The hierarchical assembly of septins revealed by high-speed AFM.

TitleThe hierarchical assembly of septins revealed by high-speed AFM.
Publication TypeJournal Article
Year of Publication2020
AuthorsJiao F, Cannon KS, Lin Y-C, Gladfelter AS, Scheuring S
JournalNat Commun
Date Published2020 10 08
KeywordsComputer Simulation, Diffusion, Hydrogen-Ion Concentration, Hydrophobic and Hydrophilic Interactions, Kinetics, Lipids, Microscopy, Atomic Force, Protein Domains, Septins, Static Electricity

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.

Alternate JournalNat Commun
PubMed ID33033254
PubMed Central IDPMC7545167
Grant ListR01 GM130934 / GM / NIGMS NIH HHS / United States
T32 GM119999 / GM / NIGMS NIH HHS / United States