title: Septin Interferes with the Temperature-Dependent Domain Formation and Disappearance of Lipid Bilayer Membranes.
abstract: Domain formation or compartmentalization in a lipid bilayer membrane has been thought to take place dynamically in cell membranes and play important roles in the spatiotemporal regulation of their physiological functions. In addition, the membrane skeleton, which is a protein assembly beneath the cell membrane, also regulates the properties as well as the morphology of membranes because of its role as a diffusion barrier against constitutive molecules of the membrane or as a scaffold for physiological reactions. Therefore, it is important to study the relationship between lipid bilayer membranes and proteins that form the membrane skeleton. Among cytoskeletal systems, septin is unique because it forms arrays on liposomes that contain phosphoinositides, and this property is thought to contribute to the formation of the annulus in sperm flagellum. In this study, a supported lipid bilayer (SLB) was used to investigate the effect of septin on lipid bilayers because SLBs rather than liposomes are suitable for observation of the membrane domains formed. We found that SLBs containing phosphatidylinositol (PI) reversibly form domains by decreasing the temperature and that septin affects both the formation and the disappearance of the cooling-induced domain. Septin inhibits the growth of cooling-induced domains during decreases in temperature and inhibits the dispersion and the disappearance of those domains during increases in temperature. These results indicate that septin complexes, i.e., filaments or oligomers assembling on the surface of lipid bilayer membranes, can regulate the dynamics of domain formation via their behavior as an anchor for PI molecules.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Yamada
authors.forename: Takumi
authors.initials: T
authors.lastname: Isogai
authors.affiliation: The Electronics-Inspired Interdisciplinary Research Institute, Toyohashi University of Technology , Toyohashi 441-8580, Japan.
authors.forename: Ryugo
authors.initials: R
authors.lastname: Tero
authors.affiliation: Structural Biology Research Center, Nagoya University , Nagoya 464-8601, Japan.
authors.forename: Yohko
authors.initials: Y
authors.lastname: Tanaka-Takiguchi
authors.forename: Toru
authors.initials: T
authors.lastname: Ujihara
authors.forename: Makoto
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Structural Biology Research Center, Nagoya University , Nagoya 464-8601, Japan.
authors.forename: Kingo
authors.initials: K
authors.lastname: Takiguchi
mesh_terms: D002462:Cell Membrane; D008051:Lipid Bilayers; D044367:Phase Transition; D058112:Septins / Q000494:pharmacology*; D013696:Temperature
chemical_list: D008051:Lipid Bilayers; D058112:Septins