A Simple Template-Dependent Ligase Ribozyme as the RNA Replicase Emerging First in the RNA World
A Simple Template-Dependent Ligase Ribozyme as the RNA Replicase Emerging First in the RNA World
复制标题
一种简单的模板依赖性连接酶核酶作为 RNA 复制酶首次出现在 RNA 领域
DOI：
10.1089/ast.2009.0385
复制
发表时间：
2010-05-01
期刊：
影响因子：
4.2
通讯作者：
Hu, Jiming
中科院分区：
文献类型：
--
作者：
Ma, Wentao;Yu, Chunwu;Hu, Jiming
“RNA世界”假说为生命起源领域的实验和理论工作提供了一个框架。关于这一假说的一个重要问题是RNA世界是如何起源的。长期以来，人们一直推测，一种依赖模板的RNA合成酶核酶应该首先出现，这种核酶催化了自身的复制（因此称为“RNA复制酶”）。然而，迄今为止，对这种复制酶的实验研究尚未成功。这主要是因为候选核酶的大序列长度，主要以聚合酶的方式起作用。在这里，我们提出，首先出现的复制酶可能是一种简单的模板依赖性连接酶核酶，它与模板RNA松散结合，催化相邻排列的核苷酸或寡核苷酸之间形成磷酸二酯键的效率相对较低。我们进行了计算机模拟来支持这一建议，并根据模拟中的参数分析考虑了可能影响核酶出现的因素。我们得出结论：(1)在rna复制的出现中，模板依赖性连接酶可能比模板依赖性聚合酶更有可能作为早期复制酶；(2)在我们的模型中，这种连接酶核酶可以在很宽的参数范围内出现并稳定地对抗寄生虫；(3)有利于模板依赖性连接酶核酶最初出现的条件不利于其扩散。
The "RNA world'' hypothesis has offered a framework for both experimental and theoretical work in the field of the origin of life. An important concern about the hypothesis is how the RNA world could originate. It has long been speculated that a template-dependent RNA synthetase ribozyme, which catalyzed its own replication (thus, an "RNA replicase''), should have emerged first. However, experimental searches for such a replicase have so far been unsuccessful. This is primarily because of the large sequence length of candidate ribozymes, which mainly work in a polymerase-like way. Here, we propose that the replicase that emerged first would be a simple template-dependent ligase ribozyme, which loosely binds to template RNA and has a relatively low efficiency of catalyzing the formation of phosphodiester bonds between adjacently aligned nucleotides or oligonucleotides. We conducted a computer simulation to support this proposal and considered the factors that might affect the emergence of the ribozyme based on the parameter analysis in the simulation. We conclude that (1) a template-dependent ligase may be more likely than a template-dependent polymerase as an early replicase in the emergence of RNA-based replication; (2) such a ligase ribozyme could emerge and be stable against parasites under a broad range of parameters in our model; (3) the conditions shown to favor the initial appearance of a template-dependent ligase ribozyme do not favor its spread.