Collaborative Research: Exploring Non-heme Oxidases in Tryptophan Metabolism: Pathways to Toxins and Bioactive Molecules

Researchers from Brandeis University and the University of California San Diego are investigating how cyanobacteria transform the common amino acid tryptophan into structurally diverse metabolites with potential applications in biotechnology, medicine, and natural product discovery. Cyanobacterial genomes represent a largely untapped reservoir of enzymes capable of producing biologically active molecules, yet the chemical principles underlying their remarkable diversity remain poorly understood. This project seeks to determine how nature uses a newly discovered family of non-heme iron-dependent enzymes to convert tryptophan and its halogenated derivatives into chemically distinct products with diverse molecular scaffolds. The research team will combine biochemical, structural, and genome-guided approaches to uncover how closely related enzymes catalyze fundamentally different oxidative transformations and identify homologs with new functions and their associated metabolic pathways. These discoveries could reveal new strategies that nature employs to expand chemical diversity and establish a broadly applicable platform for discovering and engineering biocatalysts. The project will also provide interdisciplinary training for undergraduate, graduate, and postdoctoral researchers at the interface of bioinorganic chemistry, enzymology, structural biology, and natural products research while supporting collaborative scientific education increased participation in chemical biology. The project will establish the chemical principles that govern the enzymatic functionalization of tryptophan and define the catalytic repertoire of a newly recognized family of heme-oxygenase-like diiron (HDO) oxidases and oxygenases. These enzymes catalyze diverse oxidative transformations despite sharing high sequence and structural similarity. Hence, they provide an exceptional system for understanding how protein scaffolds evolve new chemical functions. The research will determine the molecular mechanisms responsible for nitrile, oxime, and related reaction pathways using complementary spectroscopic, structural, biochemical, and bioinformatic analyses. Genome mining and comparative genomics will be used to identify new HDO homologs, define pathway architectures, predict substrate specificities, and discover previously unknown metabolites. Together, these studies will establish the mechanistic framework that links enzyme structure to catalytic outcome, enabling functional prediction of uncharacterized HDO enzymes and guiding the development and design of biocatalysts for the synthesis of high-value chemicals and biologically active molecules. 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.