Regioselective formation of RNA strands in the absence of magnesium ions
Regioselective formation of RNA strands in the absence of magnesium ions
复制标题
DOI：
10.1093/nar/gkz1125
复制
发表时间：
2020-02-20
影响因子：
14.9
通讯作者：
Richert, Clemens
中科院分区：
文献类型：
--
作者：
Motsch, Sebastian;Tremmel, Peter;Richert, Clemens
核糖核苷酸的寡聚可以在没有酶的情况下产生短RNA链。该反应产生两个区域异构磷酸二酯键之一，2',5'-或3',5'-二酯。前者的非天然连接对于双链体稳定性是有害的，并且已知在存在镁阳离子的情况下优先在均相溶液中与预活化的核苷酸发生的寡聚化中形成。我们使用核磁共振作为监测技术，研究了原位激活的核糖核苷酸寡聚化。出乎意料的是，在弱碱性 pH 条件下，在不存在镁离子的情况下，AMP 寡聚中已知的 2',5'-连接偏好被逆转。此外，在不存在 Mg2+ 盐的情况下，低聚反应出人意料地有效，产生足够长的低聚物以形成双链体。然后定量系统化学分析表明，镁离子的缺失有利于核苷酸的激活，并且高浓度的活性物质可以补偿较慢的偶联。此外，有机催化中间体可以帮助克服镁催化反应的不利区域选择性。我们的研究结果消除了人们对于在没有酶的情况下 RNA 可能难以形成的担忧。他们还表明，存在一种获取遗传物质的有效途径，不需要已知的矿物表面或已知催化 RNA 水解的阳离子。
The oligomerization of ribonucleotides can produce short RNA strands in the absence of enzymes. This reaction gives one of two regioisomeric phosphodiester linkages, a 2',5'- or a 3',5'-diester. The former, non-natural linkage is detrimental for duplex stability, and is known to form preferentially in oligomerizations occurring in homogeneous solution with preactivated nucleotides in the presence of magnesium cations. We have studied ribonucleotide oligomerization with in situ activation, using NMR as monitoring technique. Unexpectedly, the known preference for 2',5'-linkages in the oligomerization of AMP was reversed in the absence of magnesium ions at slightly basic pH. Further, oligomerization was surprisingly efficient in the absence of Mg2+ salts, producing oligomers long enough for duplex formation. A quantitative systems chemistry analysis then revealed that the absence of magnesium ions favors the activation of nucleotides, and that the high concentration of active species can compensate for slower coupling. Further, organocatalytic intermediates can help to overcome the unfavorable regioselectivity of the magnesium-catalyzed reactions. Our findings allay concerns that RNA may have been difficult to form in the absence of enzymes. They also show that there is an efficient path to genetic material that does not require mineral surfaces or cations known to catalyze RNA hydrolysis.