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PDBsum entry 4xkt
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Metal binding protein
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PDB id
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4xkt
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References listed in PDB file
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Key reference
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Title
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Three aromatic residues are required for electron transfer during iron mineralization in bacterioferritin.
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Authors
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J.M.Bradley,
D.A.Svistunenko,
T.L.Lawson,
A.M.Hemmings,
G.R.Moore,
N.E.Le brun.
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Ref.
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Angew Chem Int Ed Engl, 2015,
54,
14763-14767.
[DOI no: ]
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PubMed id
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Abstract
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Ferritins are iron storage proteins that overcome the problems of toxicity and
poor bioavailability of iron by catalyzing iron oxidation and mineralization
through the activity of a diiron ferroxidase site. Unlike in other ferritins,
the oxidized di-Fe(3+) site of Escherichia coli bacterioferritin (EcBFR) is
stable and therefore does not function as a conduit for the transfer of Fe(3+)
into the storage cavity, but instead acts as a true catalytic cofactor that
cycles its oxidation state while driving Fe(2+) oxidation in the cavity. Herein,
we demonstrate that EcBFR mineralization depends on three aromatic residues near
the diiron site, Tyr25, Tyr58, and Trp133, and that a transient radical is
formed on Tyr25. The data indicate that the aromatic residues, together with a
previously identified inner surface iron site, promote mineralization by
ensuring the simultaneous delivery of two electrons, derived from Fe(2+)
oxidation in the BFR cavity, to the di-ferric catalytic site for safe reduction
of O2 .
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