title: Phosphate accelerates displacement of Fe(III) by Fe(II) in the ferroxidase center of Pyrococcus furiosus ferritin.
abstract: The iron-storage protein, ferritin, is widely found in all Domains of life. A conserved diiron center in ferritin catalyzes oxidation of Fe(II) and regulates storage of the resultant Fe(III) oxidation product. When this center is filled with Fe(III), in bacterial or archaeal ferritin the presence of phosphate accelerates the rate of Fe(II) oxidation. The molecular mechanism underlying this stimulatory effect of phosphate is unknown. Using site directed mutagenesis of the residues in the diiron center of the archaeal ferritin from Pyrococcus furiosus we show that phosphate facilitates displacement of Fe(III) by Fe(II) from this site. Therefore, the rate of Fe(II) oxidation increases only when the ferroxidase center is filled with Fe(III).
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628BC Delft, The Netherlands.
authors.forename: Kourosh
authors.initials: K
authors.lastname: Honarmand Ebrahimi
authors.forename: Peter-Leon
authors.initials: PL
authors.lastname: Hagedoorn
authors.forename: Wilfred R
authors.initials: WR
authors.lastname: Hagen
mesh_terms: D019943:Amino Acid Substitution; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002570:Ceruloplasmin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D005293:Ferritins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010084:Oxidation-Reduction; D010710:Phosphates / Q000378:metabolism; D020027:Pyrococcus furiosus / Q000235:genetics / Q000378:metabolism*
chemical_list: D019843:Archaeal Proteins; D010710:Phosphates; D005293:Ferritins; D007501:Iron; D002570:Ceruloplasmin