XPF-like domain in human SHOC1 is required for crossover formation and protecting autosome from MSUC

During meiosis, ZMM proteins play essential roles in stabilizing the recombination intermediates and promoting crossover (CO) formation. In mice, shortage in chiasmata 1 (SHOC1) forms a trimeric complex with the other two ZMM proteins, SPO16 and TEX11, to bind recombination intermediates after strand invasion. Although genetic variants of SHOC1 are clinically associated with male infertility, their conserved functions in human gametogenesis remain enigmatic. Here, we delineated species-specific divergences between human and mouse SHOC1 complex and identified a missense variant within the XPF-like domain in SHOC1 (p.Q590R). This variant impaired DNA double-strand breaks repair by compromising its ability to bind branched DNA structures and the recruitment of crucial proteins to recombination intermediates, ultimately abolishing CO formation. Furthermore, the variant disrupted dynamic chromatin structure in pachytene spermatocytes and induced synapsis defects. Importantly, the XPF-like domain in SHOC1 was revealed to prevent autosome intrusion into the sex body compartment, thereby protecting critical autosomal loci from meiotic silencing of unsynapsed chromatin (MSUC). Overall, our study underscores the critical role of the XPF-like domain in human SHOC1 in CO formation and in protecting autosomes from MSUC.