Spontaneously oscillating synthetic cilia*

Cilia and flagella produce rapid and regular bending waves responsible for the propulsion of organisms in fluids or for the promotion of fluid transport. It is known that the main contribution to their beating is due to motor proteins, dynein, which drives sliding of the microtubule doublets. However, the fundamental mechanism of the dynein-microtubule interaction is still a puzzle.
Here we investigate their mechanical interaction and emergent behavior by analyzing a minimal synthetic system that we experimentally assemble with two microtubules and few dynein motors. We observe that the microtubule pair undergoes cyclical association/dissociation interaction through rhythmic bending, followed by a complete detachment of the microtubules and subsequent re-attachment. By considering the shearing force produced by the motors when they move along the adjacent microtubule and the finite elasticity of the system, we describe this beating cycle in terms of the curvature and dynein-microtubule binding force.