Date of Award
8-16-2024
Document Type
Open Access Dissertation
Department
Chemistry and Biochemistry
First Advisor
F. Wayne Outten
Abstract
Iron-sulfur (Fe-S) clusters are important cofactors with a primary role of electron transport that are required by proteins involved in wide range of biological pathways such as respiration, photosynthesis, and DNA repair. In Escherichia coli (E. coli), the assembly and transfer of these clusters to their target apo-protein is a highly coordinated process encoded by the multiprotein systems iscRSUAhscBAfdx and sufABCDSE operons. These clusters are assembled on a scaffold protein, where they are then transferred to a carrier protein that will deliver the cluster to the target apo-protein. The Isc and Suf systems contain their own carrier proteins IscA and SufA, respectively. There are a number of accessory proteins that have been demonstrated to accept a cluster and transfer it to downstream targets, such as ErpA, NfuA, and GrxD.
The E. coli monothiol glutaredoxin, GrxD, contains a CGFS active site that uses a conserved cysteine (C30) residue and the small molecule glutathione (GSH) per monomer to coordinate an Fe-S cluster as a homodimer. There has been work characterizing homologues of GrxD which can be found in the cytosol, mitochondria, and chloroplast of eukaryotes. In contrast, there has not been careful in vivo characterization of the E. coli GrxD as deletion has no apparent growth defect in rich media. However, it does have sensitivity to iron depletion GrxD, highlighting a critical role for GrxD under conditions that disrupt Fe-S homeostasis. In this work, we utilized a multidisciplinary approach encompassing genetic techniques accompanied by a chemoproteomic mass spectrometry analysis of the Fe-S proteome to understand the role of GrxD under iron limitation. Our results show that GrxD is functionally distinct from other Fe-S trafficking proteins, is required for Fe-S cluster delivery to ErpA under iron limitation, and the loss of GrxD disrupts overall iron homeostasis in the cell.
Rights
© 2024, Claire Elizabeth Fisher
Recommended Citation
Fisher, C. E.(2024). Characterizing the Role of the Escherchia Coli Monothiol Glutaredoxin, GRXD, as an Iron-sulfur Cluster Carrier Protein. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/7867