EXO1 promotes the meiotic MLH1-MLH3 endonuclease through conserved interactions with MLH1, MSH4 and DNA
Abstract 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 cen...
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Nature Portfolio
2025-05-01
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| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-025-59470-2 |
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| author | Megha Roy Aurore Sanchez Raphael Guerois Issam Senoussi Arianna Cerana Jacopo Sgrignani Andrea Cavalli Andrea Rinaldi Petr Cejka |
| author_facet | Megha Roy Aurore Sanchez Raphael Guerois Issam Senoussi Arianna Cerana Jacopo Sgrignani Andrea Cavalli Andrea Rinaldi Petr Cejka |
| author_sort | Megha Roy |
| collection | DOAJ |
| description | Abstract 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. |
| format | Article |
| id | doaj-art-ee7a056d3fac4bd7a8bfbb16eebb3e2a |
| institution | DOAJ |
| issn | 2041-1723 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Nature Portfolio |
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| spelling | doaj-art-ee7a056d3fac4bd7a8bfbb16eebb3e2a2025-08-20T03:05:05ZengNature PortfolioNature Communications2041-17232025-05-0116111510.1038/s41467-025-59470-2EXO1 promotes the meiotic MLH1-MLH3 endonuclease through conserved interactions with MLH1, MSH4 and DNAMegha Roy0Aurore Sanchez1Raphael Guerois2Issam Senoussi3Arianna Cerana4Jacopo Sgrignani5Andrea Cavalli6Andrea Rinaldi7Petr Cejka8Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical SciencesInstitute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical SciencesUniversité Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC)Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical SciencesInstitute of Oncology Research, Università della Svizzera italiana (USI), Faculty of Biomedical SciencesInstitute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical SciencesInstitute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical SciencesInstitute of Oncology Research, Università della Svizzera italiana (USI), Faculty of Biomedical SciencesInstitute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical SciencesAbstract 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.https://doi.org/10.1038/s41467-025-59470-2 |
| spellingShingle | Megha Roy Aurore Sanchez Raphael Guerois Issam Senoussi Arianna Cerana Jacopo Sgrignani Andrea Cavalli Andrea Rinaldi Petr Cejka EXO1 promotes the meiotic MLH1-MLH3 endonuclease through conserved interactions with MLH1, MSH4 and DNA Nature Communications |
| title | EXO1 promotes the meiotic MLH1-MLH3 endonuclease through conserved interactions with MLH1, MSH4 and DNA |
| title_full | EXO1 promotes the meiotic MLH1-MLH3 endonuclease through conserved interactions with MLH1, MSH4 and DNA |
| title_fullStr | EXO1 promotes the meiotic MLH1-MLH3 endonuclease through conserved interactions with MLH1, MSH4 and DNA |
| title_full_unstemmed | EXO1 promotes the meiotic MLH1-MLH3 endonuclease through conserved interactions with MLH1, MSH4 and DNA |
| title_short | EXO1 promotes the meiotic MLH1-MLH3 endonuclease through conserved interactions with MLH1, MSH4 and DNA |
| title_sort | exo1 promotes the meiotic mlh1 mlh3 endonuclease through conserved interactions with mlh1 msh4 and dna |
| url | https://doi.org/10.1038/s41467-025-59470-2 |
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