Glassy dynamics of a model of bacterial cytoplasm with metabolic activities

Recent experiments have revealed that cytoplasms become glassy when their metabolism is suppressed, while they maintain fluidity in a living state. The mechanism of this active fluidization is not clear, especially for bacterial cytoplasms, since they lack traditional motor proteins, which can cause directed motions. We introduce a model of bacterial cytoplasm focusing on the impact of conformational change in proteins due to metabolism. In the model, proteins are treated as particles under thermal agitation and conformation changes are treated as changes in particle volume. Simulations reveal that a small change in volume fluidizes the glassy state, accompanied by a change in fragility, as observed experimentally.