Dataset Information

Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H₂ O₂ but Slowly with O₂.

ABSTRACT: Both O₂ and H₂ O₂ can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo-EcBfr, pre-loaded anaerobically with Fe²⁺ , was exposed to O₂ or H₂ O₂ . We show that O₂ binds di-Fe²⁺ FC reversibly, two Fe²⁺ ions are oxidized in concert and a H₂ O₂ molecule is formed and released to the solution. This peroxide molecule further oxidizes another di-Fe²⁺ FC, at a rate circa 1000 faster than O₂ , ensuring an overall 1:4 stoichiometry of iron oxidation by O₂ . Initially formed Fe³⁺ can further react with H₂ O₂ (producing protein bound radicals) but relaxes within seconds to an H₂ O₂ -unreactive di-Fe³⁺ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H₂ O₂ rather than sequester iron.

SUBMITTER: Pullin J

PROVIDER: S-EPMC8049013 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H2 O2 but Slowly with O2.

Pullin Jacob J Wilson Michael T MT Clémancey Martin M Blondin Geneviève G Bradley Justin M JM Moore Geoffrey R GR Le Brun Nick E NE Lučić Marina M Worrall Jonathan A R JAR Svistunenko Dimitri A DA

Angewandte Chemie (International ed. in English) 20210401 15

Both O2 and H2 O2 can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo-EcBfr, pre-loaded anaerobically with Fe2+ , was exposed to O2 or H2 O2 . We show that O2 binds di-Fe2+ FC reversibly, two Fe2+</su ...[more]

PMID: 33482043

Similar Datasets

Project description:The structure of recombinant Pseudomonas aeruginosa bacterioferritin B (Pa BfrB) has been determined from crystals grown from protein devoid of core mineral iron (as-isolated) and from protein mineralized with approximately 600 iron atoms (mineralized). Structures were also obtained from crystals grown from mineralized BfrB after they had been soaked in an FeSO(4) solution (Fe soak) and in separate experiments after they had been soaked in an FeSO(4) solution followed by a soak in a crystallization solution (double soak). Although the structures consist of a typical bacterioferritin fold comprised of a nearly spherical 24-mer assembly that binds 12 heme molecules, comparison of microenvironments observed in the distinct structures provided interesting insights. The ferroxidase center in the as-isolated, mineralized, and double-soak structures is empty. The ferroxidase ligands (except His130) are poised to bind iron with minimal conformational changes. The His130 side chain, on the other hand, must rotate toward the ferroxidase center to coordinate iron. In comparison, the structure obtained from crystals soaked in an FeSO(4) solution displays a fully occupied ferroxidase center and iron bound to the internal, Fe((in)), and external, Fe((out)), surfaces of Pa BfrB. The conformation of His130 in this structure is rotated toward the ferroxidase center and coordinates an iron ion. The structures also revealed a pore on the surface of Pa BfrB that likely serves as a port of entry for Fe(2+) to the ferroxidase center. On its opposite end, the pore is capped by the side chain of His130 when it adopts its "gate-closed" conformation that enables coordination to a ferroxidase iron. A change to its "gate-open", noncoordinative conformation creates a path for the translocation of iron from the ferroxidase center to the interior cavity. These structural observations, together with findings obtained from iron incorporation measurements in solution, suggest that the ferroxidase pore is the dominant entry route for the uptake of iron by Pa BfrB. These findings, which are clearly distinct from those made with Escherichia coli Bfr [Crow, A. C., Lawson, T. L., Lewin, A., Moore, G. R., and Le Brun, N. E. (2009) J. Am. Chem. Soc. 131, 6808-6813], indicate that not all bacterioferritins operate in the same manner.

Dataset Information

Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H₂ O₂ but Slowly with O₂.

Publications

Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H<sub>2</sub> O<sub>2</sub> but Slowly with O<sub>2</sub>.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets