High-Resolution Cryo-EM Maps and Models: A Crystallographer's Perspective.

Author:

Wlodawer, Alexander

Li, Mi

Dauter, Zbigniew
Author Address

Protein Structure Section, Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702, USA. Electronic address: wlodawer@nih.gov., Protein Structure Section, Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702, USA; Basic Science Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA., Synchrotron Radiation Research Section, Macromolecular Crystallography Laboratory, NCI, Argonne National Laboratory, Argonne, IL 60439, USA.,

Abstract:

The appearance of ten high-resolution cryoelectron microscopy (cryo-EM) maps of proteins, ribosomes, and viruses was compared with the experimentally phased crystallographic electron density maps of four proteins. We found that maps calculated at a similar resolution by the two techniques are quite comparable in their appearance, although cryo-EM maps, even when sharpened, seem to be a little less detailed. An analysis of models fitted to the cryo-EM maps indicated the presence of significant problems in almost all of them, including incorrect geometry, clashes between atoms, and discrepancies between the map density and the fitted models. In particular, the treatment of the atomic displacement (B) factors was meaningless in almost all analyzed cryo-EM models. Stricter cryo-EM structure deposition standards and their better enforcement are needed. Published by Elsevier Ltd.

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