Model for intrinsically disordered proteins with a strong dependence of liquid-liquid phase separation on sequence

Phase separation of intrinsically disordered proteins is important for the formation of membraneless organelles, or biomolecular condensates, which play key roles in the regulation of biochemical processes within the cells. In this talk, we present the phase separation behavior of different sequences of a coarse-grained model for intrinsically disordered proteins and show that they exhibit a surprisingly rich phase behavior. Both the fraction of total hydrophobic parts and the distribution hydrophobic parts are investigated. We observed not only conventional liquid-liquid phase separation, but also reentrant phase behavior, in which the liquid phase density decreases at lower temperatures. For some sequences, we also observe formation of open phases consisting of aggregates, rather than a normal liquid. These aggregates had overall lower densities than the conventional liquid phases and complex geometries with large interconnected fibril-like or membrane-like clusters. Minor alterations in the ordering of a given set of amino acids may lead to large changes in the overall phase behavior, a fact of significant potential relevance for biology.