title: Roles of integral protein in membrane permeabilization by amphidinols.
abstract: Amphidinols (AMs) are a group of dinoflagellate metabolites with potent antifungal activity. As is the case with polyene macrolide antibiotics, the mode of action of AMs is accounted for by direct interaction with lipid bilayers, which leads to formation of pores or lesions in biomembranes. However, it was revealed that AMs induce hemolysis with significantly lower concentrations than those necessary to permeabilize artificial liposomes, suggesting that a certain factor(s) in erythrocyte membrane potentiates AM activity. Glycophorin A (GpA), a major erythrocyte protein, was chosen as a model protein to investigate interaction between peptides and AMs such as AM2, AM3 and AM6 by using SDS-PAGE, surface plasmon resonance, and fluorescent-dye leakages from GpA-reconstituted liposomes. The results unambiguously demonstrated that AMs have an affinity to the transmembrane domain of GpA, and their membrane-permeabilizing activity is significantly potentiated by GpA. Surface plasmon resonance experiments revealed that their interaction has a dissociation constant of the order of 10 microM, which is significantly larger than efficacious concentrations of hemolysis by AMs. These results imply that the potentiation action by GpA or membrane integral peptides may be due to a higher affinity of AMs to protein-containing membranes than that to pure lipid bilayers.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.
authors.forename: Nagy
authors.initials: N
authors.lastname: Morsy
authors.forename: Keiichi
authors.initials: K
authors.lastname: Konoki
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Houdai
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Matsumori
authors.forename: Tohru
authors.initials: T
authors.lastname: Oishi
authors.forename: Michio
authors.initials: M
authors.lastname: Murata
authors.forename: Saburo
authors.initials: S
authors.lastname: Aimoto
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000818:Animals; D000935:Antifungal Agents / Q000737:chemistry*; D002463:Cell Membrane Permeability; D004141:Dinoflagellida / Q000737:chemistry*; D004910:Erythrocyte Membrane / Q000737:chemistry*; D006021:Glycophorins / Q000737:chemistry; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D011714:Pyrans / Q000737:chemistry*; D020349:Surface Plasmon Resonance; D000095722:Amphidinols
chemical_list: D000475:Alkenes; D000935:Antifungal Agents; D006021:Glycophorins; D008051:Lipid Bilayers; D008081:Liposomes; D011714:Pyrans; C523181:amphidinol 2; D000095722:Amphidinols; C438973:amphidinol 3