Raft Formation in Lipid Bilayers Coupled to Curvature

Abstract

We present computer simulations of a membrane in which the local composition is coupled to the local membrane curvature. At high temperatures (i.e., above the temperature of macroscopic phase separation), finite-sized transient domains are observed, reminiscent of lipid rafts. The domain size is in the range of hundred nanometers, and set by the membrane elastic properties. These findings are in line with the notion of the membrane as a curvature-induced microemulsion. At low temperature, the membrane phase separates. The transition to the phase-separated regime is continuous and belongs to the two-dimensional Ising universality class when the coupling to curvature is weak, but becomes first-order for strong curvature-composition coupling.

Negatively Charged Lipids as a Potential Target for New Amphiphilic Aminoglycoside Antibiotics

“…These distinct assemblies of proteins and/or lipids (3) are related to the regulation of many core processes, such as chromosomal and cell division-related events (4,5). Membrane curvature is potentially responsible for preferential lipid self-assembly behaviors as well as osmosensing (6) and folding of membrane proteins (7).…”

“…This discrepancy results in a molecule with a large intrinsic negative curvature (16), also described previously for phosphatidylethanolamine (PE) (17), which facilitates the insertion of membrane proteins. The cross-sectional size difference further explains the location of cardiolipin-enriched regions at the pole and/or the division septum, which can in turn relate to the polar localization of many proteins, including * This work was supported by the Belgian Funds for Scientific Research those involved in cell division and osmosensing (6). In particular, in E. coli, cardiolipin is known to enhance the activity of the glycosyltransferase MurG involved in peptidoglycan biosynthesis (18).…”

Interplay of curvature-induced micro- and nanodomain structures in multicomponent lipid bilayers

“…1a). It was first proposed by Andelman and coworkers and further investigated by a number of authors [41,42,43,44,45,46,47,48]. Schick and coworkers argued that it might account for raft formation in membranes [45,46,47].…”

Physical mechanisms of micro- and nanodomain formation in multicomponent lipid membranes

“…The Brazovskii and the Ising line meet at t = g = 0 in a multicritical point, the so-called Lifshitz point [203,204], which is also the end point of a (first order) triple line separating the two demixed phases (with homogeneous order parameter Φ ± ) and the modulated phase at low t. Like the rest of the Brazovskii line, the Lifshitz point is also unstable with respect to thermal fluctuations. Computer simulations [143,145] suggest that it is shifted towards larger g and turns into a tricritical point, i.e., the demixing transition becomes first order and the demixing line meets the (first order) Brazovskii line in a quadruple point.…”