Collaborative Research: RUI: Interrogating Catalytic Efficiency through Kinetic, Structural and Small-Molecule Guided Investigation of L-DOPA 2,3-Dioxygenases.

Rhodes College, Memphis TN

Investigators

Abstract

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Drs. Keri Colabroy at Muhlenberg College and Larryn Peterson of Rhodes College, in collaboration with Dr. Katherine Hicks from the State University of New York at Cortland to study how extradiol dioxygenase enzymes use oxygen to chemically rearrange catecholic carbon (a primary component of lignin in woody plants) into useful materials, such as natural products. Under the direction of the faculty mentors, undergraduate research students will systematically change the size and electronic properties of these plant-based carbon sources, mutate the enzymes’ structures and study the effect of these changes on the effectiveness of the molecular conversions. These students will experience the interdisciplinary nature of the project through cross-over training at each of the participating laboratories. In addition, parts of the project will be integrated into coursework at each of the home institutions to broaden the reach of original research and help develop the skills that all undergraduate students need to succeed in STEM courses, graduate training and STEM careers. Expanding the ability to not only predict catalytic efficiency for enzyme-substrate pairs, but also purposefully engineer extradiol dioxygenase enzymes like L-DOPA 2,3-dioxygenase to be more effective on non-native substrates is necessary to utilize the powerful chemical capacity of extradiol dioxygenase enzymes to refashion naturally abundant catecholic carbon into useful materials. L-DOPA 2,3-dioxygenase exhibits enormous catalytic potential, but the prevailing understanding of “substrate oxidizability” as a guiding principle behind extradiol dioxygenase reactivity has proven inadequate. Over the course of this project, a “toolkit” of novel catechols are synthesized to vary substrate size alongside redox potential over a sufficiently large suite of substrates to be able to visualize the impacts of each variable independently and interdependently. The toolkit is then used in structural study of active site volume and in pre-steady state and equilibrium measurements of rate to measure and ultimately tune catalytic efficiency across evolutionarily diverse L-DOPA 2,3-dioxygenase homologs and their mutants. The project is conducted entirely through the efforts of undergraduate students under the direct mentorship of the coPIs and collaborator. Participating undergraduate students also crossover between the home institutions to experience the project from different perspectives, and part of the project is integrated into undergraduate coursework at each of the home institutions to reach more undergraduates with the high impact learning that comes with original research. These experiences are powerfully effective at developing the skills undergraduate students need to succeed in STEM courses, graduate training and in STEM careers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.