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PDBsum entry 1frd
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Electron transport
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PDB id
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1frd
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References listed in PDB file
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Key reference
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Title
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Molecular structure of the oxidized, Recombinant, Heterocyst [2fe-2s] ferredoxin from anabaena 7120 determined to 1.7-A resolution.
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Authors
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B.L.Jacobson,
Y.K.Chae,
J.L.Markley,
I.Rayment,
H.M.Holden.
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Ref.
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Biochemistry, 1993,
32,
6788-6793.
[DOI no: ]
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PubMed id
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Abstract
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The [2Fe-2S] ferredoxin produced in the heterocyst cells of Anabaena 7120 plays
a key role in nitrogen fixation, where it serves as an electron acceptor from
various sources and an electron donor to nitrogenase. The three-dimensional
structure of this ferredoxin has now been determined and refined to a
crystallographic R value of 16.7%, with all measured X-ray data from 30.0 to 1.7
A. The molecular motif of this ferredoxin is similar to that of other plant-type
ferredoxins with the iron-sulfur cluster located toward the outer edge of the
molecule and the irons tetrahedrally coordinated by both inorganic sulfurs and
sulfurs provided by protein cysteinyl residues. The overall secondary structure
of the molecule consists of seven strands of beta-pleated sheet, two
alpha-helices, and seven type I turns. It is of special interest that 4 of the
22 amino acid positions thought to be absolutely conserved in nonhalophilic
ferredoxins are different in the heterocyst form of the protein. Three of these
positions are located in the metal-cluster binding loop.
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