Harauz G, Stoeffler-Meilicke M, van Heel M
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, West Germany.
J Mol Evol. 1987;26(4):347-57. doi: 10.1007/BF02101154.
Multivariate statistical analysis and classification techniques are powerful tools in sorting noisy electron micrographs of single particles according to their principal features, enabling one to form average images with an enhanced signal-to-noise ratio and a better reproducible resolution. We apply this methodology here to determining the characteristic views of the large (50S) ribosomal subunits from the eubacterium Escherichia coli and the archaebacteria Methanococcus vannielii, Sulfolobus solfataricus, and Halobacterium marismortui. Average images were obtained of the subunit in the common crown and kidney projections, but views of the particle in orientations intermediate between these two extremes were also elucidated for all species. These averages show reproducible detail of up to 2.0 nm resolution, thus enabling the visualization and interspecies comparison of many structural features as a first step toward comparing the actual three-dimensional structures. Our results disprove evolutionary lineages recently postulated on the basis of electron microscopical images of ribosomal subunits.
多变量统计分析和分类技术是根据单颗粒噪声电子显微照片的主要特征进行分类的强大工具，能使人们形成具有更高信噪比和更好可重复性分辨率的平均图像。我们在此应用这种方法来确定来自真细菌大肠杆菌以及古细菌万氏甲烷球菌、嗜热栖热菌和盐沼盐杆菌的大型（50S）核糖体亚基的特征视图。获得了亚基在常见冠状和肾形投影中的平均图像，并且还阐明了所有物种在这两个极端取向之间的中间取向的颗粒视图。这些平均值显示了高达2.0纳米分辨率的可重复细节，从而能够可视化并对许多结构特征进行种间比较，这是迈向比较实际三维结构的第一步。我们的结果反驳了最近基于核糖体亚基电子显微镜图像所假定的进化谱系。
