Structural and functional insights into the interaction between Ku70/80 and Pol X family polymerases in NHEJ

Abstract Non-homologous end joining (NHEJ) is the main repair pathway for double-strand DNA breaks (DSBs) in mammals. DNA polymerases lambda (Pol λ) and mu (Pol μ), members of the Pol X family, play a key role in this process. However, their interaction within the NHEJ complexes is unclear. Here, we...

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Main Authors: Philippe Frit, Himani Amin, Sayma Zahid, Nadia Barboule, Chloe Hall, Gurdip Matharu, Steven W. Hardwick, Jeanne Chauvat, Sébastien Britton, Dima Y. Chirgadze, Virginie Ropars, Jean-Baptiste Charbonnier, Patrick Calsou, Amanda K. Chaplin
Format: Article
Language:English
Published: Nature Portfolio 2025-05-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-59133-2
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Summary:Abstract Non-homologous end joining (NHEJ) is the main repair pathway for double-strand DNA breaks (DSBs) in mammals. DNA polymerases lambda (Pol λ) and mu (Pol μ), members of the Pol X family, play a key role in this process. However, their interaction within the NHEJ complexes is unclear. Here, we present cryo-EM structures of Pol λ in complex with the DNA-PK long-range synaptic complex, and Pol μ bound to Ku70/80-DNA. These structures identify interaction sites between Ku70/80 and Pol X BRCT domains. Using mutants at the proteins interface in functional assays including cell transfection with an original gap-filling reporter, we define the role of the BRCT domain in the recruitment and activity of the two Pol X members in NHEJ and in their contribution to cell survival following DSBs. Finally, we propose a unified model for the interaction of all Pol X members with Ku70/80.
ISSN:2041-1723