‡Department of Chemistry and †Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/ja303530y
Publication Date (Web): July 26, 2012
Copyright © 2012 American Chemical Society
We report a new kind of DNA nanomachine that, fueled by Hg2+ binding and sequestration, couples mechanical motion to the multiply reversible switching of through-DNA charge transport. This mechano-electronic DNA switch consists of a three-way helical junction, one arm of which is a T-T mismatch containing Hg2+-binding domain. We demonstrate, using chemical footprinting and by monitoring charge-flow-dependent guanine oxidation, that the formation of T-Hg2+-T base pairs in the Hg2+-binding domain sharply increases electron–hole transport between the other two Watson–Crick-paired stems, across the three-way junction. FRET measurements are then used to demonstrate that Hg2+ binding/dissociation, and the concomitant increase/decrease of hole transport efficiency, are strongly linked to specific mechanical movements of the two conductive helical stems. The increase in hole transport efficiency upon Hg2+ binding is tightly coupled to the movement of the conductive stems from a bent arrangement toward a more linear one, in which coaxial stacking is facilitated. This switch offers a paradigm wherein the performance of purely mechanical work by a nanodevice can be conveniently monitored by electronic measurement.
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