Evolution of the genetic code: The ambiguity-reduction theory
Evolution of the genetic code: The ambiguity-reduction theory
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DOI：
10.1016/j.biosystems.2019.104024
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发表时间：
2019-11-01
期刊：
影响因子：
1.6
通讯作者：
Barbieri, Marcello
中科院分区：
文献类型：
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作者：
Barbieri, Marcello
实验证据表明，遗传密码是基于任意的或传统的规则，在这个意义上，任何密码子都可以与任何氨基酸相关联，这意味着它们之间没有确定的联系。这与立体化学理论的传统范式形成鲜明对比，后者声称遗传密码的规则是由化学决定的，更确切地说是由密码子和氨基酸之间的立体化学亲和力决定的。另一方面，遗传密码是基于任意规则的这一发现提出了一个令人生畏的问题：自然界中怎么会存在这样的规则？为了解决这个问题，有人指出，任意法典的规则不可能完全形成。换句话说，第一个遗传密码必然是模糊的，它的进化是通过一种系统地减少模糊性并最终消除模糊性的机制进行的，模糊性减少的概念在科学文献中被反复提及，但很少有论文真正解决其机制问题。其中一篇论文以核糖体导向模型的名义发表，以强调核糖体蛋白在这一过程中的关键作用，但后来很明显，必须考虑其他因素。这就是为什么核糖体导向模型必须扩展，这里提出了一个更一般的版本，称为模糊性减少理论。
The experimental evidence has shown that the genetic code is based on arbitrary, or conventional, rules, in the sense that any codon can be associated to any amino acid, and this means that there is no deterministic link between them. This is in sharp contrast with the traditional paradigm of the stereochemical theory, which claims that the rules of the genetic code were determined by chemistry, and more precisely by stereochemical affinities between codons and amino acids. The discovery that the genetic code is based on arbitrary rules, on the other hand, raised a formidable problem: how can such rules exist in Nature? In order to deal with this problem, it has been pointed out that the rules of an arbitrary code could not come fully formed into existence. The first genetic code, in other words, was necessarily ambiguous, and its evolution took place with a mechanism that systematically reduced its ambiguity and eventually removed it. The concept of ambiguity-reduction has been repeatedly mentioned in the scientific literature, but very few papers have actually addressed the problem of its mechanism. One of these papers was published with the name of ribosome-oriented model in order to underline the key role that the ribosomal proteins had in that process, but later on it became clear that other factors had to be taken into account. This is why the ribosome-oriented model had to be extended and here a more general version is proposed with the name of ambiguity-reduction theory.