Tag mechanism as a strategy for the RNA replicase to resist parasites in the RNA world.
Tag mechanism as a strategy for the RNA replicase to resist parasites in the RNA world.
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标签机制作为RNA复制酶抵抗RNA世界寄生虫的策略
DOI：
10.1371/journal.pone.0172702
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Ma W
中科院分区：
文献类型：
--
作者：
Wu S;Yu C;Zhang W;Yin S;Chen Y;Feng Y;Ma W
生命可能始于“RNA 世界”的想法很有吸引力。其中，一个关键事件（也许在场景的一开始）应该是催化自身复制的核酶（即RNA复制酶）的出现。尽管现在有实验证据支持这种核酶的化学可行性，但复制酶如何克服“寄生虫”问题（因为其他 RNA 也可能利用这种核酶）并蓬勃发展（如场景中所述）的进化动力学仍不清楚。有人认为，空间限制对于复制酶对抗寄生虫可能很重要。然而，更多的研究表明，当充分考虑这种核酶的利他特性时，这种机制是不够的。 “标签机制”，即用短子序列标记复制酶以供复制时识别，可能是支持复制酶繁荣的另一种机制。然而，由于寄生虫也可能给自己“装备”上标签，因此标签机制是否能发挥作用尚不清楚。在这里，我们使用蒙特卡罗模型进行了计算机模拟，以研究 RNA 世界中标签驱动（聚合酶型）RNA 复制酶发展的进化动力学。我们得出的结论是：（1）借助标签机制，复制酶能够抵抗寄生虫并繁盛起来；（2）其根本原因应该是寄生分子，特别是强寄生虫更难出现在标签驱动的系统中；（3）标签机制与空间限制机制具有协同作用——前者为复制酶逃离寄生虫提供“时间”，后者为复制酶逃离寄生虫提供“空间”。值得注意的是，标签可以很容易地充当“控制手柄”，一旦标签机制被利用，向复杂生命的进化可能会容易得多。
The idea that life may have started with an “RNA world” is attractive. Wherein, a crucial event (perhaps at the very beginning of the scenario) should have been the emergence of a ribozyme that catalyzes its own replication, i.e., an RNA replicase. Although now there is experimental evidence supporting the chemical feasibility of such a ribozyme, the evolutionary dynamics of how the replicase could overcome the “parasite” problem (because other RNAs may also exploit this ribozyme) and thrive, as described in the scenario, remains unclear. It has been suggested that spatial limitation may have been important for the replicase to confront parasites. However, more studies showed that such a mechanism is not sufficient when this ribozyme’s altruistic trait is taken into full consideration. “Tag mechanism”, which means labeling the replicase with a short subsequence for recognition in replication, may be a further mechanism supporting the thriving of the replicase. However, because parasites may also “equip” themselves with the tag, it is far from clear whether the tag mechanism could take effect. Here, we conducted a computer simulation using a Monte-Carlo model to study the evolutionary dynamics surrounding the development of a tag-driven (polymerase-type) RNA replicase in the RNA world. We concluded that (1) with the tag mechanism the replicase could resist the parasites and become prosperous, (2) the main underlying reason should be that the parasitic molecules, especially those strong parasites, are more difficult to appear in the tag-driven system, and (3) the tag mechanism has a synergic effect with the spatial limitation mechanism–while the former provides “time” for the replicase to escape from parasites, the latter provides “space” for the replicase to escape. Notably, tags may readily serve as “control handles”, and once the tag mechanism was exploited, the evolution towards complex life may have been much easier.