PDF(Pubmed)
Abstract：
Many antibiotics that bind to the ribosome inhibit translation by blocking the movement of tRNAs and mRNA or interfering with ribosome dynamics, which impairs the formation of essential translocation intermediates. Here we show how translocation inhibitors viomycin (Vio), neomycin (Neo), paromomycin (Par), kanamycin (Kan), spectinomycin (Spc), hygromycin B (HygB), and streptomycin (Str, an antibiotic that does not inhibit tRNA movement), affect principal motions of the small ribosomal subunits (SSU) during EF-G-promoted translocation. Using ensemble kinetics, we studied the SSU body domain rotation and SSU head domain swiveling in real time. We show that although antibiotics binding to the ribosome can favor a particular ribosome conformation in the absence of EF-G, their kinetic effect on the EF-G-induced transition to the rotated/swiveled state of the SSU is moderate. The antibiotics mostly inhibit backward movements of the SSU body and/or the head domains. Vio, Spc, and high concentrations of Neo completely inhibit the backward movements of the SSU body and head domain. Kan, Par, HygB, and low concentrations of Neo slow down both movements, but their sequence and coordination are retained. Finally, Str has very little effect on the backward rotation of the SSU body domain, but retards the SSU head movement. The data underscore the importance of ribosome dynamics for tRNA-mRNA translocation and provide new insights into the mechanism of antibiotic action.
摘要：
许多与核糖体结合的抗生素通过阻断tRNA和mRNA的运动或干扰核糖体动力学来抑制翻译，削弱必需易位中间体的形成。在这里，我们展示了易位抑制剂伟霉素（Vio），新霉素（Neo），巴龙霉素（Par），卡那霉素（Kan），壮观霉素（Spc），潮霉素B（HygB），和链霉素（Str，一种不抑制tRNA运动的抗生素)，在EF-G促进的易位过程中影响小核糖体亚基（SSU）的主要运动。使用整体动力学，我们实时研究了SSU体域旋转和SSU头域旋转。我们表明，尽管抗生素与核糖体结合可以在没有EF-G的情况下有利于特定的核糖体构象，它们对EF-G诱导的SSU向旋转/旋转状态过渡的动力学影响是中等的。抗生素主要抑制SSU体和/或头部结构域的向后运动。Vio,Spc,高浓度的Neo完全抑制SSU主体和头域的向后运动。菅直人,标准杆,HygB,低浓度的Neo减慢了这两种运动，但它们的顺序和协调被保留。最后,Str对SSU体域的向后旋转影响很小，但是阻碍了SSU头部的移动。数据强调了核糖体动力学对tRNA-mRNA易位的重要性，并为抗生素作用机制提供了新的见解。
