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Cryoatomic force microscopy of filamentous actin
1Department of Molecular Physiology and Biological Physics, Health Sciences Center, University of Virginia, Charlottesville, Virginia 22908-0011 USA.
Biophysical Journal
|February 2, 2000
Summary
Cryo-atomic force microscopy revealed actin filaments as right-handed helices. Higher-order structures like branched rafts were observed, challenging previous models of actin structure.
Area of Science:
- Biophysics
- Cell Biology
- Materials Science
Background:
- Actin filaments form essential cellular structures.
- Previous models of actin filament structure have been debated.
- High-resolution imaging is crucial for understanding actin polymerization.
Purpose of the Study:
- To visualize the structure of actin filaments using cryo-atomic force microscopy (cryo-AFM).
- To investigate the formation of higher-order actin structures.
- To clarify the handedness of F-actin.
Main Methods:
- Imaging phalloidin-stabilized actin filaments adsorbed to mica using cryo-AFM.
- Analysis of filament structure, periodicity, and aggregation.
- Resolution of individual actin monomers within filaments.
Main Results:
- Single actin filaments exhibit a right-handed helical structure with ~38 nm periodicity.
- Branched actin filament rafts and larger aggregates were observed.
- Filamentous rafts showed regular lateral registration with a ~13 nm axial shift.
- Actin monomers were resolvable within filaments.
- Evidence suggests left-handed F-actin models may be artifacts.
Conclusions:
- Cryo-AFM provides high-resolution structural data on actin filaments.
- Observed higher-order structures have implications for actin gel properties.
- The study supports a right-handed helical model for F-actin.