Moazed D, Robertson J M, Noller H F
Thimann Laboratories, University of California, Santa Cruz 95064.
Nature. 1988 Jul 28;334(6180):362-4. doi: 10.1038/334362a0.
The elongation factors EF-Tu and EF-G interact with ribosomes during protein synthesis: EF-Tu presents incoming aminoacyl transfer RNA to the programmed ribosome as an EF-Tu-GTP-tRNA ternary complex and EF-G promotes translocation of peptidyl-tRNA and its associated messenger RNA from the A to the P site after peptidyl transfer. Both events are accompanied by ribosome-dependent GTP hydrolysis. Here we use chemical probes to investigate the possible interaction of these factors with ribosomal RNA in E. coli ribosomes. We observe EF-G-dependent footprints in vitro and in vivo around position 1,067 in domain II of 23S rRNA, and in the loop around position 2,660 in domain VI.EF-Tu gives an overlapping footprint in vitro at positions 2,655 and 2,661, but shows no effect at position 1,067. The 1,067 region is the site of interaction of the antibiotic thiostrepton, which prevents formation of the EF-G-GTP-ribosome complex and is a site for interaction with the GTPase-related protein L11 (ref. 3). The universally conserved loop in the 2,660 region is the site of attack by the RNA-directed cytotoxins alpha-sarcin and ricin, whose effects abolish translation and include the loss of elongation factor-dependent functions in eukaryotic ribosomes.
延伸因子EF-Tu和EF-G在蛋白质合成过程中与核糖体相互作用：EF-Tu以EF-Tu-GTP- tRNA三元复合物的形式将进入的氨酰基转移RNA呈递给已编程的核糖体，而EF-G在肽基转移后促进肽基-tRNA及其相关信使RNA从A位点转移到P位点。这两个过程都伴随着核糖体依赖性的GTP水解。在这里，我们使用化学探针来研究这些因子与大肠杆菌核糖体中核糖体RNA可能的相互作用。我们在体外和体内观察到23S rRNA结构域II中1067位附近以及结构域VI中2660位附近的环上存在EF-G依赖性足迹。EF-Tu在体外2655位和2661位给出重叠足迹，但在1067位没有影响。1067区域是抗生素硫链丝菌素的相互作用位点，硫链丝菌素可阻止EF-G-GTP-核糖体复合物的形成，并且是与GTPase相关蛋白L11相互作用的位点（参考文献3）。2660区域中普遍保守的环是RNA导向的细胞毒素α-链霉溶素和蓖麻毒素的作用位点，它们的作用会消除翻译，并导致真核核糖体中延伸因子依赖性功能丧失。
