细菌凝聚酶MukBEF将DNA压缩成一个重复的,稳定的结构
Ryan B Case1, Yun-Pei Chang, Steven B Smith
1Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
概括
细菌凝聚酶 MukBEF 蛋白质将DNA压缩成一个有序的丝. 这个结构可以反复扩展和复合,揭示了染色体组织的新机制.
科学领域:
- 分子生物学分子生物学
- 生物化学 生物化学
- 遗传学 是一个遗传学.
背景情况:
- 凝固素是具有染色体部分 (SMC) 结构维护的蛋白质,对于染色体的组织和紧缩至关重要.
- 凝聚素实现染色体紧缩和分离的精确机制在很大程度上是未知的.
- MukBEF是埃舍里奇亚大肠杆菌中发现的特定的凝聚酶复合体.
研究的目的:
- 为了阐明MukBEF压缩单个DNA分子的机制.
- 为了研究MukBEF介导的DNA凝结的结构性质和动态.
- 通过MukBEF提出一种体内细菌染色体组织模型.
主要方法:
- 使用单分子DNA拉伸实验来分析MukBEF-DNA相互作用.
- 调查腺三酸盐 (ATP) 结合在凝结过程中的作用.
- 在不同的力量和条件下观察DNA线丝延伸和重凝动态.
- 评估拓聚酶I对MukBEF-DNA复合体行为的影响.
主要成果:
- 在依赖ATP的方式中,MukBEF以合作方式将DNA压缩成有序的,重复的线索.
- 将MukBEF-DNA丝拉伸到17皮克纽顿,引发了以45纳米为中心的重复过渡.
- 光线表现出可逆的延伸和再冷凝周期,即使没有ATP或免费的MukBEF.
- 观察到的凝结模式在多个循环中具有高度可重现性,并且独立于先前的变形.
- 拓聚酶I促进了可逆延伸和再凝聚,这表明被困的超绕DNA.
结论:
- MukBEF建立了一个稳定的,自我组织的DNA结构,具有显著的弹性和记忆力.
- 观察到的可逆循环表明了DNA紧缩的动态但稳定的机制.
- 这些发现支持了MukBEF在组织细菌染色体中的作用的新模型.
- 拓酶I相互作用突出了DNA拓在MukBEF介导组织中的作用.
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