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PDBsum entry 1ffv
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Contents |
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155 a.a.
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797 a.a.
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287 a.a.
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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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The effect of intracellular molybdenum in hydrogenophaga pseudoflava on the crystallographic structure of the seleno-Molybdo-Iron-Sulfur flavoenzyme carbon monoxide dehydrogenase.
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Authors
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P.Hänzelmann,
H.Dobbek,
L.Gremer,
R.Huber,
O.Meyer.
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Ref.
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J Mol Biol, 2000,
301,
1221-1235.
[DOI no: ]
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PubMed id
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Abstract
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Crystal structures of carbon monoxide dehydrogenase (CODH), a
seleno-molybdo-iron-sulfur flavoprotein from the aerobic carbon monoxide
utilizing carboxidotrophic eubacterium Hydrogenophaga pseudoflava, have been
determined from the enzyme synthesized at high (Mo(plus) CODH) and low
intracellular molybdenum content (Mo(minus) CODH) at 2.25 A and 2.35 A
resolution, respectively. The structures were solved by Patterson search methods
utilizing the enzyme from Oligotropha carboxidovorans as the initial model. The
CODHs from both sources are structurally very much conserved and show the same
overall fold, architecture and arrangements of the molybdopterin-cytosine
dinucleotide-type of molybdenum cofactor, the type I and type II [2Fe-2S]
clusters and the flavin-adenine dinucleotide. Unlike the CODH from O.
carboxidovorans, the enzyme from H. pseudoflava reveals a unique
post-translationally modified C(gamma)-hydroxy-Arg384 residue which precedes the
catalytically essential S-selanyl-Cys385 in the active-site loop. In addition,
the Trp193 which shields the isoalloxazine ring of the flavin-adenine
dinucleotide in the M subunit of the H. pseudoflava CODH is a Tyr193 in the O.
carboxidovorans CODH. The hydrogen bonding interaction pattern of the molybdenum
cofactor involves 27 hydrogen bonds with the surrounding protein. Of these,
eight are with the cytosine moiety, eight with the pyrophosphate, six with the
pyranopterin, and five with the ligands of the Mo ion. The structure of the
catalytically inactive Mo(minus) CODH indicates that an intracellular
Mo-deficiency affects exclusively the active site of the enzyme as an incomplete
non-functional molybdenum cofactor was synthesized. The 5'-CDP residue was
present in Mo(minus) CODH, whereas the Mo-pyranopterin moiety was absent. In
Mo(plus) CODH the selenium faces the Mo ion and flips away from the Mo site in
Mo(minus) CODH. The different side-chain conformations of the active-site
residues S-selanyl-Cys385 and Glu757 in Mo(plus) and Mo(minus) CODH indicate a
side-chain flexibility and a function of the Mo ion in the proper orientation of
both residues.
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Figure 2.
Figure 2. The fold of the L-subunit of the Moplus CODH
species. (a) The C-terminal domain (residues 440 to 803). (b)
The N-terminal domain (residues 7 to 435). Helices are shown in
red, b-sheets in yellow and loops in green. Colour coding of the
Moco atoms is as follows: C, green; N, blue; O, red; P, pink.
The structure representations were created as in Figure 1.
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Figure 3.
Figure 3. Representation of the active sites of the Moplus
or the Mominus CODH species. (a) Moplus CODH. The Mo ion is
complexed by the enedithiolate group of MCD. It has one hydroxy
and two oxo ligands in the first coordination sphere. In the
second coordination sphere are the residues Gln237,
C^g-hydroxy-Arg384, S-selanyl-Cys385, Gly563 (not shown for
reasons of clarity) and Glu757. Hydrogen bonds are shown as
broken lines. Colour coding of the Moco atoms is as follows: C,
green; Mo, grey; N, blue; O, red; P, pink; S, yellow; Se,
orange. (b) Superposition of the active sites of the Moplus and
the Mominus CODH species. The active sites of the Moplus or
Mominus CODH species are drawn in green and red, respectively.
The structure representations were created as in Figure 1.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2000,
301,
1221-1235)
copyright 2000.
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