Work

COSA-1–SLX-4 interaction directly links crossover designation with Holliday junction resolution

Year: 2026

Type: article

Abstract: Crossover (CO) formation between homologous chromosomes is essential for genetic diversity and accurate meiotic chromosome segregation. This process involves two key steps: the designation of a subset of meiotic double-strand breaks to CO-designated sites and subsequent CO resolution by Holliday junction (HJ) resolvase. However, how these steps are functionally coupled remains elusive. Here, we showed that COSA-1, essential for CO designation, directly interacts with the SLX-4 scaffold protein, which organizes the SLX-1, XPF-1, and MUS-81 HJ resolvases. Disrupting this interaction results in persistent unrepaired recombination intermediates and defective CO formation. Notably, these defects can be largely rescued by the artificial tethering of SLX-4 to the CO designation proteins. We further demonstrate that COSA-1 promotes assembly of the SLX-4 resolvase complex and provide evidence that this mechanism coupling CO designation with resolution is evolutionarily conserved. Together, our findings support a model in which CO designation proteins ensure accurate CO formation by directly recruiting the resolution machinery.

Source: Science Advances

DOI: 10.1126/sciadv.adx9148