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Title
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Crystal structure of desulforedoxin from Desulfovibrio gigas determined at 1.8 A resolution: a novel non-heme iron protein structure.
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Authors
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M.Archer,
R.Huber,
P.Tavares,
I.Moura,
J.J.Moura,
M.A.Carrondo,
L.C.Sieker,
J.LeGall,
M.J.Romão.
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Ref.
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J Mol Biol, 1995,
251,
690-702.
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PubMed id
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Abstract
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The crystal structure of desulforedoxin from Desulfovibrio gigas, a new
homo-dimeric (2 x 36 amino acids) non-heme iron protein, has been solved by the
SIRAS method using the indium-substituted protein as the single derivative. The
structure was refined to a crystallographic R-factor of 16.9% at 1.8 A
resolution. Native desulforedoxin crystals were grown from either PEG 4K or
lithium sulfate, with cell constants a = b = 42.18 A, c = 72.22 A (for crystals
grown from PEG 4K), and they belong to space group P3(2)21. The
indium-substituted protein crystallized isomorphously under the same conditions.
The 2-fold symmetric dimer is firmly hydrogen bonded and folds as an incomplete
beta-barrel with the two iron centers placed on opposite poles of the molecule.
Each iron atom is coordinated to four cysteinyl residues in a distorted
tetrahedral arrangement. Both iron atoms are 16 A apart but connected across the
2-fold axis by 14 covalent bonds along the polypeptide chain plus two hydrogen
bonds. Desulforedoxin and rubredoxin share some structural features but show
significant differences in terms of metal environment and water structure, which
account for the known spectroscopic differences between rubredoxin and
desulforedoxin.
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