Kinetics of domain registration in multicomponent lipid bilayer membranes

Abstract

The kinetics of registration of lipid domains in the apposing leaflets of symmetric bilayer membranes is investigated via systematic dissipative particle dynamics simulations. The decay of the distance between the centres of mass of the domains in the apposing leaflets is almost linear during early stages, and then becomes exponential during late times. The time scales of both linear and exponential decays are found to increase with decreasing the strength of interleaflet coupling. The ratio between the time scales of the exponential and linear regimes decreases with increasing the domain size, implying that the decay of the distance between the domains centres of mass is essentially linear for large domains. These numerical results are largely in agreement with the recent theoretical predictions of Han and Haataja [Soft Matter (2013) 9:2120-2124]. We also found that the domains become elongated during the registration process.

Registered and Antiregistered Phase Separation of Mixed Amphiphilic Bilayers

“…We definê φ t(b) i = 1 or 0 if the top (bottom) of site i contains an 'S' or 'U' species amphiphile. These labels are chosen to suggest saturated and unsaturated lipids, where S prefers a longer, more ordered tail structure; however they can represent any two species, or two of the lipid phases (L o , L d or gel) available to a ternary (S + U + cholesterol) bilayer (19,22,23) (24). Each lattice site may be 'pairwise' registered (SS or UU), or antiregistered (SU or US).…”

“…The phenomenological free energies and parameters in these models do not relate directly to any molecular or structural features of bilayers. Hydrophobic mismatch is often not explicitly included in coarse-grained modelling (3,5,(7)(8)(9)19), so that the competition of direct and indirect inter-leaflet couplings described above cannot be captured (20).…”

Kinetics of symmetry and asymmetry in a phase-separating bilayer membrane

“…3a. This idea is exploited in simulation [29,30] and theory [2,5,9,10], and a careful derivation by Garbès Putzel and Schick [9] shows that it entails assuming the key compositional order parameter is the relative abundance of saturated versus unsaturated lipids. Two-component Ising universality in L o -L d experiments [31] supports such a mapping.…”

Cholesterol Flip-Flop Impacts Domain Registration in Plasma Membrane Models

“…In fact, a number of recent simulation studies address the issue of domain registration and point to a variety of factors that contribute to alignment or even anti-alignment of the domains. 15 − 21 The extent of domain registration therefore involves multiple factors and appears highly system-dependent.…”

“…Interestingly, in many cases, the domains in both leaflets appear to be correlated. − Currently, multiple theories exist about the major driving force for this domain registration, including curvature coupling, interleaflet midplane tension, line tension of the domain boundary, chain interdigitation, electrostatic coupling, and cholesterol flip-flop. − Molecular dynamics (MD) simulations are, in principle, suited to unravel these driving forces. In fact, a number of recent simulation studies address the issue of domain registration and point to a variety of factors that contribute to alignment or even anti-alignment of the domains. − The extent of domain registration therefore involves multiple factors and appears highly system-dependent.…”