Smith D, Yarus M
Department of Molecular, Cellular, University of Colorado, Boulder 80309-0347.
Proc Natl Acad Sci U S A. 1989 Jun;86(12):4397-401. doi: 10.1073/pnas.86.12.4397.
We describe an assay that converts the effects of tRNA-tRNA contacts at two particular codons into a quantitative effect on beta-galactosidase level. The assay measures the separate and combined efficiency of suppression at adjacent nonsense codons in vivo using a set of specially created homologous messages. In a survey of distal anticodon arm substitutions, we find that particular mutant tRNAs occupying the P-site reduce the apparent efficiency of the suppressor tRNA reading the A-site codon by factors of 2-170. By using measured tRNA-tRNA distances and the crystallographic tRNA structure, we propose a model of the tRNA-tRNA-mRNA complex. In the model, the anticodon loops of the P-site and A-site tRNAs contact one another in a way that is consistent with our combined tRNA efficiency data. These results suggest that tRNA-tRNA interactions that modulate tRNA action are an inevitable feature of translation.
我们描述了一种检测方法，该方法可将两个特定密码子处tRNA-tRNA相互作用的效应转化为对β-半乳糖苷酶水平的定量效应。该检测方法使用一组特别构建的同源信使RNA，在体内测量相邻无义密码子处抑制作用的单独效率和综合效率。在对远端反密码子臂替代的研究中，我们发现占据P位点的特定突变tRNA会使读取A位点密码子的抑制性tRNA的表观效率降低2至170倍。通过使用测量的tRNA-tRNA距离和晶体学tRNA结构，我们提出了一个tRNA-tRNA-mRNA复合物模型。在该模型中，P位点和A位点tRNA的反密码子环以与我们的tRNA综合效率数据一致的方式相互接触。这些结果表明，调节tRNA作用的tRNA-tRNA相互作用是翻译过程中不可避免的特征。
