Iron-Sulfur Clusters in Biological Radical Reactions
The overall objective of this project is to delineate the detailed chemical mechanism of radical generation by the Fe/S-S-adenosylmethionine (the so-called radical SAM) superfamily of enzymes. These enzymes span a remarkably diverse range of reactions and are represented across the phylogenetic kingdom, with hundreds of radical SAM enzymes identified. The widespread occurrence of these enzymes throughout biology, from bacteria to humans, is indicative of the significance of the chemistry catalyzed by these enzymes. In humans, radical SAM enzymes are involved in the biosynthesis of lipoic acid, the synthesis of heme, and the biosynthesis of the molybdopterin cofactor, among many other essential functions, some as yet unidentified. Despite the diversity of reactions catalyzed, our overriding hypothesis is that the adenosylmethionine-dependent iron-sulfur enzymes all operate by a common mechanism in which a reduced cluster interacts with S-adenosylmethionine to generate an adenosyl radical intermediate, which is directly involved in catalysis. These reactions represent novel chemistry for iron-sulfur clusters. To investigate this novel chemistry, biochemical, spectroscopic, mechanistic, and structural studies of pyruvate formate-lyase activating enzyme (PFL-AE) are being pursued.
Kaitlin S. Duschene and Joan B. Broderick, "The Antiviral Protein Viperin is a Radical SAM Enzyme." FEBS Lett. 2010 584(6), 1263-1267.
Eric M. Shepard, Shawn E. McGlynn, Alexandra L. Bueling, Celestine S. Grady-Smith, Simon J. George, Mark A. Winslow, Stephen P. Cramer, John W. Peters, and Joan B. Broderick, "Synthesis of the 2Fe subcluster of the [FeFe]-hydrogenase H cluster on the HydF scaffold." Proc. Natl. Acad. Sci. U.S.A. 2010, 107(23), 10448-10453.
Eric M. Shepard, Benjamin R. Duffus, Simon J. George, Shawn E. McGlynn, Martin R. Challand, Kevin D. Swanson, Peter L. Roach, Stephen P. Cramer, John W. Peters, and Joan B. Broderick, "[FeFe]-Hydrogenase Maturation: HydG-Catalyzed Synthesis of Carbon Monoxide." J. Am. Chem. Soc. 2010 132(27), 9247-9249.
Yi Peng, Susan E. Veneziano, Gregory D. Gillispie, and Joan B. Broderick, "Pyruvate formate-lyase: Evidence for an open conformation favored in the presence of its activating enzyme." J. Biol. Chem. 2010 285, 27224-27231.
Eric M. Shepard, Eric S. Boyd, Joan B. Broderick, and John W. Peters, "Biosynthesis of complex iron-sulfur enzymes." Curr. Op. Chem. Biol. 2011, 319-327.
Kevin D. Swanson, Benjamin R. Duffus, Trevor E. Beard, John W. Peters, Joan B. Broderick, "Cyanide and Carbon Monoxide Ligand Formation in Hydrogenase Biosynthesis." Eur. J. Inorg. Chem. 2011, 935-947.
Inorganic, Biophysical, Bioinorganic