Direct Measurement of the Radical Translocation Distance in the Class I Ribonucleotide Reductase from Chlamydia trachomatis

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• 作者：Jovan Livada ; Ryan J. Martinie ; Laura M. K. Dassama ; Carsten Krebs ; J. Martin Bollinger Jr. ; Alexey Silakov
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：October 29, 2015
• 年：2015
• 卷：119
• 期：43
• 页码：13777-13784
• 全文大小：433K
• ISSN：1520-5207

文摘

Ribonucleotide reductases (RNRs) catalyze conversion of ribonucleotides to deoxyribonucleotides in all organisms via a free-radical mechanism that is essentially conserved. In class I RNRs, the reaction is initiated and terminated by radical translocation (RT) between the 伪 and 尾 subunits. In the class Ic RNR from Chlamydia trachomatis (Ct RNR), the initiating event converts the active S = 1 Mn(IV)/Fe(III) cofactor to the S = 1/2 Mn(III)/Fe(III) 鈥淩T-product鈥?form in the 尾 subunit and generates a cysteinyl radical in the 伪 active site. The radical can be trapped via the well-described decomposition reaction of the mechanism-based inactivator, 2鈥?azido-2鈥?deoxyuridine-5鈥?diphosphate, resulting in the generation of a long-lived, nitrogen-centered radical (N^{鈥?/sup>) in 伪. In this work, we have determined the distance between the Mn(III)/Fe(III) cofactor in 尾 and N鈥?/sup> in 伪 to be 43 卤 1 脜 by using double electron鈥揺lectron resonance experiments. This study provides the first structural data on the Ct RNR holoenzyme complex and the first direct experimental measurement of the inter-subunit RT distance in any class I RNR.}