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Three Aromatic Residues are Required for Electron Transfer during Iron Mineralization in Bacterioferritin

DOI: 10.1002/anie.201507486 DOI Help
PMID: 26474305 PMID Help

Authors: Justin M. Bradley (University of East Anglia) , Dimitri A. Svistunenko (University of Essex) , Tamara L. Lawson (University of East Anglia) , Andrew M Hemmings (University of East Anglia) , Geoffrey R. Moore (University of East Anglia) , Nick Le Brun (University of East Anglia)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Angewandte Chemie International Edition

State: Published (Approved)
Published: October 2015
Diamond Proposal Number(s): 9475

Open Access Open Access

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.

Journal Keywords: Bioinorganic Chemistry;Ferritin;Iron;Mineralization;Tyrosyl Radicals

Subject Areas: Biology and Bio-materials


Instruments: I03-Macromolecular Crystallography , I04-1-Macromolecular Crystallography (fixed wavelength) , I04-Macromolecular Crystallography

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