Characterization of Biochemical Properties of Bacillus subtilis RecQ Helicase

• Published in: Journal of bacteriology Vol. 196; no. 24; pp. 4216 - 4228
• Main Authors: Qin, Wei, Liu, Na-Nv, Wang, Lijun, Zhou, Min, Ren, Hua, Bugnard, Elisabeth, Liu, Jie-Lin, Zhang, Lin-Hu, Vendôme, Jeremie, Hu, Jin-Shan, Xi, Xu Guang
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.12.2014
• Subjects: Adenosine triphosphatase; Adenosine Triphosphatases - metabolism; adenosine triphosphate; Adenosine Triphosphate - metabolism; adenosinetriphosphatase; Bacillus subtilis; Bacillus subtilis - enzymology; bacteria; Bacteriology; Cell cycle; Deoxyribonucleic acid; DNA; DNA - metabolism; DNA damage; DNA helicases; DNA repair; DNA, Single-Stranded - metabolism; E coli; enzyme activity; Escherichia coli; genome; humans; Life Sciences; Magnesium - metabolism; Models, Molecular; Probiotics; Protein Binding; Recombinant Proteins - genetics; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; RecQ Helicases - metabolism; Saccharomyces cerevisiae; single-stranded DNA; Yeast
• ISSN: 0021-9193; 1098-5530
• DOI: 10.1128/JB.06367-11

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 Mg2+-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.