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PDBsum entry 1a6d
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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 of the thermosome, The archaeal chaperonin and homolog of cct.
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Authors
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L.Ditzel,
J.Löwe,
D.Stock,
K.O.Stetter,
H.Huber,
R.Huber,
S.Steinbacher.
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Ref.
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Cell, 1998,
93,
125-138.
[DOI no: ]
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PubMed id
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Abstract
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We have determined to 2.6 A resolution the crystal structure of the thermosome,
the archaeal group II chaperonin from T. acidophilum. The hexadecameric homolog
of the eukaryotic chaperonin CCT/TRiC shows an (alphabeta)4(alphabeta)4 subunit
assembly. Domain folds are homologous to GroEL but form a novel type of
inter-ring contact. The domain arrangement resembles the GroEL-GroES cis-ring.
Parts of the apical domains form a lid creating a closed conformation. The lid
substitutes for a GroES-like cochaperonin that is absent in the CCT/TRiC system.
The central cavity has a polar surface implicated in protein folding. Binding of
the transition state analog Mg-ADP-AIF3 suggests that the closed conformation
corresponds to the ATP form.
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Figure 1.
Figure 1. General Architecture of Chaperonins(A) Side view
of the hexadecameric thermosome structure.(B) Side view of the
asymmetric GroEL-GroES-(ADP)[7] complex ([77]).Domains are
colored in red (equatorial), green (intermediate), and yellow
(apical). Within each complex domains of aligned subunits are
highlighted in blue (equatorial), light blue (intermediate), and
violet (apical). Bound ADP is drawn in yellow.(C) Top view of
the thermosome α (red/violet) and β (yellow) apical domains.
β strands S12 and S13 and the N-terminal half of helix H10 (lid
segments) form the lid domain that seals off the central
chamber. Helices H10 and H11 and loop L topologically correspond
to helices H and I and the loop connecting β strands 6 and 7 in
GroEL that are involved in substrate and/or GroES binding.Figure
1A Figure 1B Figure 3 Figure 5, and Figure 6A were generated
using BOBSCRIPT ( [18]) and RASTER3D ( [3 and 54]). Figure 1C
was prepared with MOLSCRIPT ( [41]) as modified by D. Peisach
and E. Peisach and with POVRAY.
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Figure 3.
Figure 3. Subunit Structure and Contacts(A) Schematic
drawing of the secondary structural elements of a thermosome α
subunit. Helices and strands are labeled and colored as in
Figure 2. With respect to Figure 1A the view corresponds to a
90° rotation around the pseudo 8-fold axis.(B) Intra-ring
contacts between two thermosome subunits as viewed from the
inside of the particle. The α and β monomers are color coded
as in Figure 1A, and the bound nucleotides are shown in
yellow.(C) Inter-ring contacts between two thermosome α
subunits related by 2-fold symmetry.(D) GroEL inter-ring
contacts. One subunit in the upper ring is related to two
subunits in the lower ring by 2-fold axes at the right and left
edge of the upper subunit.
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The above figures are
reprinted
by permission from Cell Press:
Cell
(1998,
93,
125-138)
copyright 1998.
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