The hierarchical assembly of septins revealed by high-speed AFM.
Septins are GTP-binding proteins involved in diverse cellular processes including division and membrane remodeling. Septins form linear, palindromic heteromeric complexes that can assemble in filaments and higher-order structures. Structural studies revealed various septin architectures, but questions concerning assembly-dynamics and -pathways persist. Here we used high-speed atomic force microscopy (HS-AFM) and kinetic modeling which allowed us to determine that septin filament assembly was a diffusion-driven process, while formation of higher-order structures was complex and involved self-templating. Slightly acidic pH and increased monovalent ion concentrations favor filament-assembly, -alignment and -pairing. Filament-alignment and -pairing further favored diffusion-driven assembly. Pairing is mediated by the septin N-termini face, and may occur symmetrically or staggered, likely important for the formation of higher-order structures of different shapes. Multilayered structures are templated by the morphology of the underlying layers. The septin C-termini face, namely the C-terminal extension of Cdc12, may be involved in membrane binding.
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Related Subject Headings
- Static Electricity
- Septins
- Protein Domains
- Microscopy, Atomic Force
- Lipids
- Kinetics
- Hydrophobic and Hydrophilic Interactions
- Hydrogen-Ion Concentration
- Diffusion
- Computer Simulation
Citation
Published In
DOI
EISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Static Electricity
- Septins
- Protein Domains
- Microscopy, Atomic Force
- Lipids
- Kinetics
- Hydrophobic and Hydrophilic Interactions
- Hydrogen-Ion Concentration
- Diffusion
- Computer Simulation