Meiotic recombination genes (Saccharomyces cerevisiae)

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Meiotic double strand breaks are initiated by Spo11, a conserved topoisomerase-derived protein, together with its partner subunits. After the breaks are formed, Spo11 remains covalently attached to the 5 prime strands at both ends of the DNA. It is released through an endonucleolytic cleavage reaction, which is facilitated by MRX (Mre11, Rad50, and Xrs2) and Sae2. This reaction liberates Spo11, which is attached to a short oligonucleotide. The 5 prime strands are further processed by exonucleases, such as Exo1 in yeast, leading to the production of long single-stranded tails. These tails are coated with RPA, an ssDNA-binding protein, before being replaced by recombinases Rad51 and Dmc1. The recombinases form a nucleoprotein filament and search for sequence similarity, which is primarily located on the homologous chromosome. This process leads to the production of D-loop structures.