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Mol Cell. 2014 Jun 5;54(5):832-43. doi: 10.1016/j.molcel.2014.03.033. Epub 2014 Apr 24.

Single-molecule imaging of FtsK translocation reveals mechanistic features of protein-protein collisions on DNA.

Author information

1
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
2
Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
3
Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
4
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA. Electronic address: ecg2108@columbia.edu.

Abstract

In physiological settings, DNA translocases will encounter DNA-bound proteins, which must be dislodged or bypassed to allow continued translocation. FtsK is a bacterial translocase that promotes chromosome dimer resolution and decatenation by activating XerCD-dif recombination. To better understand how translocases act in crowded environments, we used single-molecule imaging to visualize FtsK in real time as it collided with other proteins. We show that FtsK can push, evict, and even bypass DNA-bound proteins. The primary factor dictating the outcome of collisions was the relative affinity of the proteins for their specific binding sites. Importantly, protein-protein interactions between FtsK and XerD help prevent removal of XerCD from DNA by promoting rapid reversal of FtsK. Finally, we demonstrate that RecBCD always overwhelms FtsK when these two motor proteins collide while traveling along the same DNA molecule, indicating that RecBCD is capable of exerting a much greater force than FtsK when translocating along DNA.

PMID:
24768536
PMCID:
PMC4048639
DOI:
10.1016/j.molcel.2014.03.033
[Indexed for MEDLINE]
Free PMC Article

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