Research Projects
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.
Publications
Broderick JB
, "Iron-Sulfur Clusters in Enzyme Catalysis
." Comprehensive Coordination Chemistry II: From Biology to Nanotechnology, Volume 8, L. Que and W. B. Tolman, Volume Eds., J. McCleverty and T. Meyer, Eds., Elsevier Science, 2003
Krebs C, Broderick WE, Henshaw TF, Broderick JB, Huynh BH
, "Coordination of Adenosylmethionine to a Unique Iron Site of the [4Fe-4S] of Pyruvate Formate-Lyase Activating Enzyme: A MÃssbauer Spectroscopic Study
." J. Am. Chem. Soc. 124 912-913 (2002)
Buis JM, Broderick JB
, "Pyruvate Formate-Lyase Activating Enzyme: Elucidation of a Novel Mechanism for Glycyl Radical Formation
." Arch. Bioch. Biophys. 433 288-296 (2005)
Walsby C, Ortillo D, Broderick WE, Broderick JB, Hoffman BM
, "An Anchoring Role for FeS Clusters: Chelation of the Amino Acid Moiety of S-Adenosylmethionine to the Unique Iron Site of the [4Fe-4S] Cluster of Pyruvate Formate-Lyase Activating Enzyme,
." J. Am. Chem. Soc. 124 11270-11271 (2002)
Walsby C, Ortillo D, Yang J, Nnyepi MR, Broderick WE, Hoffman BM, Broderick JB
, "Spectroscopic Approaches to Elucidating Novel Iron-Sulfur Chemistry in the "Radical SAM" Protein Superfamily
." Inorg. Chem. 44 727-741 (2005)
Personnel:
Joan Broderick
Keywords:
Bioinorganic, Biophysical, Inorganic
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