Molecular machines perform elegant work with high efficiency in biological systems. They have inspired attempts to create artificial machines that mimic the ability to produce controlled motion (1, 2). We describe the construction of an extendable DNA walker-track system. A monomer DX track with three foot-holders is constructed, and the biped walker moves along the cylinder side of the track. Therefore the terminus of the monomer track could be used to create sticky ends for track extension and the total steps the walker could take increases as more monomer tracks are added. A dimer DX track with six foot-holders demonstrates the feasibility of track extension. By means of sequential addition of DNA set/unset strands (3, 4), the walker is programmed to move forward and then backward along the track. PAGE analysis demonstrates that the walker-track complex forms well. Psoralen cross-link monitoring is performed with an aliquot of material at each step. The PAGE analysis results further establish the step-wise formation of the expected products.



The schematic above shows the attachment of walker to the monomer DX track via a set strand (a), and the attachment of walker to a dimer DX track (b).

References

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3. W. B. Sherman and N. C. Seeman, Nano Lett.4, 1203-1207 (2004).
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