A manganese(IV)/iron(III) cofactor in Chlamydia trachomatis ribonucleotide reductase
A manganese(IV)/iron(III) cofactor in Chlamydia trachomatis ribonucleotide reductase
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DOI：
10.1126/science.1141179
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发表时间：
2007-05-25
期刊：
影响因子：
56.9
通讯作者：
Bollinger, J. Martin, Jr.
中科院分区：
文献类型：
--
作者：
Jiang, Wei;Yun, Danny;Bollinger, J. Martin, Jr.
在常规的I类核糖核苷酸还原酶（RNR）中，R2亚基中的二铁（II/II）辅因子与氧反应以产生二铁（III/IV）中间体，其产生稳定的酪氨酰基自由基（Y.）。鼠疫耶尔森可逆地将R1亚基中的半胱氨酸残基氧化成半胱氨酰基（C.），其提取底物的3’-氢以引发其还原。沙眼衣原体的RNR缺少Y.，有人提出R2中的二铁（III/IV）配合物直接生成C.在R1中。通过酶活性测量和光谱方法，我们表明这种RNR实际上使用了一种以前未知的稳定的锰（IV）/铁（III）辅因子来进行自由基引发。
In a conventional class I ribonucleotide reductase (RNR), a diiron(II/II) cofactor in the R2 subunit reacts with oxygen to produce a diiron(III/IV) intermediate, which generates a stable tyrosyl radical (Y.). The Y. reversibly oxidizes a cysteine residue in the R1 subunit to a cysteinyl radical (C.), which abstracts the 3'-hydrogen of the substrate to initiate its reduction. The RNR from Chlamydia trachomatis lacks the Y., and it had been proposed that the diiron(III/IV) complex in R2 directly generates the C. in R1. By enzyme activity measurements and spectroscopic methods, we show that this RNR actually uses a previously unknown stable manganese(IV)/iron( III) cofactor for radical initiation.