Enzyme-Mediated Synthesis of Functionalized Terpene Structures Project Summary/Abstract This application addresses broad challenge area (06), Enabling Technologies, and specific Challenge Topic 06-GM-109: Green chemistry and engineering for drug discovery, development, and production. Terpenes, constituting one of the most diverse groups of compounds synthesized by biological systems, have been used as antibacterial, antifungal, and anticancer agents in the treatment of human disease. Despite the high value of many terpenes as therapeutic targets, chemical synthesis routes have proven elusive due to the presence of several chiral centers in the terpene core and the need for differential protection and deprotection of functional groups. In the last ten years there has been tremendous progress in the chemical synthesis of complex functionalized terpenes using metal-based catalysts to execute regio and stereospecific reactions, and having access to small quantities of terpenes has been sufficient to confirm the therapeutic value of a number of drug candidates. However, going forward we will need cost-effective and green synthetic methods to produce quantities of therapeutic terpenes sufficient for drug development and commercialization. To address this problem, we propose a green chemistry platform for the synthesis of terpene olefins and functionalized terpenes of therapeutic value. First, through expression of selected known and novel terpene synthases in engineered microbial hosts, we will generate terpene olefins that constitute core structures of therapeutic compounds. Second, we will functionalize these terpene olefins using mutants of a highly efficient bacterial cytochrome P450 monooxygenase. Finally, we will optimize expression of these enzymes in microbial strains that we have engineered to overproduce universal terpene precursors in order to achieve high-level production of terpene olefins and oxidized terpenes of therapeutic value. Successful completion of this proposal will provide a microbial platform for the economical and clean synthesis of terpene olefins and oxidized terpenes of therapeutic value. This work has three significant impacts on human health. First, the microbial terpenes can then be used as late intermediates in the synthesis of complete therapeutic terpenes and terpene analogs, thus accelerating the discovery of terpene-based therapeutics. Second, microbial production of terpenes is more cost-effective and environment-friendly when compared to traditional organic synthesis methods that rely on expensive starting materials and toxic solvents and catalysts. Finally, the generality of the proposed platform will streamline the synthesis of other functionalized terpenes via the introduction and mutagenesis of new enzymes in our host strains.
There are many natural products in the terpene family with promising or proven therapeutic characteristics. As yields from natural sources are frequently low, and typical chemical synthesis routes are often challenging and expensive, we aim to facilitate economical and clean enzyme-mediated synthesis of a number of these products. In addition, our plan enables green synthesis of product analogs for drug discovery and improvement programs though the use of mutant enzymes.
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