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PDBsum entry 1vjw
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Oxidoreductase
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PDB id
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1vjw
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References listed in PDB file
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Key reference
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Title
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Small structural changes account for the high thermostability of 1[4fe-4s] ferredoxin from the hyperthermophilic bacterium thermotoga maritima.
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Authors
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S.Macedo-Ribeiro,
B.Darimont,
R.Sterner,
R.Huber.
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Ref.
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Structure, 1996,
4,
1291-1301.
[DOI no: ]
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PubMed id
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Abstract
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BACKGROUND: The characterization of the structural features that account for the
high thermostability of some proteins is of great scientific and
biotechnological interest. Proteins from hyperthermophilic organisms with
optimum growth temperatures of 80 degrees C and higher generally show high
intrinsic stabilities. The comparison of high resolution X-ray structures of
these proteins with their counterparts from mesophilic organisms has therefore
helped to identify potentially stabilizing forces in a number of cases. Small
monomeric proteins which comprise only a single domain, such as ferredoxins, are
especially suitable for such comparisons since the search for determinants of
protein stability is considerably simplified. RESULTS: The 1.75 A crystal
ferredoxin from Thermotoga
maritima (FdTm) was determined and compared with other monocluster-containing
ferredoxins with different degrees of thermostability. CONCLUSIONS: A comparison
of the three-dimensional structure of FdTm with that of ferredoxins from
mesophilic organisms suggests that the very high thermostability of FdTm is
unexpectedly achieved without large changes of the overall protein structure.
Instead, an increased number of potentially stabilizing features is observed in
FdTm, compared with mesophilic ferredoxins. These include stabilization of alpha
helices, replacement of residues in strained conformation by glycines, strong
docking of the N-terminal methionine and an overall increase in the number of
hydrogen bonds. Most of these features stabilize several secondary structure
elements and improve the overall rigidity of the polypeptide backbone. The
decreased flexibility will certainly play a relevant role in shielding the
iron-sulfur cluster against physiologically high temperatures and further
improve the functional integrity of FdTm.
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Figure 1.
Figure 1. Representation of the Fd[Tm] structure. (a) Stereo
view of the Cα backbone; each fifth residue is labeled. (b)
Schematic representation of the Fd[Tm] structure. B1, B2: β
sheets; H1, H2: α helices; A–E: turns. Iron atoms of the
cluster are shown in red and all sulfur atoms are shown in
yellow. Figure 1. Representation of the Fd[Tm] structure. (a)
Stereo view of the Cα backbone; each fifth residue is labeled.
(b) Schematic representation of the Fd[Tm] structure. B1, B2: β
sheets; H1, H2: α helices; A–E: turns. Iron atoms of the
cluster are shown in red and all sulfur atoms are shown in
yellow.
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Figure 5.
Figure 5. Conserved folding topology within monocluster-type
ferredoxins. Least-square superposition of the Cα tracings of
Fd[Tm] (blue), Fd[Dg] (orange), Fd[Daf] (green) and Fd[Bt]
(violet). For clarity only the Fd[Tm] cluster is shown and
residue labels refer to Fd[Tm]. Figure 5. Conserved folding
topology within monocluster-type ferredoxins. Least-square
superposition of the Cα tracings of Fd[Tm] (blue), Fd[Dg]
(orange), Fd[Daf] (green) and Fd[Bt] (violet). For clarity only
the Fd[Tm] cluster is shown and residue labels refer to Fd[Tm].
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The above figures are
reprinted
by permission from Cell Press:
Structure
(1996,
4,
1291-1301)
copyright 1996.
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