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

DOI: 10.1002/ange.201507486 DOI 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 E. Leā€…Brun (University of East Anglia)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Angewandte Chemie , VOL 127 , PAGES 14976 - 14980

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

Abstract: Ferritins are iron storage proteins that overcome theproblems of toxicity and poor bioavailability of iron bycatalyzing iron oxidation and mineralization through theactivity of adiiron ferroxidase site.Unlike in other ferritins,the oxidized di-Fe3+site of Escherichia coli bacterioferritin(EcBFR) is stable and therefore does not function as aconduitfor the transfer of Fe3+into the storage cavity,but instead actsas atrue catalytic cofactor that cycles its oxidation state whiledriving Fe2+oxidation in the cavity.Herein, we demonstratethat EcBFR mineralization depends on three aromatic residuesnear the diiron site,Tyr25, Tyr58, and Trp133, and thatatransient radical is formed on Tyr25. The data indicate thatthe aromatic residues,together with apreviously identifiedinner surface iron site,promote mineralization by ensuring thesimultaneous delivery of two electrons,derived from Fe2+oxidation in the BFR cavity,tothe di-ferric catalytic site forsafe 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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