Consider the pathway in Figure 4A.1 in the textbook (Chapter 4, Section 8) for the production of lysine, methionine, isoleucine, and threonine. You need to produce lysine. Describe a strategy for making large amounts of lysine. Your strategy can consist of adding various amino acids to the medium and choosing mutant cells altered in regulation. Assume that you can identify up to two points of mutation (removal of feedback inhibition). L-aspartic acid aspartyl aspartic semi- phosphate homo- serine L-threonine aldehyde m (a) -L-lysine L-methionine- L-isoleucine (b) L-threonine a-ketobutyric acid pyruvic acid -L-isoleucine a-ketoisovaleric acid L-valine Figure 4A.1 A simplified diagram of the aspartate pathway in E. coli. Each solid arrow designates a reaction catalyzed by one enzyme. The biosynthetic products of the pathway (in boldface) are all allosteric inhibitors of one or more reactions. Careful study of this di- agram reveals that with a single exception (the inhibition exerted by valine) the inhibition imposed by one amino acid does not cause starvation for a different amino acid. Part (a) shows the regulatory interrelationships of the L-lysine, L-methionine, and L-isoleucine branches of the pathway. Part (b) shows the regulatory interrelationships of the L-isoleucine, L-valine, and L-leucine branches L-leucine