Crystal Structure of the Di-iron/Radical Protein of Ribonucleotide Reductase from Corynebacterium ammoniagenes
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- 作者：Martin Hö ; gbom ; Yasmin Huque ; Britt-Marie Sjö ; berg ; and Pä ; r Nordlund
- 刊名：Biochemistry
- 出版年：2002
- 出版时间：January 29, 2002
- 年：2002
- 卷：41
- 期：4
- 页码：1381 - 1389
- 全文大小：402K
- 年卷期：v.41,no.4(January 29, 2002)
- ISSN：1520-4995
文摘
Ribonucleotide reductase (RNR) is the enzyme performing de novo production of the fourdeoxyribonucleotides needed for DNA synthesis. All mammals as well as some prokaryotes express theclass I enzyme which is an 
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ALIGN="middle">2 protein. The smaller of the homodimers, denoted R2, contains a di-ironcarboxylate site which, upon reaction with molecular oxygen, generates a stable tyrosyl radical neededfor catalysis. The three-dimensional structure of the oxidized class Ib RNR R2 from Corynebacteriumammoniagenes has been determined at 1.85 Å resolution and refined to an R-value of 15.8% (Rfree =21.3%). In addition, structures of both the reduced iron-containing, and manganese-substituted proteinhave been solved. The C. ammoniagenes R2 has been proposed to be manganese-dependent. The presentstructure provides evidence that manganese is not oxidized by the protein, in agreement with recentbiochemical 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 ofthe oxidized C. ammoniagenes R2 also reveals an additional water molecule bridging the radical and theiron site, which has not previously been seen in any other R2 structure and which might have importantmechanistic implications.
2ALIGN="middle">2 protein. The smaller of the homodimers, denoted R2, contains a di-ironcarboxylate site which, upon reaction with molecular oxygen, generates a stable tyrosyl radical neededfor catalysis. The three-dimensional structure of the oxidized class Ib RNR R2 from Corynebacteriumammoniagenes has been determined at 1.85 Å resolution and refined to an R-value of 15.8% (Rfree =21.3%). In addition, structures of both the reduced iron-containing, and manganese-substituted proteinhave been solved. The C. ammoniagenes R2 has been proposed to be manganese-dependent. The presentstructure provides evidence that manganese is not oxidized by the protein, in agreement with recentbiochemical 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 ofthe oxidized C. ammoniagenes R2 also reveals an additional water molecule bridging the radical and theiron site, which has not previously been seen in any other R2 structure and which might have importantmechanistic implications.