Characterizing CmodAA-Containing Biosynthetic Pathways of Nonribosomal Peptides

With the support of the Chemistry in Life Processes program in the Division of Chemistry, Bo Li of the University of North Carolina at Chapel Hill is studying the formation of dehydroamino acids in the biosynthesis of nonribosomal peptides. Nonribosomal peptides are a major class of biologically and industrially important natural products and they are synthesized by microorganisms using enzyme assembly lines known as nonribosomal peptide synthetases (NRPSs). Dehydroamino acids are critical for the biological activities of the natural products that contain them; however, how NRPSs incorporate these amino acids had not been experimentally studied until recently. The PI will study how NRPSs integrate dehydroamino acids into diverse natural products using biochemical, structural, and bioinformatic approaches. The work is expected to advance understanding of the molecular details of the biosynthesis of natural products, particularly the novel biofilm-forming natural products under study here. The proposed study will allow graduate students to acquire specialize training in biological and natural product chemistry and provide summer research opportunities to undergraduates. This research project seeks to understand the biosynthesis of α,β-dehydroamino acids in natural products, which is catalyzed by a unique subgroup of NRPS condensation domains (CmodAA). The research will focus on bicyclic alkaloids, including pyrrolizidines and cyclocarbamates that exhibit diverse bioactivities. In the biosynthesis of these natural products, the function of CmodAA domains and flavin-dependent monooxygenases will be characterized. An uncharacterized CmodAA-containing biosynthetic gene cluster will be investigated to identify potentially novel natural products. This project will use a combination of approaches in biochemistry, structural biology, synthetic chemistry, and bioinformatics. As an important scientific broader impact, this research is expected to enable the incorporation of dehydroamino acids into nonribosomal peptides for engineered biosynthesis and synthetic biology, in general. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.