Single-particle applications at intermediate resolution.
Electron microscopy together with single-particle image processing is an excellent method for structure determination of biological assemblies that exist in multiple identical copies. Typical assemblies contain several proteins and/or nucleic acids in a defined and reproducible arrangement. Coherent averaging of electron microscopic images of 5000-100,000 copies of these assemblies allows the determination of three-dimensional structures at ca. 1-3-nm resolution. At this intermediate resolution, it is possible to map individual subunits and thus to understand the architecture and quaternary structure of the assemblies. The intermediate resolution structural information gives a solid basis on which pseudo-atomic models of the assemblies can be modeled provided that high-resolution structures of smaller entities are known. The architecture of the assemblies, their pseudo-atomic models, and knowledge on their plasticity during function give a comprehensive understanding of large-scale structural dynamics of multicopy biological complexes. In this review, we will introduce the experimental pipeline and discuss selected examples.
University of Edinburgh, United Kingdom.
Bettina
B
Böttcher
Katharina
K
Hipp
D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008854:Microscopy, Electron / Q000379:methods; D008958:Models, Molecular; D011487:Protein Conformation