Cryo-EM of macromolecular assemblies at near-atomic resolution

Nat Protoc. 2010 Sep;5(10):1697-708. doi: 10.1038/nprot.2010.126. Epub 2010 Sep 30.

Abstract

With single-particle electron cryomicroscopy (cryo-EM), it is possible to visualize large, macromolecular assemblies in near-native states. Although subnanometer resolutions have been routinely achieved for many specimens, state of the art cryo-EM has pushed to near-atomic (3.3-4.6 Å) resolutions. At these resolutions, it is now possible to construct reliable atomic models directly from the cryo-EM density map. In this study, we describe our recently developed protocols for performing the three-dimensional reconstruction and modeling of Mm-cpn, a group II chaperonin, determined to 4.3 Å resolution. This protocol, utilizing the software tools EMAN, Gorgon and Coot, can be adapted for use with nearly all specimens imaged with cryo-EM that target beyond 5 Å resolution. Additionally, the feature recognition and computational modeling tools can be applied to any near-atomic resolution density maps, including those from X-ray crystallography.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Algorithms
  • Cryoelectron Microscopy / methods*
  • Crystallography, X-Ray
  • Group II Chaperonins / ultrastructure*
  • Macromolecular Substances
  • Models, Molecular
  • Protein Conformation
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Software*

Substances

  • Macromolecular Substances
  • Group II Chaperonins