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

Justin M. Bradley, Dimitri A. Svistunenko, Tamara L. Lawson, Andrew M. Hemmings, Geoffrey R. Moore, Nick E. Le Brun (Lead Author)

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Ferritins are iron storage proteins that overcome problems of toxicity and poor bioavailability of iron by catalysing 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. Here we demonstrate that EcBFR mineralization depends on three near-diiron site aromatic residues, 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.
Original languageEnglish
Pages (from-to)14976–14980
Number of pages5
JournalAngewandte Chemie-International Edition
Issue number49
Early online date16 Oct 2015
Publication statusPublished - 1 Dec 2015


  • Bioanorganische Chemie
  • Eisen
  • Ferritin
  • Mineralisierung
  • Tyrosylradikale

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