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Progress and Potential of Electron Cryotomography as Illustrated by Its Application to Bacterial Chemoreceptor Arrays
Annual Review of Biophysics ( IF 10.4 ) Pub Date : 2017-05-22 00:00:00 , DOI: 10.1146/annurev-biophys-070816-033555
Ariane Briegel 1 , Grant Jensen 2, 3
Affiliation  

Electron cryotomography (ECT) can produce three-dimensional images of biological samples such as intact cells in a near-native, frozen-hydrated state to macromolecular resolution (∼4 nm). Because one of its first and most common applications has been to bacterial chemoreceptor arrays, ECT's contributions to this field illustrate well its past, present, and future. While X-ray crystallography and nuclear magnetic resonance spectroscopy have revealed the structures of nearly all the individual components of chemoreceptor arrays, ECT has revealed the mesoscale information about how the components are arranged within cells. Receptors assemble into a universally conserved 12-nm hexagonal lattice linked by CheA/CheW rings. Membrane-bound arrays are single layered; cytoplasmic arrays are double layered. Images of in vitro reconstitutions have led to a model of how arrays assemble, and images of native arrays in different states have shown that the conformational changes associated with signal transduction are subtle, constraining models of activation and system cooperativity. Phase plates, better detectors, and more stable stages promise even higher resolution and broader application in the near future.

中文翻译:


电子冷冻层析技术的进展及其在细菌化学感受器阵列中的应用潜力

电子冷冻断层扫描(ECT)可以产生生物样品(例如完整细胞)的三维图像,这些图像处于接近自然的冷冻水合状态,达到大分子分辨率(约4 nm)。由于ECT是细菌化学感受器阵列的第一个也是最常见的应用之一,因此ECT对这一领域的贡献很好地说明了它的过去,现在和未来。尽管X射线晶体学和核磁共振波谱已经揭示了化学感受器阵列几乎所有单个成分的结构,但ECT却揭示了有关这些成分如何在细胞内排列的中尺度信息。受体组装成一个由CheA / CheW环链接的普遍保守的12 nm六角形晶格。膜结合的阵列是单层的。细胞质阵列是双层的。体外重建的图像导致了阵列如何组装的模型,而处于不同状态的天然阵列的图像表明与信号转导相关的构象变化是激活和系统协作性的微妙的约束模型。相板,更好的检测器和更稳定的载物台有望在不久的将来提供更高的分辨率和更广泛的应用。

更新日期:2017-05-22
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