Department of Molecular Biosciences , The University of Texas at Austin , Austin , Texas 78712 , United States.
Biochemistry. 2019 Mar 19;58(11):1460-1463. doi: 10.1021/acs.biochem.8b00834. Epub 2018 Nov 14.
One of the most remarkable, but typically unremarked, aspects of the translation apparatus is the pleiotropic pliability of tRNA. This humble cloverleaf/L-shaped molecule must implement the first genetic code, via base pairing and wobble interactions, but is also largely responsible for the specificity of the second genetic code, the pairings between amino acids, tRNA synthetases, and tRNAs. Despite the overarching similarities between tRNAs, they must nonetheless be specifically recognized by cognate tRNA synthetases and largely rejected by noncognate synthetases. Conversely, despite the differences between tRNAs that allow such discrimination, they must be uniformly accepted by the ribosome, in part via the machinations of the translation elongation factors, which work with a diverse coterie of tRNA-amino acid conjugates to balance binding and loading. While it is easy to ascribe both discrimination and acceptance to the individual proteins (synthetases and EF-Tu/eEF-1) that recognize tRNAs, there is a large body of evidence that suggests that the sequences, structures, and dynamics of tRNAs are instrumental in the choices these proteins make.
翻译机器最显著但通常未被注意到的特点之一是 tRNA 的多功能可塑性。这种谦逊的三叶草/L 形分子必须通过碱基配对和摆动相互作用来实现第一个遗传密码，但它也是第二个遗传密码特异性的主要原因，即氨基酸、tRNA 合成酶和 tRNA 之间的配对。尽管 tRNA 之间有总体相似性，但它们必须被同源 tRNA 合成酶特异性识别，并且被非同源合成酶大量拒绝。相反，尽管允许这种区分的 tRNA 之间存在差异，但它们必须被核糖体统一接受，部分原因是通过翻译延伸因子的巧妙设计，这些因子与各种 tRNA-氨基酸缀合物一起工作，以平衡结合和加载。虽然很容易将识别 tRNA 的单个蛋白质（合成酶和 EF-Tu/eEF-1）的区分和接受归因于它们，但有大量证据表明，tRNA 的序列、结构和动态在这些蛋白质做出的选择中起着重要作用。
