Abstract

Being able to organize the complex biomolecular chemistry that takes place in cells in space and time is essential for life. Liquid-liquid phase separation has emerged as an important biological organizing principle that can result in the formation of dynamic membraneless compartments, also known as coacervate droplets. By studying model coacervate droplets in vitro, we are able to probe how their unique chemical microenvironment can affect reactivity, self-assembly, phase behaviour and potentially aggregation of biomolecules. Here, we focus on how mixtures of coacervates will typically lead to hierarchically organized multiphase compartments, and how the enhanced assembly of proteins such FtsZ into filaments inside these compartments gives rise to spontaneous elongation and splitting upon supply of energy. These insights are not only relevant to better understand living cells in health and disease, but also to guide efforts to build a functional synthetic cell.