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PDBsum entry 1s3h
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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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Transcarboxylase 5s structures: assembly and catalytic mechanism of a multienzyme complex subunit.
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Authors
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P.R.Hall,
R.Zheng,
L.Antony,
M.Pusztai-Carey,
P.R.Carey,
V.C.Yee.
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Ref.
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EMBO J, 2004,
23,
3621-3631.
[DOI no: ]
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PubMed id
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Abstract
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Transcarboxylase is a 1.2 million Dalton (Da) multienzyme complex from
Propionibacterium shermanii that couples two carboxylation reactions,
transferring CO(2)(-) from methylmalonyl-CoA to pyruvate to yield propionyl-CoA
and oxaloacetate. Crystal structures of the 5S metalloenzyme subunit, which
catalyzes the second carboxylation reaction, have been solved in free form and
bound to its substrate pyruvate, product oxaloacetate, or inhibitor
2-ketobutyrate. The structure reveals a dimer of beta(8)alpha(8) barrels with an
active site cobalt ion coordinated by a carbamylated lysine, except in the
oxaloacetate complex in which the product's carboxylate group serves as a ligand
instead. 5S and human pyruvate carboxylase (PC), an enzyme crucial to
gluconeogenesis, catalyze similar reactions. A 5S-based homology model of the PC
carboxyltransferase domain indicates a conserved mechanism and explains the
molecular basis of mutations in lactic acidemia. PC disease mutations reproduced
in 5S result in a similar decrease in carboxyltransferase activity and crystal
structures with altered active sites.
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Figure 5.
Figure 5 Active sites of 5S complexes. The free 5S active site
is shown with its Lys[C]184 (ball-and-stick with gray carbon
atoms and bonds), cobalt ion (pink sphere), water ligands (red
spheres), and side chains of residues which interact with either
the cobalt ion or bound ligand. Superimposed are oxaloacetate
(yellow), pyruvate (pale pink), and 2-ketobutyrate (cyan)
ligands from their respective complexes.
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Figure 6.
Figure 6 Active sites of 5S mutants. (A) Composite 5S active
site showing the 5S-A59T crystal structure. The Thr59 side chain
(orange and red ball-and-stick) interacts with Gln26, which in
the complex structures forms hydrogen bonds with the bound
ligands. For reference, oxaloacetate (yellow, as bound in
5S-oxal) and residues with which it interacts (Arg22 and Gln26),
Met186 (gray, conformation in free 5S; pale pink, conformation
in 5S-oxal), cobalt ion (pink sphere), and carbamylated
Lys[C]184 are also shown. The orientation of this figure is
related to that of Figure 5 by  90°
rotation about the vertical axis combined with 90°
rotation about the horizontal axis. (B) Composite 5S active site
showing the 5S-M186I crystal structure. The I186 side chain
(cyan ball-and-stick structure) would be expected to make close
contacts with substrate or product; oxaloacetate (yellow, as
bound in 5S-oxal) and Ala59 are shown for reference.
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The above figures are
reprinted
from an Open Access publication published by Macmillan Publishers Ltd:
EMBO J
(2004,
23,
3621-3631)
copyright 2004.
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Secondary reference #1
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Title
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Expression and crystallization of several forms of the propionibacterium shermanii transcarboxylase 5s subunit.
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Authors
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P.R.Hall,
R.Zheng,
M.Pusztai-Carey,
F.Van den akker,
P.R.Carey,
V.C.Yee.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2004,
60,
521-523.
[DOI no: ]
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PubMed id
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Figure 1.
Figure 1 EM-based model (adapted from Wrigley et al.,
1977[Wrigley, N. G., Chiao, J.-P. & Wood, H. G. (1977). J. Biol.
Chem. 252, 1500-1504.]).
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The above figure is
reproduced from the cited reference
with permission from the IUCr
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