RNA聚合酶III转录启动的结构基础
Guillermo Abascal-Palacios1, Ewan Phillip Ramsay1, Fabienne Beuron1
1The Institute of Cancer Research, London SW7 3RP, UK.
Nature
|January 19, 2018
概括
研究人员使用电子显微镜可视化RNA聚合酶 (Pol) III转录启动复合体. TFIIIB结合重组了Pol III,促进了DNA开放和转录的启动,揭示了跨聚合酶的保存机制.
科学领域:
- 分子生物学
- 结构生物学
- 生物化学
背景情况:
- RNA聚合酶 (Pol) III转录重要的非编码RNA (tRNA,5S rRNA,U6 snRNA).
- 在癌症中很常见.
- 通过Pol III启动转录需要转录因子TFIIIB形成一个预启动复合体 (PIC).
研究的目的:
- 确定Pol III转录启动的结构基础.
- 为了可视化Pol III预启动复合体 (PIC) 和未结合的Pol III.
- 阐明TFIIIB在Pol III PIC形成和DNA开放中的作用.
主要方法:
- 低温电子显微镜 (低温电子显微镜) 的重建.
- 对Pol III和Pol III-TFIIIB-DNA复合物的高分辨率结构分析.
主要成果:
- 获得了Pol III PIC的3.4-4.0 Å分辨率结构和不受约束的apo-Pol III的3.1 Å结构.
- TFIIIB包围了DNA并重组了Pol III,其中Bdp1重新排列了C37和C34的子单位.
- 促进DNA开放,解开的DNA与Pol III裂接触.
- 在拓上,Pol III PIC的结构与Pol II PIC相似,但与Pol I PIC不同.
结论:
- 这些结构揭示了Pol III转录启动的分子机制.
- 结合TFIIIB对于DNA开放和PIC形成至关重要.
- 在不同的RNA聚合酶中存在保存的转录启动机制.
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