在转位过程中,延长因子G的大规模移动和核糖体的广泛形状变化
H Stark1, M V Rodnina, H J Wieden
1Imperial College of Science Medicine and Technology, Department of Biochemistry, London, United Kingdom.
Cell
|February 17, 2000
概括
延长因子G (EF-G) 驱动着tRNA在核糖体上的运动. 化EM结构揭示了EF-G的存在.
科学领域:
- 分子生物学分子生物学
- 结构生物学 结构生物学
- 生物化学 生物化学
背景情况:
- 延长因子G (EF-G) 对于细菌蛋白质合成至关重要.
- EF-G促进转移RNA (tRNA) 在核糖体上的转移,将其从A位移到P位移动.
- 了解EF-G在转位过程中的结构动态是阐明蛋白质合成机制的关键.
研究的目的:
- 为了可视化EF-G-核糖体复合体在tRNA转位之前和之后的结构变化.
- 调查EF-G在其功能周期中的构造状态.
- 为了确定由EF-G结合和活性诱导的核糖体中的结构重组.
主要方法:
- 使用冷电子显微镜 (cryo-EM) 来获得高分辨率的3D重建.
- 在转移前和转移后的状态下准备了EF-G与核糖体的复合体.
- 结构分析的重点是EF-G域与核糖体子单元之间的相互作用.
主要成果:
- 在转移前和转移后的状态下,EF-G-核糖体复合体的三维重建被生成.
- 在转移前状态下,EF-G域1与50S L7/12茎相互作用,域4与S4蛋白附近的30S亚单元接触.
- 在转移过程中,EF-G经历了显著的重定位,域4最终到达解码中心,核糖体表现出实质性的结构变化,特别是在30S子单元中.
结论:
- 在转移之前和之后,EF-G采用了不同的形状.
- 核糖体结构变化,特别是30S子单元的头与身体交叉点,与EF-G作用有关.
- 这些发现表明EF-G介导的tRNA转位的机制.
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