Beatrice Nettuno, University of Munich

Phase Separation as a Mechanism for Actin Treadmilling

We demonstrate that the phase separation of a protein facilitating actin polymerization (VASP) is crucial for the treadmilling of actin filaments. Phase separation enhances the formation and stabilization of bundles, where a balance between polymerization and depolymerization (mediated by cofilin) is achieved. Outside the bundles, filaments tend to depolymerize, while inside, their growth is enhanced, leading to bundle coarsening. We predict that modulating the phase separation strength changes the treadmilling properties of the filaments, with both excessive and insufficient phase separation halting the process. Our agent-based simulations align with experimental observations, validating our theoretical predictions.