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首页> 美国卫生研究院文献>Proceedings of the National Academy of Sciences of the United States of America >Interactions between tRNA identity nucleotides and their recognition sites in glutaminyl-tRNA synthetase determine the cognate amino acid affinity of the enzyme.
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Interactions between tRNA identity nucleotides and their recognition sites in glutaminyl-tRNA synthetase determine the cognate amino acid affinity of the enzyme.

机译：tRNA同一性核苷酸与其在谷氨酰胺-tRNA合成酶中的识别位点之间的相互作用决定了该酶的同源氨基酸亲和力。

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摘要

Sequence-specific interactions between aminoacyl-tRNA synthetases and their cognate tRNAs both ensure accurate RNA recognition and prevent the binding of noncognate substrates. Here we show for Escherichia coli glutaminyl-tRNA synthetase (GlnRS; EC 6.1.1.18) that the accuracy of tRNA recognition also determines the efficiency of cognate amino acid recognition. Steady-state kinetics revealed that interactions between tRNA identity nucleotides and their recognition sites in the enzyme modulate the amino acid affinity of GlnRS. Perturbation of any of the protein-RNA interactions through mutation of either component led to considerable changes in glutamine affinity with the most marked effects seen at the discriminator base, the 10:25 base pair, and the anticodon. Reexamination of the identity set of tRNA(Gln) in the light of these results indicates that its constituents can be differentiated based upon biochemical function and their contribution to the apparent Gibbs' free energy of tRNA binding. Interactions with the acceptor stem act as strong determinants of tRNA specificity, with the discriminator base positioning the 3' end. The 10:25 base pair and U35 are apparently the major binding sites to GlnRS, with G36 contributing both to binding and recognition. Furthermore, we show that E. coli tryptophanyl-tRNA synthetase also displays tRNA-dependent changes in tryptophan affinity when charging a noncognate tRNA. The ability of tRNA to optimize amino acid recognition reveals a novel mechanism for maintaining translational fidelity and also provides a strong basis for the coevolution of tRNAs and their cognate synthetases.
机译：氨酰基-tRNA合成酶及其同源tRNA之间的序列特异性相互作用既可确保准确的RNA识别，又可防止非同源底物的结合。在这里，我们显示了大肠杆菌的谷氨酰胺基tRNA合成酶（GlnRS; EC 6.1.1.18），tRNA识别的准确性也决定了同源氨基酸识别的效率。稳态动力学表明，tRNA身份核苷酸及其在酶中的识别位点之间的相互作用调节了GlnRS的氨基酸亲和力。通过任一种组分的突变而引起的任何蛋白质-RNA相互作用的扰动都会导致谷氨酰胺亲和力发生显着变化，其中在区分基，10：25碱基对和反密码子上的作用最为明显。根据这些结果，对tRNA（Gln）身份集合的重新检查表明，可以根据生化功能及其对tRNA结合的表观吉布斯自由能的贡献来区分其成分。与受体茎的相互作用是tRNA特异性的重要决定因素，区分基位于3'端。 10:25碱基对和U35显然是GlnRS的主要结合位点，而G36既促进了结合又促进了识别。此外，我们显示，当对非同源tRNA充电时，大肠杆菌色氨酸tRNA合成酶还显示出色氨酸亲和力中依赖tRNA的变化。 tRNA优化氨基酸识别的能力揭示了维持翻译保真度的新机制，也为tRNA及其同源合成的协同进化提供了坚实的基础。

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