Resumen
Eukaryotic cells contain three cytoskeletal filament systems that exhibit very distinct assembly properties, supramolecular architectures, dynamic behaviour and mechanical properties. Microtubules and microfilaments are relatively stiff polar structures whose assembly is modulated by the state of hydrolysis of the bound nucleotide. In contrast, intermediate filaments (IFs) are more flexible apolar structures assembled from a ∼45 nm long coiled-coil dimer as the elementary building block. The differences in flexibility that exist among the three filament systems have been described qualitatively by comparing electron micrographs of negatively stained dehydrated filaments and by directly measuring the persistence length of F-actin filaments (∼3-10 μm) and microtubules (∼1-8 mm) by various physical methods. However, quantitative data on the persistence length of IFs are still missing. Toward this goal, we have carried out atomic force microscopy (AFM) in physiological buffer to characterise the morphology of individual vimentin IFs adsorbed to different solid supports. In addition, we compared these images with those obtained by transmission electron microscopy (TEM) of negatively stained dehydrated filaments. For each support, we could accurately measure the apparent persistence length of the filaments, yielding values ranging between 0.3 μm and 1 μm. Making simple assumptions concerning the adsorption mechanism, we could estimate the persistence length of an IF in a dilute solution to be ∼1 μm, indicating that the lower measured values reflect constraints induced by the adsorption process of the filaments on the corresponding support. Based on our knowledge of the structural organisation and mechanical properties of IFs, we reason that the lower persistence length of IFs compared to that of F-actin filaments is caused by the presence of flexible linker regions within the coiled-coil dimer and by postulating the occurrence of axial slipping between dimers within IFs.
Idioma original | English |
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Páginas (desde-hasta) | 1241-1250 |
Número de páginas | 10 |
Publicación | Journal of Molecular Biology |
Volumen | 335 |
N.º | 5 |
DOI | |
Estado | Published - ene. 30 2004 |
Publicado de forma externa | Sí |
Nota bibliográfica
Funding Information:We thank S. Stoll for discussions and support concerning the data analysis software, and J. Spatz for discussions concerning the glass modification protocol. L.K. was supported by a fellowship awarded by the “Fondation pour la Recherche Médicale”. The work was funded by a grant awarded to H.H. by Deutsche Forschungsgemeinschaft (DFG, HE1853/4-1), an NCCR program grant on “Nanoscale Science” awarded to U.A. by the Swiss National Science Foundation, The M.E. Müller Foundation of Switzerland, and the Canton Basel Stadt.
ASJC Scopus Subject Areas
- Biophysics
- Structural Biology
- Molecular Biology
PubMed: MeSH publication types
- Comparative Study
- Journal Article
- Research Support, Non-U.S. Gov't