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


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-Fe(3+) site of Escherichia coli bacterioferritin (EcBFR) is stable and therefore does not function as a conduit for the transfer of Fe(3+) into the storage cavity, but instead acts as a true catalytic cofactor that cycles its oxidation state while driving Fe(2+) 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 Fe(2+) oxidation in the BFR cavity, to the di-ferric catalytic site for safe reduction of O2.

SUBMITTER: Bradley JM 

PROVIDER: S-EPMC4691338 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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

Bradley Justin M JM   Svistunenko Dimitri A DA   Lawson Tamara L TL   Hemmings Andrew M AM   Moore Geoffrey R GR   Le Brun Nick E NE  

Angewandte Chemie (International ed. in English) 20151016 49


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-Fe(3+) site of Escherichia coli bacterioferritin (EcBFR) is stable and therefore does not function as a conduit for the transfer of Fe(3+) into the storage cavity, but instead acts as a true catalytic cofactor that cycles its oxidation state while dr  ...[more]

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