在分支后立即形成结合体的冷EM结构
Wojciech P Galej1, Max E Wilkinson1, Sebastian M Fica1
1MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
Nature
|July 27, 2016
概括
结合体
科学领域:
- 分子生物学
- 结构生物学
- 生物化学
背景情况:
- 前体信使RNA (mRNA前体) 拼接是一个基本的生物过程.
- 拼接涉及两个催化步骤,形成一个拉里亚特-子中间体.
- 一个很大的分子机器, 编排这个过程.
研究的目的:
- 在拉里亚特形成后立即阐明结合体的结构动态.
- 在关键的拼接中间阶段可视化拼接体的分子结构.
主要方法:
- 使用冷电子显微镜 (cryo-EM) 来确定结构.
- 对结合体复合体获得了高分辨率 (3.8 Å) 的结构数据.
主要成果:
- 结构显示5'-拼接部位被切割,但靠近催化Mg2+部位.
- 内的5'-酸盐与分支腺素结合在一起.
- 涉及U2/U6 snRNA,U5 snRNA和拼接因子 (Isy1,Yju2,Cwc25) 的特定相互作用使拉里亚特中间体稳定.
- 5'-外基因被定位为随后的结合.
结论:
- 这种冷-EM结构提供了前所未有的洞察力,
- 这种结构澄清了稳定拉里亚特中间体的分子基础,并为第二个拼接步骤定位了组件.
- 这些发现表明,在外结之前存在内重塑的机制.
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