Thompson R C, Stone P J
Proc Natl Acad Sci U S A. 1977 Jan;74(1):198-202. doi: 10.1073/pnas.74.1.198.
The fidelity of protein synthesis is substantially greater than the specificity of codon-anticodon recognition that would be expected from the known energetics of base-pairing in solution. To test the suggestion that the specificity of recognition may be increased by "kinetic proofreading" associated with GTP hydrolysis [J. J. Hopfield (1974) Proc. Natl. Acad. Sci. USA 71, 4135-4139], we have studied the interaction of ternary complexes of polypeptide elongation factor Tu, aminoacyl-tRNA, and GTP with poly(U)-programed ribosomes. With most noncognate ternary complexes, including two that pair correctly with the 5' and 3' bases of UUU, rejection occurred without GTP hydrolysis, presumably by the reverse of the initial binding reaction. However, with complexes containing Leu- or Ile-tRNAs, which may pair correctly with the 3' and middle bases, GTP hydrolysis was stimulated though the aa-tRNA was not retained on the ribosome. These results demonstrate the existence of a GTP-dependent proofreading step in aminoacyl-tRNA recognition on ribosomes. They also suggest that the 5' base of the codon is more prone than the middle base to errors that can be corrected by proofreading.
蛋白质合成的保真度远高于根据溶液中碱基配对已知能量学所预期的密码子 - 反密码子识别特异性。为了检验关于识别特异性可能通过与GTP水解相关的“动力学校对”而提高的观点[J. J. 霍普菲尔德（1974年）《美国国家科学院院刊》71, 4135 - 4139]，我们研究了多肽延伸因子Tu、氨酰 - tRNA和GTP的三元复合物与聚（U）编程核糖体的相互作用。对于大多数非同源三元复合物，包括两个能与UUU的5'和3'碱基正确配对的复合物，在没有GTP水解的情况下就发生了排斥，推测是通过初始结合反应的逆向进行。然而，对于含有亮氨酸或异亮氨酸tRNA的复合物，它们可能与3'和中间碱基正确配对，尽管氨酰 - tRNA没有保留在核糖体上，但GTP水解受到了刺激。这些结果证明在核糖体上氨酰 - tRNA识别过程中存在一个依赖GTP的校对步骤。它们还表明密码子的5'碱基比中间碱基更容易出现可通过校对纠正的错误。
