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Review
. 2016 Mar 8;110(5):1008-12.
doi: 10.1016/j.bpj.2016.02.001.

The Current Revolution in Cryo-EM

Edward H Egelman  1
Affiliations
Review

The Current Revolution in Cryo-EM

Edward H Egelman. Biophys J. .
No abstract available

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Figures

Figure 1
Figure 1
The number per year of 3D cryo-EM reconstructions deposited to the Electron Microscopy Data Bank (EMDB) at better than 5.0 Å resolution. To see this figure in color, go online.
Figure 2
Figure 2
A cryo-EM showing two Sulfolobus islandicus rod-shaped virus 2 (SIRV2) virions (18). SIRV2 is a virus that infects a hyperthermophile living in nearly boiling acid. Almost all of the long capsid seen is formed by several thousand identical copies of a coat protein that wraps around and protects the DNA. The arrows point to double-stranded DNA that can be seen emerging from the ends of the virions. The scale bar is 500 Å.
Figure 3
Figure 3
The interior of a 3D reconstruction from SIRV2 (18). Most of the capsid protein in the virus is found in the form of α-helices, and at a resolution of ∼3.8 Å the pitch and right-handed twist of these α-helices are readily visible in the density map (transparent gray surface). Every capsid protein is identical, and the building block of this assembly is a symmetrical dimer formed by two copies of the capsid protein. Thus, the yellow and green helices come from two different subunits and form antiparallel helices because the polypeptide chains are oriented in opposite directions from each. At the available resolution, bulky aromatic side chains can be visualized (arrows). Because the sequence of the capsid protein is known, this allows for an unambiguous threading of the sequence through these helices. To see this figure in color, go online.
Figure 4
Figure 4
A small region from the 2.2 Å resolution cryo-EM reconstruction of β-galactosidase (20). The resolution is high enough to see an ordered and bound water molecule in the center (yellow). To see this figure in color, go online.
Figure 5
Figure 5
A region from the type VI secretion system sheath of Vibrio cholerae (21), reconstructed by cryo-EM at ∼3.2 Å resolution. The atomic model that was built into the reconstruction (transparent gray surface) has three different molecules shown in cyan, red, and blue. At a resolution worse than ∼4 Å, one might have ambiguities in tracing the individual polypeptide chains present in each molecule. The resolution that was achieved prevented any such ambiguities, and it was clear that the β-sheet shown involved two strands from one molecule (cyan), and one strand from each of two different molecules (red and blue). To see this figure in color, go online.
See this image and copyright information in PMC

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