How multivalent crosslinker proteins affect the self-assembly of actomyosin networks

Actomyosin networks are nonequilibrium active matter systems with millions of nanometer-scale proteins that self-assemble to form complex biomechanical structures 10,000 times larger than its constituent proteins. These networks play a key role in the morphology of neuronal dendritic spines whose plasticity regulates long-term memory formation and retention. We use a coarse-grained model to simulate actomyosin networks with both active and passive multivalent crosslinker proteins. Passive crosslinkers bind filaments statically while active crosslinkers (motor proteins) exert force and walk along the polarized filaments. So far, only systems with divalent crosslinkers have been simulated in large scales. Our computational simulations allow us to understand how and when active and passive multivalent crosslinkers promote bundled, scaffolded, isotropic, or clustered phases of the networks. More specifically, our model reveals the dependencies between the network structure and the multivalent crosslinker’s type, concentration, and properties.