Prospects of electron cryotomography to visualize macromolecular complexes inside cellular compartments:: implications of crowding
Prospects of electron cryotomography to visualize macromolecular complexes inside cellular compartments:: implications of crowding
复制标题
DOI：
10.1016/s0301-4622(02)00307-1
复制
发表时间：
2003-01-01
影响因子：
3.8
通讯作者：
Baumeister, W
中科院分区：
文献类型：
--
作者：
Grünewald, K;Medalia, O;Baumeister, W
电子冷冻断层扫描具有独特的潜力，三维可视化的大分子复合物在其自然环境中的工作。这种方法是基于重建的三维体积从倾斜系列的电子显微镜照片保存在其原生状态的玻璃化细胞。已经实现了5-8 nm的分辨率，并且进一步改进的前景良好。由于许多细胞内的活动进行的复合物在兆道尔顿范围内的尺寸为20-50纳米，目前的分辨率应足以确定他们中的许多断层扫描。然而，残留的噪音和细胞成分的密集包装阻碍了解释。最近，已经收集了关于玻璃化的真核细胞的断层摄影数据（Medalia等人，Science（2002）in press）.他们的细胞质被发现是显着不那么拥挤，比以前研究的原核生物，在雅阁与其他（间接）生物物理方法记录的原核和真核细胞之间的拥挤差异。这一观察结果具有双重意义。首先，复合物应该更容易识别真核细胞质的断层图像。这适用于识别已知的复合物和表征新的复合物。给出了后者的一个例子--一个5重对称粒子。其次，电子冷冻断层扫描提供了一个尖锐的探针，检查拥挤在不同的细胞室。(C)2002 Elsevier Science B. V.保留所有权利。
Electron cryotomography has unique potential for three-dimensional visualization of macromolecular complexes at work in their natural environment. This approach is based on reconstructing three-dimensional volumes from tilt series of electron micrographs of cells preserved in their native states by vitrification. Resolutions of 5-8 nm have already been achieved and the prospects for further improvement are good. Since many intracellular activities are conducted by complexes in the megadalton range with dimensions of 20-50 nm, current resolutions should suffice to identify many of them in tomograms. However, residual noise and the dense packing of cellular constituents hamper interpretation. Recently, tomographic data have been collected on vitrified eukaryotic cells (Medalia et al., Science (2002) in press). Their cytoplasm was found to be markedly less crowded than in the prokaryotes previously studied, in accord with differences in crowding between prokaryotic and eukaryotic cells documented by other (indirect) biophysical methods. The implications of this observation are twofold. First, complexes should be more easily identifiable in tomograms of eukaryotic cytoplasm. This applies both to recognizing known complexes and characterizing novel complexes. An example of the latter-a 5-fold symmetric particle is-given. Second, electron cryotomography offers an incisive probe to examine crowding in different cellular compartments. (C) 2002 Elsevier Science B.V. All rights reserved.