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Polymer-like model to study the dynamics of dynamin filaments on deformable membrane tubes

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Item Type:Preprint
Title:Polymer-like model to study the dynamics of dynamin filaments on deformable membrane tubes
Creators Name:Noel, J.K. and Noé, F. and Daumke, O. and Mikhailov, A.S.
Abstract:Peripheral membrane proteins with intrinsic curvature can act both as sensors of membrane curvatureand shape modulators of the underlying membranes. A well-studied example of such proteins is themechano-chemical GTPase dynamin that assembles into helical filaments around membrane tubes andcatalyzes their scission in a GTPase-dependent manner. It is known that the dynamin coat alone, withoutGTP, can constrict membrane tubes to radii of about 10 nanometers, indicating that the intrinsic shape andelasticity of dynamin filaments should play an important role in membrane remodeling. However, molecularand dynamic understanding of the process is lacking. Here, we develop a dynamical polymer-chain modelfor a helical elastic filament bound on a deformable membrane tube of conserved mass, accounting forthermal fluctuations in the filament and lipid flows in the membrane. We obtained the elastic parametersof the dynamin filament by molecular dynamics simulations of its tetrameric building block and also fromcoarse-grained structure-based simulations of a 17-dimer filament. The results show that the stiffness ofdynamin is comparable to that of the membrane. We determine equilibrium shapes of the filament andthe membrane, and find that mostly the pitch of the filament, not its radius, is sensitive to variations inmembrane tension and stiffness. The close correspondence between experimental estimates of the innertube radius and those predicted by the model suggests that dynamin’s “stalk” region is responsible for itsGTP-independent membrane-shaping ability. The model paves the way for future mesoscopic modeling ofdynamin with explicit motor function.
Source:bioRxiv
Publisher:Cold Spring Harbor Laboratory Press (U.S.A)
Article Number:686873
Date:28 June 2019
Official Publication:https://doi.org/10.1101/686873

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