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PDBsum entry 1llw
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Oxidoreductase
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PDB id
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1llw
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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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Structural studies on the synchronization of catalytic centers in glutamate synthase.
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Authors
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R.H.Van den heuvel,
D.Ferrari,
R.T.Bossi,
S.Ravasio,
B.Curti,
M.A.Vanoni,
F.J.Florencio,
A.Mattevi.
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Ref.
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J Biol Chem, 2002,
277,
24579-24583.
[DOI no: ]
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PubMed id
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Abstract
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The complex iron-sulfur flavoprotein glutamate synthase (GltS) plays a prominent
role in ammonia assimilation in bacteria, yeasts, and plants. GltS catalyzes the
formation of two molecules of l-glutamate from 2-oxoglutarate and l-glutamine
via intramolecular channeling of ammonia. GltS has the impressive ability of
synchronizing its distinct catalytic centers to avoid wasteful consumption of
l-glutamine. We have determined the crystal structure of the
ferredoxin-dependent GltS in several ligation and redox states. The structures
reveal the crucial elements in the synchronization between the glutaminase site
and the 2-iminoglutarate reduction site. The structural data combined with the
catalytic properties of GltS indicate that binding of ferredoxin and
2-oxoglutarate to the FMN-binding domain of GltS induce a conformational change
in the loop connecting the two catalytic centers. The rearrangement induces a
shift in the catalytic elements of the amidotransferase domain, such that it
becomes activated. This machinery, over a distance of more than 30 A, controls
the ability of the enzyme to bind and hydrolyze the ammonia-donating substrate
l-glutamine.
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Figure 1.
Fig. 1. The overall structure of Fd-GltS with the
N-terminal amidotransferase domain depicted in cornflower blue,
the FMN-binding domain in yellow, the central domain in magenta,
and the C-terminal domain in green. The FMN cofactor and the
3Fe-4S cluster are shown in black ball-and-stick, and the
ammonia channel is outlined by red spheres. Dashed lines connect
the borders of disordered loops.
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Figure 3.
Fig. 3. Interdomain communication in Fd-GltS. The
transparent coloring of the Fd-GltS monomer is identical to the
coloring in Fig. 1 as is the orientation. Highlighted are the
proposed elements involved in interdomain channeling and
synchronization; Fd loop (residues 907-933), loop 4 (residues
968-1013), and loop 31-39. The FMN cofactor, 3Fe-4S cluster, and
residues Cys-1 and Glu-1013 are shown as black ball-and-stick.
The ammonia channel is outlined by red spheres.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2002,
277,
24579-24583)
copyright 2002.
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