Conformational changes of the small ribosomal subunit during elongation factor G-dependent tRNA-mRNA translocation
Conformational changes of the small ribosomal subunit during elongation factor G-dependent tRNA-mRNA translocation
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DOI：
10.1016/j.jmb.2004.08.097
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发表时间：
2004-11-05
影响因子：
5.6
通讯作者：
Wintermeyer, W
中科院分区：
文献类型：
--
作者：
Peske, F;Savelsbergh, A;Wintermeyer, W
易位是两个tRNA和mRNA在核糖体上的协调运动，由延伸因子G（EF-G）催化。该反应伴随着核糖体的构象重排，但尚未得到很好的表征。在这里，我们通过限制核糖体的构象灵活性来分析这些重排，通过抗生素结合到核糖体的特定位点。巴龙霉素（Paromomycin，Par）、紫霉素（Viomycin，Vio）、大观霉素（Spc）和潮霉素B（Hyg B）可抑制tRNA-mRNA的移动，而其他部分转位反应，包括tRNA-mRNA移动之前的核糖体解锁重排，则不受影响。EF-G的功能循环，即EF-G（.）GTP到核糖体，GTP水解，Pi释放和EF-G（.）来自核糖体的GDP也不受影响，表明EF-G周转不直接与tRNA-mRNA运动偶联。易位的抑制。Par和Vio的作用是由于稳定了tRNA在A位点的结合，而Spc和HygB对tRNA-mRNA的运动有直接的抑制作用。链霉素（Str）对易位基本上没有影响，尽管它导致tRNA对A位点的亲和力大幅增加。这些结果表明，在解码区附近的Spc和HygB的结合位点的构象变化是重要的tRNA-mRNA的运动，而Str似乎稳定的核糖体的构象，易于快速易位，从而补偿对tRNA亲和力的影响。(C)2004爱思唯尔有限公司保留所有权利。
Translocation, a coordinated movement of two tRNAs together with mRNA on the ribosome, is catalyzed by elongation factor G (EF-G). The reaction is accompanied by conformational rearrangements of the ribosome that are, as yet, not well characterized. Here, we analyze those rearrangements by restricting the conformational flexibility of the ribosome by antibiotics binding to specific sites of the ribosome. Paromomycin (Par), viomycin (Vio), spectinomycin (Spc), and hygromycin B (HygB) inhibited the tRNA-mRNA movement, while the other partial reactions of translocation, including the unlocking rearrangement of the ribosome that precedes tRNA-mRNA movement, were not affected. The functional cycle of EF-G, i.e. binding of EF-G(.)GTP to the ribosome, GTP hydrolysis, Pi release, and dissociation of EF-G(.)GDP from the ribosome, was not affected either, indicating that EF-G turnover is not coupled directly to tRNA-mRNA movement. The inhibition of translocation. by Par and Vio is attributed to the stabilization of tRNA binding in the A site, whereas Spc and HygB had a direct inhibitory effect on tRNA-mRNA movement. Streptomycin (Str) had essentially no effect on translocation, although it caused a large increase in tRNA affinity to the A site. These results suggest that conformational changes in the vicinity of the decoding region at the binding sites of Spc and HygB are important for tRNA-mRNA movement, whereas Str seems to stabilize a conformation of the ribosome that is prone to rapid translocation, thereby compensating the effect on tRNA affinity. (C) 2004 Elsevier Ltd. All rights reserved.