METABOLIC DESIGN - HOW TO ENGINEER A LIVING CELL TO DESIRED METABOLITE CONCENTRATIONS AND FLUXES

A biotechnological aim of genetic engineering is to increase the intra cellular concentration or secretion of valuable compounds, while makin g the other concentrations and fluxes optimal for viability and produc tivity. Efforts to accomplish this based on over-expression of the enz yme, catalyzing the so-called ''rate-limiting step,'' have not been su ccessful. Here we develop a method to determine the enzyme concentrati ons that are required to achieve such an aim. This method is called Me tabolic Design Analysis and is based on the perturbation method and th e modular (''top-down'') approach-formalisms that were first developed for the analysis of biochemical regulation such as, Metabolic Control Analysis. Contrary to earlier methods, the desired alterations of cel lular metabolism need not be small or confined to a single metabolite or flux. The limits to the alterations of fluxes and metabolite concen trations are identified. To employ Metabolic Design Analysis, only lim ited kinetic information concerning the pathway enzymes is needed. (C) 1998 John Wiley & Sons, Inc.