Resumen
Morphologically, glutaraldehyde-fixed and -dried intermediate filaments (IFs) appear flexible, and with a width of 8-12 nm when observed by electron microscopy. Sometimes, the filaments are even unraveled on the carbon-coated grid and reveal a protofilamentous architecture. In this study, we have used atomic force microscopy to further investigate the morphology of IFs in a more physiological environment. First, we have imaged hydrated glutaraldehyde-fixed IFs adsorbed to a graphite support. In such conditions, human vimentin and desmin IFs appeared compact with a height of 5-8 nm and revealed either a beading repeat or a helical morphology. Second, we have analyzed the architecture of hydrated vimentin, desmin, and neurofilament IFs adsorbed to mica, graphite, and hydrophilic glass without the presence of fixative. On mica, vimentin IFs had a height of only 3-5 nm, whereas desmin IFs appeared as 8-10 nm height filaments with a helical twist. Neurofilaments were 10-12 nm in height with a pronounced 30-50 nm beading along their length. On graphite, the different IFs were either not adsorbing properly or their architecture was modified yielding, for example, broad, flattened filaments. Finally, hydrophilic glass was the surface which seemed to best preserve the architecture of the three IFs, even if, in some cases, unraveled vimentin filaments were observed on this support. These results are straightening the idea that mature IFs are dynamic polymers in vitro and that IFs can be distinguished from each others by their physicochemical properties.
Idioma original | English |
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Páginas (desde-hasta) | 268-276 |
Número de páginas | 9 |
Publicación | Journal of Structural Biology |
Volumen | 150 |
N.º | 3 |
DOI | |
Estado | Published - jun. 2005 |
Publicado de forma externa | Sí |
Nota bibliográfica
Funding Information:We acknowledge the help of Nicole Taschner for analyzing the AFM images. We also thank Jörg Langowski, Ueli Aebi, and Harald Herrmann for constant support and fruitful discussions. R.K. was supported by a fellowship from the “International phD program” of the DKFZ (Deutsches Krebsforschungszentrum). L.K. was supported by a grant from the Swiss Society for Research on Muscular Diseases awarded to Ueli Aebi and Sergei Strelkov. This work was also supported by grants from the NCCR “Nano” and the Swiss National Science Foundation, both awarded to Ueli Aebi.
ASJC Scopus Subject Areas
- Structural Biology