Single-particle electron microscopy analysis of macromolecular assemblies

Abstract

Structural biology strives to understand function of biomolecules through the determination of their molecular structures. Traditionally, X-ray crystallography has been considered as the “gold-standard” method for three-dimensional structure determination at high-resolution. Unfortunately, a major bottleneck of this technique lies in the need for well-ordered crystals, which limits studies of challenging targets such as integral membrane proteins or heterogeneous samples. On the other hand, electron microscopy (EM) allows for the study of macromolecular assemblies in near-native conditions without the need for crystallization. Not only does it pose fewer restrictions on sample purity, the total amount of the materials used for EM can be orders of magnitude less than that required for structural analysis with other techniques. Recent development of direct electron detectors and image-processing algorithms have revolutionized the field of single-particle cryo-EM and resulted in a number of near-atomic and atomic resolution reconstructions. This spectacular progress will likely enable cryo-EM to become an indispensable tool for structure-based drug discovery.