Incorporation of aminoacyl-tRNA into the ribosome as seen by cryo-electron microscopy
Incorporation of aminoacyl-tRNA into the ribosome as seen by cryo-electron microscopy
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DOI：
10.1038/nsb1003
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发表时间：
2003-11-01
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影响因子：
--
通讯作者：
Frank, J
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文献类型：
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作者：
Valle, M;Zavialov, A;Frank, J
氨基酰基-tRNA（aa-tRNA）作为aa-tRNA、延伸因子Tu（EF-Tu）和GTP的三元复合物的一部分递送至核糖体。在此，我们提出了一个冷冻电子显微镜（cryo-EM）研究，在近似9埃的分辨率，显示在aa-tRNA掺入到大肠杆菌的70 S核糖体，aa-tRNA的灵活性允许初始密码子识别和它的住宿到核糖体A位点。此外，在核糖体50 S亚基的GTP酶相关中心（GAC）中观察到的构象变化可能提供了核糖体促进aa-tRNA相对于EF-Tu的相对运动的机制。这种相对重排似乎促进了密码子被引入的aa- tRNA识别，并为EF-Tu的GTdR活性提供了密码子-反密码子识别依赖性信号。根据这些新发现，我们提出了一种机制，可以解释核糖体上mRNA解码过程中的事件顺序。
Aminoacyl-tRNAs (aa-tRNAs) are delivered to the ribosome as part of the ternary complex of aa- tRNA, elongation factor Tu (EF-Tu) and GTP. Here, we present a cryo-electron microscopy (cryo-EM) study, at a resolution of similar to9 Angstrom, showing that during the incorporation of the aa- tRNA into the 70S ribosome of Escherichia coli, the flexibility of aa- tRNA allows the initial codon recognition and its accommodation into the ribosomal A site. In addition, a conformational change observed in the GTPase-associated center (GAC) of the ribosomal 50S subunit may provide the mechanism by which the ribosome promotes a relative movement of the aa- tRNA with respect to EF-Tu. This relative rearrangement seems to facilitate codon recognition by the incoming aa- tRNA, and to provide the codon-anticodon recognition-dependent signal for the GTPase activity of EF-Tu. From these new findings we propose a mechanism that can explain the sequence of events during the decoding of mRNA on the ribosome.