ATP-dependent DNA helicase that unwinds single- and double-stranded DNA in a 3'-5' direction (PubMed:28228481). Participates in DNA replication and repair (By similarity). Involved in 5'-end resection of DNA during double-strand break (DSB) repair (By similarity). Negatively regulates sister chromatid exchange (SCE) (By similarity). Stimulates DNA 4-way junction branch migration and DNA Holliday junction dissolution (By similarity). Binds DNA (PubMed:28228481). Binds single-stranded DNA (ssDNA), forked duplex DNA and DNA Holliday junction (By similarity). ATP + H2O = ADP + H(+) + phosphate Binds 1 zinc ion per subunit. Monomer (PubMed:28228481). Homodimer (via N-terminus) (PubMed:28228481). Homotetramer (via N-terminus); dimer of dimers (PubMed:28228481). Homohexamer (via N-terminus) (PubMed:28228481). Self-association negatively regulates DNA unwinding amplitude and rate (PubMed:28228481). Oligomer complexes dissociate into monomer in presence of ATP (PubMed:28228481). The N-terminal region mediates dimerization and homooligomerization (PubMed:28228481). Both the helicase ATP-binding domain and the helicase C-terminal domain form intramolecular interactions with the HRDC domain in a ATP-dependent manner (By similarity). The HRDC domain is required for single-stranded DNA (ssDNA) and DNA Holliday junction binding (By similarity). Belongs to the helicase family. RecQ subfamily.