Single-Molecule Imaging Reveals a Collapsed Conformational State for DNA-Bound Cohesin.
Single-Molecule Imaging Reveals a Collapsed Conformational State for DNA-Bound Cohesin.
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DOI：
10.1016/j.celrep.2016.04.003
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发表时间：
2016-05-03
期刊：
影响因子：
8.8
通讯作者：
Greene EC
中科院分区：
文献类型：
--
作者：
Stigler J;Çamdere GÖ;Koshland DE;Greene EC
黏连蛋白是真核生物基因组分层组织的关键，在染色体生物学的许多方面起着关键作用。与DNA结合的粘附素的构象仍然不清楚，这使得我们对粘附素如何实现其生物学功能的理解存在重大空白。在这里，我们使用单分子显微镜直接观察结合到DNA的cohesin的动态和功能特性。我们发现，粘附素可以进行快速的一维（1D）扩散沿着DNA，但个别核小体，核小体阵列，和其他蛋白质的障碍显着限制其流动性。我们进一步证明，DNA马达蛋白可以很容易地推动cohesin沿着DNA，但他们不能通过内部的cohesin环。总之，我们的研究结果表明，DNA结合的cohesin有一个中心孔，这是大大小于预期。这些发现对于理解粘附素和其他SMC蛋白如何与染色质相互作用并沿着染色质分布具有直接意义。
Cohesin is essential for the hierarchical organization of the eukaryotic genome and plays key roles in many aspects of chromosome biology. The conformation of cohesin bound to DNA remains poorly defined, leaving crucial gaps in our understanding of how cohesin fulfills its biological functions. Here we use single molecule microscopy to directly observe the dynamic and functional characteristics of cohesin bound to DNA. We show that cohesin can undergo rapid one-dimensional (1D) diffusion along DNA, but individual nucleosomes, nucleosome arrays, and other protein obstacles significantly restrict its mobility. We further demonstrate that DNA motor proteins can readily push cohesin along DNA, but they cannot pass through the interior of the cohesin ring. Together, our results reveal that DNA-bound cohesin has a central pore that is substantially smaller than anticipated. These findings have direct implications for understanding how cohesin and other SMC proteins interact with and distribute along chromatin.