Motor Properties of Molecular Spiders

Biological molecular motors are highly complex, multi-subunit assemblies that transduce chemical energy into mechanical work when performing critical cellular tasks. Recent work has focused not only on understanding their operational principles, but on designing new molecular motors ab initio. One example is “molecular spiders”, synthetic biomolecular walkers able to generate biased motion by coupling the chemical energy from substrate binding and cleavage to directed mechanical steps.¹ To investigate their performance as molecular motors, and to determine how to optimize their motor properties, we have performed Monte Carlo simulations.² Our simulations reveal that the mean velocity of spider motion decreases as the number of spider legs increases, while processivity increases. Mean velocity can be increased, however, by simultaneously tuning the length of spider legs and the unbinding rate of a leg from a substrate site. Our investigations of the force- and time-dependent efficiency show that the spiders are not very efficient as molecular motors (with a maximum efficiency on the order of 1%). These studies will assist our group in the experimental construction of a related synthetic biomolecular walker, the “lawnmower” [see poster by Kovacic et al.] 1. R. Pei et al., J. Am. Chem. Soc. 128, 12693 (2006); K. Lund et al., Nature 465, 206 (2010). 2. L. Samii, H. Linke, M.J. Zuckermann, and N.R. Forde, Phys. Rev. E 81, 21106 (2010); L. Samii, H. Linke, P.M.C. Curmi, M. J. Zuckermann, and N.R. Forde, Phys. Rev. E, 84, 031111 (2011).