Fluctuation-driven contractility without motors

Contractility in cells is usually due to molecular motor activity, such as in the case of the contractile ring, in which actin and myosin generate during cytokinesis. Recent experiments, however, have suggested non-motor-based contraction in some cells. Here, we present a model for contraction based on stochastic binding of actin filaments that are known to have an asymmetric force response. This leads to continuous net contraction via a Brownian ratchet-like mechanism, provided that the crosslinking is active and violates detailed balance. Using this model, we calculate the force-velocity relation and find a stall force for the system, which could be used to test this model.