A mechanism for the association of amino acids with their codons and the origin of the genetic code
A mechanism for the association of amino acids with their codons and the origin of the genetic code
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DOI：
10.1073/pnas.0501049102
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发表时间：
2005-03-22
影响因子：
11.1
通讯作者：
Morowitz, HJ
中科院分区：
文献类型：
--
作者：
Copley, SD;Smith, E;Morowitz, HJ
遗传密码具有某些无法用机械解释的规律。这些包括密码子的第一个碱基和合成编码的氨基酸的前体之间以及密码子的第二个碱基和编码的氨基酸的疏水性之间的强相关性。这些规律在将现代密码投影到由编码一组简单氨基酸的双联体密码子组成的更简单的代码上时更加引人注目。如果在大分子出现之前，简单的氨基酸是在二核苷酸与源自还原三羧酸循环或还原乙酸途径的α-酮酸的共价复合物中合成的，则可以解释这些规律。二核苷酸的碱基和磷酸盐被认为提高了小分子反应网络中产生氨基酸的合成反应的速率，该反应网络先于RNA翻译装置，但在氨基酸与其密码子的前两个碱基之间建立了关联，当翻译在进化过程中后期出现时，这种关联得以保留。
The genetic code has certain regularities that have resisted mechanistic interpretation. These include strong correlations between the first base of codons and the precursor from which the encoded amino acid is synthesized and between the second base of codons and the hydrophobicity of the encoded amino acid. These regularities are even more striking in a projection of the modern code onto a simpler code consisting of doublet codons encoding a set of simple amino acids. These regularities can be explained if, before the emergence of macromolecules, simple amino acids were synthesized in covalent complexes of dinucleotides with alpha-keto acids originating from the reductive tricarboxylic acid cycle or reductive acetate pathway. The bases and phosphates of the dinucleotide are proposed to have enhanced the rates of synthetic reactions leading to amino acids in a small-molecule reaction network that preceded the RNA translation apparatus but created an association between amino acids and the first two bases of their codons that was retained when translation emerged later in evolution.