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Negative-Stain Transmission Electron Microscopy of Molecular Complexes for Image Analysis by 2D Class Averaging.

John R GallagherAlexander J KimNeetu M GulatiAudray K Harris
Published in: Current protocols in microbiology (2020)
Negative-stain transmission electron microscopy (EM) is a technique that has provided nanometer resolution images of macromolecules for about 60 years. Developments in cryo-EM image processing have maximized the information gained from averaging large numbers of particles. These developments can now be applied back to negative-stain image analysis to ascertain domain level molecular structure (10 to 20 Å) more quickly and efficiently than possible by atomic resolution cryo-EM. Using uranyl acetate stained molecular complexes of influenza hemagglutinin bound to Fab 441D6, we describe a simple and efficient means to collect several hundred micrographs with SerialEM. Using RELION, we illustrate how tens of thousands of complexes can be auto-picked and classified to accurately describe the domain level topology of this unconventional hemagglutinin head-domain epitope. By comparing to the cryo-EM density map of the same complex, we show that questions about epitope mapping and conformational heterogeneity can readily be answered by this negative-stain method. © 2019 The Authors.
Keyphrases
  • electron microscopy
  • single molecule
  • deep learning
  • healthcare
  • high density
  • molecular dynamics
  • optical coherence tomography
  • mass spectrometry
  • machine learning
  • optic nerve