Background: The evolutionary pathway of tRNA established the linking of the genetic code and protein synthesis, thus, revealing the characteristics of the prebiotic tRNA is crucial for presenting a feasible scenario for the emergence of life. Results: Analysis of bacterial tRNA sequences reveals that for nine amino acids, mostly those considered to be the most ancient ones, the acceptor-TΨC arm carries cognate coding triplets far beyond statistical expectation. The contemporary determinants for the recognition of tRNAs and mini-helices by the cognate synthetases and by EF-Tu, are part of these conserved triplets. We also find a strong correlation between the extent of the coding triplet conservation and amino acids whose contemporary synthetases belong to class IIa. Conclusions: Identification of conserved coding triplets within the tRNA acceptor-TΨC stem, along with the analysis of their distinctive layout, is suggestive of a continuous evolutionary path that could have led to the appearance of the early translation system.

中文翻译：

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转移RNA受体臂中的编码三联体及其在目前和过去的tRNA识别中的作用

背景：tRNA的进化途径建立了遗传密码与蛋白质合成之间的联系，因此，揭示益生元tRNA的特征对于提出可行的生命出现场景至关重要。结果：对细菌tRNA序列的分析表明，对于9个氨基酸（大多数被认为是最古老的氨基酸），受体TΨC臂携带的同源编码三联体远远超出了统计预期。这些保守的三联体的一部分，是当代公认的同源合成酶和EF-Tu识别tRNA和小螺旋的决定因素。我们还发现编码三联体保守程度和其当代合成酶属于IIa类氨基酸之间有很强的相关性。结论：