The radical site in chlamydial ribonucleotide reductase defines a new R2 subclass
The radical site in chlamydial ribonucleotide reductase defines a new R2 subclass
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DOI：
10.1126/science.1098419
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发表时间：
2004-07-09
期刊：
影响因子：
56.9
通讯作者：
Nordlund, P
中科院分区：
文献类型：
--
作者：
Högbom, M;Stenmark, P;Nordlund, P
核糖核苷酸还原酶（RNR）合成用于DNA合成的脱氧核糖核苷酸。正常的I类核糖核苷酸还原酶的R2蛋白含有产生稳定的酪氨酰自由基的二铁位点，这是酶活性所必需的。沙眼衣原体R2的结构和电子顺磁共振研究揭示了一种缺乏酪氨酰自由基位点的蛋白质。相反，蛋白质在重构时产生铁偶联自由基。二铁位点的配位结构类似于二铁氧化酶/单加氧酶的配位结构，并支持该自由基在RNR机制中的作用。C.沙眼衣原体R2金属位点表征了一组新的R2蛋白，迄今已在8种生物体中发现，其中3种是人类病原体。
Ribonucleotide reductase (RNR) synthesizes the deoxyribonucleotides for DNA synthesis. The R2 protein of normal class I ribonucleotide reductases contains a diiron site that produces a stable tyrosyl free radical, essential for enzymatic activity. Structural and electron paramagnetic resonance studies of R2 from Chlamydia trachomatis reveal a protein lacking a tyrosyl radical site. Instead, the protein yields an iron-coupled radical upon reconstitution. The coordinating structure of the diiron site is similar to that of diiron oxidases/monoxygenases and supports a role for this radical in the RNR mechanism. The specific ligand pattern in the C. trachomatis R2 metal site characterizes a new group of R2 proteins that so far has been found in eight organisms, three of which are human pathogens.