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Elucidating the role of metal-protein and metal-peptide interactions in microbial cellular stress

Ph.D. Defense- Outlaw, Taylor
Friday, June 14, 2024
11:00 am - 12:00 pm
Taylor Outlaw, Ph.D. Candidate

Taylor Outlaw, Ph.D. Candidate

Katherine Franz Ph.D., Advisor

Abstract: Metals play a vital role in living organisms by regulating many essential life processes. Metal homeostasis is essential for a healthy cell, as metal overload and metal starvation can largely affect how biomolecules interact with one another. For this reason, cells from all kingdoms of life have evolved mechanisms to control metal content including metal importers and exporters, metal storage proteins, metallochaperones, and metal-induced transcription factors.
This dissertation will focus on the role of zinc and copper in specific biological systems.
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a highly conserved enzyme, most famous for its role in glycolysis. Previous work by the Franz and Fitzgerald labs showed that copper-induced structural stability of GAPDH from E. coli (ecGAPDH) alongside Cu2+-induced ecGAPDH inhibition in lysates. Building upon these findings, my dissertation work characterized the effects of copper on recombinant ecGAPDH through activity assays, circular dichroism, ICP-MS, and copper-binding experiments. Both Cu2+ and Cu+ can inhibit the activity of ecGAPDH, though inhibition occurs via distinct mechanisms. In the presence of excess metal, ecGAPDH is capable of binding multiple equivalents of copper, without changes to global secondary structure. This leads us to question the role that ecGAPDH, and other homologs, could play in intracellular copper trafficking. Next, I present progress towards the antifungal mechanism of histatin-5, a salivary natural product with metal-dependent activity. The relationship between histatin-5, copper, zinc, and Candida albicans has proven to be complex and is susceptible to changes in temperature and extracellular environment. This nuanced relationship is likely a part of the more complex oral microbiome, which can use metals and metal chelating proteins as an innate immune response. Finally, I present my chemical education research project, sponsored by the Bonk Fellowship, that analyzed second-semester organic chemistry students' problem-solving strategies, specifically focusing on the resources activated while ranking the acidity of various organic molecules and solving problems on E2, E1, and E1cB elimination reactions.