Practice question

Following Spo11 removal, broken meiotic and mitotic chromosomes must be resected to expose recombinogenic single strands. In budding yeast the MRX complex containing Mre11, Rad50 and Xrs2, and equivalent MRN complex in mammals, performs this initiation step. Rad50 tethers ends via zinc-hook domains, while Mre11 provides endonuclease activity stimulated by Sae2/CtIP to nick 5' terminated strands internal to the break. Subsequent long-range resection by Exo1 and Dna2-Sgs1 generates extended 3' overhangs required for Rad51 filament assembly and homologous template search.