3e2c
Escherichia coli Bacterioferritin Mutant E128R/E135R
Structural highlights
FunctionBFR_ECOLI Iron-storage protein, whose ferroxidase center binds Fe(2+) ions, oxidizes them by dioxygen to Fe(3+), and participates in the subsequent Fe(3+) oxide mineral core formation within the central cavity of the protein complex. The mineralized iron core can contain as many as 2700 iron atoms/24-meric molecule.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBacterioferritin (BFR) is a bacterial member of the ferritin family that functions in iron metabolism and protects against oxidative stress. BFR differs from the mammalian protein in that it is comprised of 24 identical subunits and is able to bind 12 equivalents of heme at sites located between adjacent pairs of subunits. The mechanism by which iron enters the protein to form the dinuclear (ferroxidase) catalytic site present in every subunit and the mineralized iron core housed within the 24-mer is not well understood. To address this issue, the properties of a catalytically functional assembly variant (E128R/E135R) of Escherichia coli BFR are characterized by a combination of crystallography, site-directed mutagenesis, and kinetics. The three-dimensional structure of the protein (1.8 A resolution) includes two ethylene glycol molecules located on either side of the dinuclear iron site. One of these ethylene glycol molecules is integrated into the surface of the protein that would normally be exposed to solvent, and the other is integrated into the surface of the protein that would normally face the iron core where it is surrounded by the anionic residues Glu(47), Asp(50), and Asp(126). We propose that the sites occupied by these ethylene glycol molecules define regions where iron interacts with the protein, and, in keeping with this proposal, ferroxidase activity decreases significantly when they are replaced with the corresponding amides. Structural and Mechanistic Studies of a Stabilized Subunit Dimer Variant of Escherichia coli Bacterioferritin Identify Residues Required for Core Formation.,Wong SG, Tom-Yew SA, Lewin A, Le Brun NE, Moore GR, Murphy ME, Mauk AG J Biol Chem. 2009 Jul 10;284(28):18873-81. Epub 2009 May 13. PMID:19439409[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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