functional role of the accessory protein PAXX [paralog of x-ray repair cross-complementing protein 4 (XRCC4) and XRCC4-like factor (XLF)] in this mechanism. Here, we report high-resolution cryo–electron microscopy (cryo-EM) and x-ray crystallography structures of the PAXX C-terminal Ku-binding motif bound to Ku70/80 and cryo-EM structures of PAXX bound to two alternate DNA-dependent protein kinase (DNA-PK) end-bridging dimers, mediated by either Ku80 or XLF. We identify residues critical for the Ku70/PAXX interaction in vitro and in cells. We demonstrate that PAXX and XLF can bind simultaneously to the Ku heterodimer and act as structural bridges in alternate forms of DNA-PK dimers. Last, we show that engagement of both proteins provides a complementary advantage for DNA end synapsis and end joining in cells.