DNA-dependent ATPase that stimulates strand exchange; modifies the topology of double-stranded DNA; drives ATP-hydrolysis-dependent sequence alignment during homologous recombination; involved in repair of dsDNA breaks during both mitosis and meiosis; promotes strand invasion, catalyzes nucleosome remodeling, and removes Rad51p from dsDNA; member of the SWI/SNF family of DNA translocases; forms nuclear foci upon DNA replication stress