Unraveling the dynamics that enable unusual heme enzyme reactivity

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ABSTRACT Enzymes are crucial biological catalysts that expedite challenging reactions across all domains of life. While the development of structural biology methods over the past century has enabled visualization of these fascinating systems, our understanding of the dynamic processes that facilitate enzyme reactivity remains limited due to the timescales on which they occur. The overarching goal in my research group is to develop and apply time-resolved methods capable of visualizing these processes to elucidate the mechanisms of metal-containing enzymes important for human health and medicine. Heme-dependent enzymes are of particular interest due to their role in aerobic metabolism ranging from signal transduction, antibiotic biosynthesis and immune response. Despite sharing similar structural motifs and catalytic intermediates, heme-dependent enzymes are capable of catalyzing a wide range of reactions beyond their archetypal hydroxylation outcomes. This project aims to investigate the structural features and dynamic behavior that enables this atypical reactivity from dioxygenation to nitration and beyond. In particular, we plan to repurpose biochemical tools capable of pausing turnover, such as substrate/cofactor analogs and site-directed mutagenesis, as well as apply state-of-the-art time- resolved methods that my group is currently developing, to visualize short-lived catalytic intermediates via a combination of X-ray crystallographic and spectroscopic approaches. Although applied to specific systems herein, the proposed methodologies may have utility in the study of heme-enzymes more broadly, as well as other metalloenzymes. Likewise, the anticipated results have the potential to impact both biocatalysis and the downstream development of biotechnologies and therapeutics in the treatment of cancers and infectious diseases.