title: Farnesol and geranylgeraniol modulate the structural properties of phosphatidylethanolamine model membranes.
abstract: The biological activity of farnesol (FN) and geranylgeraniol (GG) and their isoprenyl groups is related to membrane-associated processes. We have studied the interactions of FN and GG with 1,2-dielaidoyl-sn-glycero-3-phosphoethanolamine (DEPE) membranes using DSC and X-ray diffraction. Storage of samples at low temperature for a long time favors a multidomain system formed by a lamellar crystalline (Lc) phase and isoprenoids (ISPs) aggregates. We demonstrate that ISPs alter the thermotropic behavior of DEPE, thereby promoting a HII growth in a lamellar Lc phase with a reduced degree of hydration. The HII phase occurs with the same repeat distance (dHII=5.4 nm) as the Lc phase and upon heating it expands considerably (deltad/deltaT approximately 0.22 nm/ degrees C). The dimensional stabilization of this HII phase coincides with the transition temperature of the Lc to Lalpha phase. Thereafter, the system DEPE/ISP will progress by increasing the nonlamellar-forming propensity and reaching a single HII phase at high temperature. The cooling scan followed a similar structural path, except that the system went into a stable gel phase Lbeta with a repeat distance, dLbeta=6.5 nm, in co-existence with a HII phase. The formation of ISP microdomains in model PE membranes substantiates the importance of the isoprenyl group in the binding of isoprenylated proteins to membranes and in lipid-lipid interactions through modulation of the membrane structure.
authors.affiliation: Max-Planck Institute for Colloids and Interfaces, HASYLAB, Notkestrasse 85, D-22603, Hamburg, Germany.
authors.forename: Sérgio S
authors.initials: SS
authors.lastname: Funari
authors.forename: Jesús
authors.initials: J
authors.lastname: Prades
authors.forename: Pablo V
authors.initials: PV
authors.lastname: Escribá
authors.forename: Francisca
authors.initials: F
authors.lastname: Barceló
mesh_terms: D002152:Calorimetry, Differential Scanning; D004224:Diterpenes / Q000737:chemistry*; D005204:Farnesol / Q000737:chemistry*; D008081:Liposomes; D008567:Membranes, Artificial; D008954:Models, Biological; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D012542:Scattering, Radiation; D014965:X-Rays
chemical_list: D004224:Diterpenes; D008081:Liposomes; D008567:Membranes, Artificial; D010714:Phosphatidylethanolamines; C483858:phosphatidylethanolamine; D005204:Farnesol; C020888:1,2-dielaidoylphosphatidylethanolamine; C017338:geranylgeraniol