Characterization of Bacterial Ferrous Iron Transport: the Feo System

Date
2013-01-11
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Abstract
The Feo system is the main ferrous iron uptake pathway for the majority of prokaryotic organisms. The feo operon consists of two proteins, ferrous iron transport proteins A (FeoA) and B (FeoB). Many studies in relation to the system’s role in bacterial virulence and the crystal structures of the N-terminal domain of FeoB (NFeoB) have been reported, however, none have explored the solution characteristics associated with FeoA and FeoB. This dissertation presents the solution structure of Escherichia coli FeoA along with the backbone amide dynamics of this protein. Further, NMR dynamic studies of E. coli NFeoB, along with interaction studies between FeoA and NFeoB are presented. Lastly, a detailed bioinformatics analysis of this system is presented to bring together our findings and new hypotheses are suggested. Our studies provide insight to the function of FeoA from a structural perspective and its potential role in interacting with FeoB, a co-regulated gene. The solution structure of FeoA shows a resemblance to eukaryotic SH3 protein-protein interaction domains. The addition of an α-helix in FeoA for one of the conserved interaction loops in eukaryotic SH3-domains results in a greater resemblance towards SH3-like domains present in prokaryotic metalloregulators, that are involved in transcriptional regulation. Backbone dynamics on the fast NMR timescale of FeoA indicate a rigid monomeric structure. The backbone dynamics of the apo and guanine nucleotide forms of NFeoB on the fast NMR timescale suggest communication between the N-terminal cytoplasmic domains of FeoB and the transmembrane domain of FeoB. Backbone dynamics on the slow NMR timescale indicate that global conformational changes associated with guanine-nucleotide binding may be important for the association of NFeoB with the transmembrane domain. Interaction studies between FeoA and NFeoB indicate a transient interaction under the conditions tested. Furthermore, 31P NMR studies with FeoA and NFeoB suggests that FeoA does not act as an activator of the G-domain of FeoB as previously suggested. Bioinformatics analyses of the Feo system provide different perspectives towards the roles of FeoA and FeoB; along with the unique conservation of certain domains in FeoB that are important to its function.
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Keywords
Biology--Molecular, Biochemistry
Citation
Lau, C. K. (2013). Characterization of Bacterial Ferrous Iron Transport: the Feo System (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25270