Nucleic Acids Research Advance Access originally published online on February 28, 2007
Nucleic Acids Research 2007 35(6):1802-1811; doi:10.1093/nar/gkm019
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Nucleic Acids Research, 2007, Vol. 35, No. 6 1802-1811
© 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Nucleic Acid Enzymes |
Controlling the motor activity of a transcription-repair coupling factor: autoinhibition and the role of RNA polymerase
DNA-Protein Interactions Unit, Department of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
*To whom correspondence should be addressed. Tel: +(44) 117 928 9708; Fax: +(44) 117 928 8274; Email: n.j.savery{at}bris.ac.uk
Received November 17, 2006. Revised December 22, 2006. Accepted January 2, 2007.
Motor proteins that couple ATP hydrolysis to movement along nucleic acids play a variety of essential roles in DNA metabolism. Often these enzymes function as components of macromolecular complexes, and DNA translocation by the motor protein drives movement of other components of the complex. In order to understand how the activity of motor proteins is regulated within multi-protein complexes we have studied the bacterial transcription-repair coupling factor, Mfd, which is a helicase superfamily 2 member that binds to RNA polymerase (RNAP) and removes stalled transcription complexes from DNA. Using an oligonucleotide displacement assay that monitors protein movement on double-stranded DNA we show that Mfd has little motor activity in isolation, but exhibits efficient oligonucleotide displacement activity when bound to a stalled transcription complex. Deletion of the C-terminal domain of Mfd increases the ATPase activity of the protein and allows efficient oligo-displacement in the absence of RNAP. Our results suggest that an autoinhibitory domain ensures the motor activity of Mfd is only functional within the correct macromolecular context: recruitment of Mfd to a stalled transcription complex relieves the autoinhibition and unmasks the motor activity.
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