Claesson C, Lustig F, Borén T, Simonsson C, Barciszewska M, Lagerkvist U
Department of Medical Biochemistry, University of Göteborg, Sweden.
J Mol Biol. 1995 Mar 24;247(2):191-6. doi: 10.1006/jmbi.1994.0132.
Using an in vitro protein-synthesizing system that allowed us to monitor separately the reading of each glycine codon, we have previously shown, that in constructs based on glycine tRNA1 from Escherichia coli the nature of the nucleotide in position 32 determines the ability of the anticodon UCC to discriminate between the glycine codons. Thus, with a U in position 32 the anticodon UCC discriminated according to the wobble rules, but with a C in this position it had lost its ability to discriminate. In the present paper we show that the same is true also for constructs based on mycoplasma glycine tRNA. When C32 in the wild type was changed to U32, the anticodon UCC discriminated between the glycine codons, while in wild type mycoplasma glycine tRNA it did not. Furthermore, when U32 was changed to C32 in glycine tRNA1(CCC), the anticodon CCC loses its ability to discriminate. We therefore conclude that the nature of the nucleotide in position 32 determines the discriminatory ability of both anticodons UCC and CCC in the glycine tRNA1 structural background, and that the same is true for the anticodon UCC in the mycoplasma glycine tRNA background.
利用一种体外蛋白质合成系统，使我们能够分别监测每个甘氨酸密码子的读取情况，我们先前已表明，在基于大肠杆菌甘氨酸tRNA1构建的结构中，第32位核苷酸的性质决定了反密码子UCC区分甘氨酸密码子的能力。因此，当第32位为U时，反密码子UCC根据摆动规则进行区分，但当该位置为C时，它就失去了区分能力。在本文中，我们表明基于支原体甘氨酸tRNA构建的结构也是如此。当野生型中的C32变为U32时，反密码子UCC能够区分甘氨酸密码子，而在野生型支原体甘氨酸tRNA中则不能。此外，当甘氨酸tRNA1(CCC)中的U32变为C32时，反密码子CCC失去了区分能力。因此，我们得出结论，第32位核苷酸的性质决定了甘氨酸tRNA1结构背景下反密码子UCC和CCC的区分能力，对于支原体甘氨酸tRNA背景下的反密码子UCC也是如此。
