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Access Type

WSU Access

Date of Award

January 2023

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Pharmaceutical Sciences

First Advisor

Timothy L. Stemmler

Abstract

Iron is an essential metal in biology, requiring strong cellular regulatory mechanisms. In prokaryotes, the Ferric Uptake Regulation (Fur) pathway helps control Iron-Sulfur (Fe-S) cluster biosynthesis. Fe-S clusters are ubiquitous in nature and they are conserved biological cofactors that are found in almost all life forms. There are however multiple pathways that control iron-sulfur cluster biosynthesis, including the Iron-Sulfur Cluster Assembly Pathway, a pathway found in both prokaryotic and eukaryotic organisms. The ISC multiprotein complex that accomplishes Fe-S cluster assembly consists of six proteins, complexed as a dimer of hexomers that includes the scaffold and frataxin proteins, which are the topic of my work, as well as 4 additional proteins. The scaffold is the protein upon which Fe-S clusters are assembled, and the interaction between the scaffold and frataxin is important for Fe-S cluster assembly and cell (and organism) viability, as illustrated in the human diseases Friedreich’s ataxia and ISCU Myopathy. Here we study the role of the bacterial protein YlaN as it relates to the Fur pathway in S. aureus, and we determined that YlaN acts as an iron-binding protein that relieves Fur-repression of gene expression. We study the C-terminus of the scaffold protein as part of the ISC pathway, and we found that the protein’s C-terminus is required for cluster assembly but not for iron-binding. Finally, we studied the effect of Fe and multiprotein complex formation on the biophysical characteristics of Isu1, followed by studying the same biophysical characteristics at a variety of pH levels. Understanding the dynamic characteristics of YlaN and Isu1 helps advance our understanding of the different iron-sulfur cluster biosynthesis pathways.

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