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Electron Microscopy of Biological Macromolecules: Bridging the Gap between What Physics Allows and What We Currently Can Get

Published online by Cambridge University Press:  22 January 2004

Dieter Typke ,
Kenneth H. Downing  and
Robert M. Glaeser
Dieter Typke
Affiliation:
Donner Laboratory, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA
Kenneth H. Downing
Affiliation:
Donner Laboratory, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA
Robert M. Glaeser
Affiliation:
Donner Laboratory, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3206, USA
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Abstract

The resolution achieved in low-dose electron microscopy of biological macromolecules is significantly worse than what can be obtained on the same microscopes with more robust specimens. When two-dimensional crystals are used, it is also apparent that the high-resolution image contrast is much less than what it could be if the images were perfect. Because specimen charging is one factor that might limit the contrast and resolution achieved with biological specimens, we have investigated the use of holey support films that have been coated with a metallic film before depositing specimens onto a thin carbon film that is suspended over the holes. Monolayer crystals of paraffin (C44H90) are used as a test specimen for this work because of the relative ease in imaging Bragg spacings at ∼0.4 nm resolution, the relative ease of measuring the contrast in these images, and the similar degree of radiation sensitivity of these crystals when compared to biological macromolecules. A metallic coating on the surrounding support film does, indeed, produce a significant improvement in the high-resolution contrast for a small fraction of the images. The majority of images show little obvious improvement, however, and even the coated area of the support film continues to show a significant amount of beam-induced movement under low-dose conditions. The fact that the contrast in the best images can be as much as 25%–35% of what it would be in a perfect image is nevertheless encouraging, demonstrating that it should be possible, in principle, to achieve the same performance for every image. Routine data collection of this quality would make it possible to determine the structure of large, macromolecular complexes without the need to grow crystals of these difficult specimen materials.

Keywords

specimen motionsupport filmsimage contract
Type
Research Article
Information
Microscopy and Microanalysis , Volume 10 , Issue 1 , February 2004 , pp. 21 - 27
Copyright
© 2004 Microscopy Society of America

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References

REFERENCES

Brink, J. & Chiu, W. (1991). Contrast analysis of cryo-images of n-paraffin recorded at 400 kV out to 2.1 Å resolution. J Microsc 161, 279–295.Google Scholar
Bullough, P. & Henderson, R. (1987). Use of spot-scan procedure for recording low-dose micrographs of beam-sensitive specimens. Ultramicroscopy 21, 223–230.CrossRefGoogle Scholar
Downing, K.H. & Glaeser, R.M. (1986). Improvement in high resolution image quality of radiation-sensitive specimens achieved with reduced spot size of the electron beam. Ultramicroscopy 20, 269–278.CrossRefGoogle Scholar
Glaeser, R.M. (1999). Review: Electron crystallography: Present excitement, a nod to the past, anticipating the future. J Struct Biol 128, 3–14.CrossRefGoogle Scholar
Glaeser, R.M. & Downing, K.H. (2004). Specimen charging on thin films with one conducting layer: Discussion of physical principles. Microsc Microanal 10, in press.CrossRefGoogle Scholar
Hayward, S.B. & Glaeser, R.M. (1980). Use of low temperatures for electron diffraction and imaging of biological macromolecular arrays. In Electron Microscopy at Molecular Dimensions, Baumeister, W. & Vogell, W. (Eds.), pp. 226–233. Berlin: Springer-Verlag.CrossRef
Henderson, R. (1995). The potential and limitations of neutrons, electrons and X-rays for atomic resolution microscopy of unstained biological molecules. Q Rev Biophys 28, 171–193.CrossRefGoogle Scholar
Henderson, R. & Glaeser, R.M. (1985). Quantitative analysis of image contrast in electron micrographs of beam-sensitive crystals. Ultramicroscopy 16, 139–150.CrossRefGoogle Scholar
Jakubowski, U., Baumeister, W., & Glaeser, R.M. (1989). Evaporated carbon stabilizes thin, frozen-hydrated specimens. Ultramicroscopy 31, 351–356.CrossRefGoogle Scholar
Mitsuoka, K., Hirai, T., Murata, K., Miyazawa, A., Kidera, A., Kimura, Y., & Fujiyoshi, Y. (1999). The structure of bacteriorhodopsin at 3.0 Å resolution based on electron crystallography: Implication of the charge distribution. J Mol Biol 286, 861–882.Google Scholar
Miyazawa, A., Fujiyoshi, Y., Stowell, M., & Unwin, N. (1999). Nicotinic acetylcholine receptor at 4.6 Å resolution: Transverse tunnels in the channel wall. J Mol Biol 288, 765–786.Google Scholar
Rader, S.S. & Lamvik, M.K. (1992). High-conductivity amorphous TiSi substrates for low-temperature electron microscopy. J Microsc 168, 71–77.CrossRefGoogle Scholar