Single-stranded 3'-5' DNA helicase that plays a key role in homology-driven double-strand break (DSB) repair (PubMed:18472307, PubMed:34880204). Involved in different DSB repair mechanisms that are guided by annealing of extensive stretches of complementary bases at break ends, such as microhomology-mediated end-joining (MMEJ), single-strand annealing (SSA) or synthesis-dependent strand annealing (SDSA) (PubMed:34880204). ATP + H2O = ADP + H(+) + phosphate Localizes to sites of DNA damage. Belongs to the helicase family. SKI2 subfamily.