title: The B-type channel is a major route for iron entry into the ferroxidase center and central cavity of bacterioferritin.
abstract: Bacterioferritin is a bacterial iron storage and detoxification protein that is capable of forming a ferric oxyhydroxide mineral core within its central cavity. To do this, iron must traverse the bacterioferritin protein shell, which is expected to occur through one or more of the channels through the shell identified by structural studies. The size and negative electrostatic potential of the 24 B-type channels suggest that they could provide a route for iron into bacterioferritin. Residues at the B-type channel (Asn-34, Glu-66, Asp-132, and Asp-139) of E. coli bacterioferritin were substituted to determine if they are important for iron core formation. A significant decrease in the rates of initial oxidation of Fe(II) at the ferroxidase center and subsequent iron mineralization was observed for the D132F variant. The crystal structure of this variant shows that substitution of residue 132 with phenylalanine caused a steric blockage of the B-type channel and no other material structural perturbation. We conclude that the B-type channel is a major route for iron entry into both the ferroxidase center and the iron storage cavity of bacterioferritin.
authors.affiliation: From the Department of Biochemistry and Molecular Biology, the Centre for Blood Research and.
authors.forename: Steve G
authors.initials: SG
authors.lastname: Wong
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Grigg
authors.affiliation: Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom.
authors.forename: Nick E
authors.initials: NE
authors.lastname: Le Brun
authors.affiliation: Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom.
authors.forename: Geoffrey R
authors.initials: GR
authors.lastname: Moore
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and.
authors.forename: Michael E P
authors.initials: ME
authors.lastname: Murphy
authors.affiliation: From the Department of Biochemistry and Molecular Biology, the Centre for Blood Research and grant.mauk@ubc.ca.
authors.forename: A Grant
authors.initials: AG
authors.lastname: Mauk
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D008667:Metalloproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D017354:Point Mutation; D055672:Static Electricity
chemical_list: D029968:Escherichia coli Proteins; D008667:Metalloproteins; C026121:bfr protein, E coli; D007501:Iron
keywords: Bacterioferritin, Iron Storage, Iron Core; Escherichia coli (E. coli); Ferritin; Iron; Site-directed Mutagenesis; X-ray Crystallography