Iron is essential for life and growth in most organisms. Although it is abundant, iron exists mostly as insoluble iron-oxyhydroxide. Bacteria secrete siderophores to chelate iron and transport it into the cell via specific outer membrane receptors. The FhuA receptor protein transports ferrichrome, a siderophore produced by Ustilago sphaerogena. We determined the binding affinity of variants from the conserved 'lock region' of FhuA and also created and characterized variants of the highly conserved R452 to determine its role in ferrichrome transport. We hypothesize that during transport the plug domain of FhuA does not leave the barrel; rather it undergoes a conformational change to form a channel. We mutated selected amino acids to cysteine to form disulfide bonds to tether the plug, preventing its displacement or unfolding during transport. The tetra-cysteine mutant 72/615/109/356C was able to bind and transport radiolabeled ferrichrome. One double-cysteine mutant, 104/149C, was purified for crystallization.
","abstract_html":"<p>Iron is essential for life and growth in most organisms. Although it is abundant, iron exists mostly as insoluble iron-oxyhydroxide. Bacteria secrete siderophores to chelate iron and transport it into the cell via specific outer membrane receptors. The FhuA receptor protein transports ferrichrome, a siderophore produced by <em>Ustilago sphaerogena</em>. We determined the binding affinity of variants from the conserved 'lock region' of FhuA and also created and characterized variants of the highly conserved R452 to determine its role in ferrichrome transport. We hypothesize that during transport the plug domain of FhuA does not leave the barrel; rather it undergoes a conformational change to form a channel. We mutated selected amino acids to cysteine to form disulfide bonds to tether the plug, preventing its displacement or unfolding during transport. The tetra-cysteine mutant 72/615/109/356C was able to bind and transport radiolabeled ferrichrome. One double-cysteine mutant, 104/149C, was purified for crystallization.</p>","abstract_has_math":false,"creators":["Cooke, Jennifer K."],"institution":null,"degree_name":"MS (Master of Science)","degree_level":"Thesis - unrestricted","degree_discipline":"Biology","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2009,"date_issued":"2009-05-09T07:00:00Z","date_published":"2009-05-09T07:00:00Z","updated_at":"2026-07-24T02:20:55Z","subjects":["iron transport","siderophore","FhuA","Bacteriology","Life Sciences","Microbiology"],"languages":[],"rights":["Copyright by the authors."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://dc.etsu.edu/etd/1792","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Cooke, Jennifer K."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.issued","label":"Date","values":["2009-05-09T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis - unrestricted"]},{"key":"thesis:degree_name","label":"Degree Name","values":["MS (Master of Science)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["iron transport","siderophore","FhuA","Bacteriology","Life Sciences","Microbiology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["Copyright by the authors."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://dc.etsu.edu/context/etd/article/3144/viewcontent/CookeJ042209f.pdf","https://dc.etsu.edu/etd/1792"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Iron is essential for life and growth in most organisms. Although it is abundant, iron exists mostly as insoluble iron-oxyhydroxide. Bacteria secrete siderophores to chelate iron and transport it into the cell via specific outer membrane receptors. The FhuA receptor protein transports ferrichrome, a siderophore produced by Ustilago sphaerogena. We determined the binding affinity of variants from the conserved 'lock region' of FhuA and also created and characterized variants of the highly conserved R452 to determine its role in ferrichrome transport. We hypothesize that during transport the plug domain of FhuA does not leave the barrel; rather it undergoes a conformational change to form a channel. We mutated selected amino acids to cysteine to form disulfide bonds to tether the plug, preventing its displacement or unfolding during transport. The tetra-cysteine mutant 72/615/109/356C was able to bind and transport radiolabeled ferrichrome. One double-cysteine mutant, 104/149C, was purified for crystallization.
"]},{"key":"dc:title","label":"Title","values":["Molecular Mechanism of Ferricsiderophore Transport via the Outer Membrane Receptor FhuA in Escherichia coli."]}]}],"canonical_facts":{"dc:creator":["Cooke, Jennifer K."],"dc:date.issued":["2009-05-09T07:00:00Z"],"dc:description.abstract":["Iron is essential for life and growth in most organisms. Although it is abundant, iron exists mostly as insoluble iron-oxyhydroxide. Bacteria secrete siderophores to chelate iron and transport it into the cell via specific outer membrane receptors. The FhuA receptor protein transports ferrichrome, a siderophore produced by Ustilago sphaerogena. We determined the binding affinity of variants from the conserved 'lock region' of FhuA and also created and characterized variants of the highly conserved R452 to determine its role in ferrichrome transport. We hypothesize that during transport the plug domain of FhuA does not leave the barrel; rather it undergoes a conformational change to form a channel. We mutated selected amino acids to cysteine to form disulfide bonds to tether the plug, preventing its displacement or unfolding during transport. The tetra-cysteine mutant 72/615/109/356C was able to bind and transport radiolabeled ferrichrome. One double-cysteine mutant, 104/149C, was purified for crystallization.
"],"dc:identifier":["https://dc.etsu.edu/context/etd/article/3144/viewcontent/CookeJ042209f.pdf","https://dc.etsu.edu/etd/1792"],"dc:rights":["Copyright by the authors."],"dc:subject":["iron transport","siderophore","FhuA","Bacteriology","Life Sciences","Microbiology"],"dc:title":["Molecular Mechanism of Ferricsiderophore Transport via the Outer Membrane Receptor FhuA in Escherichia coli."],"thesis:degree_discipline":["Biology"],"thesis:degree_level":["Thesis - unrestricted"],"thesis:degree_name":["MS (Master of Science)"]},"updated_at":"2026-07-24T02:20:55Z"}