The INO80 complex removes H2A.Z to promote presynaptic filament formation during homologous recombination

INO80 is an evolutionary conserved nucleosome remodelling complex that acts in transcription, replication and genome stability. It is required for resistance against genotoxic agents and involved in the repair of DNA double-strand breaks (DSB) by homologous recombination (HR). However, causes underlying the HR defect of INO80-C mutant cells have been controversially discussed. We here unite previous findings using a high-resolution system to study HR in the yeast Saccharomyces cerevisiae. We find that INO80-C has at least two distinct functions during HR, which promote DNA end resection and presynaptic filament formation, respectively. Importantly, specifically the second function is linked to the histone variant H2A.Z. In the absence of H2A.Z, presynaptic filament formation and HR are restored in INO80-C-deficient mutants, suggesting that presynaptic filament formation is the crucial INO80-C function during HR.