A nanoscale reciprocating rotary mechanism with coordinated mobility control
Biological molecular motors transform chemical energy into mechanical work by coupling a cycle of catalytic reactions to large scale structural transitions. Mechanical deformation can be surprisingly efficient in realizing such coupling, as demonstrated by the celebrated example of F1Fo ATP synthase. Here, we describe a synthetic molecular mechanism that transforms a rotary motion of an asymmetric camshaft into reciprocating large-scale transitions in the structure of the surrounding stator orchestrated by mechanical deformation. We designed the mechanism using DNA origami, characterized the structure of the components and the entire mechanism using cryo-electron microscopy, and examined the mechanisms dynamic behavior using single-particle fluorescence microscopy and molecular dynamics simulations. The data indicates that, while the camshaft can rotate inside the stator by diffusion, mechanical deformation of the stator makes the camshaft pause at a set of preferred orientations. By changing the mechanical stiffness of the stator, we could accelerate or suppress the Brownian rotation within the mechanism, thereby demonstrating an allosteric coupling between the movement of the camshaft and of the stator, and the ability to tailor the free energy landscape that governs the rotary motion. Our mechanism provides a framework for the manufacture of artificial nanomachines that, just like the man-made machines in the macroscopic world, function because of coordinated movements of their components.