Practice question

Meiotic recombination is initiated intentionally to promote homolog pairing and crossovers. Spo11, conserved protein related to archaeal Topoisomerase VI catalytic subunit Top6A, performs controlled cleavage of both strands of single duplex simultaneously, generating double-strand break with covalent phosphotyrosyl links at 5' ends. Unlike single-strand nicks created during replication or base excision repair, these DSBs are highly recombinogenic and activate downstream MRX resection. Absence of Spo11 leads to failure of synapsis and infertility, highlighting essence of programmed DSBs, not spontaneous lesions, for meiosis.