title: Pardaxin induces aggregation but not fusion of phosphatidylserine vesicles.
abstract: The effects on membranes of pardaxin, an amphipathic polypeptide, purified from the gland secretion of the Red Sea Moses sole flatfish Pardachirus marmoratus are dose-dependent and range from formation of voltage-gated, cation-selective pores to lysis. We have now investigated the interactions of pardaxin with small unilamellar liposomes. Light scattering showed that pardaxin (10(-7)-10(-9) M) mediated the aggregation of liposomes composed of phosphatidylserine but not of phosphatidylcholine. Aggregation of phosphatidylserine vesicles was impaired by vesicle depolarization. Furthermore, pardaxin-mediated aggregation between fluorescent-labeled PS vesicles was accompanied by leakage of the vesicle contents, and not by fusogenic process within the aggregates. We suggest that pardaxin is a unique polypeptide, that induces vesicle aggregation and membrane destabilization, but not membrane fusion; the mechanism of the aggregation activity of pardaxin is related to its amphipathic properties.
mesh_terms: D002463:Cell Membrane Permeability; D005397:Fish Venoms / Q000494:pharmacology*; D005456:Fluorescent Dyes; D006096:Gramicidin / Q000494:pharmacology; D008081:Liposomes; D008561:Membrane Fusion; D008564:Membrane Potentials / Q000187:drug effects; D009281:Naphthalenes; D010718:Phosphatidylserines; D011726:Pyridinium Compounds; D012965:Sodium Chloride / Q000494:pharmacology; D013050:Spectrometry, Fluorescence
chemical_list: D005397:Fish Venoms; D005456:Fluorescent Dyes; D008081:Liposomes; D009281:Naphthalenes; D010718:Phosphatidylserines; D011726:Pyridinium Compounds; D006096:Gramicidin; C046466:N,N'-4-xylylenebis(pyridinium); D012965:Sodium Chloride; C017603:pardaxin; C046465:8-amino-1,3,6-naphthalenetrisulfonic acid