Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
J Synchrotron Radiat. 2011 Jan;18(1):2-5. doi: 10.1107/S0909049510036812. Epub 2010 Nov 5.
Electron cryo-tomography is a potential approach to analyzing the three-dimensional conformation of frozen hydrated biological macromolecules using electron microscopy. Since projections of each individual object illuminated from different orientations are merged, electron tomography is capable of structural analysis of such heterogeneous environments as in vivo or with polymorphism, although radiation damage and the missing wedge are severe problems. Here, recent results on the structure of eukaryotic flagella, which is an ATP-driven bending organelle, from green algae Chlamydomonas are presented. Tomographic analysis reveals asymmetric molecular arrangements, especially that of the dynein motor proteins, in flagella, giving insight into the mechanism of planar asymmetric bending motion. Methodological challenges to obtaining higher-resolution structures from this technique are also discussed.
电子低温断层扫描是一种利用电子显微镜分析冷冻水合生物大分子三维构象的潜在方法。由于每个从不同方向照明的单个物体的投影被合并，因此电子断层扫描能够分析活细胞或多态性等异质环境的结构，尽管辐射损伤和缺失楔形是严重的问题。这里介绍了来自绿藻衣藻的真核鞭毛结构的最新结果，鞭毛是一种 ATP 驱动的弯曲细胞器。断层扫描分析揭示了鞭毛中不对称的分子排列，特别是动力蛋白马达蛋白的排列，这为平面不对称弯曲运动的机制提供了深入的了解。还讨论了从该技术获得更高分辨率结构的方法学挑战。
