The ssDNA-binding protein MEIOB sustains synaptonemal complex integrity by stabilizing recombination intermediates during male meiosis

The synaptonemal complex (SC) is fundamental to meiotic recombination and crossover formation between homologous chromosomes. In yeast, the SC is assembled and sustained by the ZZS complex (Zip2-Zip4-Spo16). However, how ZZS components are recruited and stabilized at chromosomes, and whether their mammalian orthologs (SHOC1-TEX11-SPO16) play similar roles, remain poorly understood. Here, we report that germ cell-specific ablation of the meiosis-specific single-stranded DNA-binding protein MEIOB in mice causes premature chromosomal desynapsis in early pachytene spermatocytes, leading to their elimination before mid-pachytene. Mechanistically, MEIOB associates with SPO16 in vitro , and Spo16 -deficient pachytene-like spermatocytes display comparable premature desynapsis and severely reduced MEIOB foci on chromosomal axes. Moreover, the recruitment of another ZZS component, TEX11, to recombination intermediates is markedly diminished in Meiob knockout pachytene spermatocytes. Together, our findings suggest that the MEIOB-SPATA22 complex may cooperate with SPO16 to support SC integrity and crossover formation during mammalian meiosis.