SCF-Fbxo42 promotes synaptonemal complex assembly by downregulating PP2A-B56

Meiosis creates genetic diversity by recombination and segregation of chromosomes. The synaptonemal complex assembles during meiotic prophase I and assists faithful exchanges between homologous chromosomes, but how its assembly/disassembly is regulated remains to be understood. Here we report how two major post-translational modifications, phosphorylation and ubiquitination, co-operate to promote synaptonemal complex assembly. We found that the ubiquitin ligase complex SCF is important for assembly and maintenance of the synaptonemal complex in Drosophila female meiosis. This function of SCF is mediated by two substrate recognising F-box proteins, Slmb/βTrcp and Fbxo42. SCF-Fbxo42 downregulates the phosphatase subunit PP2A-B56, which is important for synaptonemal complex assembly and maintenance.