用大肠杆菌DNA旋转酶捕获状包裹和T段的结构基础
Elizabeth Michalczyk1,2, Zuzanna Pakosz-Stępień3, Jonathon D Liston3
1Doctoral School of Exact and Natural Sciences, Jagiellonian University, Kraków 30-348, Poland.
概括
研究人员使用冷电子显微镜 (cryo-EM) 可视化了一个关键的DNA超线圈步骤. 这揭示了DNA旋转酶如何形成一种性DNA循环,对于其在DNA复制和修复中的功能至关重要.
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:
- DNA旋转酶是一种II类型的拓酶,通过引入负超线圈来管理DNA拓是必不可少的.
- 它的催化机制,涉及DNA裂变和链穿越,在分子层面上还不完全理解.
- 过渡性性DNA循环中间体从未被直接观察到.
研究的目的:
- 为了可视化DNA旋转酶活性中介的性DNA循环.
- 通过DNA旋转酶阐明DNA超的结构基础.
- 为了研究莫西素 (MFX) 对酶的结构和机制的影响.
主要方法:
- 使用高分辨率冷电子显微镜 (cryo-EM) 来确定大肠杆菌DNA旋转酶的结构.
- 结构与没有诺基诺隆抗生素moxifloxacin (MFX) 得到.
- 该酶用专门设计的217bp DNA基质进行研究,以稳定一种性循环.
主要成果:
- 高分辨率的冷电磁结构捕获了一个正超绕的八个数的DNA循环.
- 该DNA循环由GyrAβ-pinwheel域稳定,观察到一个平坦的光盘.
- 对无药物和MFX结合结构的比较揭示了前催化状态,催化部位有一个单一的金属离子.
结论:
- 这项研究提供了基质DNA循环中间体的直接结构证据.
- 这些发现表明T段捕获独立于ATPase域二分化.
- ATPase 域二分化可能发生在 DNA 链经过后,而不是之前.
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