Structure and Divergent Mechanisms of Heme oxygenase-like dimetal oxidases/oxygenases

With the support of the Chemistry of Life Processes program in the Division of Chemistry, Professor Makris from North Carolina State University is studying the structures and functions of a newly discovered class of enzymes from bacteria termed the heme oxygenase-like dimetal oxidases/oxygenases (HDOs). The HDOs that are the focus of this proposal are involved in the generation of compounds that serve as drugs or enable pathogens to proliferate. The goal of the research is to provide a molecular rationale for how structurally similar proteins can mediate different transformations with amino-acid substrates. Bioinformatics, structural, and mechanistic enzymology will be leveraged by students to create a publicly available online database (HDoBase) that will facilitate HDO discovery. The research project seeks to determine how structurally similar dimetal proteins can perform radically different transformations on substrates. A combined approach that uses time-resolved structural, kinetic, and spectroscopic methods will evaluate the key principles underlying reaction diversity in four representative HDO subtypes and will streamline future enzyme discovery and annotation. Studies are aimed at the structural elucidation of diferric-peroxide intermediates that are common to the reaction trajectories of many HDOs. The program will investigate how these species are differentially tuned to catalyze transformations directly, or generate downstream oxidants for substrate C-H and N-H bond activation, or radical hole-hopping reactions. The combined roles of the secondary coordination sphere, substrate-positioning, and substrate-type in this process will be systematically evaluated. 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.