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PDBsum entry 1b2r
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Oxidoreductase
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PDB id
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1b2r
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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 basis of the catalytic role of glu301 in anabaena pcc 7119 ferredoxin-Nadp+ reductase revealed by x-Ray crystallography.
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Authors
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T.Mayoral,
M.Medina,
J.Sanz-Aparicio,
C.Gómez-Moreno,
J.A.Hermoso.
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Ref.
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Proteins, 2000,
38,
60-69.
[DOI no: ]
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PubMed id
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Abstract
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The three-dimensional crystal structure of the Glu301Ala site-directed mutant of
ferredoxin-NADP+ reductase from Anabaena PCC 7119 has been determined at 1.8A
resolution by x-ray diffraction. The overall folding of the Glu301Ala FNR mutant
shows no significant differences with respect to that of the wild-type enzyme.
However, interesting conformational changes are detected in the side chain of
another glutamate residue, Glu139, which now points towards the FAD cofactor in
the active center cavity. The new conformation of the Glu139 side chain is
stabilized by a network of five hydrogen bonds to several water molecules, which
seem to hold the carboxylate side chain in a rather fixed position. This
interacting network connects the Glu139 side chain to the Ser80 side chain
through a series of three water molecules. These observations are discussed in
terms of the reactivity of Glu301Ala ferredoxin-NADP+ reductase towards its
substrates, and the role of Glu301 in the catalysis is re-examined. Moreover, a
structural explanation of the different reoxidation properties of this mutant is
given on the basis of the reported structure by modeling the hypothetical flavin
C(4a)-hydroperoxide intermediate. The model shows that the distal oxygen of the
peroxide anion could be in an appropriate situation to act as the proton donor
in the reoxidation process.
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Figure 4.
Figure 4. A section of the molecular surface near the FAD group
(represented as CPK and seen approximately in the same
orientation) in (a) FNR wild-type enzyme and in (b) the
Glu301Ala FNR. A new pocket is formed next to the FAD group
increasing the solvent accessibility surface by 8 Å.[2]
The C4a atom of isoalloxazine ring is highlighted (see Fig. 5
for labeling).
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Figure 5.
Figure 5. The flavin-C(4a)-hydroperoxide model. a: Schematic
diagram. b: Stereo view of the superposition of the
flavin-C(4a)-hydroperoxide model (dashed lines) and the flavin
ring of the Glu301Ala FNR structure (solid lines). The arrow
indicates the rotation needed to generate the Od allowed region
(see text).
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2000,
38,
60-69)
copyright 2000.
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Secondary reference #1
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Title
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X-Ray structure of the ferredoxin:NADP+ reductase from the cyanobacterium anabaena pcc 7119 at 1.8 a resolution, And crystallographic studies of NADP+ binding at 2.25 a resolution.
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Authors
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L.Serre,
F.M.Vellieux,
M.Medina,
C.Gomez-Moreno,
J.C.Fontecilla-Camps,
M.Frey.
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Ref.
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J Mol Biol, 1996,
263,
20-39.
[DOI no: ]
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PubMed id
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Figure 5.
Figure 5. Interaction between FNR and ferredoxin. The charged residues, which are probably involved in the binding
of FNR with ferredoxin and are currently mutated, are represented by thick lines.
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Figure 8.
Figure 8. A stereoscopic view of the difference electron density at the NADP
+
site (contoured at 2s) calculated with
phases from a model obtained by refining the native FNR X-ray model at 1.8 Å resolution (omitting residue 1 to 8,
the sulfate ion and the water molecules) by simulated annealing and energy minimization against the amplitudes from
the FNR-NADP
+
crystal. The final NADP
+
position is represented.
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The above figures are
reproduced from the cited reference
with permission from Elsevier
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