Selection of tRNA by the ribosome requires a transition from an open to a closed form
Selection of tRNA by the ribosome requires a transition from an open to a closed form
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DOI：
10.1016/s0092-8674(02)01086-3
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发表时间：
2002-11-27
期刊：
影响因子：
64.5
通讯作者：
Ramakrishnan, V
中科院分区：
文献类型：
--
作者：
Ogle, JM;Murphy, FV;Ramakrishnan, V
核糖体选择 tRNA 的结构和机制解释一直难以捉摸。在这里，我们报告了 30S 核糖体亚基的晶体结构，其中密码子和近同源 tRNA 反密码子茎环结合在解码中心，并比较了溶液中等效复合物的亲和力。在核糖体与近同源 tRNA 的相互作用中，沃森-克里克几何结构的偏差会导致密码子-反密码子小沟处氢键伙伴的无补偿去溶剂化。因此，同源 tRNA 诱导的 30S 闭合形式的转变对于近同源 tRNA 是不利的，除非巴龙霉素诱导部分重排。我们得出的结论是，tRNA 选择需要稳定的闭合 30S 构象，从而在结构上合理化许多先前有关翻译保真度的数据。
A structural and mechanistic explanation for the selection of tRNAs by the ribosome has been elusive. Here, we report crystal structures of the 30S ribosomal subunit with codon and near-cognate tRNA anticodon stem loops bound at the decoding center and compare affinities of equivalent complexes in solution. In ribosomal interactions with near-cognate tRNA, deviation from Watson-Crick geometry results in uncompensated desolvation of hydrogen-bonding partners at the codon-anticodon minor groove. As a result, the transition to a closed form of the 30S induced by cognate tRNA is unfavorable for near-cognate tRNA unless paromomycin induces part of the rearrangement. We conclude that stabilization of a closed 30S conformation is required for tRNA selection, and thereby structurally rationalize much previous data on translational fidelity.