Detachment of a fluid membrane from a substrate and vesiculation

Abstract

The detachment dynamics of a fluid membrane with an isotropic spontaneous curvature from a flat substrate are studied by using meshless membrane simulations. The membrane is detached from an open edge leading to vesicle formation. With strong adhesion, the competition between the bending and adhesion energies determines the minimum value of the spontaneous curvature for the detachment. In contrast, with weak adhesion, a detachment occurs at smaller spontaneous curvatures due to the membrane thermal undulation. When parts of the membrane are pinned on the substrate, the detachment becomes slower and a remained membrane patch forms straight or concave membrane edges. The edge undulation induces vesiculation of long strips and disk-shaped patches. Therefore, membrane rolling is obtained only for membrane strips shorter than the wavelength for deformation into unduloid. This suggests that the rolling observed for Ca 2+ -dependent membranebinding proteins, annexins A3, A4, A5, and A13, results from by the anisotropic spontaneous curvature induced by the proteins.

Binding of curvature-inducing proteins onto tethered vesicles

“…In contrast, for the present system, the difference in the spontaneous curvature gives more dominant effects. Unduloid-like deformations have been reported in tethered vesicles after fore release [54], as well as in tubular vesicles with polymer anchoring [55] and rolled membranes during detachment from a substrate [37]. In contrast, phase separation can make cylindrical tubes unstable under strong forces.…”

“…For a largescale simulation, we developed two types of meshless membrane models [26,27], in which membrane particles self-assemble into a single-layer membrane and the mechanical properties can be varied over a wide range. Here, we employ a spin meshless membrane model [27], since it can vary the spontaneous curvature and has been applied to membrane deformation by curvature-inducing proteins with an isotropic spontaneous curvature [28,29] and with an anisotropic spontaneous curvature [30][31][32][33][34][35], as well as topological changes of membranes [36,37]. In mean-field theory, we assume a uniform distribution of the bound proteins in each membrane component.…”

Binding of Curvature-Inducing Proteins onto Biomembranes

“…Various dynamics, such as rolling and budding, have been observed. Although budding and subsequent vesicle formation were simulated by the meshless simulation of the membrane with a homogeneous spontaneous curvature [170], rolling has not yet been reproduced. Thus, the interactions between curvature-inducing proteins and membranes with open edges should be further explored.…”

Investigation of Shape Transformations of Vesicles, Induced by Their Adhesion to Flat Substrates Characterized by Different Adhesion Strength

“…In real biological systems such as animal tissues, cells' membrane can adhere to surfaces, which are not flat and not rigid, for example to the neighboring cells. Considering the relative simplicity of our system, we may anticipate to discover many new phenomena related to adhesion of biological cells to themselves or to rigid objects [1,2,21]. The adhesion of cells may induce novel and very interesting phenomena in large collection of cells in biological tissue or in artificial cell cultures.…”