Wu X Q, Gross H J
Institut für Biochemie, Bayerische Julius-Maximilians-Universität, Biozentrum, Würzburg, Germany.
Nucleic Acids Res. 1993 Dec 11;21(24):5589-94. doi: 10.1093/nar/21.24.5589.
Selenocysteine tRNA [tRNA((Ser)Sec)] is charged with serine by the same seryl-tRNA synthetase (SerRS) as the canonical serine tRNAs. Using site-directed mutagenesis, we have introduced a series of mutations into human tRNA((Ser)Sec) and tRNA(Ser) in order to study the identity elements of tRNA((Ser)Sec) for serylation and the effect of the orientation of the extra arm. Our results show that the long extra arm is one of the major identity elements for both tRNA(Ser) and tRNA((Ser)Sec) and gel retardation assays reveal that it appears to be a prerequisite for binding to the cognate synthetase. The long extra arm functions in an orientation-dependent, but not in a sequence-specific manner. The discriminator base G73 is another important identity element of tRNA((Ser)Sec), whereas the T- and D-arms play a minor role for the serylation efficiency.
硒代半胱氨酸转运RNA [tRNA((Ser)Sec)] 与典型的丝氨酸转运RNA一样，由同一种丝氨酰转运RNA合成酶（SerRS）将丝氨酸装载到其上。我们利用定点诱变技术，在人tRNA((Ser)Sec) 和tRNA(Ser) 中引入了一系列突变，以研究tRNA((Ser)Sec) 用于丝氨酰化的识别元件以及额外臂方向的影响。我们的结果表明，长的额外臂是tRNA(Ser) 和tRNA((Ser)Sec) 的主要识别元件之一，凝胶阻滞分析显示，它似乎是与同源合成酶结合的一个先决条件。长的额外臂以方向依赖但非序列特异性的方式发挥作用。鉴别碱基G73是tRNA((Ser)Sec) 的另一个重要识别元件，而T臂和D臂对丝氨酰化效率的作用较小。
