FIGL1 and its novel partner FLIP form a conserved complex that regulates homologous recombination.

Abstract

Homologous recombination is central to repair DNA double-strand breaks (DSB), either accidently arising in mitotic cells or in a programed manner at meiosis. Crossovers resulting from the repair of meiotic breaks are essential for proper chromosome segregation and increase genetic diversity of the progeny. However, mechanisms regulating CO formation remain elusive. Here, we identified through protein-protein interaction and genetic screens FIDGETIN-LIKE-1 INTERACTING PROTEIN (FLIP) as a new partner of the previously characterized anti-crossover factor FIDGETIN-LIKE-1 (FIGL1) in Arabidopsis thaliana. We showed that FLIP limits meiotic crossover together with FIGL1. Further, FLIP and FIGL1 form a protein complex conserved from Arabidopsis to Human. FIGL1 interacts with the recombinases RAD51 and DMC1, the enzymes that catalyze the DNA stand exchange step of homologous recombination. Arabidopsis flip mutants recapitulates the figl1 phenotype, with enhanced meiotic recombination associated with change in DMC1 dynamics. Our data thus suggest that FLIP and FIGL1 form a conserved complex that regulates the crucial step of strand invasion in homologous recombination.