This proposal is focused on exploring the fundamental chemical mechanism of a large superfamily of enzymes called radical SAM enzymes. These enzymes occur in humans in such diverse functions as cofactor synthesis and the antiviral response, and are found in nature in all kingdoms of life. The radical SAM superfamily is large, with thousands of identified members catalyzing a range of reactions;they have in common the utilization of a specific type of metal cluster (a [4Fe-4S] cluster) and S-adenosyl-L-methionine (SAM) to initiate radical chemistry on their substrates. The current proposal will focus primarily on three members of the radical SAM superfamily (pyruvate formate-lyase activating enzyme, lysine 2,3-aminomutase, and viperin) that have diverse functions, and experiments will range from fundamental mechanistic, spectroscopic, and structural studies aimed at delineating details of the chemical mechanisms to basic functional studies aimed at understanding the role of an important mammalian radical SAM enzyme.
The specific aims of the proposal are: 1) To identify specific steps in the catalytic mechanisms of these enzymes by using techniques designed to trap reaction intermediates, 2) To explore valence localization in the [4Fe-4S] cluster of these enzymes, its causes, and its implications for function, 3) To structurally characterize the interaction between one radical SAM enzyme and its protein substrate, and 4) to functionally characterize a human radical SAM enzyme involved in the antiviral response.

Public Health Relevance

The proposed work will provide fundamental new insights into a class of enzymes that are widespread in nature. These enzymes participate in numerous processes relevant to public health, including the response of the human body to viral infections and the synthesis of essential vitamins.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Macromolecular Structure and Function A Study Section (MSFA)
Program Officer
Anderson, Vernon
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Montana State University - Bozeman
Schools of Arts and Sciences
United States
Zip Code
Shisler, Krista A; Broderick, Joan B (2014) Glycyl radical activating enzymes: structure, mechanism, and substrate interactions. Arch Biochem Biophys 546:64-71
Ghose, Shourjo; Hilmer, Jonathan K; Bothner, Brian et al. (2014) Solution phase dynamics of the DNA repair enzyme spore photoproduct lyase as probed by H/D exchange. FEBS Lett 588:3023-9
Crain, Adam V; Broderick, Joan B (2014) Pyruvate formate-lyase and its activation by pyruvate formate-lyase activating enzyme. J Biol Chem 289:5723-9
Silver, Sunshine C; Gardenghi, David J; Naik, Sunil G et al. (2014) Combined Mössbauer spectroscopic, multi-edge X-ray absorption spectroscopic, and density functional theoretical study of the radical SAM enzyme spore photoproduct lyase. J Biol Inorg Chem 19:465-83
Broderick, Joan B; Duffus, Benjamin R; Duschene, Kaitlin S et al. (2014) Radical S-adenosylmethionine enzymes. Chem Rev 114:4229-317
Duschene, Kaitlin S; Veneziano, Susan E; Silver, Sunshine C et al. (2009) Control of radical chemistry in the AdoMet radical enzymes. Curr Opin Chem Biol 13:74-83
Nnyepi, Mbako R; Peng, Yi; Broderick, Joan B (2007) Inactivation of E. coli pyruvate formate-lyase: role of AdhE and small molecules. Arch Biochem Biophys 459:1-9