Involved in DNA double-strand break (DSB) repair (PubMed:18243819). Acts probably with NurA to stimulate resection of the 5' strand and produce the long 3' single-strand that is required for RadA loading (By similarity). Exhibits DNA-dependent ATPase activity and DNA helicase activity (PubMed:18243819). Loads on either a 3' or a 5' DNA tail for subsequent DNA unwinding (PubMed:18243819). Can also unwind blunt-ended dsDNA, Holliday junction and splayed-arm DNA (PubMed:18243819). ATP + H2O = ADP + H(+) + phosphate ATPase activity is slightly stimulated by either circular single- or double-stranded DNA with a weak preference for double-stranded DNA (PubMed:18243819). Helicase activity is stimulated by Mre11 (PubMed:18243819). Forms a hexamer or a heptamer (PubMed:18243819). Interacts with Mre11 (PubMed:18243819). Belongs to the HerA family.