Direct observation of elementary processes enables acceleration of DNA-nanoparticle motor up to 100 nm/s

Host:  David Sivak

Synopsis

DNA-modified nanoparticle motors are burnt-bridge Brownian ratchets moving on RNA-modified surfaces driven by a RNA-degrading enzymes in solution. Although these artificial molecular motors have large flexibility in design, the major drawback is their much lower velocities (~3 nm/s at most) than those of motor proteins (10–1000 nm/s). Here we reveal elementary processes of the motion of DNA-gold nanoparticle motor to improve the bottleneck process which limits the velocity. High-speed/high-precision single-particle tracking resolves steps and pauses of several tens of nanometers and seconds, respectively. The bottleneck is enzyme binding, and high, micromolar enzyme concentrations result in dramatic decrease in the pause length down to 0.1 s without changing the step size. The velocity increases up to ~100 nm/s, while the run length (processivity) decreases distinctly from 3.5 to 0.6 μm (150 to 40). Kinetic simulations reproduce the enzyme concentration dependence quantitatively, and reveals the factors and mechanisms which limit the maximum velocity and processivity for future improvement.