title: The HRDC domain of E. coli RecQ helicase controls single-stranded DNA translocation and double-stranded DNA unwinding rates without affecting mechanoenzymatic coupling.
abstract: DNA-restructuring activities of RecQ-family helicases play key roles in genome maintenance. These activities, driven by two tandem RecA-like core domains, are thought to be controlled by accessory DNA-binding elements including the helicase-and-RnaseD-C-terminal (HRDC) domain. The HRDC domain of human Bloom's syndrome (BLM) helicase was shown to interact with the RecA core, raising the possibility that it may affect the coupling between ATP hydrolysis, translocation along single-stranded (ss)DNA and/or unwinding of double-stranded (ds)DNA. Here, we determined how these activities are affected by the abolition of the ssDNA interaction of the HRDC domain or the deletion of the entire domain in E. coli RecQ helicase. Our data show that the HRDC domain suppresses the rate of DNA-activated ATPase activity in parallel with those of ssDNA translocation and dsDNA unwinding, regardless of the ssDNA binding capability of this domain. The HRDC domain does not affect either the processivity of ssDNA translocation or the tight coupling between the ATPase, translocation, and unwinding activities. Thus, the mechanochemical coupling of E. coli RecQ appears to be independent of HRDC-ssDNA and HRDC-RecA core interactions, which may play roles in more specialized functions of the enzyme.
authors.affiliation: Department of Biochemistry, ELTE-MTA "Momentum" Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary.
authors.forename: Gábor M
authors.initials: GM
authors.lastname: Harami
authors.affiliation: Department of Biochemistry, ELTE-MTA "Momentum" Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary.
authors.forename: Nikolett T
authors.initials: NT
authors.lastname: Nagy
authors.affiliation: Department of Biochemistry, ELTE-MTA "Momentum" Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary.
authors.forename: Máté
authors.initials: M
authors.lastname: Martina
authors.affiliation: Laboratory of Molecular Biophysics, National Heart, Lung and Blood Institute, National Institutes of.
authors.forename: Keir C
authors.initials: KC
authors.lastname: Neuman
authors.affiliation: Department of Biochemistry, ELTE-MTA "Momentum" Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary.
authors.forename: Mihály
authors.initials: M
authors.lastname: Kovács
mesh_terms: D004269:DNA, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology*; D006801:Humans; D017434:Protein Structure, Tertiary; D011938:Rec A Recombinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D053484:RecQ Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D011938:Rec A Recombinases; C506724:RecQ protein, E coli; D053484:RecQ Helicases