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PDBsum entry 2c7e
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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-Bound states of groel captured by cryo-Electron microscopy.
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Authors
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N.A.Ranson,
G.W.Farr,
A.M.Roseman,
B.Gowen,
W.A.Fenton,
A.L.Horwich,
H.R.Saibil.
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Ref.
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Cell, 2001,
107,
869-879.
[DOI no: ]
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PubMed id
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Abstract
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The chaperonin GroEL drives its protein-folding cycle by cooperatively binding
ATP to one of its two rings, priming that ring to become folding-active upon
GroES binding, while simultaneously discharging the previous folding chamber
from the opposite ring. The GroEL-ATP structure, determined by cryo-EM and
atomic structure fitting, shows that the intermediate domains rotate downward,
switching their intersubunit salt bridge contacts from substrate binding to ATP
binding domains. These observations, together with the effects of ATP binding to
a GroEL-GroES-ADP complex, suggest structural models for the ATP-induced
reduction in affinity for polypeptide and for cooperativity. The model for
cooperativity, based on switching of intersubunit salt bridge interactions
around the GroEL ring, may provide general insight into cooperativity in other
ring complexes and molecular machines.
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Figure 5.
Figure 5. Intersubunit Contacts(a) A closeup view of the
intermediate domain orientation in the unliganded T ring of
GroEL-ATP.(b) A similar view of the intermediate domain
orientation in the ATP-bound R ring. The equatorial (green),
intermediate (yellow), and apical (red) domains of parts of two
adjacent subunits are shown inside a blue/yellow wire mesh
surface representing the EM density. The change in color of the
mesh indicates the boundary between the two subunits in each
view. The T ring contains density at the E386-R197 salt bridge.
In the R ring, E386 makes a new contact near K80 and D83 in the
neighboring equatorial domain.
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Figure 7.
Figure 7. Domain Twisting Caused by ATP Binding to the Open
Ring of GroEL-GroES-ADPCryo-EM structure to 12.5 Å
resolution of the GroES-ADP[7]-GroEL-ATP[7] complex isolated
from a reaction mixture. The cryo-EM map is shown as a blue
transparent surface, with the atomic structure docked in. The
GroEL domains are colored as in Figure 2, and GroES is cyan. The
precision of the fit is demonstrated by the side view (a). The
white circle in (a) indicates the position of the R197-E386
contact. The free apical domains (lower ring in [a]) are docked
into the end view (b) with a counterclockwise rotation of
20° ± 5°. The white dotted lines are orientation
markers for comparison of the apical rotation here with that in
Figure 3a.
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The above figures are
reprinted
by permission from Cell Press:
Cell
(2001,
107,
869-879)
copyright 2001.
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