The RuvA-RuvB complex in the presence of ATP renatures cruciform structure in supercoiled DNA with palindromic sequence, indicating that it may promote strand exchange reactions in homologous recombination. RuvAB is a helicase that mediates the Holliday junction migration by localized denaturation and reannealing. RuvA stimulates, in the presence of DNA, the weak ATPase activity of RuvB. Binds both single- and double-stranded DNA (dsDNA). Binds preferentially to supercoiled rather than to relaxed dsDNA. ATP + H2O = ADP + H(+) + phosphate Homotetramer; forms a complex with RuvB. In 15% of cell localizes to discrete nucleoid foci (probable DNA damage sites) upon treatment with mitomycin C (MMC) for 2 hours. Expression of the ruv region is induced by damage to DNA and is regulated by LexA as part of the SOS response. RuvA and RuvB are also involved in mutagenesis induced by UV and X irradiation and by some chemicals (PubMed:3279394). Induced by hydroxyurea (PubMed:20005847). Belongs to the RuvA family.