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Three aromatic residues are required for electron transfer during iron mineralization in bacterioferritin

Bradley, JM and Svistunenko, DA and Lawson, TL and Hemmings, AM and Moore, GR and Le Brun, NE (2015) 'Three aromatic residues are required for electron transfer during iron mineralization in bacterioferritin.' Angewandte Chemie - International Edition, 54 (49). 14763 - 14767. ISSN 1433-7851

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Abstract

© 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. 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
Subjects: Q Science > QD Chemistry
Divisions: Faculty of Science and Health > Biological Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 28 Jan 2016 16:49
Last Modified: 23 Jan 2019 01:16
URI: http://repository.essex.ac.uk/id/eprint/15992

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