Effect of fringe-artifact correction on sub-tomogram averaging from Zernike phase-plate cryo-TEM
Effect of fringe-artifact correction on sub-tomogram averaging from Zernike phase-plate cryo-TEM
复制标题
DOI：
10.1016/j.jsb.2015.07.009
复制
发表时间：
2015-09-01
影响因子：
3
通讯作者：
Sui, Haixin
中科院分区：
文献类型：
--
作者：
Kishchenko, Gregory P.;Danev, Radostin;Sui, Haixin
Zernike相位板（ZPP）成像技术在低温电子显微镜中可显著提高对比度，但在成像过程中会出现条纹伪影。已经提出了一种计算去边缘化方法，但它没有被广泛采用，也许是因为去边缘化的重要性还没有被清楚地证明。为了测试的目的，我们采用泽尔尼克相位板成像在低温电子断层扫描研究的径向辐条复合物连接到微管双峰。我们发现，通过ZPP成像的对比度增强使得非线性去噪对滤波参数不敏感，使得简单的低频带通滤波在地图质量上得到相同的改善。我们采用子断层图像平均，这补偿了“丢失的楔形”的影响，并大大提高了地图的质量。我们发现，条纹（由相位板中的中心孔的突然切断引起的）可以导致从文献中众所周知的结构的不正确的表示。预期的结构恢复幅度缩放，在文献中提出的。我们的研究结果表明，去边缘是一个重要的一部分，图像处理的大分子复合物与ZPP成像的冷冻电子断层扫描。(C)2015 Elsevier Inc. All rights reserved.
Zernike phase-plate (ZPP) imaging greatly increases contrast in cryo-electron microscopy, however fringe artifacts appear in the images. A computational de-fringing method has been proposed, but it has not been widely employed, perhaps because the importance of de-fringing has not been clearly demonstrated. For testing purposes, we employed Zernike phase-plate imaging in a cryo-electron tomographic study of radial-spoke complexes attached to microtubule doublets. We found that the contrast enhancement by ZPP imaging made nonlinear denoising insensitive to the filtering parameters, such that simple low-frequency band-pass filtering made the same improvement in map quality. We employed sub-tomogram averaging, which compensates for the effect of the "missing wedge" and considerably improves map quality. We found that fringes (caused by the abrupt cut-on of the central hole in the phase plate) can lead to incorrect representation of a structure that is well-known from the literature. The expected structure was restored by amplitude scaling, as proposed in the literature. Our results show that de-fringing is an important part of image-processing for cryo-electron tomography of macromolecular complexes with ZPP imaging. (C) 2015 Elsevier Inc. All rights reserved.