Involved in the recombinational repair of double-strand breaks (DSB) in DNA during mitosis and meiosis. Has DNA dependent ATPase activity. Promotes D-loop (displacement loop) formation with RAD51 recombinase. Modifies the topology of double-stranded DNA during the D-loop reaction to facilitate the invasion of the homologous duplex molecule by the initiating single-stranded DNA substrate. Required for adaptation from G2/M checkpoint arrest induced by a double strand break, by participating in monitoring the extent of single-stranded DNA produced by resection of DNA ends. This role is distinct from its roles in recombination. Promotes colocalization of RAD51 and DMC1 during meiotic recombination. Involved in crossover interference (By similarity). ATP + H2O = ADP + H(+) + phosphate Interacts with RAD51 and DMC1. Belongs to the SNF2/RAD54 helicase family.