B.S. in Biochemistry, University of California, Santa Barbara
Ph.D. in Biochemistry and Molecular Biology, University of California, Riverside (Russ Hille)
Post-Doctoral research associate, University of California-Davis (R. David Britt)
Research in the Wilcoxen lab will examine the structure-function relationship of metalloenzymes using biochemical and biophysical tools. We will explore, on a molecular level, how metalloenzymes generate highly reactive species, direct the reaction coordinate, and prevent unwanted side reactions. Researchers will develop skills in protein expression and purification, air free techniques with biological samples, and spectroscopic techniques such as UV-vis and electron paramagnetic resonance spectroscopy.
Radical SAM Enzymes:
Radical SAM enzymes are a going superfamily of enzymes with over 100k members, making it the largest superfamily of enzymes. Despite the abundance of sequence information little is known of the chemistry these enzymes catalyze. With only ~80 reactions identified, there is much more chemistry to be discovered and reaction mechanisms elucidated. We are particularly interested in radical SAM enzymes with auxiliary domains containing additional co-factors and co-substrates. Our primary goal is to understand how the protein environment guides the reaction path, from generating a primary carbon radical to subsequent substrate radical intermediates and product while preventing unwanted side reactions and dangerous side products.
Molybdenum enzymes are present in all kingdoms of life catalyzing oxygen atom transfers between substrate and water. We are interested in how the protein environment tunes the molybdenum center through direct ligation to the molybdenum or through non-covalent interactions with the organic cofactor that coordinates molybdenum in the protein active site. We approach this project in two ways, the first is to understand the structure and function of the enzymes as present in biology by studying highly purified enzyme. We examine the kinetics and electronic structure to gain insight into the mechanism of the enzyme, utilizing the differences observed in variants of the enzyme to guide out hypotheses. A second approach is to generate tools to study the enzyme that can help guide our understanding of the biological proteins.
Recent Publications (Last 2 years, additional on Lab website)
Tanifuji, K., Jasniewski, A.J., Villarreal, D., Stiebritz, M.T., Lee, C.C., Wilcoxen, J., Okhi, Y., Chatterjee, R., Bogacz, I., Junko Yano, J., Kern, J., Hedman, B., Hodgson, K.O., Britt, R.D., Hu, Y., and Ribbe, M.W. Tracing the incorporation of the “ninth sulfur” into the nitrogenase cofactor precursor with selenite and tellurite Nature Chemistry 2021
Shahid, S., Ali, M., Legaspi-Humiston, D., Wilcoxen, J., and Pacheco, A.A.*. A Kinetic Investigation of the Early Steps in Cytochrome c Nitrite Reductase (ccNiR)-Catalyzed Reduction of Nitrite. Biochemistry 2021 60, 2098-2115
Rettenberg, L.A., Wilcoxen, J., Jasniewski, A.J., Lee, C.C., Tanifuji, K., Hu, Y., Britt, R.D., and Ribbe, M. Identity and function of an essential nitrogen ligand of the nitrogenase cofactor biosynthesis protein NifB. Nature Communications 2020 11, Article number: 1757
Amtawong, J., Balcells, D., Wilcoxen, J., Handford, R.C., Biggins, N., Nguyen, A.I., Britt, R.D., Tilley, T.D. Isolation and Study of Ruthenium–Cobalt Oxo Cubanes Bearing a High-Valent, Terminal RuV–Oxo with Significant Oxyl Radical Character. J. Am. Chem. Soc. 2019 141, 19859-19869
Jasniewski, A.J., Wilcoxen, J., Tanifuji, K., Hedman, B., Hodgson, K.O., Britt, R.D., Hu, Y., Ribbe M.W. Spectroscopic Characterization of an Eight‐Iron Nitrogenase Cofactor Precursor That Lacks the “9th Sulfur”. Angew. Chem. 2019
Hu, S., Offenbacher, A., Thompson, E., Gee, C., Wilcoxen, J., Carr, C., Prigozhin, D., Yang, V., Alber, T., Britt, R.D., Fraser, J., Klinman, J.
Biophysical Characterization of a Disabled Double Mutant of Soybean Lipoxygenase: The “Undoing” of Precise Substrate Positioning Relative to Metal Cofactor and an Identified Dynamical Network J. Am. Chem. Soc. 2019, 141, 1555-1567