Moazed D, Noller H F
Thimann Laboratories, University of California, Santa Cruz 95064.
Cell. 1989 May 19;57(4):585-97. doi: 10.1016/0092-8674(89)90128-1.
Three sets of conserved nucleotides in 23 rRNA are protected from chemical probes by binding of tRNA to the ribosomal A, P, and E sites, respectively. They are located almost exclusively in domain V, primarily in or adjacent to the loop identified with the peptidyl transferase function. Some of these sites are also protected by antibiotics such as chloramphenicol, which could explain how these drugs interfere with protein synthesis. Certain tRNA-dependent protections are abolished when the 3'-terminal A or CA or 2',3'-linked acyl group is removed, providing direct evidence for the interaction of the conserved CCA terminus of tRNA with 23S rRNA. When the EF-Tu.GTP.aminoacyl-tRNA ternary complex is bound to the ribosome, no tRNA-dependent A site protections are detected in 23S rRNA until EF-Tu is released. Thus, EF-Tu prevents interaction of the 3' terminus of the incoming aminoacyl-tRNA with the peptidyl transferase region of the ribosome during anticodon selection, thereby permitting translational proofreading.
23 rRNA中的三组保守核苷酸分别通过tRNA与核糖体A、P和E位点的结合而免受化学探针的作用。它们几乎完全位于结构域V中，主要位于与肽基转移酶功能相关的环内或其附近。其中一些位点也受到氯霉素等抗生素的保护，这可以解释这些药物如何干扰蛋白质合成。当tRNA的3'-末端A或CA或2',3'-连接的酰基被去除时，某些依赖于tRNA的保护作用就会消失，这为tRNA保守的CCA末端与23S rRNA的相互作用提供了直接证据。当EF-Tu·GTP·氨酰-tRNA三元复合物与核糖体结合时，在EF-Tu释放之前，在23S rRNA中未检测到依赖于tRNA的A位点保护作用。因此，EF-Tu在反密码子选择过程中阻止进入的氨酰-tRNA的3'末端与核糖体的肽基转移酶区域相互作用，从而允许翻译校对。
