Evolved interactions stabilize many coexisting phases in multicomponent liquids

Phase separation has emerged as an essential concept for the spatial organization inside biological cells. However, despite the clear relevance to virtually all physiological functions, we understand surprisingly little about what phases form in a system of many interacting components, like in cells. Here we introduce a numerical method based on physical relaxation dynamics to study the coexisting phases in such systems. We use our approach to optimize interactions between components, similar to how evolution might have optimized the interactions of proteins. These evolved interactions robustly lead to a defined number of phases, despite substantial uncertainties in the initial composition, while random or designed interactions perform much worse. Moreover, the optimized interactions are robust to perturbations, and they allow fast adaption to new target phase counts. We thus show that genetically encoded interactions of proteins provide versatile control of phase behavior. The phases forming in our system are also a concrete example of a robust emergent property that does not rely on fine-tuning the parameters of individual constituents.

Automated summary

Phase separation is an important concept for spatial organization in biological cells, but little is known about the phases formed in systems with many interacting components. Researchers have developed a numerical method based on physical relaxation dynamics to study coexisting phases in such systems. By optimizing interactions between components, similar to how proteins' interactions might have evolved, they found that these evolved interactions robustly lead to a defined number of phases and provide versatile control of phase behavior.