Composition can buffer protein dynamics within liquid-like condensates

Most non-membrane-bound compartments in cells that form via phase separation have complex composition. While phase separation of individual proteins that form these compartments is well-documented, the mechanisms that modulate dynamics of individual proteins in multicomponent systems remain unclear. Here, we used in vitro reconstitution and in vivo experiments to investigate how the dynamics of a scaffold protein PGL-3 is regulated within the liquid-like ‘P granule’ compartment inC. elegans. Using mutational and biophysical perturbations, we generated PGL-3 constructs that form condensates in vitro with widely varying dynamics. Using these PGL-3 constructs, we show that introducing other P granule components buffers against change of dynamics within liquid-like condensates. This dynamics-buffering effect is mediated by weak interactions among two or more components. Such dynamics-buffering may contribute to robust functional output of cellular liquid-like compartments.