The three-dimensional structure of halorhodopsin to 5 Å by electron crystallography:: A new unbending procedure for two-dimensional crystals by using a global reference structure
The three-dimensional structure of halorhodopsin to 5 Å by electron crystallography:: A new unbending procedure for two-dimensional crystals by using a global reference structure
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DOI：
10.1073/pnas.080064697
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发表时间：
2000-04-25
影响因子：
11.1
通讯作者：
Henderson, R
中科院分区：
文献类型：
--
作者：
Kunji, ERS;von Gronau, S;Henderson, R
原则上，电子显微镜不需要高度有序的晶体来确定高分辨率的结构。尽管如此。任何类型的晶体都有助于将分子限制在更有限的取向和位置范围内，由此更容易进行结构测定。我们描述了一种改进的程序，用于确定晶体的障碍，我们已经应用到有序性差的二维晶体的氯化物泵盐细菌salinarum盐视紫红质。新的图像分析程序涉及使用从全球三维地图计算的参考投影来进行初始互相关分析。再加上大量的图像与场发射枪显微镜，这使我们能够计算一个三维结构的盐视紫红质。其中七个跨膜螺旋和某些分子特征，如视黄醛的β-紫罗酮环，现在已被解析。
Electron microscopy does not, in principle, require highly ordered crystals to determine a high-resolution structure. Nevertheless. crystals of any type help to constrain the molecules into a more limited range of orientations and positions, from which it is easier to carry out structure determination. We describe an improved procedure for determination of crystalline disorder, which we have applied to poorly ordered two-dimensional crystals of the chloride pump halorhodopsin from Halobacterium salinarum. The new image analysis procedure involves the use of a reference projection calculated from a global three-dimensional map to carry out the initial cross-correlation analysis. Coupled with a greater number of images taken with field emission gun microscopes, this has allowed us to calculate a three-dimensional structure for halorhodopsin. in which the seven transmembrane helices and certain molecular features, such as the beta-ionone ring of retinal, are now resolved.