Real-time detection of single-molecule DNA compaction by condensin I
Real-time detection of single-molecule DNA compaction by condensin I
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DOI：
10.1016/j.cub.2004.04.038
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发表时间：
2004-05-25
期刊：
影响因子：
9.2
通讯作者：
Hirano, T
中科院分区：
文献类型：
--
作者：
Strick, TR;Kawaguchi, T;Hirano, T
背景：凝聚蛋白被认为有助于有丝分裂染色体组装过程中的大规模DNA压缩。它仍然是未知的，但是，如何复杂的重新配置DNA结构在一个mechanistic level.Results：我们已经进行了单分子DNA nanomipulation实验，直接测量在实时DNA压实非洲爪蟾凝聚素I复合物。缩合蛋白可以在不存在ATP的情况下与纳米操纵的DNA结合，但它仅在可水解的ATP存在下压缩DNA。线性压缩通过纳米操纵的DNA的端到端延伸的减少来证明。该反应导致DNA的完全压缩（即，零端到端延伸）。当DNA受到弱拉伸力（F = 0.4 picoNewton [pN]）时，在竞争DNA的存在下观察到离散和可逆的DNA压缩事件。步长分布较宽，在60 nm处有一个峰（约180 bp），并有一个长尾。这种分布基本上不受DNA底物的拓扑状态的影响。将力增加到F = 10 pN会驱动系统逐步反转压实。在破坏凝聚素-DNA相互作用后观察到的步长分布显示出在类似于30 nm（类似于90 bp）处的尖锐峰以及延伸到数百nanumer.Conclusions的长尾：DNA纳米操纵试验使我们能够首次证明凝聚素以ATP水解依赖的方式物理压缩DNA。我们的研究结果表明，凝聚素复合物可以诱导DNA压缩动态和可逆地引入环沿着的DNA。
Background: Condensin is thought to contribute to large-scale DNA compaction during mitotic chromosome assembly. It remains unknown, however, how the complex reconfigures DNA structure at a mechanistic level.Results: We have performed single-molecule DNA nanomanipulation experiments to directly measure in real-time DNA compaction by the Xenopus laevis condensin I complex. Condensin can bind to the nanomanipulated DNA in the absence of ATP, but it compacts the DNA only in the presence of hydrolyzable ATP. Linear compaction is evidenced by a reduction in the end-to-end extension of nanomanipulated DNA. The reaction results in total compaction of the DNA (i.e., zero end-to-end extension). Discrete and reversible DNA compaction events are observed in the presence of competitor DNA when the DNA is subjected to weak stretching forces (F = 0.4 picoNewton [pN]). The distribution of step sizes is broad and displays a peak at similar to60 nm (similar to180 bp) as well as a long tail. This distribution is essentially unaffected by the topological state of the DNA substrate. Increasing the force to F = 10 pN drives the system toward step-wise reversal of compaction. The distribution of step sizes observed upon disruption of condensin-DNA interactions displays a sharp peak at similar to30 nm (similar to90 bp) as well as a long tail stretching out to hundreds of nanometers.Conclusions: The DNA nanomanipulation assay allows us to demonstrate for the first time that condensin physically compacts DNA in an ATP-hydrolysis-dependent manner. Our results suggest that the condensin complex may induce DNA compaction by dynamically and reversibly introducing loops along the DNA.