The early history of tRNA recognition by aminoacyl-tRNA synthetases
The early history of tRNA recognition by aminoacyl-tRNA synthetases
复制标题
DOI：
10.1007/bf02705187
复制
发表时间：
2006-10-01
影响因子：
2.9
通讯作者：
Giege, Richard
中科院分区：
文献类型：
--
作者：
Giege, Richard
本文将对氨基酰-tRNA合成酶的发现、这些酶对正确表达遗传密码的重要性以及早期结构数据和相关的酶学研究进行综述。尽管结构不同，但所有合成酶都遵循tRNA氨酰化的两步机制。然而，特异性并不是绝对的，因为合成酶被证明可以催化误充电反应。这些反应的特点是催化速率低，可能导致电荷水平不完全。同源tRNA氨酰化反应也可能发生不完全荷电，反映了正向酰化反应和反向脱酰反应(酶和化学)之间的平衡。将回顾描述给定tRNA中的结构特征的早期策略，这些结构特征解释了同源合成酶对tRNA的优先氨基酰化作用。其中包括(I)由同一合成酶识别的tRNA(RNAs)的序列比较，(Ii)修饰的tRNA的活性测量(通过化学或酶方法)和(Iii)从片段中重组活性的tRNA。结果，反密码子和tRNA氨基酸接受臂的重要性以及可被tRNA样结构模拟的整体tRNA结构的重要性被强调。总而言之，早期数据为现代身份认同概念提供了坚实的背景。
Discovery of aminoacyl-tRNA synthetases and importance of these enzymes for correct genetic code expression as well as early structural data and related enzymology will be reviewed. Despite structural diversity, all synthetases follow a two-step mechanism for tRNA aminoacylation. Specificity, however, is not absolute since synthetases were shown to catalyze mischarging reactions. These reactions are characterized by low catalytic rates and can lead to incomplete charging levels. Incomplete charging can also occur for cognate tRNA aminoacylation and reflects the equilibrium between the forward acylation and the reverse deacylation (enzymatic and chemical) reactions. Early strategies to characterize the structural features within a given tRNA that account for its preferential aminoacylation by the cognate synthetase will be reviewed. Among them were (i) sequence comparisons of tRNA (RNAs) recognized by a same synthetase,(ii) activity measurements of modified tRNAs (by chemical or enzymatic means) and (iii) reconstitutions of active tRNAs from fragments. As a result, the importance of anticodon and tRNA amino acid accepting arms were highlighted as well as that of the overall tRNA architecture that can be mimicked by tRNA-like structures. Altogether early data gave the robust background to the modern concept of identity.