Samuelsson T, Axberg T, Borén T, Lagerkvist U
J Biol Chem. 1983 Nov 10;258(21):13178-84.
We have used a protein-synthesizing in vitro system programmed with the phage message MS2-RNA to investigate the ability of glycyl-tRNAs with different anticodons to read the glycine codons. Under conditions of no competition, when the glycyl-tRNA analyzed was the only source of glycine for protein synthesis, each of the isoacceptors tested, tRNA1Gly (anticodon CCC), tRNA2Gly (anticodon N/UCC), tRNA3Gly (anticodon GCC) from Escherichia coli, and tRNAGly (anticodon UCC) from Mycoplasma mycoides, could read all of the glycine codons in the MS2 coat protein cistron (GGU, GGC, GGA, and GGG). However, tRNA1Gly seemed to have difficulties reading through the whole cistron. Experiments in which two glycyl-tRNAs competed for the same codon showed that the mycoplasma tRNAGly (anticodon UCC) was almost as efficient in the unorthodox reading of the codons GGU and GGC as it was in conventional reading. It would seem to be the only tRNAGly present in Mycoplasma mycoides and our results are consistent with this finding since the mycoplasma tRNAGly appears to have been designed to read all four glycine codons with approximately equal efficiency. The competition experiments furthermore showed that E. coli tRNA1Gly (anticodon CCC) reads the codon GGA more efficiently than it reads GGU and GGC suggesting that the mispair C . A between the wobble position of the anticodon and the third codon position might have appreciable stability.
我们利用一个用噬菌体信息MS2-RNA编程的体外蛋白质合成系统，来研究具有不同反密码子的甘氨酰-tRNA读取甘氨酸密码子的能力。在无竞争条件下，当所分析的甘氨酰-tRNA是蛋白质合成中甘氨酸的唯一来源时，所测试的每种同功受体，来自大肠杆菌的tRNA1Gly（反密码子CCC）、tRNA2Gly（反密码子N/UCC）、tRNA3Gly（反密码子GCC）以及来自蕈状支原体的tRNAGly（反密码子UCC），都能读取MS2外壳蛋白顺反子中的所有甘氨酸密码子（GGU、GGC、GGA和GGG）。然而，tRNA1Gly似乎在通读整个顺反子方面存在困难。两个甘氨酰-tRNA竞争相同密码子的实验表明，支原体tRNAGly（反密码子UCC）在非传统读取密码子GGU和GGC时的效率几乎与传统读取时相同。它似乎是蕈状支原体中唯一存在的tRNAGly，我们的结果与这一发现一致，因为支原体tRNAGly似乎被设计为以大致相同的效率读取所有四个甘氨酸密码子。竞争实验还表明，大肠杆菌tRNA1Gly（反密码子CCC）读取密码子GGA的效率高于读取GGU和GGC，这表明反密码子摆动位置与密码子第三位之间的错配C·A可能具有相当的稳定性。
