Three-dimensional reconstruction of individual helical nano-filament structures from atomic force microscopy topographs
Three-dimensional reconstruction of individual helical nano-filament structures from atomic force microscopy topographs
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DOI：
10.1515/bmc-2020-0009
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发表时间：
2020-01-01
影响因子：
--
通讯作者：
Xue, Wei-Feng
中科院分区：
文献类型：
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作者：
Lutter, Liisa;Serpell, Christopher;Xue, Wei-Feng
原子力显微镜（AFM）是一种功能强大的工具，它可以产生具有高信噪比的单个纳米结构的详细形貌图像，而不需要整体平均。然而，原子力显微镜在结构生物学中的应用一直受到阻碍的尖端样品卷积效应，扭曲的纳米结构，特别是那些尺寸相似的悬臂梁探针针尖在原子力显微镜中使用的图像。在这里，我们表明，针尖样品卷积的结果在一个功能依赖和不均匀分布的图像分辨率的AFM形貌。我们展示了如何利用这种效应可以在结构研究的纳米尺寸向上凸的物体，如球形或丝状分子组件沉积在一个平坦的表面上，因为它会导致“放大”这样的物体在AFM拓扑图。随后，这种增强效果是通过接触点的AFM形貌图的反卷积利用。在这里，这种方法的应用是通过3D重建的表面包络的个别螺旋状淀粉样蛋白丝，而不需要交叉粒子平均使用的接触去卷积的AFM拓扑图。解决固有异质群体内单个大分子组装体的结构变化对于许多生物现象如淀粉样蛋白毒性和朊病毒株的机理理解至关重要。本文提出的方法也将促进原子力显微镜用于单分子组装体的高分辨率结构研究和综合结构生物学分析。
Atomic force microscopy, AFM, is a powerful tool that can produce detailed topographical images of individual nano-structures with a high signal-to-noise ratio without the need for ensemble averaging. However, the application of AFM in structural biology has been hampered by the tip-sample convolution effect, which distorts images of nano-structures, particularly those that are of similar dimensions to the cantilever probe tips used in AFM. Here we show that the tip-sample convolution results in a feature-dependent and non-uniform distribution of image resolution on AFM topographs. We show how this effect can be utilised in structural studies of nano-sized upward convex objects such as spherical or filamentous molecular assemblies deposited on a flat surface, because it causes 'magnification' of such objects in AFM topographs. Subsequently, this enhancement effect is harnessed through contact-point based deconvolution of AFM topographs. Here, the application of this approach is demonstrated through the 3D reconstruction of the surface envelope of individual helical amyloid filaments without the need of cross-particle averaging using the contact-deconvoluted AFM topographs. Resolving the structural variations of individual macromolecular assemblies within inherently heterogeneous populations is paramount for mechanistic understanding of many biological phenomena such as amyloid toxicity and prion strains. The approach presented here will also facilitate the use of AFM for high- resolution structural studies and integrative structural biology analysis of single molecular assemblies.