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PDBsum entry 1kv7
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Oxidoreductase
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PDB id
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1kv7
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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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Crystal structure and electron transfer kinetics of cueo, A multicopper oxidase required for copper homeostasis in escherichia coli.
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Authors
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S.A.Roberts,
A.Weichsel,
G.Grass,
K.Thakali,
J.T.Hazzard,
G.Tollin,
C.Rensing,
W.R.Montfort.
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Ref.
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Proc Natl Acad Sci U S A, 2002,
99,
2766-2771.
[DOI no: ]
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PubMed id
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Abstract
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CueO (YacK), a multicopper oxidase, is part of the copper-regulatory cue operon
in Escherichia coli. The crystal structure of CueO has been determined to 1.4-A
resolution by using multiple anomalous dispersion phasing and an automated
building procedure that yielded a nearly complete model without manual
intervention. This is the highest resolution multicopper oxidase structure yet
determined and provides a particularly clear view of the four coppers at the
catalytic center. The overall structure is similar to those of laccase and
ascorbate oxidase, but contains an extra 42-residue insert in domain 3 that
includes 14 methionines, nine of which lie in a helix that covers the entrance
to the type I (T1, blue) copper site. The trinuclear copper cluster has a
conformation not previously seen: the Cu-O-Cu binuclear species is nearly linear
(Cu-O-Cu bond angle = 170 degrees) and the third (type II) copper lies only 3.1
A from the bridging oxygen. CueO activity was maximal at pH 6.5 and in the
presence of >100 microM Cu(II). Measurements of intermolecular and
intramolecular electron transfer with laser flash photolysis in the absence of
Cu(II) show that, in addition to the normal reduction of the T1 copper, which
occurs with a slow rate (k = 4 x 10(7) M(-1)x (-1)), a second electron transfer
process occurs to an unknown site, possibly the trinuclear cluster, with k = 9 x
10(7) M(-1) x (-1), followed by a slow intramolecular electron transfer to T1
copper (k approximately 10 s(-1)). These results suggest the methionine-rich
helix blocks access to the T1 site in the absence of excess copper.
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Figure 2.
Fig. 2. Representative electron density (2 F[o]  F[c]  [c]) after
automatic model building and one round of refinement, before
manual intervention. The model shown is in the region
surrounding the trinuclear copper center and was built
automatically with ARP/WARP.
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Figure 4.
Fig. 4. Stereoview showing the geometry of the T1 and
trinuclear copper sites. Shown are the copper atoms (cyan),
oxygen atoms (red), HCH residues (499-501), nitrogens (blue),
and sulfurs (yellow) from ligating histidines, cysteines, and
methionines. T1 Cu is ligated to His-443, His-503, Cys-500, and
Met-510. T2 Cu is ligated to His-101, His-446, and a water
molecule. Cu2 is ligated to His-103, His-141, His-501, and the
bridging oxygen. Cu3 is ligated to His-143, His-448, His-499,
and the bridging oxygen.
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