title: Design and characterization of endosomal-pH-responsive coiled coils for constructing an artificial membrane fusion system.
abstract: A weakly acidic pH-responsive polypeptide is believed to have the potential for an endosome escape function in a polypeptide-triggered delivery system. For constructing a membrane fusion device with pH-responsiveness, we have designed novel polypeptides that are capable of forming an α2 coiled coil structure. Circular dichroism spectroscopy reveals that a polypeptide, AP-LZ(EH5), with a Glu and His salt-bridge pair at a staggered position in the hydrophobic core forms a stable coiled coil structure only at endosomal pH values (pH 5.0 to 5.5). On the basis of their endosomal-pH responsiveness, a boronic acid/polypeptide conjugate (BA-H5-St) was also designed as a pilot molecule to construct a pH-responsive, one-way membrane fusion system with a sugarlike compound (phosphatidylinositol: PI)-containing liposome as a target. Membrane fusion behavior was characterized by lipid-mixing, inner-leaflet lipid-mixing, and contents-mixing assays. These studies reveal that membrane fusion is clearly observed when the pH of the experimental system is changed from 7.4 (physiological condition) to 5.0 (endosomal condition).
authors.affiliation: Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, Narashino, Chiba 275-8575, Japan. kashiwada.ayumi@nihon-u.ac.jp
authors.forename: Ayumi
authors.initials: A
authors.lastname: Kashiwada
authors.forename: Mana
authors.initials: M
authors.lastname: Tsuboi
authors.forename: Naohide
authors.initials: N
authors.lastname: Takamura
authors.forename: Enrico
authors.initials: E
authors.lastname: Brandenburg
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Matsuda
authors.forename: Beate
authors.initials: B
authors.lastname: Koksch
mesh_terms: D001897:Boronic Acids / Q000737:chemistry*; D002942:Circular Dichroism; D011992:Endosomes / Q000737:chemistry*; D018698:Glutamic Acid / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008081:Liposomes / Q000737:chemistry*; D008561:Membrane Fusion; D008567:Membranes, Artificial; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D001897:Boronic Acids; D008081:Liposomes; D008567:Membranes, Artificial; D010455:Peptides; D018698:Glutamic Acid