Controlling Meiotic Recombinational Repair – Specifying the roles of ZMMs, Sgs1 and Mms4 in Crossover Formation. Saccharomyces cerevisiae strain:S96 X YJM879 hybrid

Crossovers play a critical role in ensuring proper alignment and segregation of homologous chromosomes during meiosis. How the cell balances recombination between the different modes of repair – crossover vs. noncrossover – is not completely understood. Also limited is the understanding of what constrains the extent of DNA repair such that multiple events do not arise from a single double-strand break (DSB). Here, by interpreting signatures that result from recombination genome-wide, we find that synaptonemal complex proteins needed for proper chromosome synapsis promote crossing over in distinct ways. Zip3 (RNF212) promotes asymmetric cutting of the double Holliday-junction intermediate whereas Msh4 does not. Moreover, our analysis suggests that Mms4 (Eme1), rather than just being a minor resolvase for crossovers is crucial in preventing chromosome entanglements by removing 3’- flaps to promote second-end capture for both crossovers and noncrossovers. Recombination signature analysis opens a new window into the function of Holliday Junction-associated proteins.