Polyketides are one of the largest families of natural products with an astonishing structural variety and a remarkable range of biological activities. Polyketides are biosynthesized in fungi by polyketide synthase (PKS) multienzymes whose individual enzymatic domains are used repeatedly. While only a single PKS multienzyme is sufficient to produce most fungal polyketides, some of these natural products are assembled by two collaborating fungal PKSs. Such collaborations represent significant departures from the canonical biosynthetic logic of fungal polyketide biosynthesis. The overarching goal of the current project is to clarify the presently unknown molecular mechanistic details of the assembly of polyketides on such collaborating PKSs, using the biosynthesis of resorcylic acid lactones (RAL) and the related dihydroxybenzeneacetic acid lactones (DAL) as models. Specifically, the project aims to: 1: Characterize the biosynthesis of dehydrocurvularin, a DAL-type natural product; 2: Express RAL and DAL polyketide synthetases, their appropriate mutants, and hybrid enzymes in alternative microbial hosts, and evaluate the production of polyketides using these enzymes and synthetic substrates; and 3: Demonstrate combinatorial biosynthesis by combining related biosynthetic pathways. These experiments will clarify the programming rules that dictate the assembly of polyketides from simpler metabolites, and control the final shape (cyclization patterns) of such natural products. The lessons learned will advance our understanding of iterative enzymatic catalysis, and contribute to the development of combinatorial biosynthetic methods for the production of "designer" polyketides that may be used as novel agrochemicals or high value specialty chemicals in the future.
Broader Impacts
Equally important, the project will incorporate training, education and outreach activities. Extensive research-based training opportunities will be provided to graduate and undergraduate students, including those from minority and underrepresented groups. The project will also train community college undergraduate student interns, and may host high school seniors as interns under the auspices of a successful outreach program of the University of Arizona. All students will learn the interdisciplinary science of microbial metabolite biosynthesis and the practice of combinatorial biosynthesis, thus preparing them for careers in the biotechnology industry and in academic research. Further, professional development opportunities will also be provided to K-12 educators to learn about natural products and their biosynthesis by microorganisms: this knowledge may later be integrated into their science curricula.
This project is jointly supported by the Metabolic Biochemistry Program of the Division of Molecular and Cellular Biosciences and the Chemistry of Life Processes Program in the Chemistry Division.
