How membrane curvature influences lipid distribution is under intensive research. In this short report, after a brief review of recent studies, the results of our coarse-grained (CG) molecular dynamics simulations of ...How membrane curvature influences lipid distribution is under intensive research. In this short report, after a brief review of recent studies, the results of our coarse-grained (CG) molecular dynamics simulations of membranes with “hemifused ribbons” geometry are discussed. When membranes of a binary mixture of (dipalmitoyl-phosphatidylcholine (DPPC) / diol-eoyl-phosphatidylethanolamine (DOPE) were used, DOPE accumulated in the negatively curved region of the monolayer that formed as the proximal monolayers fused (i.e., cis leaflets). However, the enrichment was dependent on the presence of tethering molecules which kept the curvature high (the curvature radius of ~1 nm), placing the cis monolayers ~2-2.5 nm from each other. Simulations in which DOPE was replaced with dioleoyl-phosphatidylcholine (DOPC) showed an insignificant degree of DOPC accumulation, suggesting the importance of lateral interaction among DOPE molecules for the curvature sorting. The above composition was not close to a demixing point and our radial distribution function analysis suggested that the DOPE accumulation was not assisted by the lipid phase separation which has been shown to promote curvature-driven lipid sorting. Relevance of curvature-driven lipid sorting to biological membrane fusion is discussed.展开更多
We investigate how an externally imposed curvature influences lipid segregation on two-phase-coexistent membranes.We show that the bending-modulus contrast of the two phases and the curvature act together to yield a r...We investigate how an externally imposed curvature influences lipid segregation on two-phase-coexistent membranes.We show that the bending-modulus contrast of the two phases and the curvature act together to yield a reduced effective line tension.On largely curved membranes,a state of multiple domains(or rafts) forms due to a mechanism analogous to that causing magnetic-vortex formation in type-II superconductors.We determine the criterion for such a multi-domain state to occur;we then calculate respectively the size of the domains formed on cylindrically and spherically curved membranes.展开更多
Cholesterol,as a common lipid on mammalian cell membranes,plays an important role in the formation of lipid rafts.Recent experiments suggest that the strength of cholesterol's regulation on lipid rafts can be affe...Cholesterol,as a common lipid on mammalian cell membranes,plays an important role in the formation of lipid rafts.Recent experiments suggest that the strength of cholesterol's regulation on lipid rafts can be affected by the length of the unsaturated phospholipid acyl chain on the membrane.In order to understand this observation,a simplified toy model containing three different molecules is proposed in this paper,where the tail length of phospholipids is considered.This model shows the regulation of membrane cholesterol on the phase separation of the lipid mixture and the formation of nano-domains,and also suggests that the configuration entropy of phospholipid tails is an essential factor.展开更多
Membrane tension plays a significant role in many cellular processes including cell adhesion, migration and spreading. Despite the importance of membrane tension, it remains difficult to measure in vivo. Recently, the...Membrane tension plays a significant role in many cellular processes including cell adhesion, migration and spreading. Despite the importance of membrane tension, it remains difficult to measure in vivo. Recently, the development of non-invasive fluorescent probes have made great progress, especially excitedstate deplanarization in molecular rotors has been applied to image membrane tension in living cells.Nevertheless, an intrinsic limitation of such kind of probe is that they depend on the lipid packing, and how the lipid packing responds to the membrane tension change remains unclear. Therefore, in this work,we used a polarity-sensitive membrane probe to investigate the possible response mechanism of lipid packing to the change of membrane tension that was regulated by osmotic shocks. The results showed that an increase in membrane tension could stretch the lipids apart with large displacements, and this change was not homogeneous on the whole membrane, instead, increase of membrane tension induced phase separation.展开更多
文摘How membrane curvature influences lipid distribution is under intensive research. In this short report, after a brief review of recent studies, the results of our coarse-grained (CG) molecular dynamics simulations of membranes with “hemifused ribbons” geometry are discussed. When membranes of a binary mixture of (dipalmitoyl-phosphatidylcholine (DPPC) / diol-eoyl-phosphatidylethanolamine (DOPE) were used, DOPE accumulated in the negatively curved region of the monolayer that formed as the proximal monolayers fused (i.e., cis leaflets). However, the enrichment was dependent on the presence of tethering molecules which kept the curvature high (the curvature radius of ~1 nm), placing the cis monolayers ~2-2.5 nm from each other. Simulations in which DOPE was replaced with dioleoyl-phosphatidylcholine (DOPC) showed an insignificant degree of DOPC accumulation, suggesting the importance of lateral interaction among DOPE molecules for the curvature sorting. The above composition was not close to a demixing point and our radial distribution function analysis suggested that the DOPE accumulation was not assisted by the lipid phase separation which has been shown to promote curvature-driven lipid sorting. Relevance of curvature-driven lipid sorting to biological membrane fusion is discussed.
基金Project supported by the Hundred-Talent Program of the Chinese Academy of Sciences(FY)the National Science Foundation of USA via Grant DMR-1106014(RLBS,JVS)
文摘We investigate how an externally imposed curvature influences lipid segregation on two-phase-coexistent membranes.We show that the bending-modulus contrast of the two phases and the curvature act together to yield a reduced effective line tension.On largely curved membranes,a state of multiple domains(or rafts) forms due to a mechanism analogous to that causing magnetic-vortex formation in type-II superconductors.We determine the criterion for such a multi-domain state to occur;we then calculate respectively the size of the domains formed on cylindrically and spherically curved membranes.
基金fiancial support from the National Natural Science Foundation of China(NSFC No.61475196)。
文摘Cholesterol,as a common lipid on mammalian cell membranes,plays an important role in the formation of lipid rafts.Recent experiments suggest that the strength of cholesterol's regulation on lipid rafts can be affected by the length of the unsaturated phospholipid acyl chain on the membrane.In order to understand this observation,a simplified toy model containing three different molecules is proposed in this paper,where the tail length of phospholipids is considered.This model shows the regulation of membrane cholesterol on the phase separation of the lipid mixture and the formation of nano-domains,and also suggests that the configuration entropy of phospholipid tails is an essential factor.
基金financially supported by Research and Development Program in Key Areas of Guangdong Province,China (No.2019B020209009)National Natural Science Foundation of China(Nos. 21727814, 22034005, 81872829)the China Postdoctoral Science Foundation (No. 2020M680502)。
文摘Membrane tension plays a significant role in many cellular processes including cell adhesion, migration and spreading. Despite the importance of membrane tension, it remains difficult to measure in vivo. Recently, the development of non-invasive fluorescent probes have made great progress, especially excitedstate deplanarization in molecular rotors has been applied to image membrane tension in living cells.Nevertheless, an intrinsic limitation of such kind of probe is that they depend on the lipid packing, and how the lipid packing responds to the membrane tension change remains unclear. Therefore, in this work,we used a polarity-sensitive membrane probe to investigate the possible response mechanism of lipid packing to the change of membrane tension that was regulated by osmotic shocks. The results showed that an increase in membrane tension could stretch the lipids apart with large displacements, and this change was not homogeneous on the whole membrane, instead, increase of membrane tension induced phase separation.
