(5bs) Metabolic Engineering of Terpenoid Production in Microbes: Challenges and Opportunities

Recent developments in synthetic biology and metabolic engineering offer new possibilities for the large scale production of complex natural products through the engineering of biosynthetic pathways in surrogate microbial hosts. However, challenges associated with this task include (1) the expression of many foreign, large, or multidomain enzymes that may complicate processes and (2) the accumulation of toxic foreign metabolites in the new host. With my chemical and biochemical expertise, my research interest in this area is to reconstruct complex biosynthetic pathways through engineering of natural product molecular machinery in microbial hosts. My ultimate research goals will be on pathway engineering of bioactive molecules and developing microbial cell factories for overproduction of biochemical and biofuels from renewable resources.

The anticancer drug Taxol is a unique and challenging example with many interesting biochemical features. The complete biosynthetic pathway consists of 19 enzymes in the native organism, a formidable challenge to transplant to the microbial host. Additionally, production in the native organism, as well as chemical synthesis is uneconomical and unscalable for the production of Taxol. Thus engineering the biosynthesis of Taxol is a challenging option to accelerate the development of complex biosynthetic pathway engineering in microbes for large scale sustainable production of Taxol and analogous terpenoid molecules. It requires the design of a microbial cellular environment, capable of supplying precursors needed for Taxol biosynthesis and the functional reconstitution of the heterologous Taxol biosynthetic enzymes. In our research we used metabolic engineering and synthetic biology tools to modulate the upstream endogenous non-mevalonate pathway in E. coli with downstream heterologous Taxol biosynthetic pathways, resulting in a strain capable of overproducing early Taxol precursors. Additionally, our multivariate modular approach to the pathway engineering unraveled the regulation of the non-mevalonate isoprenoid pathway in bacteria. Thus the current study has opened up the new possibilities high level microbial production rich and diverse chemical structures in terpenoid molecules. As engineered pathways are extended to include very long pathways, such as the complete 19 enzyme Taxol pathway, new cell engineering, pathway engineering and protein engineering, tools will need to be developed to stably express the pathway and synthesize the product.