Harnessing light and model endosymbiosis to produce natural products

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Project Abstract A large portion of important drugs and pharmaceutical intermediates either originate from plants or are synthesized from petrochemical-based products. Several natural products of significantly high value to human life (e.g., antibiotics, pharmaceuticals like Artemisinin, anticancer agents like Taxol (paclitaxel) among others) have been produced by organisms that are not optimal for industrial production. Although some of these natural products can be chemically synthesized, the complex structures of several of these compounds makes chemical synthesis difficult and commercially infeasible. As a result, there is increasing need to develop sustainable and readily tractable technological platforms to synthesize these drugs and pharmaceutical intermediates. The central objective of this proposal is to develop a sustainable technological platform that harnesses light energy and biocatalysis to synthesize molecules of significant relevance to human life. We envision doing this by establishing cyanobacterial endosymbionts within yeasts cells, such that the endosymbiotic cyanobacteria provide ATP and assimilated carbon (generated from photosynthesis) to the yeast cells, which utilize it to produce biologically important natural products. This platform will allow us to couple the remarkable biosynthetic and biocatalytic potential of yeast to the photosynthetic ability of cyanobacteria to develop a sustainable and simple bioproduction platform to produce natural products of significant value to human life (vide infra). Premise: (i) Saccharomyces cerevisiae has been recently harnessed to produce high titers of biologically important molecules such as amorphadiene and artemisinic acid, (precursors to Artemisinin) and taxadiene (a key precursor to Taxol), (ii) we had previously developed model endosymbiosis between S. cerevisiae /E. coli to study mitochondrial evolution are currently engineering yeast/cyanobacteria endosymbiosis (preliminary data in Specific Aim 1) and (iii) our preliminary data on engineering model yeast/cyanobacteria endosymbiosis. In this proposal, we will focus on three key areas: (i) We have engineered experimental platform to establish endosymbiosis between model cyanobacteria, Synechococcus elongatus, and model budding yeast, S. cerevisiae. We will expand this platform by engineering novel cyanobacterial mutants as putative endosymbionts. We will extensively characterize the engineered yeast/cyanobacteria endosymbiosis to develop strategies to improve their stability, growth rate and homogeneity. (ii) We will create a metabolite-driven synthetic communication system to control endosymbiosis and optimize our platform for metabolic engineering. (iii) We will utilize our photosynthetic endosymbiotic platform to produce key precursors of FDA approved compounds, Artemisinin and Taxol. These studies will be the first step towards our long-term goal of developing a photosynthetic and genetically tractable endosymbiotic platform for the bioproduction of biologically important novel natural products as well as molecules like biopolymers and biofuels.