Fig 5. Predictions and experimental results of the perturbation of the size of limited enzyme pools during growth using a mixture of EFMs.

In the cost vector plots, panels a) and b), the red vector denotes the optimal solution in the unperturbed organism. Upon experimental perturbation, the available area in constraint space can change, indicated by the shaded grey areas. The green, blue, and grey vectors show the new optimal solutions under increasingly strong perturbations. The predicted effect on the flux through the acetate branch is shown in panels c and d). a,c) Analysis of perturbations that tighten both protein pools with the same amount shows that flux and growth rate will decrease proportionally, as observed experimentally (e)) for the overexpression of LacZ on different carbon sources (data from Basan et al. [4]). b,d) Perturbations that tighten an enzyme pool that is mostly used by one EFM (here denoted by CO₂) initially cause an increase in flux through the other EFM in the mixture(Ac). Eventually, at stronger limitations, this flux also decreases. f) This behaviour is observed, a.o., for translation inhibitor experiments using chloramphenicol (S1 Appendix Section 7).