Crystal structures of an unmodified bacterial tRNA reveal intrinsic structural flexibility and plasticity as general properties of unbound tRNAs
Crystal structures of an unmodified bacterial tRNA reveal intrinsic structural flexibility and plasticity as general properties of unbound tRNAs
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DOI：
10.1261/rna.073478.119
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发表时间：
2020-03-01
期刊：
影响因子：
4.5
通讯作者：
Mondragon, Alfonso
中科院分区：
文献类型：
--
作者：
Chan, Clarence W.;Badong, Deanna;Mondragon, Alfonso
普遍存在于生命的所有领域，tRNA构成细胞生理学的重要组成部分，在蛋白质合成中发挥不可或缺的作用，并且历史上一直是广泛的生物化学和生物物理研究的主题，作为原型折叠RNA分子。虽然构象灵活性是tRNA结构的公认特征，但它通常被认为是响应于诱导事件（例如tRNA合成酶的结合或氨酰-tRNA进入核糖体的适应性）而表现出的适应性特性。在这项研究中，我们提出了一种tRNA分子的晶体学数据，通过显示结构的灵活性和可塑性是tRNA的内在特性，即使在没有其他因素的情况下也是显而易见的，从而扩展了这种范式。基于在同一晶体中观察到的两种密切相关的构象，我们认为未结合的tRNA本身是灵活的和动态的分子。此外，我们表明，形成的T-环构象的tRNA T Psi C茎环，一个良好的特点和经典的RNA结构基序，是可能的，即使在没有观察到的重要相互作用，在完全折叠的tRNA。
Ubiquitous across all domains of life, tRNAs constitute an essential component of cellular physiology, carry out an indispensable role in protein synthesis, and have been historically the subject of a wide range of biochemical and biophysical studies as prototypical folded RNA molecules. Although conformational flexibility is a well-established characteristic of tRNA structure, it is typically regarded as an adaptive property exhibited in response to an inducing event, such as the binding of a tRNA synthetase or the accommodation of an aminoacyl-tRNA into the ribosome. In this study, we present crystallographic data of a tRNA molecule to expand on this paradigm by showing that structural flexibility and plasticity are intrinsic properties of tRNAs, apparent even in the absence of other factors. Based on two closely related conformations observed within the same crystal, we posit that unbound tRNAs by themselves are flexible and dynamic molecules. Furthermore, we demonstrate that the formation of the T-loop conformation by the tRNA T Psi C stem-loop, a well-characterized and classic RNA structural motif, is possible even in the absence of important interactions observed in fully folded tRNAs.