Terminal association of Rad54 protein with the Rad51–dsDNA filament

Abstract

Rad54 protein is a Snf2-related dsDNA-specific ATPase essential for homologous recombination mediated by Rad51 protein, the eukaryotic RecA ortholog. Snf2-related enzymes couple ATP hydrolysis with translocation on dsDNA to remodel or dissociate a wide variety of protein–dsDNA complexes. Rad54 and Rad51 interact through species-specific contacts and mutually stimulate their biochemical activities. Specifically, Rad51 bound to dsDNA, the product of homologous recombination after DNA-strand exchange, stimulates the Rad54 ATPase up to 6-fold, leading to the turnover of Rad51 in the product complex. Electron microscopy visualized the Rad51–Rad54 interaction on dsDNA, showing that an oligomeric form of Rad54 associates preferentially with termini of the Rad51–dsDNA filament. Our data support a mechanism of processive dsDNA–Rad51 filament dissociation by the translocating Rad54 protein.