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PDBsum entry 1kgo
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Metal binding protein
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PDB id
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1kgo
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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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Crystal structure of the di-Iron/radical protein of ribonucleotide reductase from corynebacterium ammoniagenes.
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Authors
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M.Högbom,
Y.Huque,
B.M.Sjöberg,
P.Nordlund.
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Ref.
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Biochemistry, 2002,
41,
1381-1389.
[DOI no: ]
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PubMed id
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Abstract
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Ribonucleotide reductase (RNR) is the enzyme performing de novo production of
the four deoxyribonucleotides needed for DNA synthesis. All mammals as well as
some prokaryotes express the class I enzyme which is an alpha(2)beta(2) protein.
The smaller of the homodimers, denoted R2, contains a di-iron carboxylate site
which, upon reaction with molecular oxygen, generates a stable tyrosyl radical
needed for catalysis. The three-dimensional structure of the oxidized class Ib
RNR R2 from Corynebacterium ammoniagenes has been determined at 1.85 A
resolution and refined to an R-value of 15.8% (R(free) = 21.3%). In addition,
structures of both the reduced iron-containing, and manganese-substituted
protein have been solved. The C. ammoniagenes R2 has been proposed to be
manganese-dependent. The present structure provides evidence that manganese is
not oxidized by the protein, in agreement with recent biochemical data, and that
no obvious structural abnormalities are seen in the oxidized and reduced
iron-containing forms, giving further support that the protein is indeed an
iron-dependent RNR R2. The di-manganese structure also provides an explanation
for the magnetic properties of this site. The structure of the oxidized C.
ammoniagenes R2 also reveals an additional water molecule bridging the radical
and the iron site, which has not previously been seen in any other R2 structure
and which might have important mechanistic implications.
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