克里斯普尔适应偏差解释了对获取外来DNA的偏好
Asaf Levy1, Moran G Goren2, Ido Yosef2
1Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
Nature
|April 16, 2015
概括
克里斯普尔-卡斯系统获得了用于细菌免疫的外来DNA. 间距获取依赖于复制和DNA断裂,Chi位点和RecBCD阻止自我DNA集成.
科学领域:
- 微生物学 微生物学
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
背景情况:
- 克里斯普尔-卡斯系统为细菌提供了对菌体和质粒的适应性免疫力.
- 间隔器获取,将外来DNA片段集成到CRISPR阵列中,对于这种免疫是至关重要的.
- 确保从外来DNA获取优选DNA而不是自身DNA的机制仍然不清楚.
研究的目的:
- 阐明CRISPR-Cas系统中从外来DNA中获取优先间隔器的机制.
- 为了确定规范在间隔器获取过程中避免自身染色体DNA的因素.
- 了解复制和DNA修复途径在CRISPR适应中的作用.
主要方法:
- 在大肠杆菌 (Escherichia coli) 中研究了间隔器的获取.
- 分析了复制,DNA断裂,Chi部位和RecBCD复合物的作用.
- 利用遗传和分子生物学技术来评估DNA的整合和修复.
主要成果:
- 间距获取取决于DNA复制,并通过DNA断裂在停滞的复制叉来促进.
- 细菌染色体上Chi位点的极限间距从自身DNA中获得.
- 在获取过程中,RecBCD复合物调解避免自我DNA.
结论:
- 在大肠杆菌中,CRISPR-Cas间隔器的获取主要是由RecBCD介导的复制分叉中的双链断裂的处理驱动的.
- 对外来DNA的偏好是通过Chi位点分布和对外来DNA更高的复制叉密度的结合来实现的.
- 这种模型解释了观察到的偏好,即从复制量高的等离子体和菌体获得间隔器.
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