Prophase roles of replication protein A in crossover formation and meiotic progression

Meiotic recombination is initiated by programmed DNA double-strand breaks (DSBs), which are subsequently processed to generate single-stranded DNA (ssDNA). Replication protein A (RPA), a heterotrimeric ssDNA-binding complex, plays essential roles in DNA replication, repair, and recombination; however, the specific functions of RPA in meiotic recombination progression and chromosome morphogenesis remain unclear. Here, we investigate the role of RPA in recombination and meiotic progression by conditionally depleting Rfa1, the large subunit of the RPA complex, using an auxin-inducible degron (AID) system in Saccharomyces cerevisiae. We show that Rfa1 depletion causes severe defects in meiotic recombination, including impaired DSB processing, defective chromosome axis assembly, compromised synaptonemal complex formation, and failure of ZMM-dependent crossover recombination. Notably, inhibition of Mek1 protein kinase activity, which bypasses the recombination checkpoint, does not rescue these defects in Rfa1-depleted cells. Together, these findings identify RPA as a key factor that stabilizes recombination intermediates and coordinates prophase I events with chromosome synapsis and crossover formation during meiosis.