Practical Electron Microscopy and Database

The field of biological electron microscopy (EM) has been revolutionized by several key developments, such as electron crystallography, single-particle tomography, and cryo-electron microscopy (cryo-EM), all supported by large-scale computational advancements. Starting with the electron crystallography work by DeRosier and Klug [1] in 1968, it became possible to generate 3D density maps from electron microscope images. Significant milestones include the determination of atomic-scale structures from 2D crystals, single-particle cryo-EM reconstructions of identical particles at 6 Å resolution, and 3D cryo-EM tomography of the same particle, also at 6 Å resolution. These techniques enabled breakthroughs such as determining the first membrane protein structure, producing high-resolution density maps of the protein shell of an icosahedral virus, and imaging entire cells. By embedding biological macromolecules in vitreous ice, radiation damage is minimized, allowing for high-resolution, non-invasive visualization of the 3D structure of eukaryotic cells, including their organelles, cytoskeleton, and molecular machinery, with a resolution ranging from 6 Å to 2 nm, though limited by radiation damage. For further reading, see works by Henderson, [2] Crowther, [3] Baumeister and Glaeser, [4] and the books by Glaeser et al. [5] and Frank. [6]

[1] A. Klug, Nobel Lecture (December 8, 1982).
[2] R. Henderson, Q. Rev. Biophys., 28, 171 (1995).
[3] R. A. Crowther, Phil. Trans. R. Soc. B, 363, 2441 (2008).
[4] A. Sali, R. M. Glaeser, T. Earnest and W. Baumeister, Nature, 422, 216 (2003).
[5] R. M. Glaeser, K. Downing, D. DeRosier, W. Chiu and J. Frank, “Electron Crystallography of Biological Macromolecules,” Oxford University Press, New York (2007).
[6] J. Frank, “Three-Dimensional Electron Microscopy of Macromolecular Assemblies: Visualization of Biological Molecules in Their Native State,” Oxford University Press, New York (2006).