Directing protein-based patterns with advective bulk flow

We theoretically predict and experimentally show that the propagation direction of Min-protein patterns in vitro can be controlled by a hydrodynamic flow of the bulk solution, and that the response to flow depends on the concentration ratio of MinE to MinD. For low E:D ratios, the membrane-bound wave patterns propagate downstream relative to the bulk flow while they propagate upstream for large E:D ratios. For intermediate E:D ratios, we find a multistability of both propagation directions relative to the flow. Theoretical analysis of the mathematical model reveals the mechanism underlying upstream propagation of Min patterns and links it to the fast conformational switching of MinE in the bulk. Accordingly, a MinE mutant without that switch exhibits only downstream propagation in experiments. Our work demonstrates how hydrodynamic flow can be used to control protein-based pattern formation and to gain insight into the underlying pattern forming mechanisms. From a broader perspective, the bulk flow is a perturbation that breaks the mirror symmetry of the system and therefore is a nonequilibrium analog of an external magnetic field applied to a ferromagnet.