在CMG螺旋酶中,单链DNA门使复制分叉激活
Michael R Wasserman1, Grant D Schauer2, Michael E O'Donnell3
1Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY 10065, USA.
Cell
|July 27, 2019
概括
CMG螺旋酶使用一种新型的DNA门在双链和单链DNA之间进行过渡. 这种机制允许CMG在复制和修复过程中移动到双链DNA上,然后回到单链DNA重新开始复制.
科学领域:
- 分子生物学
- 进行DNA复制
- 生物物理
背景情况:
- CMG螺旋酶对于真核DNA复制至关重要,在起源时围绕dSDNA形成一个环.
- CMG必须过渡到ssDNA以实现酶活性,并处理像反向叉一样的修复中间体.
- 了解CMG的DNA结合和转移对于理解复制和修复忠实性至关重要.
研究的目的:
- 研究CMG在dsDNA和ssDNA之间转换的机制.
- 确定参与CMGDNA基质切换的结构组件和调控因素.
- 阐明CMG如何在复制和修复过程中处理复杂的DNA结构.
主要方法:
- 相对单分子光和力显微镜.
- 在体外测定以观察CMG-DNA相互作用和转位.
- 生物化学分析CMG-DNA结合和线程传递.
主要成果:
- CMG 具有内在的 ssDNA 门,可促进 ssDNA 和 dsDNA 之间的转换.
- 不结合的CMG利用这个门在分叉交叉处移动到dsDNA上.
- CMG在dsDNA上表现出快速扩散,并且可以重新激活ssDNA以启动复制体组装.
- 增强了CMG的DNA结合亲和力,促进了链的通过.
结论:
- 该ssDNA门是一个关键的功能,使CMG的动态DNA基质参与.
- 这种关门机制解释了CMG在起源时的dsDNA到ssDNA过渡及其在分叉修复中的作用.
- CMG 导航和结合 dsDNA 的能力对于维持复制分叉稳定性和重新启动至关重要.
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