Residual double strand break repair during meiosis in budding yeast is promoted by PIF1 , RAD54 and RDH54/TID1

In the budding yeast, Saccharomyces cerevisiae, 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 RDH54/TID1 can partially compensate for RAD54, while PIF1 functions independently from both RAD54 and RDH54/TID1 in this process.