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PDBsum entry 1fqt
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Oxidoreductase
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PDB id
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1fqt
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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A cluster exposed: structure of the rieske ferredoxin from biphenyl dioxygenase and the redox properties of rieske fe-S proteins.
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Authors
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C.L.Colbert,
M.M.Couture,
L.D.Eltis,
J.T.Bolin.
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Ref.
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Structure, 2000,
8,
1267-1278.
[DOI no: ]
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PubMed id
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Abstract
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BACKGROUND: Ring-hydroxylating dioxygenases are multicomponent systems that
initiate biodegradation of aromatic compounds. Many dioxygenase systems include
Rieske-type ferredoxins with amino acid sequences and redox properties
remarkably different from the Rieske proteins of proton-translocating
clusters
lie near the protein surface, operate at potentials above +300 mV at pH 7, and
express pH- and ionic strength-dependent redox behavior. The reduction
potentials of the dioxygenase ferredoxins are approximately 150 mV and are
pH-independent. These distinctions were predicted to arise from differences in
the exposure of the cluster and/or interactions of the histidine ligands.
RESULTS: The crystal structure of BphF, the Rieske-type ferredoxin associated
with biphenyl dioxygenase, was determined by multiwavelength anomalous
diffraction and refined at 1.6 A resolution. The structure of BphF was compared
with other Rieske proteins at several levels. BphF has the same two-domain fold
as other Rieske proteins, but it lacks all insertions that give the others
unique structural features. The BphF Fe-S cluster and its histidine ligands are
exposed. However, the cluster has a significantly different environment in that
five fewer polar groups interact strongly with the cluster sulfide or the
cysteinyl ligands. CONCLUSIONS: BphF has structural features consistent with a
minimal and perhaps archetypical Rieske protein. Variations in redox potentials
among Rieske clusters appear to be largely the result of local electrostatic
interactions with protein partial charges. Moreover, it appears that the
redox-linked ionizations of the Rieske proteins from proton-translocating
complexes are also promoted by these electrostatic interactions.
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Figure 5.
Figure 5. Stereoscopic Illustrations of the Environment of
the Rieske Fe-S Center in the BphF Monomer and in the
CrystalPanel (a) illustrates the cluster binding domain in
monomer B. Some side chains directed away from the Fe-S cluster
were truncated to improve the visibility of features nearer to
the cluster. C, N, O, S, and Fe atoms are colored gray, blue,
red, yellow, and red-brown, respectively. Four water molecules
are plotted as violet balls. Panel (b) illustrates the
environment of the cluster in the crystal. The course of
portions of the backbone for two molecules related by a 2[1]
screw axis are plotted in green and gold, respectively. The
colors of protein and water atoms are the same as in (a). Two
intermolecular hydrogen bonds are represented by dotted lines
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The above figure is
reprinted
by permission from Cell Press:
Structure
(2000,
8,
1267-1278)
copyright 2000.
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