Visualization of supercoiled DNA with atomic force microscopy in situ
Visualization of supercoiled DNA with atomic force microscopy in situ
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DOI：
10.1073/pnas.94.2.496
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发表时间：
1997-01-21
影响因子：
11.1
通讯作者：
Shlyakhtenko, LS
中科院分区：
文献类型：
--
作者：
Lyubchenko, YL;Shlyakhtenko, LS
超螺旋DNA的三级结构是许多遗传功能的重要因素，并且明显受到环境条件的影响。我们应用原子力显微镜（AFM）对不同离子条件下沉积的超螺旋DNA进行成像。我们采用了一种样品制备技术，可以对缓冲溶液中结合到表面的 DNA 进行高分辨率 AFM 成像，而无需干燥样品（AFM 原位）。 AFM数据显示，在低离子强度下，DNA分子是松散缠绕的、形状不规则的超螺旋，在高浓度、接近生理的盐溶液中形成超螺旋，在这种离子条件下，超螺旋环通常被紧密的螺旋-螺旋接触区域分开。获得的数据直接且明确地表明超螺旋 DNA 的整体几何形状很大程度上取决于离子条件。这一事实以及DNA螺旋之间紧密接触的形成是超螺旋DNA与其生物学功能相关的重要特征。
Tertiary structure of supercoiled DNA is a significant factor in a number of genetic functions and is apparently affected by environmental conditions, We applied atomic force microscopy (AFM) for imaging the supercoiled DNA deposited at different ionic conditions. We have employed a technique for the sample preparation that permits high-resolution AFM imaging of DNA bound to the surface in buffer solutions without drying the sample (AFM in situ). The AFM data show that at low ionic strength, DNA molecules are loosely interwound supercoils with an irregular shape, Plectonemic superhelices are formed in high-concentration, near-physiological salt solutions, At such ionic conditions, super-helical loops are typically separated by regions of close helix-helix contacts. The data obtained show directly and unambiguously that overall geometry of supercoiled DNA depends dramatically on ionic conditions. This fact and the formation of close contacts between DNA helices are important features of supercoiled DNA related to its biological functions.