The scenario on the origin of translation in the RNA world: in principle of replication parsimony.
The scenario on the origin of translation in the RNA world: in principle of replication parsimony.
复制标题
RNA世界中翻译起源的情景：复制简约原则
DOI：
10.1186/1745-6150-5-65
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发表时间：
2010-11-27
期刊：
影响因子：
5.5
通讯作者：
Ma W
中科院分区：
文献类型：
--
作者：
Ma W
背景现在人们认为，在生命的起源中，蛋白质应该是在RNA世界中“发明”的。然而，由于一个可能的基于RNA的原翻译系统的复杂性，这个进化过程似乎相当复杂，相关的场景仍然非常模糊。考虑到RNA可以特异性地结合氨基酸，已经合理地假设初始肽可能已经在含有多个氨基酸结合位点的“RNA模板”上合成。这种“直接RNA模板（DRT）”机制是有吸引力的，因为它应该是RNA合成肽的最简单机制，因此很可能最初在RNA世界中被采用。假设的提出在此，考虑到“复制简约性”原理--遗传信息在选择压力下倾向于以简约的方式被利用，由于其复制成本（例如，在RNA世界中，用于RNA复制的核苷酸和核酶）。因为即使对于短肽，DRT也会相当长，所以其复制成本将是巨大的。因此，DRT机制合成的功能肽的多样性和长度将受到严重限制。衔接子（原tRNA）的出现使DRT的互补链（这里称为“C-DRT”）能够指导DRT自身合成的相同肽的合成。由于C-DRT是DRT复制的必要部分，因此合成功能肽的确定拷贝所需的DRT复制次数较少，从而节省了复制成本。通过衔接子的作用，C-DRT可以转化为更短的模板（这里称为“原mRNA”），并取代DRT的作用，从而显着节省复制成本。对应于小亚基rRNA的原rRNA随后将出现以帮助原tRNA和原mRNA的结合，允许减少它们之间的碱基对（最终导致三联体反密码子/密码子对），从而进一步节省复制成本。在这种情况下，节省的复制成本将允许出现更多和更长的功能肽，最后是蛋白质。这一假说可称为“DRT-RP”假说。（“RP”代表“复制简约性”）。验证假设这里描述的场景对一些关键场景的实验工作是开放的，包括紧凑的DRT机制，从aa-适体开发衔接子，在没有原rRNA参与的情况下由原tRNA和原mRNA合成肽等。有趣的是，最近的一项计算机模拟研究表明，在这种情况下，复制简约性驱动的进化过程之一是可行的。假设的含义一个基于RNA的原型翻译系统可以根据“复制简约性”原理从DRT机制中逐渐产生-以节省功能肽的RNA模板的复制成本。一个令人惊讶的推论是，复杂的生物合成氨基酸可能比简单的益生元氨基酸更早进入遗传密码，这与常识相反。总的来说，目前的讨论澄清了关于翻译起源的模糊场景，它生动地展示了生命如何“管理”利用自然界中潜在的化学资源，最终以一种有效的方式超过进化。
BackgroundIt is now believed that in the origin of life, proteins should have been "invented" in an RNA world. However, due to the complexity of a possible RNA-based proto-translation system, this evolving process seems quite complicated and the associated scenario remains very blurry. Considering that RNA can bind amino acids with specificity, it has been reasonably supposed that initial peptides might have been synthesized on "RNA templates" containing multiple amino acid binding sites. This "Direct RNA Template (DRT)" mechanism is attractive because it should be the simplest mechanism for RNA to synthesize peptides, thus very likely to have been adopted initially in the RNA world. Then, how this mechanism could develop into a proto-translation system mechanism is an interesting problem.Presentation of the hypothesisHere an explanation to this problem is shown considering the principle of "replication parsimony" --- genetic information tends to be utilized in a parsimonious way under selection pressure, due to its replication cost (e.g., in the RNA world, nucleotides and ribozymes for RNA replication). Because a DRT would be quite long even for a short peptide, its replication cost would be great. Thus the diversity and the length of functional peptides synthesized by the DRT mechanism would be seriously limited. Adaptors (proto-tRNAs) would arise to allow a DRT's complementary strand (called "C-DRT" here) to direct the synthesis of the same peptide synthesized by the DRT itself. Because the C-DRT is a necessary part in the DRT's replication, fewer turns of the DRT's replication would be needed to synthesize definite copies of the functional peptide, thus saving the replication cost. Acting through adaptors, C-DRTs could transform into much shorter templates (called "proto-mRNAs" here) and substitute the role of DRTs, thus significantly saving the replication cost. A proto-rRNA corresponding to the small subunit rRNA would then emerge to aid the binding of proto-tRNAs and proto-mRNAs, allowing the reduction of base pairs between them (ultimately resulting in the triplet anticodon/codon pair), thus further saving the replication cost. In this context, the replication cost saved would allow the appearance of more and longer functional peptides and, finally, proteins. The hypothesis could be called "DRT-RP" ("RP" for "replication parsimony").Testing the hypothesisThe scenario described here is open for experimental work at some key scenes, including the compact DRT mechanism, the development of adaptors from aa-aptamers, the synthesis of peptides by proto-tRNAs and proto-mRNAs without the participation of proto-rRNAs, etc. Interestingly, a recent computer simulation study has demonstrated the plausibility of one of the evolving processes driven by replication parsimony in the scenario.Implication of the hypothesisAn RNA-based proto-translation system could arise gradually from the DRT mechanism according to the principle of "replication parsimony" --- to save the replication cost of RNA templates for functional peptides. A surprising side deduction along the logic of the hypothesis is that complex, biosynthetic amino acids might have entered the genetic code earlier than simple, prebiotic amino acids, which is opposite to the common sense. Overall, the present discussion clarifies the blurry scenario concerning the origin of translation with a major clue, which shows vividly how life could "manage" to exploit potential chemical resources in nature, eventually in an efficient way over evolution …
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影响因子：
5.6
作者：
CRICK, FHC
通讯作者：
CRICK, FHC
影响因子：
3.9
作者：
Freeland, SJ;Hurst, LD
通讯作者：
Hurst, LD
影响因子：
14.9
作者：
Geiger, A;Burgstaller, P;Famulok, M
通讯作者：
Famulok, M
影响因子：
4.5
作者：
Janas, Teresa;Widmann, Jeremy Joseph;Yarus, Michael
通讯作者：
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DOI：
10.1023/a:1022627311114
发表时间：
2003-01-01
期刊：
Journal of Structural and Functional Genomics
影响因子：
--
作者：
Brosius, Juergen
通讯作者：
Brosius, Juergen