Kinetic and structural characterization of an intermediate in the biomineralization of bacterioferritin

Abstract

The mechanism by which iron‐storage proteins take up and oxidise iron(II) is not understood. We show by rapid‐kinetic and EPR measurements that iron uptake, in vitro, by a bacterial iron‐storage protein, bacterioferritin, involves at least three kinetically distinguishable phases: phase 1, the binding of Fe(II) ions, probably at a dimeric iron ferroxidase centre; phase 2, oxidation of the Fe(II) dimer and production of mononuclear Fe(III); and phase 3, iron core formation.

Direct observation of the iron binding sites in a ferritin

“…It is conceivable that only one Fe atom is released from the ferroxidase site to move into the cavity for iron-core formation and that the other Fe atom remains. Such a possibility has been envisaged for EC-BFR [15].…”

Iron Detoxification Properties of Escherichia coliBacterioferritin

“…Previous studies of iron uptake by EcBFR using O 2 as oxidant have shown that Fe(II) binding at the dinuclear centers of the protein followed by its rapid oxidation and core formation occur in three distinct phases (6,19). We describe the stoichiometric equations and the kinetics of iron oxidation and hydrolysis in EcBFR using H 2 O 2 as the oxidant.…”

A Bacterial Iron Exporter for Maintenance of Iron Homeostasis

“…Protein added to the buffer was calibrated as blank. Iron oxidation stoichiometry was calculated as described previously (22).…”

“…The (22). We overexpressed in E. coli the portion of the mbfA gene encoding the FLD and purified the peptide (Fig.…”