The structure of a filamentous bacteriophage.
The structure of a filamentous bacteriophage.
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DOI：
10.1016/j.jmb.2006.06.027
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发表时间：
2006-08
影响因子：
5.6
通讯作者：
Ying A. Wang;Xiong Yu;S. Overman;M. Tsuboi;G. Thomas;E. Egelman
中科院分区：
文献类型：
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作者：
Ying A. Wang;Xiong Yu;S. Overman;M. Tsuboi;G. Thomas;E. Egelman
许多薄的螺旋聚合物，包括细菌毛和丝状噬菌体，一直被认为是高分辨率的电子显微镜研究的阻力。鉴于亚基组织的直接可视化是不可能的，对这种细丝的四元结构的研究一直依赖于建模或X射线纤维衍射等技术。我们报告了第一个丝状病毒，噬菌体FD的图像重建，用冷冻电子显微镜。尽管这些很薄的(直径为∼70？)的细丝散布得很弱，但我们已经能够使用迭代螺旋重建程序达到∼8？的标称分辨率。我们证明了病毒存在两种不同的构象，并且在两种状态下，亚基的包装方式与先前基于X射线纤维衍射或固体核磁共振研究提出的相互冲突的模型不同。野生型FD的很大一部分群体要么无序，要么处于多种构象状态，而在Y21M突变的存在下，这种异质性大大降低，这与之前的观察结果一致。这些结果表明，螺旋重建的新计算方法可以极大地扩展以相当高的分辨率可视化非均相蛋白质聚合物的能力。
Many thin helical polymers, including bacterial pili and filamentous bacteriophage, have been seen as refractory to high-resolution studies by electron microscopy. Studies of the quaternary structure of such filaments have depended upon techniques such as modeling or X-ray fiber diffraction, given that direct visualization of the subunit organization has not been possible. We report the first image reconstruction of a filamentous virus, bacteriophage fd, by cryoelectron microscopy. Although these thin (∼70 Å in diameter) rather featureless filaments scatter weakly, we have been able to achieve a nominal resolution of ∼8 Å using an iterative helical reconstruction procedure. We show that two different conformations of the virus exist, and that in both states the subunits are packed differently than in conflicting models previously proposed on the basis of X-ray fiber diffraction or solid-state NMR studies. A significant fraction of the population of wild-type fd is either disordered or in multiple conformational states, while in the presence of the Y21M mutation, this heterogeneity is greatly reduced, consistent with previous observations. These results show that new computational approaches to helical reconstruction can greatly extend the ability to visualize heterogeneous protein polymers at a reasonably high resolution.