<i>PIF1</i> , <i>RAD54</i> and <i>RDH54/TID1</i> promote residual double strand break repair during meiosis in the budding yeast, <i>Saccharomyces cerevisiae</i>

In the budding yeast, <i>Saccharomyces cerevisiae</i>, repair of programmed double strand breaks occurs in two phases during prophase I of meiosis. During Phase 1 interhomolog recombination is mediated by the meiosis-specific Dmc1 recombinase. Crossover-specific recombination intermediates enable synapsis of homologous chromosomes, resulting in a transition to Rad51-mediated recombination in Phase 2 that repairs any residual double strand breaks so that chromosomes are intact when cells progress into the first meiotic division. Studying Phase 2 recombination is challenging because the number of breaks present at pachynema (the prophase I stage when all the homologs are synapsed) is small and a low frequency of new breaks continues to be made. Using a newly developed method for analyzing Phase 2 recombination, this work discovered that <i>RDH54</i>/<i>TID1</i> can partially compensate for <i>RAD54</i>, while <i>PIF1</i> functions independently from both <i>RAD54</i> and <i>RDH54</i>/<i>TID1</i> in this process.