title: Saccharomyces cerevisiae Hrq1 requires a long 3'-tailed DNA substrate for helicase activity.
abstract: RecQ helicases are well conserved proteins from bacteria to human and function in various DNA metabolism for maintenance of genome stability. Five RecQ helicases are found in humans, whereas only one RecQ helicase has been described in lower eukaryotes. However, recent studies predicted the presence of a second RecQ helicase, Hrq1, in fungal genomes and verified it as a functional gene in fission yeast. Here we show that 3'-5' helicase activity is intrinsically associated with Hrq1 of Saccharomyces cerevisiae. We also determined several biochemical properties of Hrq1 helicase distinguishable from those of other RecQ helicase members. Hrq1 is able to unwind relatively long duplex DNA up to 120-bp and is significantly stimulated by a preexisting fork structure. Further, the most striking feature of Hrq1 is its absolute requirement for a long 3'-tail (⩾70-nt) for efficient unwinding of duplex DNA. We also found that Hrq1 has potent DNA strand annealing activity. Our results indicate that Hrq1 has vigorous helicase activity that deserves further characterization to expand our understanding of RecQ helicases.
authors.affiliation: Department of Biological Sciences, College of Natural Science, Inha University, 100 Inha-ro, Nam-gu, Incheon 402-751, South Korea.
authors.forename: Sung-Hun
authors.initials: SH
authors.lastname: Kwon
authors.forename: Do-Hee
authors.initials: DH
authors.lastname: Choi
authors.forename: Rina
authors.initials: R
authors.lastname: Lee
authors.forename: Sung-Ho
authors.initials: SH
authors.lastname: Bae
mesh_terms: D004277:DNA, Single-Stranded / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D053484:RecQ Helicases / Q000737:chemistry* / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D004277:DNA, Single-Stranded; D029701:Saccharomyces cerevisiae Proteins; C579040:Hrq1 protein, S cerevisiae; D053484:RecQ Helicases