Enzymes can activate and mobilize dense biomolecular condensates across scales

Biomolecular condensates have so far been studied in terms of their structural, compositional, and functional properties. However, condensate enzymatic activity - a key aspect of cellular metabolism - remains unexplored due to the complexity of the system. In this study, using a combination of experimental, computational and theoretical techniques, we have discovered that the non-equilibrium activity which originates from catalytic reactions couples with the environment through various feedback mechanisms across five orders of magnitude of length scales. We observe that condensed enzymes catalyze more rapidly in the presence of crowding proteins and show that the increased enzymatic activity within these droplets stems from the emergence of lower-energy protein conformations induced by the highly crowded environment. Despite the crowding in the environment of the droplet, which might suggest an effective increase in its overall viscosity, we find that it becomes more agile, as evidenced by the observation of enhanced diffusion and macroscopic flow, due to the enzymatic activity. These findings shed light on the dynamic interplay between enzymatic activity, composition and crowding in condensates, and their roles on the mobility and accessibility of various functional units in these environments, expanding our understanding of liquid-liquid phase separation in metabolically active conditions. Enzymes operate in highly crowded cellular environments, yet the impact of crowding on their function remains poorly understood. Here, the authors demonstrate that enzyme activity increases molecular mobility in crowded protein droplets, suggesting a feedback mechanism between catalysis and the physical properties of the surrounding environment.