title: Direct observation of the iron binding sites in a ferritin.
abstract: X-Ray analysis of the ferritin of Escherichia coli (Ec-FTN) and of Ec-FTN crystals soaked in (NH4)2Fe(SO4)2 has revealed the presence of three iron-binding sites per subunit. Two of these form a di-iron site in the centre of the subunit as has been proposed for the 'ferroxidase centres' of human ferritin H chains. This di-iron site, lying within the 4-alpha-helix bundle, resemble those of ribonucleotide reductase, methane monoxygenase and haemerythrin. The third iron is bound by ligands unique to Ec-FTN on the inner surface of the protein shell. It is speculated that this state may represent the nucleation centre of a novel type of Fe(III) cluster, recently observed in Ec-FTN.
authors.affiliation: Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, UK.
authors.forename: P D
authors.initials: PD
authors.lastname: Hempstead
authors.forename: A J
authors.initials: AJ
authors.lastname: Hudson
authors.forename: P J
authors.initials: PJ
authors.lastname: Artymiuk
authors.forename: S C
authors.initials: SC
authors.lastname: Andrews
authors.forename: M J
authors.initials: MJ
authors.lastname: Banfield
authors.forename: J R
authors.initials: JR
authors.lastname: Guest
authors.forename: P M
authors.initials: PM
authors.lastname: Harrison
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004926:Escherichia coli; D005293:Ferritins / Q000378:metabolism / Q000648:ultrastructure*; D007501:Iron / Q000378:metabolism*; D008958:Models, Molecular; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D005293:Ferritins; D007501:Iron