Restriction of Ku translocation protects telomere ends
Safeguarding chromosome ends against fusions via nonhomologous end joining (NHEJ) is essential for genome integrity. Paradoxically, the conserved NHEJ core factor Ku binds telomere ends. How it is prevented from promoting NHEJ remains unclear, as does the mechanism that allows Ku to coexist with telomere-protective DNA binding proteins, Rap1 in Saccharomyces cerevisiae. Here, we find that Rap1 directly inhibits Ku's NHEJ function at telomeres. A single Rap1 molecule near a double-stand break suppresses NHEJ without displacing Ku in cells. Furthermore, Rap1 and Ku form a complex on short DNA duplexes in vitro. Cryo-EM shows Rap1 blocks Ku's inward translocation on DNA - an essential step for NHEJ at DSBs. Nanopore sequencing of telomere fusions confirms this mechanism protects native telomere ends. These findings uncover a telomere protection mechanism where Rap1 restricts Ku's inward translocation. This switches Ku from a repair-promoting to a protective role preventing NHEJ at telomeres.
Authors
- Sabrina Pobiega (ORCID: https://orcid.org/0009-0004-7740-2646)
- Stéphane Marcand (ORCID: https://orcid.org/0000-0001-5199-1885)
- Éric Le Cam (ORCID: https://orcid.org/0000-0002-6832-6117)
- Gerard Mazón (ORCID: https://orcid.org/0000-0002-9791-5666)
- Philippe Cuniasse (ORCID: https://orcid.org/0000-0001-9334-2891)
- Florian Roisné-Hamelin (ORCID: https://orcid.org/0000-0002-8390-2485)
- Jean‐Baptiste Charbonnier (ORCID: https://orcid.org/0000-0002-5219-1983)
- Xavier Veaute (ORCID: https://orcid.org/0000-0003-4868-247X)
- Virginie Ropars (ORCID: https://orcid.org/0000-0002-3372-6030)
- Didier Busso (ORCID: https://orcid.org/0000-0003-3027-7900)
- Alice Deshayes (ORCID: https://orcid.org/0000-0002-3542-7413)
- Olivier Alibert (ORCID: https://orcid.org/0000-0002-2686-2034)
- Paloma F. Varela (ORCID: https://orcid.org/0000-0001-5078-7102)
- Stefano Mattarocci (ORCID: https://orcid.org/0000-0002-5105-6018)
- Sonia Baconnais (ORCID: https://orcid.org/0000-0003-1350-6441)
- Vincent Morin
- Maelenn Chevreuil
- Johannes Mehringer
Institutions
- Centre National de la Recherche Scientifique (FR)
- Inserm (FR)
- Institut Pasteur (FR)
- Université Paris Cité (FR)
- Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR)
- Université Paris-Saclay (FR)
- Institut Gustave Roussy (FR)
- Centre National de Recherche en Génomique Humaine (FR)
- Institut de Biologie Intégrative de la Cellule (FR)
- CEA Paris-Saclay (FR)
- Institut de Radiobiologie Cellulaire et Moléculaire (FR)
- Kurt-Schwabe-Institut für Mess- und Sensortechnik Meinsberg (DE)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-07-24
- DOI
- https://doi.org/10.1038/s41467-025-61864-1
- Citations
- 2
- Primary Topic
- Telomeres, Telomerase, and Senescence
- Type
- article
- Field-Weighted Citation Impact
- 2.33
Funders
- Equipex
- Agence Nationale de la Recherche
- Institut National de la Santé et de la Recherche Médicale
- Fondation pour la Recherche Médicale
- Fondation ARC pour la Recherche sur le Cancer
- Ligue Contre le Cancer
- Centre National de la Recherche Scientifique
- Université Paris-Saclay
- Grand Équipement National De Calcul Intensif
- French Infrastructure for Integrated Structural Biology