Kurland C G, Rigler R, Ehrenberg M, Blomberg C
Proc Natl Acad Sci U S A. 1975 Nov;72(11):4248-51. doi: 10.1073/pnas.72.11.4248.
We suggest that the interaction between a codon and its cognate tRNA induces conformational changes in the tRNA. We further suggest that sites on the ribosome preferentially bind tRNA in those conformations which require proper matching of codon and anticodon. According to this model, the codon functions as an allosteric effector which influences the conformation at various sites in the tRNA. This is made possible by the ribosome, which we suggest traps tRNA molecules in those conformation states that maximize the energy difference between cognate and noncognate codon-anticodon interactions. Studies of the interactions between tRNA molecules and their cognate codons in the absence of the ribosome have suggested that triplet-triplet interaction between codon and anticodon is far too weak to account for the specificity of the tRNA selection mechanism during protein synthesis. In contrast, we suggest that such affinity measurements do not adequately describe the interaction between a codon and its cognate tRNA. Thus, such experiments can not detect conformational changes in the tRNA, and, in particular, those stabilized by the ribosome.
我们认为密码子与其同源tRNA之间的相互作用会诱导tRNA发生构象变化。我们进一步认为，核糖体上的位点优先结合处于需要密码子和反密码子正确匹配构象的tRNA。根据该模型，密码子作为一种别构效应物，影响tRNA不同位点的构象。核糖体使得这成为可能，我们认为核糖体将tRNA分子捕获在那些能使同源和非同源密码子-反密码子相互作用的能量差异最大化的构象状态中。在没有核糖体的情况下对tRNA分子与其同源密码子之间相互作用的研究表明，密码子和反密码子之间的三联体-三联体相互作用太弱，无法解释蛋白质合成过程中tRNA选择机制的特异性。相比之下，我们认为这种亲和力测量不能充分描述密码子与其同源tRNA之间的相互作用。因此，此类实验无法检测到tRNA的构象变化，尤其是那些由核糖体稳定的构象变化。
