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| Subject Categories: Genome Stability & Dynamics |
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| The EMBO Journal
(2008) 27, 1388–1398, doi:10.1038/emboj.2008.69 Published online 3 April 2008 |
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| Motor step size and ATP coupling efficiency of the dsDNA translocase EcoR124I EMBO Open |
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| Ralf Seidel1, 2, Joost GP Bloom1, Cees Dekker1 and Mark D Szczelkun3 |
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1 Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands 2 DNA Motors Group, Biotechnological Centre, University of Technology Dresden, Dresden, Germany 3 DNA–Protein Interactions Unit, Department of Biochemistry, University of Bristol, Bristol, UK To whom correspondence should be addressed Cees Dekker, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands. Tel.: +31 15 278 6094; Fax: +31 15 278 1202; E-mail: c.dekker@tudelft.nl Mark D Szczelkun, DNA–Protein Interactions Unit, Department of Biochemistry, University of Bristol, Bristol BS8 1TD, UK. Tel.: +44 117 331 2158; Fax: +44 117 331 2168; E-mail: mark.szczelkun@bristol.ac.uk Received 18 October 2007; Accepted 3 March 2008; Published online 3 April 2008. |
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| Abstract |
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| The Type I restriction-modification enzyme EcoR124I is an archetypical helicase-based dsDNA translocase that moves unidirectionally along the 3'–5' strand of intact duplex DNA. Using a combination of ensemble and single-molecule measurements, we provide estimates of two physicochemical constants that are fundamental to a full description of motor protein activity—the ATP coupling efficiency (the number of ATP consumed per base pair) and the step size (the number of base pairs transported per motor step). Our data indicate that EcoR124I makes small steps along the DNA of 1 bp in length with 1 ATP consumed per step, but with some uncoupling of the ATPase and translocase cycles occurring so that the average number of ATP consumed per base pair slightly exceeds unity. Our observations form a framework for understanding energy coupling in a great many other motors that translocate along dsDNA rather than ssDNA. |
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| Keywords: ATPase, helicase, molecular motor, single molecule, stopped flow |
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Top of page MORE ARTICLES LIKE THISThese links to content published by NPG are automatically generated NEWS AND VIEWSNature Structural & Molecular Biology News and Views (01 Sep 2004) Nature Structural & Molecular Biology News and Views (01 Aug 2006) RESEARCHMotor step size and ATP coupling efficiency of the dsDNA translocase EcoR124I The EMBO Journal Article The EMBO Journal Article (07 Dec 2005) |
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