title: Characterization of biochemical properties of Bacillus subtilis RecQ helicase.
abstract: RecQ family helicases function as safeguards of the genome. Unlike Escherichia coli, the Gram-positive Bacillus subtilis bacterium possesses two RecQ-like homologues, RecQ[Bs] and RecS, which are required for the repair of DNA double-strand breaks. RecQ[Bs] also binds to the forked DNA to ensure a smooth progression of the cell cycle. Here we present the first biochemical analysis of recombinant RecQ[Bs]. RecQ[Bs] binds weakly to single-stranded DNA (ssDNA) and blunt-ended double-stranded DNA (dsDNA) but strongly to forked dsDNA. The protein exhibits a DNA-stimulated ATPase activity and ATP- and Mg(2+)-dependent DNA helicase activity with a 3' → 5' polarity. Molecular modeling shows that RecQ[Bs] shares high sequence and structure similarity with E. coli RecQ. Surprisingly, RecQ[Bs] resembles the truncated Saccharomyces cerevisiae Sgs1 and human RecQ helicases more than RecQ[Ec] with regard to its enzymatic activities. Specifically, RecQ[Bs] unwinds forked dsDNA and DNA duplexes with a 3'-overhang but is inactive on blunt-ended dsDNA and 5'-overhung duplexes. Interestingly, RecQ[Bs] unwinds blunt-ended DNA with structural features, including nicks, gaps, 5'-flaps, Kappa joints, synthetic replication forks, and Holliday junctions. We discuss these findings in the context of RecQ[Bs]'s possible functions in preserving genomic stability.
authors.affiliation: College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Qin
authors.affiliation: College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China.
authors.forename: Na-Nv
authors.initials: NN
authors.lastname: Liu
authors.affiliation: Faculty of Medicine, Kunming University of Science and Technology, Kunming, Yunnan, China Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA.
authors.forename: Lijun
authors.initials: L
authors.lastname: Wang
authors.affiliation: Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure Cachan, Institut d'Alembert, Cachan, France.
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure Cachan, Institut d'Alembert, Cachan, France.
authors.forename: Hua
authors.initials: H
authors.lastname: Ren
authors.affiliation: Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure Cachan, Institut d'Alembert, Cachan, France Faculté de Pharmacie, Université Paris-sud 11, Chatenay-Malabry, France.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bugnard
authors.affiliation: Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure Cachan, Institut d'Alembert, Cachan, France.
authors.forename: Jie-Lin
authors.initials: JL
authors.lastname: Liu
authors.affiliation: Faculty of Medicine, Kunming University of Science and Technology, Kunming, Yunnan, China Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA.
authors.forename: Lin-Hu
authors.initials: LH
authors.lastname: Zhang
authors.affiliation: Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure Cachan, Institut d'Alembert, Cachan, France.
authors.forename: Jeremie
authors.initials: J
authors.lastname: Vendôme
authors.affiliation: Faculty of Medicine, Kunming University of Science and Technology, Kunming, Yunnan, China Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA jhu336@yahoo.com xxi01@ens-cachan.fr.
authors.forename: Jin-Shan
authors.initials: JS
authors.lastname: Hu
authors.affiliation: College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure Cachan, Institut d'Alembert, Cachan, France jhu336@yahoo.com xxi01@ens-cachan.fr.
authors.forename: Xu Guang
authors.initials: XG
authors.lastname: Xi
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001412:Bacillus subtilis / Q000201:enzymology*; D004247:DNA / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D053484:RecQ Helicases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004277:DNA, Single-Stranded; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; D053484:RecQ Helicases; D008274:Magnesium