Génétique Moléculaire, Génomique, Microbiologie, UMR 7156, CNRS, Université de Strasbourg, Strasbourg, France.
Génétique Moléculaire, Génomique, Microbiologie, UMR 7156, CNRS, Université de Strasbourg, Strasbourg, France.
Enzymes. 2020;48:117-147. doi: 10.1016/bs.enz.2020.04.003. Epub 2020 Jun 12.
The aminoacylation reaction is one of most extensively studied cellular processes. The so-called "canonical" reaction is carried out by direct charging of an amino acid (aa) onto its corresponding transfer RNA (tRNA) by the cognate aminoacyl-tRNA synthetase (aaRS), and the canonical usage of the aminoacylated tRNA (aa-tRNA) is to translate a messenger RNA codon in a translating ribosome. However, four out of the 22 genetically-encoded aa are made "noncanonically" through a two-step or indirect route that usually compensate for a missing aaRS. Additionally, from the 22 proteinogenic aa, 13 are noncanonically used, by serving as substrates for the tRNA- or aa-tRNA-dependent synthesis of other cellular components. These nontranslational processes range from lipid aminoacylation, and heme, aa, antibiotic and peptidoglycan synthesis to protein degradation. This chapter focuses on these noncanonical usages of aa-tRNAs and the ways of generating them, and also highlights the strategies that cells have evolved to balance the use of aa-tRNAs between protein synthesis and synthesis of other cellular components.
氨酰化反应是研究最广泛的细胞过程之一。所谓的“经典”反应是由同源氨酰-tRNA 合成酶（aaRS）直接将氨基酸（aa）加载到其相应的转移 RNA（tRNA）上进行的，而氨酰化 tRNA（aa-tRNA）的经典用途是在翻译核糖体中翻译信使 RNA 密码子。然而，在这 22 种遗传编码的 aa 中，有 4 种是通过两步或间接途径“非经典”产生的，通常是为了弥补缺失的 aaRS。此外，在这 22 种蛋白质 aa 中，有 13 种被非经典地使用，作为 tRNA 或 aa-tRNA 依赖性合成其他细胞成分的底物。这些非翻译过程的范围从脂质氨酰化、血红素、aa、抗生素和肽聚糖合成到蛋白质降解。本章重点介绍 aa-tRNA 的这些非经典用途和产生它们的方法，并强调细胞为平衡蛋白质合成和其他细胞成分合成之间的 aa-tRNA 利用而进化出的策略。
