Prospects of electron cryotomography to visualize macromolecular complexes inside cellular compartments: Implications of crowding

Kay Grünewald, Ohad Medalia, Ariane Gross, Alasdair C. Steven, Wolfgang Baumeister

Research output: Contribution to journalArticlepeer-review

93 Scopus citations

Abstract

Electron cryotomography has unique potential for three-dimensional visualization of macromolecular complexes at work in their natural environment. This approach is based on reconstructing three-dimensional volumes from tilt series of electron micrographs of cells preserved in their native states by vitrification. Resolutions of 5-8 nm have already been achieved and the prospects for further improvement are good. Since many intracellular activities are conducted by complexes in the megadalton range with dimensions of 20-50 nm, current resolutions should suffice to identify many of them in tomograms. However, residual noise and the dense packing of cellular constituents hamper interpretation. Recently, tomographic data have been collected on vitrified eukaryotic cells (Medalia et al., Science (2002) in press). Their cytoplasm was found to be markedly less crowded than in the prokaryotes previously studied, in accord with differences in crowding between prokaryotic and eukaryotic cells documented by other (indirect) biophysical methods. The implications of this observation are twofold. First, complexes should be more easily identifiable in tomograms of eukaryotic cytoplasm. This applies both to recognizing known complexes and characterizing novel complexes. An example of the latter - a 5-fold symmetric particle is - given. Second, electron cryotomography offers an incisive probe to examine crowding in different cellular compartments.

Original languageEnglish
Pages (from-to)577-591
Number of pages15
JournalBiophysical Chemistry
Volume100
Issue number1-3
DOIs
StatePublished - 1 Dec 2002
Externally publishedYes

Keywords

  • Electron tomography
  • Eukaryote/prokaryote distinction
  • Macromolecular crowding
  • Vitrification

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Organic Chemistry

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