A Highly Reactive Imidazolium-Bridged Dinucleotide Intermediate in Nonenzymatic RNA Primer Extension.
A Highly Reactive Imidazolium-Bridged Dinucleotide Intermediate in Nonenzymatic RNA Primer Extension.
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DOI：
10.1021/jacs.6b07977
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发表时间：
2016-09-14
影响因子：
15
通讯作者：
Szostak JW
中科院分区：
文献类型：
--
作者：
Walton T;Szostak JW
Because of its importance for the origin of life, the nonenzymatic copying of RNA templates has been the subject of intense study for several decades. Previous characterizations of template-directed primer extension using 5′-phosphoryl-2-methylimidazole-activated nucleotides (2-MeImpNs) as substrates have assumed a classical in-line nucleophilic substitution mechanism, in which the 3′-hydroxyl of the primer attacks the phosphate of the incoming monomer, displacing the 2-methylimidazole leaving group. However, we have found that the initial rate of primer extension depends on the pH and concentration at which the activated monomer is maintained prior to the primer extension reaction. These and other results suggest an alternative mechanism, in which two monomers react with each other to form an imidazolium-bridged dinucleotide intermediate, which then binds to the template. Subsequent attack of the 3′-hydroxyl of the primer displaces an activated nucleotide as the leaving group and results in extension of the primer by one nucleotide. Analysis of monomer solutions by NMR indicates formation of the proposed imidazolium-bridged dinucleotide in the expected pH-dependent manner. We have used synthetic methods to prepare material that is enriched in this proposed intermediate and show that it is a highly reactive substrate for primer extension. The formation of an imidazolium-bridged dinucleotide intermediate provides a mechanistic interpretation of previously observed catalysis by an activated nucleotide located downstream from the site of primer extension.
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影响因子：
15
作者：
Li, Li;Lelyveld, Victor S.;Szostak, Jack W.
通讯作者：
Szostak, Jack W.
影响因子：
15
作者：
WU, TF;ORGEL, LE
通讯作者：
ORGEL, LE
影响因子：
15
作者：
Zhu TF;Szostak JW
通讯作者：
Szostak JW
离开组对DNA和RNA无酶复制中的结合和反应性的影响。
影响因子：
14.9
作者：
Kervio E;Sosson M;Richert C
通讯作者：
Richert C
影响因子：
15
作者：
Heuberger BD;Pal A;Del Frate F;Topkar VV;Szostak JW
通讯作者：
Szostak JW