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An In Vitro Assay to Detect tRNA-Isopentenyl Transferase Activity
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特定的tRNA氨基化通过一个小的体外选择的 ribozyme 的结构基础
Hong Xiao1, Hiroshi Murakami, Hiroaki Suga
1Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024, USA.
Nature
|June 13, 2008
概括
这项研究揭示了flexizyme的结构,flexizyme是一种氨基酸转移RNA (tRNA) 的 ribozyme. 这些发现表明,特定的tRNA氨基化需要最小的核酸,为早期蛋白质合成进化提供了见解.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 生命的起源研究 生命的起源研究
背景情况:
- 蛋白酶在现代生物体中催化tRNA氨基化.
- RNA催化剂 (核糖酶) 在RNA世界中对氨基酸酶化至关重要.
- 柔性酶是一种精选的 ribozyme,它用 fenilalanine 衍生物对tRNA进行氨基酸.
研究的目的:
- 为了阐明flexizyme与其RNA基质结合的结构.
- 了解特定的tRNA识别和氨基化由flexizyme的机制.
- 探索早期蛋白质合成的进化影响.
主要方法:
- 在2.8A分辨率的X射线晶体学.
- 柔性酶与基质RNA融合的结构确定.
- 在体外选择和随机化 ribozyme 核心残留物.
主要成果:
- 柔性酶精确地氨基酸化了tRNA的3'-OH终端.
- 对于特定的tRNA氨基化,最小的核酸是足够的.
- Flexizyme通过与CCA终端和局部相互作用的基配对来识别tRNA.
- 两个不同的柔性体形状表明,诱导适应增强了特异性.
结论:
- Flexizyme的结构揭示了使用少数核酸的特定tRNA氨基化机制.
- 这些发现支持RNA世界假设和蛋白质合成的进化.
- 柔性酶的特异性机制可能类似于基于蛋白质的氨基酸-tRNA合成酶.
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