Event

Phase separation of biological molecules has emerged as a key mechanism by which cells organize their interior spaces. Investigating the physical principles by which these biomolecular condensates facilitate cellular functions which are generically out-of-equilibrium remains a grand challenge at the intersection of statistical physics and cell biology. The inherent complexity of biological systems has posed a significant obstacle to conceptual progress in this field. We leverage the algal pyrenoid—an experimentally tractable condensate responsible for 30% of global CO2 fixation—as a powerful model system. Notably during cell division the pyrenoid consisting of the CO2-fixing enzyme Rubisco and the linker protein EPYC1 undergoes rapid dissolution and recondensation. We identify a kinase KEY1 that regulates pyrenoid dissolution and proves to be essential for maintaining pyrenoid number size and function. We develop a minimal mathematical model of kinase activity that recapitulates the dynamic behaviors seen in vivo and suggests how molecular fluxes driven by kinase activity can robustly control condensate formation and localization.