将转录修复合因子Mfd加载到停滞的延伸复合体上的结构基础
Joshua Brewer1, Eliza Llewellyn1,2, James Chen1,3
1Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065.
bioRxiv : the preprint server for biology
|September 15, 2025
概括
转录合修复 (TCR) 对于DNA修复至关重要. 这项研究揭示了TCR期间Mfd转位酶的新结构细节,改善了我们对DNA修复机制的理解.
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:
- 转录合修复 (TCR) 消除了阻断RNA聚合酶 (RNAP) 的DNA病变.
- 细菌Mfd转位酶通过取代停滞的RNAP延长复合体 (EC) 和招募修复蛋白来调解TCR.
- 之前的冷EM研究可视化了七个Mfd-EC复合物,但缺乏早期中间体的分辨率.
研究的目的:
- 解决TCR中早期Mfd-EC中间体的结构.
- 为了更深入地了解Mfd在EC移位期间的形状变化.
- 阐明Mfd加载和EC排位的机制.
主要方法:
- 使用冷电子显微镜 (cryo-EM) 可视化Mfd-EC复合体.
- 在gamma-phosphate模仿物BeF3-.的存在下,mfd被ATP预装载.
- 使用有限的ATP水解循环来积累早期中间体.
主要成果:
- 该L1中间体被分辨到3.5 Å分辨率,揭示绑定ADP-BeF3-.
- 在L1和L2之间发现了一种新的中间体L1.5,L1.5.
- 此外,Mfd的大型结构转型,特别是L1-L2转型,也得到了进一步的特征.
结论:
- 该研究提供了早期Mfd-EC中间体的高分辨率结构,增强了对TCR启动的理解.
- 鉴定L1.5中间体为Mfd的形状动态提供了新的见解.
- 这些发现有助于建立一个更全面的Mfd介导的转录合修复模型.
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