Bradley, Justin M and Svistunenko, Dimitri A and Lawson, Tamara L and Hemmings, Andrew M and Moore, Geoffrey R and Le Brun, Nick E (2015) 'Three Aromatic Residues are Required for Electron Transfer during Iron Mineralization in Bacterioferritin.' Angewandte Chemie International Edition, 54 (49). pp. 14763-14767. ISSN 1433-7851
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Abstract
Ferritins are iron storage proteins that overcome the problems of toxicity and poor bioavailability of iron by catalyzing iron oxidation and mineralization through the activity of a diiron ferroxidase site. Unlike in other ferritins, the oxidized di-Fe3+ site of Escherichia coli bacterioferritin (EcBFR) is stable and therefore does not function as a conduit for the transfer of Fe3+ into the storage cavity, but instead acts as a true catalytic cofactor that cycles its oxidation state while driving Fe2+ oxidation in the cavity. Herein, we demonstrate that EcBFR mineralization depends on three aromatic residues near the diiron site, Tyr25, Tyr58, and Trp133, and that a transient radical is formed on Tyr25. The data indicate that the aromatic residues, together with a previously identified inner surface iron site, promote mineralization by ensuring the simultaneous delivery of two electrons, derived from Fe2+ oxidation in the BFR cavity, to the di-ferric catalytic site for safe reduction of O2. A radical view of bacterioferritin: Three aromatic residues located close to the catalytic ferroxidase site are shown to be important for iron mineralization. A transient radical is associated with Tyr25, consistent with a mechanism where electrons from Fe2+ oxidation are transferred to the oxidized, di-Fe3+ ferroxidase site, ensuring that two electrons arrive at the site simultaneously and avoid formation of toxic reactive oxygen species.
Item Type: | Article |
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Uncontrolled Keywords: | bioinorganic chemistry; ferritin; iron; mineralization; tyrosyl radicals |
Subjects: | Q Science > QD Chemistry |
Divisions: | Faculty of Science and Health Faculty of Science and Health > Life Sciences, School of |
SWORD Depositor: | Elements |
Depositing User: | Elements |
Date Deposited: | 28 Jan 2016 16:49 |
Last Modified: | 15 Jan 2022 00:33 |
URI: | http://repository.essex.ac.uk/id/eprint/15992 |
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