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PDBsum entry 2c7c
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Contents |
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(+ 8 more)
525 a.a.
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(+ 1 more)
93 a.a.
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References listed in PDB file
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Key reference
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Title
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Allosteric signaling of ATP hydrolysis in groel-Groes complexes.
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Authors
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N.A.Ranson,
D.K.Clare,
G.W.Farr,
D.Houldershaw,
A.L.Horwich,
H.R.Saibil.
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Ref.
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Nat Struct Mol Biol, 2006,
13,
147-152.
[DOI no: ]
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PubMed id
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Abstract
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The double-ring chaperonin GroEL and its lid-like cochaperonin GroES form
asymmetric complexes that, in the ATP-bound state, mediate productive folding in
a hydrophilic, GroES-encapsulated chamber, the so-called cis cavity. Upon ATP
hydrolysis within the cis ring, the asymmetric complex becomes able to accept
non-native polypeptides and ATP in the open, trans ring. Here we have examined
the structural basis for this allosteric switch in activity by cryo-EM and
single-particle image processing. ATP hydrolysis does not change the
conformation of the cis ring, but its effects are transmitted through an
inter-ring contact and cause domain rotations in the mobile trans ring. These
rigid-body movements in the trans ring lead to disruption of its intra-ring
contacts, expansion of the entire ring and opening of both the nucleotide pocket
and the substrate-binding domains, admitting ATP and new substrate protein.
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Figure 2.
Figure 2. Solution structures of GroEL–ATP[7]–GroES and
GroEL–ADP[7]–GroES. (a) Surface representation of the
side view of the GroEL–ATP[7]–GroES complex. (b) Surface
representation of the side view of the GroEL–ADP[7]–GroES
complex. (c,d) Central sections through the cryo-EM maps are
shown as a semitransparent surface in either gold (c; ATP) or
blue (d; ADP), with the atomic coordinates for the GroEL
equatorial (green; residues 3–136 and 410–524), intermediate
(yellow; residues 137–191 and 374–409), apical (red;
residues 192–373, except for 353–361 at the tip of the
mobile helical hairpin in the trans ring) and GroES (magenta)
fitted in. The seven-fold axis of the GroEL–GroES oligomer is
vertical and in the image plane for all figures. The resolutions
of the ATP- and ADP-bound maps are 7.7 Å and 8.7 Å,
respectively, determined by Fourier shell correlation at a
cutoff of 0.5. Fourier shell correlation curves for both
reconstructions are shown in Supplementary Figure 1.
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Figure 4.
Figure 4. Disruption of intra-ring contacts between the
equatorial domains of the trans ring. (a) The interface
between neighboring equatorial domains in the trans ring of the
ATP-bound complex. The EM-derived electron density is shown as a
gold mesh, with the adjacent equatorial domains in blue and
magenta. In the ATP complex (and all crystal structures of GroEL
complexes), two  -strands
from each subunit form a four-stranded -sheet
that is a major contact holding the ring of equatorial domains
together (highlighted by a black rectangle). (b) The
corresponding view of the ADP-bound complex (with EM density
shown as a blue mesh and equatorial domains in green and orange)
shows that a small (  3°)
rotation of the equatorial domain results in the two strands
from the orange subunit moving upward (in this view) and the two
strands from the green subunit moving downward, pulling apart
the -sheet
contact. (c,d) Structure of the rear half of the ring of
equatorial domains from the ATP-bound (c) and ADP-bound (d)
complexes. The seven-fold axis is vertical and in the image
plane, and these views are reached by tipping a and b forward by
30°.
(e) A comparison of the intra-strand (main chain) distances in
the ATP (blue and magenta) and ADP (green and gold) complexes,
showing that the strand separation increases by 4–5 Å
upon ATP hydrolysis.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Mol Biol
(2006,
13,
147-152)
copyright 2006.
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