Stochastic Ratcheting on a Funneled Energy Landscape is Necessary for Highly Efficient Contractility of Actomyosin Force Dipoles

摘要: Current understanding of how contractility emerges in disordered actomyosin networks non-muscle cells is still largely based on the intuition derived from earlier works muscle contractility. This view, however, overlooks free energy gain following passive cross-linker binding, which, even absence active fluctuations, provides a thermodynamic drive towards highly overlapping filamentous states. In this work, we shed light phenomenon, showing that cross-linkers, when considered context two anti-parallel filaments, generate noticeable contractile forces. However, as binding cross-linkers increased, sharp onset kinetic arrest follows, greatly diminishing effectiveness mechanism, allowing network to contract only with weakly resisting tensions at its boundary. We have carried out stochastic simulations elucidating followed by mean-field treatment predicts forces asymptotically scale small and large energies, respectively. Furthermore, considering an filament pair, myosin II, found non-processive nature these motors leads inefficient force generation, due recoil slippage overlap during periods motor dissociated. discovered can serve structural ratchet unbound time spans, resulting vast amplification. Our results non-equilibrium effects transiently proteins biological matter, observed actin cytoskeleton, efficient dipoles result synergy dynamics, via ratcheting mechanism funneled landscape.