Interplay netween Dbf4-dependent Cdc7 kinase and polo-like kinase unshackles mitotic recombination mechanisms by promoting synaptonemal complex disassembly

Meiotic recombination is initiated by self-inflicted DNA breaks and primarily involves homologous chromosomes, whereas mitotic recombination involves sister chromatids. Whilst the mitotic recombinase Rad51 exists during meiosis, its activity is suppressed in favour of the meiosis-specific recombinase, Dmc1, thus establishing a meiosis-specific mode of homologous recombination (HR). A key contributor to the suppression of Rad51 activity is the synaptonemal complex (SC), a meiosis-specific chromosomal structure that adheres homologous chromosomes along their entire lengths. Here, in budding yeast, we show that two major cell cycle kinases, Dbf4-dependent Cdc7 kinase (DDK) and Polo-kinase (Cdc5), collaborate to link the mode change of HR to the meiotic cell cycle by. This regulation of HR is through the SC. During prophase I, DDK is shown to maintain SC integrity and thus inhibition of Rad51. Cdc5, which is produced during the prophase I/metaphase I transition, interacts with DDK to cooperatively destroy the SC and remove Rad51 inhibition. By enhancing the interaction between DDK and Cdc5 or depleting DDK at late prophase I, meiotic DNA breaks are repaired even in the absence of Dmc1 by utilising Rad51. We propose that the interplay between DDK and Polo-kinase reactivates mitotic HR mechanisms to ensure complete repair of DNA breaks before meiotic chromosomem segregation.