title: Coupling of the fusion and budding of giant phospholipid vesicles containing macromolecules.
abstract: Mechanisms that enabled primitive cell membranes to self-reproduce have been discussed based on the physicochemical properties of fatty acids; however, there must be a transition to modern cell membranes composed of phospholipids [Budin I, Szostak JW (2011) Proc Natl Acad Sci USA 108:5249-5254]. Thus, a growth-division mechanism of membranes that does not depend on the chemical nature of amphiphilic molecules must have existed. Here, we show that giant unilamellar vesicles composed of phospholipids can undergo the coupled process of fusion and budding transformation, which mimics cell growth and division. After gaining excess membrane by electrofusion, giant vesicles spontaneously transform into the budded shape only when they contain macromolecules (polymers) inside their aqueous core. This process is a result of the vesicle maximizing the translational entropy of the encapsulated polymers (depletion volume effect). Because the cell is a lipid membrane bag containing highly concentrated biopolymers, this coupling process that is induced by physical and nonspecific interactions may have a general importance in the self-reproduction of the early cellular compartments.
authors.affiliation: Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Yamadaoka 1-5, Suita, Osaka 565-0871, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Terasawa
authors.forename: Kazuya
authors.initials: K
authors.lastname: Nishimura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Matsuura
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yomo
mesh_terms: D058045:Artificial Cells / Q000737:chemistry / Q000378:metabolism; D005075:Biological Evolution; D002455:Cell Division; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D003911:Dextrans / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008561:Membrane Fusion; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological; D008956:Models, Chemical; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000737:chemistry / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry; D053835:Unilamellar Liposomes / Q000737:chemistry* / Q000378:metabolism
chemical_list: D003911:Dextrans; D008081:Liposomes; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D010743:Phospholipids; D053835:Unilamellar Liposomes; D011092:Polyethylene Glycols; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol; C028694:1-palmitoyl-2-oleoylphosphatidylcholine