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PDBsum entry 3c91
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Contents |
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(+ 8 more)
227 a.a.
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(+ 8 more)
203 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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Mechanism of gate opening in the 20s proteasome by the proteasomal atpases.
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Authors
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J.Rabl,
D.M.Smith,
Y.Yu,
S.C.Chang,
A.L.Goldberg,
Y.Cheng.
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Ref.
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Mol Cell, 2008,
30,
360-368.
[DOI no: ]
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PubMed id
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Abstract
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Substrates enter the cylindrical 20S proteasome through a gated channel that is
regulated by the ATPases in the 19S regulatory particle in eukaryotes or the
homologous PAN ATPase complex in archaea. These ATPases contain a conserved
C-terminal hydrophobic-tyrosine-X (HbYX) motif that triggers gate opening upon
ATP binding. Using cryo-electron microscopy, we identified the sites in the
archaeal 20S where PAN's C-terminal residues bind and determined the structures
of the gate in its closed and open forms. Peptides containing the HbYX motif
bind to 20S in the pockets between neighboring alpha subunits where they
interact with conserved residues required for gate opening. This interaction
induces a rotation in the alpha subunits and displacement of a reverse-turn loop
that stabilizes the open-gate conformation. This mechanism differs from that of
PA26/28, which lacks the HbYX motif and does not cause alpha subunit rotation.
These findings demonstrated how the ATPases' C termini function to facilitate
substrate entry.
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Figure 3.
Figure 3. Conformational Change of 20S α Ring Induced by the
Gate-Opening Peptides
(A) Top view of superimposed density
maps of 20S (gold mesh) and 20S-AHLDVLYA complex (blue
transparent surface).
(B) Top view of the 20S-AHLDVLYA
density map (blue) with the structure of the open-gate 20S
docked.
(C) Top view of the 20S density map (gold) with the
structure of the closed-gate 20S docked.
(D) Superimposed
structures of 20S with the open and the closed gate.
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Figure 6.
Figure 6. Mechanism of Gate Opening in the 20S Induced by PAN
and PA26 Complexes
(A) (Left) Overlay of the α ring
structures, before and after the binding of the gate-opening
peptides. (Right) Enlarged view of the dashed area from the
left. Pro17 is shifted because of the rotation in α subunit.
(B) (Left) Overlay of the structure of the α ring, before
and after PA26 binding. (Right) Enlarged view of the dashed
area. Pro17 is shifted by the activation loop of PA26 (data not
shown). Notice that Pro17 in red and magenta structures is in a
similar position.
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The above figures are
reprinted
by permission from Cell Press:
Mol Cell
(2008,
30,
360-368)
copyright 2008.
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