A mechanical model reveals that non-axisymmetric buckling lowers the energy barrier associated with membrane neck constriction

@article{Vasan2019AMM,
  title={A mechanical model reveals that non-axisymmetric buckling lowers the energy barrier associated with membrane neck constriction},
  author={Ritvik Vasan and Shiva Rudraraju and Matthew Akamatsu and Krishna C. Garikipati and Padmini Rangamani},
  journal={bioRxiv},
  year={2019}
}
Membrane neck formation is essential for scission, which, as recent experiments on tubules have demonstrated, can be location dependent. The diversity of biological machinery that can constrict a neck such as dynamin, actin, ESCRTs and BAR proteins, and the range of forces and deflection over which they operate, suggest that the constriction process is functionally mechanical and robust to changes in biological environment. In this study, we used a mechanical model of the lipid bilayer to… 

Transport Phenomena in Fluid Films with Curvature Elasticity

TLDR
A theory for the coupled in-plane viscous flow of lipids, diffusion of transmembrane proteins, and curvature elastic deformation of lipid bilayers is presented and the conservation laws and equations of motion for this system are derived.

The Mechanics and Thermodynamics of Tubule Formation in Biological Membranes

TLDR
A comprehensive review of experimental observations of tubule formation is presented and context from the framework of continuum modeling to explore the scope for future research in this area with an emphasis on iterative modeling and experimental measurements that will enable us to expand the mechanistic understanding of tubulation processes in cells.

Formation of protein-mediated tubes is governed by a snapthrough transition

TLDR
A mathematical framework to model cylindrical tubular protrusions formed by proteins that induce anisotropic spontaneous curvature is presented and it is found that the tube radius depends on an effective tension that includes contributions from the bare membrane tension and the protein-induced curvature.

Quantification and demonstration of the constriction-by-rachet mechanism in the dynamin molecular motor

TLDR
This experimental and computational study provides an example of how collective motor action in megadalton molecular assemblies can be approached and explicitly resolved and finds strong nucleotide-dependent conformational changes.

Non-uniform distribution of myosin-mediated forces governs red blood cell membrane curvature through tension modulation

TLDR
It is predicted that RBC membrane tension and the orientation of the applied forces play important roles in regulating this force-shape landscape and the findings of heterogeneous force distributions on the plasma membrane for RBC shape maintenance may also have implications for shape maintenance in different cell types.

Local sensitivity analysis of the “membrane shape equation” derived from the Helfrich energy

The Helfrich energy is commonly used to model the elastic bending energy of lipid bilayers in membrane mechanics. The governing differential equations for certain geometric characteristics of the

Local sensitivity analysis of the ‘Membrane shape equation’ derived from the Helfrich energy

TLDR
This paper presents a careful analytical and numerical study of certain aspects of parametric sensitivity of Helfrich’s model and demonstrates the application of the scheme to the formation of spherical buds and pearled shapes in membrane vesicles.

Morphodynamics of Active Nematic Fluid Surfaces

Morphodynamic equations governing the behaviour of active nematic fluids on deformable curved surfaces are constructed in the large deformation limit. Emphasis is placed on the formulation of

The ESCRTs – converging on mechanism

TLDR
New structural and biophysical studies have shed much light on the physical mechanism of ESCRT-mediated membrane remodeling and scission, and the field is converging towards a consensus on the broad outlines of a mechanism that is driven by a progressive ATP-dependent treadmilling exchange of ESC RT subunits, as well as compositional change and geometric transitions in ESCRT filaments.

Investigating the morphological dynamics of the plasma membrane by high-speed atomic force microscopy.

TLDR
High-speed atomic force microscopy with correlative imaging with fluorescence microscopy allows for the direct visualisation of morphological changes of the plasma membrane together with the dynamic assembly or disassembly of proteins during the entire course of endocytosis in a living cell.

References

SHOWING 1-10 OF 108 REFERENCES

Shape dynamics, lipid hydrodynamics, and the complex viscoelasticity of bilayer membranes [corrected].

TLDR
A continuum model of the shape dynamics and lipid hydrodynamics is formulated and numerically implemented, which describes the bilayer by its midsurface and by a lipid density field for each monolayer, and validated with the well understood tether extension.

The role of traction in membrane curvature generation

Membrane curvature controls dynamin polymerization

TLDR
It is shown that the force generated by dynamin polymerization, 18 pN, is sufficient to deform membranes yet can still be counteracted by high membrane tension, suggesting that dynamin may be precisely recruited to membrane buds’ necks because of their high curvature.

Protein-induced membrane curvature alters local membrane tension.

Shape matters in protein mobility within membranes

TLDR
Using a single-molecule tracking technique on two transmembrane proteins that bend the membrane differently and are reconstituted in giant unilamellar vesicles, it is shown that the mobility of a membrane protein is crucially dependent on the local membrane deformation self-generated around the protein, which can be tuned by adjusting membrane tension.

Relaxation dynamics of fluid membranes.

  • M. ArroyoA. DeSimone
  • Biology
    Physical review. E, Statistical, nonlinear, and soft matter physics
  • 2009
TLDR
A continuum model which includes a form of the governing equations for a two-dimensional viscous fluid moving on a curved, time-evolving surface concludes that membrane viscosity plays a dominant role in the relaxation dynamics of fluid membranes of sizes comparable to those found in eukaryotic cells.

Theory and algorithms to compute Helfrich bending forces: a review

TLDR
This work systematically derive and compares the different routes to obtain bending forces from the Helfrich energy, namely the variational approach and the thin-shell theory, which lead to mathematically identical expressions.

Gaussian curvature directs the distribution of spontaneous curvature on bilayer membrane necks.

TLDR
This work uses an augmented Helfrich model for lipid bilayers to solve the shape equation on catenoids to find the field of spontaneous curvature that satisfies mechanical equilibrium of membrane necks, and explores how heterogeneities in spontaneous curvatures distribution can couple with Gaussian curvature to result in membrane necks of different geometries.
...