DNA Machines: Bipedal Walker and Stepper

The assembly of a bipedal walker and of a bipedal stepper using DNA constructs is described. These DNA machines are activated by H+/OH- and Hg2+/cysteine triggers. The bipedal walker is activated on a DNA template consisting of four nucleic acid footholds. The forward walking of the DNA on the template track is activated by Hg2+ ions and H+ ions, respectively, using the thymine-Hg2+-thymine complex or the i-motif structure as the DNA translocation driving forces. The backward walking is activated by OH- ions and cysteine, triggers that destroy the i-motif or thymine-Hg2+-thymine complexes. Similarly, the bipedal stepper is activated on a circular DNA template consisting of four tethered footholds. With the Hg2+/cysteine and H+/OH- triggers, clockwise or anticlockwise stepping is demonstrated. The operation of the DNA machines is followed optically by the appropriate labeling of the walker-foothold components with the respective fluorophores/quenchers units.