Helicase with 3'-5' helicase activity involved in genome stability (PubMed:22064477). Functions in the nucleotide excision repair (NER) pathway and plays a critical role in DNA interstrand cross-link repair (PubMed:22064477). Unwinds relatively long duplex DNA up to 120-bp and requires a long 3'-tail of at least 70 nucleotides for efficient unwinding of duplex DNA (By similarity). Shows both processive helicase and DNA strand annealing activities (By similarity). Affects telomere length by a non-catalytic mechanism, probably through inhibiting telomerase by competing with it for ssDNA binding (By similarity). ATP + H2O = ADP + H(+) + phosphate Forms heptamer rings (By similarity). Interacts with rhp14 (PubMed:22064477). Leads to hypersensitivity to DNA interstrand cross-linking (ICL) agents mitomycin C (MMC) and cisplatin, in response to both chronic and acute exposures. Belongs to the helicase family. HRQ1 subfamily.