Modelling bacterial threonine metabolism

  1. Download the model file. Consult the lecture slides from day 2 for a diagram of the threonine pathway.
  2. Try to answer the following using the model:
    1. What are the flux control coefficients of the 5 steps? For the purposes of this question, we have multiplied the rate equations for the 5 steps by the factors F1 ... F5. These are initially set to 1 (the reference state), so setting F1 to 2 doubles the rate of reaction 1, and so on. (Here we are treating the two aspartate kinase reactions as a single enzyme as a simplification.
    2. What degree of inhibition (or suppression of expression) of each of the enzymes is needed to reduce the flux to 50% of its initial value?
    3. Which single enzymes can be over-expressed (and by how much) to achieve a 50% increase in threonine flux relative to the initial state of the model and what relative level of over-expression is needed?

To answer these, you need to adjust the parameters that act on the enzyme values. The factors F1 ... F5 are initially set to 1 (the reference state), so setting F1 to 2 doubles the rate of reaction 1, and so on.