EXO1 promotes the meiotic MLH1-MLH3 endonuclease through conserved interactions with MLH1, MSH4 and DNA
The endonuclease activity of MLH1-MLH3 (MutLγ) is stimulated by MSH4-MSH5 (MutSγ), EXO1, and RFC-PCNA to resolve meiotic recombination intermediates such as double Holliday junctions (HJs) into crossovers. We show that EXO1 directly interacts with MLH1 via the EXO1 MIP motif and a patch centered around EXO1-I403. Disrupting this interaction unexpectedly only partially inhibited MutLγ. We found that EXO1 also directly interacts with MutSγ. Crucially, a single point mutation in EXO1 (W371E) impairs its interaction with MSH4 and completely abolished its ability to activate DNA nicking by MutLγ without affecting its intrinsic nuclease function. Finally, disrupting magnesium coordinating residues in the nuclease domain of EXO1 has no impact on MutSγ-MutLγ activity, while the integrity of EXO1 residues mediating interactions with double-stranded DNA (dsDNA) is important. Our findings suggest EXO1 is an integral structural component of the meiotic resolvase complex, supported by conserved interactions with MutSγ, MutLγ and dsDNA. We propose that EXO1 helps tether MutSγ-MutLγ to dsDNA downstream of HJ recognition to promote DNA cleavage.
Authors
- Aurore Sanchez (ORCID: https://orcid.org/0009-0000-8949-2379)
- Andrea C. Rinaldi (ORCID: https://orcid.org/0000-0002-9352-1037)
- Raphaël Guérois (ORCID: https://orcid.org/0000-0001-5294-2858)
- Jacopo Sgrignani (ORCID: https://orcid.org/0000-0002-8633-1032)
- Petr Ćejka (ORCID: https://orcid.org/0000-0002-9087-032X)
- Andrea Cavalli (ORCID: https://orcid.org/0000-0003-4063-4502)
- Arianna Cerana
- Issam Senoussi
- M. M. Roy (ORCID: https://orcid.org/0009-0001-7053-1195)
Institutions
- Centre National de la Recherche Scientifique (FR)
- Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR)
- Université Paris Sciences et Lettres (FR)
- Université Paris-Saclay (FR)
- Board of the Swiss Federal Institutes of Technology (CH)
- ETH Zurich (CH)
- Sorbonne Université (FR)
- Institut de Biologie Intégrative de la Cellule (FR)
- Dynamique de l'information génétique : bases fondamentales et cancer (FR)
- CEA Paris-Saclay (FR)
- Università della Svizzera italiana (CH)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-05-03
- DOI
- https://doi.org/10.1038/s41467-025-59470-2
- Citations
- 4
- Primary Topic
- DNA Repair Mechanisms
- Type
- article
- Field-Weighted Citation Impact
- 3.22
Funders
- National Science Foundation
- Agence Nationale de la Recherche
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Grand Équipement National De Calcul Intensif