Protein coacervation-driven active forces power protocell dynamics.

Protein coacervates formed by liquid-liquid phase separation are emerging as active force generators, independent of ATP-driven motors. Nevertheless, the coordination and force scaling of protein coacervates remain largely unexplored. Here, we engineer a temperature-responsive elastin-based protocell model displaying temperature-modulated contractility and attendant force harnessing. By leveraging the phase separation properties, we modulate the protocell dynamics associated with volume contraction and membrane budding. Crosslinking of the elastin-based membrane influences the contraction dynamics such that the accumulation of mechanical forces in the protocells results in the spontaneous expulsion of internally trapped protein liquid-liquid phase separation (LLPS) complexes. We use a simple mathematically model to show how protein coacervation can amplify small piconewton-scale forces to perform large-scale mechanical work, highlighting the mechanical potential of protein coacervation dynamics. Taken together, our results provide a model framework for harnessing protein coacervates-driven forces and offer a step to future applications in synthetic biology, biomaterials and next-generation soft robotics.