Witten 2025 Colloquium Guest Speaker – Joan B. Broderick

Start dateNovember 13, 2025 12:30 pm

End dateNovember 13, 2025 1:45 pm

Radical SAM Enzymes: Nature’s Choice for Radical Reactions

Joan B. Broderick
Montana State University

Bio

Joan Broderick is Professor and Head of the Department of Chemistry and Biochemistry at Montana State University. She is a bio-inorganic chemist who studies how iron-sulfur clusters and S-adenosylmethionine are used by nature to initiate radical reactions essential to life. Other research interests include the biological assembly of complex metal clusters, and the trafficking, storage, and utilization of iron and sulfur in biology. Broderick holds a B.S. in Chemistry from Washington State University, and a Ph.D. in Inorganic Chemistry from Northwestern University, where she was an NSF graduate fellow in the lab of Tom O’Halloran and studied mechanistic aspects of the non-heme iron enzyme chlorocatechol dioxygenase. She was an American Cancer Society Postdoctoral Fellow with JoAnne Stubbe at MIT where she focused on mechanism of the coenzyme B12-dependent ribonucleotide reductase. Broderick held faculty positions at Amherst College and Michigan State University before moving to Montana State University in 2005. Her awards include the American Chemical Society Bader Award in Bioinorganic or Bioorganic Chemistry, the Saltman Award of the Metals in Biology Gordon Conference, the MSU Women in Science Distinguished Professorship, the MSU Presidential Medallion, the Illinois Distinguished Lectureship in Inorganic Chemistry, and the Calvin Lectureship at UC-Berkeley. She served on the Department of Energy Basic Energy Sciences Advisory Committee and the ASBMB Council, and she is an Associate Editor of JBC. She is a Fellow of the AAAS and a member of the National Academy of Sciences and the American Academy of Arts & Sciences.

Abstract

Radical S-adenosyl-l-methionine (SAM) enzymes catalyze diverse and challenging reactions across all life’s kingdoms. These reactions are initiated by transfer of an electron from a site-differentiated [4Fe-4S]+ cluster to a coordinated SAM, leading to homolytic cleavage of the S-C5′ bond of SAM. We have used time-resolved freeze-quench trapping coupled to EPR and ENDOR spectroscopy to demonstrate the progression of radical SAM reactions through sequential radical intermediates, and provided important clues to how Nature uses inorganic chemistry to harness, with exquisite regioselective and stereoselective control, the highly reactive 5′-deoxyadenosyl primary carbon radical for initiation of radical-based chemical transformations essential to life.

Witten 2025 Colloquium Guest Speaker – Joan B. Broderick

Radical SAM Enzymes: Nature’s Choice for Radical Reactions

Joan B. Broderick Montana State University

Joan B. Broderick
Montana State University