Meiosis specific SF2-type 3'-5' DNA helicase; involved in the conversion of double-stranded breaks to later recombination intermediates and in crossover control; catalyzes the unwinding of Holliday junctions; has ssDNA and dsDNA stimulated ATPase activity; preferentially binds D-loop DNA; interacts directly with the N-OB domain of Rpa1p; helicase processivity is stimulated by the replication protein A (RPA) complex; ZMM family member