Dynamics of Nucleosomal Structures Measured by High-Speed Atomic Force Microscopy
Dynamics of Nucleosomal Structures Measured by High-Speed Atomic Force Microscopy
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DOI：
10.1002/smll.201401318
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发表时间：
2015-02-25
期刊：
影响因子：
13.3
通讯作者：
Dekker, Cees
中科院分区：
文献类型：
--
作者：
Katan, Allard J.;Vlijm, Rifka;Dekker, Cees
DNA 的可及性取决于核小体的数量、位置和稳定性，核小体是由 8 个组蛋白核心组成的复合物，DNA 包裹在其周围。由于核小体的结构和动力学影响重要的细胞过程，因此它们是当前许多研究的主题。在这里，高速原子力显微镜用于可视化核小体和四体（蛋白质核心中包含 4 个而不是 8 个组蛋白的亚核小体结构）的动态过程。核小体可以在一个过程中自发分解（以 1 秒的时间尺度）。对于四体，观察到多种动态现象。例如，在拆卸过程中，可以看到 DNA 环（长度约为 25 nm）的形成，该环在几分钟内保持稳定。对于完整的四体，观察到沿 DNA 的稳定位置之间滑动和可逆跳跃形式的动态。数据强调，四体不仅仅是静态物体，而且是高度动态的。由于四体（与核小体相反）可以在转录过程中保留在 DNA 上，因此观察到的四体动力学对于理解转录过程中的核小体动力学相关。这些结果说明了核小体动力学的多样性，并证明了高速 AFM 表征蛋白质-DNA 相互作用的能力。
The accessibility of DNA is determined by the number, position, and stability of nucleosomes, complexes consisting of a core of 8 histone proteins with DNA wrapped around it. Since the structure and dynamics of nucleosomes affects essential cellular processes, they are the subject of many current studies. Here, high-speed atomic force microscopy is used to visualize dynamic processes in nucleosomes and tetrasomes (subnucleosomal structures that contain 4 rather than 8 histones in the protein core). Nucleosomes can spontaneously disassemble in a process (at a 1 second timescale). For tetrasomes, multiple dynamic phenomena are observed. For example, during disassembly the formation of a DNA loop (similar to 25 nm in length) is seen, which remains stable for several minutes. For intact tetrasomes, dynamics in the form of sliding and reversible hopping between stable positions along the DNA are observed. The data emphasize that tetrasomes are not merely static objects but highly dynamic. Since tetrasomes (in contrast to nucleosomes) can stay on the DNA during transcription, the observed tetrasome dynamics is relevant for an understanding of the nucleosomal dynamics during transcription. These results illustrate the diversity of nucleosome dynamics and demonstrate the ability of high speed AFM to characterize protein-DNA interactions.