Control of threonine pathway in E. coli. Application to biotechnologies.

Threonine is an essential amino acid for mammals and birds and an adequate supply is necessary for growth and maintenance. Its production has become the aim of metabolic bioengineering and genetic manipulations. We propose in this paper a rational approach for increasing threonine production in an E. coli strain based on metabolic control theory. We have derived a way to measure the control coefficients of threonine pathway in vivo. The method consists in modelling the results of presteady-state experiments. The in vivo concentrations and activities of the enzymes can then be measured and introduced into the model, so that the in vivo steady-state of the pathway can be evaluated. With such a model it is possible to calculate the theoretical values of the control coefficients of the threonine synthesis flux in vivo.