Chemical Probes to Study Methionine Redox Biology

Project Summary/Abstract Protein methionine residues are emerging as essential redox sites for physiological processes spanning signal transduction, antioxidant defense, and regulation of protein function. At the same time, aberrant elevations in methionine oxidation induced by oxidative stress and/or inactivation of methionine sulfoxide reductase enzymes can contribute to cancer, neurodegenerative and vascular diseases, and life span. To decipher contributions of methionine redox physiology and pathology, we are developing new chemical reagents to selectively label reactive methionine sites from proteins to proteomes. The scientific premise is that providing access to a modular chemical toolbox for methionine bioconjugation will help unveil new functional methionine sites in proteins to further understanding of physiological and pathological contributions through covalent methionine tagging. Selective methionine bioconjugation using redox-based probes that emulate the innate oxidative chemistry of these residues offers chemical innovation, while demonstrating scientific rigor through the combined use of diverse synthetic, modeling, proteomic, and biochemical approaches to provide general tools for probing the reactive methionine landscape. Specifically, we seek to (1) design robust and highly specific oxaziridine probes by establishing a predictive model for tuning selectivity and stability of methionine adducts, (2) identify proteome-wide oxidatively-sensitive methionine sites and analyze motifs to reveal principles of methionine hyperreactivity, and (3) biochemically characterize targets involved in reversible redox regulation, with a particular focus on cancer-dependent targets where methionine oxidation can influence cellular metabolism.