在目标搜索过程中进行DNA表面探测和操作员绕过
Emil Marklund1, Brad van Oosten1, Guanzhong Mao1
1Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
Nature
|June 26, 2020
概括
个别的拉克抑制蛋白 (LacI) 沿着DNA滑动,经常在隙之间跳跃. 这种滑动机制加快了DNA搜索速度, 但可能导致绕过目标序列,
科学领域:
- 分子生物学
- 生物物理
- 遗传学
背景情况:
- 绑定特定DNA序列的蛋白质利用3D扩散和1D滑动在非特定DNA上.
- 了解这种一维滑动的动态对于理解基因组探索至关重要.
研究的目的:
- 在1D滑动过程中描述个别LAC抑制剂 (LACI) 分子的DNA探索动态.
- 在DNA上研究拉基的旋转运动和跳槽行为.
主要方法:
- 使用实时单分子聚焦激光追踪与光相关谱 (SMCT-FCS) 监测微秒时间尺度上的LacI旋转.
- 使用单分子光共振能量转移 (smFRET) 直接观察序列绕过事件.
主要成果:
- 拉基因表现出旋转合的滑动,每次旋转大约有40个基数对 (bp),超过了DNA的螺旋曲率.
- 观察到LacI每200-700μs跳过一到两个槽,表明频繁绕过目标部位.
- 由于弱非特异性蛋白质-DNA相互作用, 显示了滑动速度和搜索精度之间的权衡.
结论:
- 拉基的1D滑动机制涉及频繁的槽跳跃,平衡搜索速度与潜在的目标绕过.
- 开发的SMCT-FCS技术为研究生物相互作用中的微秒时间尺度分子动力学提供了强大的工具.
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