Joan B. Broderick, Associate Director of Outreach and Education for the ABRC

Research Interests

Research in the Broderick group is focused on mechanistic enzymology of bioinorganic systems.  We are particularly interested in enzymes that utilize iron-sulfur clusters and S-adenosylmethionine (AdoMet or SAM) to initiate radical-mediated reactions; such enzymes are part of the radical-AdoMet superfamily, and may represent one of the most ancient and widespread biological means to carry out radical-based chemistry. 

A characteristic feature of the radical-AdoMet enzymes is the presence of a site-differentiated [4Fe-4S] cluster in the enzyme; this site-differentiated cluster is essential to catalysis, as the unique iron coordinates AdoMet, poising it for reductive cleavage to generate the adenosyl radical intermediate common to all radical-AdoMet enzymatic reactions.  The deoxyadenosyl radical then proceeds to react with substrate to initiate a radical-based transformation.  Examples of substrates for radical-AdoMet enzymes include a glycyl residue in pyruvate formate lyase, which is converted to a stable catalytically-essential radical, an octanoyl substituent on a protein, which then undergoes sulfur insertions to generate a lipoyl cofactor, and dethiobiotin, which also undergoes radical-mediated sulfur insertion reactions to produce biotin.  Two radical-AdoMet enzymes, as well as a GTPase, are essential to the biosynthesis of the H-cluster of hydrogenase, and we are collaborating with John Peters to elucidate the substrates involved and the specific reactions catalyzed.  This work will provide fundamental insights into the role of ligand modifications in tuning the chemistry of iron-sulfur clusters, and into the roles of these ancient radical-AdoMet enzymes in facilitating catalytic redox chemistry of hydrogen.

Our approaches to studying the fascinating radical-AdoMet enzymes are varied and involve numerous collaborators.  We use biochemical, spectroscopic, and structural approaches to addressing key questions regarding structural and electronic requirements for catalysis, structures of reaction intermediates, and detailed chemical mechanisms.

Selected Publications

J.L. Vey, J. Yang, M. Li, W.E. Broderick, J.B. Broderick, and C.L. Drennan “Structural basis for glycyl radical formation by pyruvate formate-lyase activating enzyme” Proc. Natl. Acad. Sci. U.S.A. 105, 16137-16141. (2008)

S.E. McGlynn, E.M. Shepard, M.A. Winslow, AV. Naumov, K.S. Duschene, M.C. Posewitz, W.E. Broderick, J.B. Broderick, and J.W. Peters “HydF as a Scaffold in [FeFe] Hydrogenase H-Cluster Biosynthesis” FEBS Letters 582, 2183-2187. (2008)

M.R. Nnyepi, Y. Peng, and J.B. Broderick “On the Activation and Inactivation of Pyruvate Formate-Lyase” Arch. Bioch. Biophys. 459, 1-9 (2007)

S. McGlynn, S.S. Ruebush, A.V. Naumov, L.E. Nagy, A. Dubini, P.W. King, J.B. Broderick, M.C. Posewitz, and J.W. Peters. In vitro activation fo [FeFe] hydrogenase: New insights into hydrogenase maturation. JBIC 12(4) 443-447. (2007)

J.M. Buis, J. Cheek, E. Kalliri,and J.B. Broderick “Characterization of an Active Spore Photoproduct Lyase, an Enzyme in the Radical SAM Superfamily,” J. Biol. Chem. 381, 25994-26003 (2006)

C. Walsby, D. Ortillo, J. Yang, M.R. Nnyepi, W.E. Broderick, B.M. Hoffman, and J.B. Broderick “Spectroscopic Approaches to Elucidating Novel Iron-Sulfur Chemistry in the “Radical SAM” Protein Superfamily” Inorg. Chem. 44, 727-741 (2005)

J.M. Buis and J.B. Broderick. “Pyruvate Formate-Lyase Activating Enzyme: Elucidation of a Novel Mechanism for Glycyl Radical Formation,” Arch. Bioch. Biophys. 433, 288-296. (2005)

Lab Personnel

Eric Shepard
Post-doctoral Associate
eshepard@montana.edu

Alexandra Bueling
Graduate Student
abueling@montana.edu

Sunshine Silver
Graduate Student;
ssilver@chemistry.montana.edu

Rachel Hutcheson
Graduate Student
rudelhoven@chemistry.montana.edu

Kaitlin Duschene
Research Associate
kduschene@chemistry.montana.edu

Collaborators

Brian M. Hoffman (Electron-Nuclear Double Resonance, EPR)
Department of Chemistry
Northwestern University

Boi Hanh (Vincent) Huynh (Mössbauer Spectroscopy)
Department of Physics
Emory University

Catherine L. Drennan (X-ray crystallography)
Department of Chemistry
MIT

Edward I. Solomon (X-Ray absorption spectroscopy and computations)
Department of Chemistry
Stanford University

J. Timothy Sage (NRVS Spectroscopy)
Department of Physics
Northeastern University

MORE>

Return to regular view	Text-only	Updated: 12/4/08