Off-campus WSU users: To download campus access dissertations, please use the following link to log into our proxy server with your WSU access ID and password, then click the "Off-campus Download" button below.
Non-WSU users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Access Type
WSU Access
Date of Award
January 2025
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Pharmaceutical Sciences
First Advisor
Timothy L. Stemmler
Abstract
Metals play an indispensable role in biology. In eukaryotes, disruption of metal homeostasis, either by genetics leading to metal overload or exposure to toxic heavy metals, has fatal health outcomes. Metal chelation therapy is the primary treatment for these disorders to facilitate elimination of excess or toxic metals. However, many of these chelators are met with limited efficacy due to their poor selectivity between the target metal and essential physiological metals. This is compounded by their tight binding affinities, resulting in disruption of metal homeostasis and essential cellular functions. A major focus of this work is characterizing the novel iron chelator, ATH434, previously shown to have promising results reducing iron overload within in vivo animal models and in clinical trials.
Here, our biophysical studies of ATH434 indicate the compound coordinates Fe2+ using oxygen and nitrogen ligands in a 1:1 stoichiometric ratio through partial coordination with water. Additionally, ATH434’s sub micromolar affinity for Fe2+ and Fe3+ poises ATH434 to sequester excess Fe2+ with affinity values and a coordination architecture that mimics endogenous iron chaperones. Further analyses of ATH434 indicate that, in addition to its therapeutic potential, the drug also behaves as a metal responsive fluorophore capable of detecting in vitro transition metal binding. Here we show ATH434 also binds other transition metals (Co2+, Ni2+, Cu2+, Zn2+, and Cd2+) with low micromolar affinity. Our studies demonstrate ATH434 is a tool compound compatible with high-throughput screening and we demonstrate the application of ATH434 in identifying a novel Cd specific peptide, HSQKVF. Metals also play an essential role in other biological processes, including prokaryotic metabolism and survival, as well as environmental applications where they can serve as catalysts for sustainable energy solutions. To investigate the role of metals in prokaryotic systems, we’ve expanded our evaluation of metals in biology to characterize the role of the bacterial protein Fpa within the mammalian pathogen Staphylococcus aureus. Using X-ray absorption spectroscopy and metal binding assays, we demonstrate Fpa is an iron binding protein consistent with its physiological role in Fe homeostasis. Finally, we’ve further broadened our focus to demonstrate the function of Ni as a catalyst within a de novo metalloprotein that can act as an alternative energy source by facilitating Ni mediated photocatalytic H2 evolution, as a clean and sustainable fuel source. Our studies indicate the peptide oligomer, 4SCC, exhibits photocatalytic activity in the Ni2+ bound form and we identify the catalytic metal binding site composed of four sulfur ligands via X-ray absorption spectroscopy. Overall, this work highlights the versatility of metals in biological systems and emphasizes the importance of continued investigation to identify the function of metals in fundamental biological processes and disease.
Recommended Citation
Pall, Ashley, "Evaluation Of Metal Homeostasis In Select Biological Systems" (2025). Wayne State University Dissertations. 4212.
https://digitalcommons.wayne.edu/oa_dissertations/4212