Concurrent D-loop cleavage by Mus81 and Yen1 yields half-crossover precursors

• Published in: Nucleic acids research 2024-07, Vol.52 (12), p.7012-7030
• Main Authors: Carreira, Raquel, Lama-Diaz, Tomas, Crugeiras, Maria, Aguado, F Javier, Sebesta, Marek, Krejci, Lumir, Blanco, Miguel G
• Format: Article
• Language: English
• Subjects: Crossing Over, Genetic; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Endonucleases - genetics; Endonucleases - metabolism; Genome Integrity, Repair and; Holliday Junction Resolvases - genetics; Holliday Junction Resolvases - metabolism; Homologous Recombination; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism
• ISSN: 0305-1048; 1362-4962; 1362-4962
• DOI: 10.1093/nar/gkae453

Homologous recombination involves the formation of branched DNA molecules that may interfere with chromosome segregation. To resolve these persistent joint molecules, cells rely on the activation of structure-selective endonucleases (SSEs) during the late stages of the cell cycle. However, the premature activation of SSEs compromises genome integrity, due to untimely processing of replication and/or recombination intermediates. Here, we used a biochemical approach to show that the budding yeast SSEs Mus81 and Yen1 possess the ability to cleave the central recombination intermediate known as the displacement loop or D-loop. Moreover, we demonstrate that, consistently with previous genetic data, the simultaneous action of Mus81 and Yen1, followed by ligation, is sufficient to recreate the formation of a half-crossover precursor in vitro. Our results provide not only mechanistic explanation for the formation of a half-crossover, but also highlight the critical importance for precise regulation of these SSEs to prevent chromosomal rearrangements.