Fig. 3

Emergence of metabolic multimodality. We used the PMM approximation to find regimes for multimodality through perturbations to the enzyme kinetics. We vary the kinetic parameter K to control the dependency of the Poisson parameter λ(n_etot) in Eq. (4) on the total enzyme abundance. Parameter values are λ_∞ = 750 molecules and K = {10.0400, 2.1630, 0.4660} molecules obtained by variations to the kinetic rate constants k_cat and k_rev with a constant ratio k_cat/k_rev. We shape the mean enzyme abundance with the promoter switching rates k_on = {1.56, 5.9, 20} × 10⁻⁴ s⁻¹ and k_off = {9.8, 9.3, 8} × 10⁻⁴ s⁻¹. From the PMM, we found intricate patterns of multimodal distributions in the metabolite, all of which show an excellent match with the corresponding Gillespie simulations. The simulated time courses show metabolite numbers traversing various quasi-stationary regimes