Breaking Cryo-EM Resolution Barriers to Facilitate Drug Discovery.
Merk, A., Bartesaghi, A., Banerjee, S., Falconieri, V., Rao, P., Davis, M.I., Pragani, R., Boxer, M.B., Earl, L.A., Milne, J.L., Subramaniam, S.(2016) Cell 165: 1698-1707
- PubMed: 27238019 
- DOI: https://doi.org/10.1016/j.cell.2016.05.040
- Primary Citation of Related Structures:  
5K0Z, 5K10, 5K11, 5K12 - PubMed Abstract: 
Recent advances in single-particle cryoelecton microscopy (cryo-EM) are enabling generation of numerous near-atomic resolution structures for well-ordered protein complexes with sizes ≥ ∼200 kDa. Whether cryo-EM methods are equally useful for high-resolution structural analysis of smaller, dynamic protein complexes such as those involved in cellular metabolism remains an important question. Here, we present 3.8 Å resolution cryo-EM structures of the cancer target isocitrate dehydrogenase (93 kDa) and identify the nature of conformational changes induced by binding of the allosteric small-molecule inhibitor ML309. We also report 2.8-Å- and 1.8-Å-resolution structures of lactate dehydrogenase (145 kDa) and glutamate dehydrogenase (334 kDa), respectively. With these results, two perceived barriers in single-particle cryo-EM are overcome: (1) crossing 2 Å resolution and (2) obtaining structures of proteins with sizes < 100 kDa, demonstrating that cryo-EM can be used to investigate a broad spectrum of drug-target interactions and dynamic conformational states.
Organizational Affiliation: 
Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.