Helicase with 3'-5' helicase activity involved in genome stability (PubMed:23456718, PubMed:24440721, PubMed:24700328). Functions in the RAD4-dependent nucleotide excision repair (NER) pathway and plays a critical role in DNA interstrand cross-link repair (PubMed:24440721, PubMed:24682993). 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 (PubMed:23026052). Activity is significantly stimulated by a preexisting fork structure (PubMed:24682993). Shows both processive helicase and DNA strand annealing activities (PubMed:24682993). Affects telomere length by a non-catalytic mechanism, probably through inhibiting telomerase by competing with it for ssDNA binding (PubMed:24440721). ATP + H2O = ADP + H(+) + phosphate Optimum pH is 6.0-8.0. Forms heptamer rings (PubMed:24440721). Interacts with RAD4 (PubMed:24682993). By heat shock. Leads to increased mitotic recombination and spontaneous mutation, as well as to sensitivity to 4-nitroquinoline 1-oxide and cisplatin (PubMed:23456718). Causes also hypersensitivity to DNA interstrand cross-links (ICLs) and telomere addition to DNA breaks (PubMed:24440721). Present with 259 molecules/cell in log phase SD medium. Belongs to the helicase family. HRQ1 subfamily.