Decision-making in a synthetic cell: the limits of biological computation

We measured the dynamics of decision-making by a minimal bistable gene network integrated in a synthetic cell model, free of external perturbations. Reducing the number of gene copies from 10 5 to about 10 per cell revealed a transition from deterministic and slow computation to a fuzzy and rapid regime dominated by singleprotein fluctuations. Fuzzy computation appeared at DNA and protein concentrations 100-fold lower than necessary in equilibrium, suggesting rate enhancement by co-expressional localization. Whereas the high-copy regime was characterized by a sharp transition, hysteresis and robust memory, the low-copy limit showed incipient strong fluctuations, switching between states, and a signature of cellular individuality across the decision-making point. Our work establishes synthetic cells operating rapidly at the single molecule level to integrate gene regulatory networks with metabolic pathways for sustained survival with low energetic cost. One Sentence Summary Decision-making in a synthetic cell can be slow and precise or rapid and probabilistic by reducing the number of computing molecules by five decades down to single-molecule fluctuations.