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PDBsum entry 1mo8
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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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Atp-Induced conformational changes of the nucleotide-Binding domain of na,K-Atpase.
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Authors
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M.Hilge,
G.Siegal,
G.W.Vuister,
P.Güntert,
S.M.Gloor,
J.P.Abrahams.
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Ref.
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Nat Struct Biol, 2003,
10,
468-474.
[DOI no: ]
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PubMed id
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Abstract
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The Na,K-ATPase hydrolyzes ATP to drive the coupled extrusion and uptake of Na+
and K+ ions across the plasma membrane. Here, we report two high-resolution NMR
structures of the 213-residue nucleotide-binding domain of rat alpha1
Na,K-ATPase, determined in the absence and the presence of ATP. The nucleotide
binds in the anti conformation and shows a relative paucity of interactions with
the protein, reflecting the low-affinity ATP-binding state. Binding of ATP
induces substantial conformational changes in the binding pocket and in residues
located in the hinge region connecting the N- and P-domains. Structural
comparison with the Ca-ATPase stabilized by the inhibitor thapsigargin, E2(TG),
and the model of the H-ATPase in the E1 form suggests that the observed changes
may trigger the series of events necessary for the release of the K+ ions and/or
disengagement of the A-domain, leading to the eventual transfer of the
gamma-phosphate group to the invariant Asp369.
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Figure 2.
Figure 2. ATP binding to the N-domain of NaK  1.
(a) Titration curves for ATP (red), ADP (green) and MgATP
(blue) giving K[d] values of 5.1, 24.2 and 25.1 mM,
respectively, with standard deviations of  0.4,
5.3 and 8.6, respectively. (b) Mapping of chemical shift changes
on the molecular surface of the N-domain of NaK  1.
The color code reflects the normalized weighted average of the
1H and 15N chemical shifts calculated as ((   2[NH]
+ 2[N]
/ 25) / 2)1/2 / [max],
where [max]
is the maximum observed weighted shift difference in p.p.m.38.
The most significant changes are in red and the moderate changes
in yellow. (c) The ATP-binding pocket displaying one of the
energy-minimized CYANA conformers with ATP and amino acids
critical for ATP binding in ball-and-stick representation. (d)
Stereo view of the conformational changes at the N and C termini
in response to ATP binding. The ATP-bound form of the N-domain
is colored blue; the native form of the protein is colored
yellow. Binding of ATP (shown in ball and stick; carbon atoms,
black; nitrogen, blue; oxygen, red; and phosphorons, magenta)
causes a displacement of strands  1
and 6.
The disordered loop between residues 391 -408 has been removed
for clarity.
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Figure 3.
Figure 3. Docking and superposition of the native (green) and
ATP-bound (red) N-domain of NaK 1,
the E2(TG) form of Ca-ATPase (violet) and E1 form of H-ATPase
(blue). (a) Solution structure of the ATP-bound N-domain of
NaK 1
and the crystal structure of the E2(TG) form of SERCA1a docked
in the 11-Å Cryo-EM structure of Na,K-ATPase illustrating the
relative positions of the three cytosolic domains, the TM-domain
and the subunit,
as well as the difference in positions of the N-domains. The
surface corresponds to  75%
of the expected molecular volume. (b) Enlarged view of the
native and ATP-bound N-domains of NaK 1.
(c) Superposition of native and ATP-bound N-domain with the
E2(TG) form of Ca-ATPase. (d) Superposition of native and
ATP-bound N-domain with the model for the E1 form of H-ATPase.
Panels c and d focus on residues in the hinge region between the
N- and P-domains.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Biol
(2003,
10,
468-474)
copyright 2003.
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