SoftBio Theory Seminar: Single-molecule trajectories of reactants in chemically active condensates - stochastic dynamics and thermodynamics

Biomolecular condensates provide distinct chemical environments, which control various cellular processes without requiring a membrane. The diffusive dynamics and chemical kinetics of individual molecules inside condensates can be studied experimentally by fluorescent labelling, offering key insights into subcellular dynamics. I will present how biomolecular condensates govern the kinetics of chemical reactions and how this is reflected in the noisy dynamics of labelled molecules. This will allow me to discuss how the physics of phase separation influences the evolution of single-molecule trajectories and governs their statistics. I will show that, out of equilibrium, the interactions leading to phase separation induce systematic directed motion at the level of single molecules. I will discuss how this can provide an alternative explanation for the chemotaxis of active enzymes, which has been experimentally observed. I will then present how we can use stochastic thermodynamics to quantify how far from equilibrium condensates are. In closing, I will extend these considerations to other biophysical systems studied at the single-molecule level.