(66e) Improving Cofactor Availability through Metabolic Engineering for Recombinant Phytochemicals Production

Many pharmaceuticals we use today originate from plant secondary metabolites such as Taxol and Artemisinin which are still extracted from natural sources. To solve the supply constraints encountered when using plant extracts, significant progress has been made in cloning the biosynthetic pathways into microorganisms to produce these compounds through fermentative processes. However, these approaches typically suffer from low yields. One issue that has received minimal attention is the availability of the NADPH, a necessary cofactor in many plant biosynthetic pathways, especially when cytochrome p450s are involved. Our group has been focusing on utilizing metabolic engineering to optimize NADPH availability. Specifically, our progress has covered the reconstruction of the NADPH-dependent (+)-catechin biosynthetic pathway within Escherichia coli. We have developed a constraint based model that uses an evolutionary algorithm to identify beneficial gene knockouts in order to improve NADPH yields. So far, we have increased (+)-catechin yields 10-fold using knockout strains and overexpression of NADPH-producing enzymes. In addition, we have applied our optimized strains to synthesis of novel flavonoid analogues using a mutational biosynthesis approach.