title: Different modes of inhibition by adamantane amine derivatives and natural polyamines of the functionally reconstituted influenza virus M2 proton channel protein.
abstract: The influenza virus M2 protein, target of the antiviral drugs amantadine and rimantadine, forms a proton channel which functions during virus uncoating and maturation by modifying the pH in virions as well as in trans-Golgi vesicles. We studied the influence of different ionic gradients on the inhibition of the proton translocation activity of isolated, baculovirus-expressed M2 protein reconstituted into liposomes. Two distinct patterns of inhibition were observed. A group of amphiphilic amines including amantadine, cyclooctylamine and rimantadine inhibited M2 effectively in the presence of physiological Na+ concentrations. The 10-fold greater activity of rimantadine over amantadine and the 100-fold stronger effect of cyclooctylamine compared to cyclopentylamine matched the relative activities in influenza virus-infected cells. A completely different inhibitory pattern emerged for the polyamines spermine, spermidine and putrescine. Polyamines have recently been identified as the 'intrinsic' rectifiers of a class of potassium channels and shown to interact with acidic amino acid residues lining and flanking the channel pore. In the presence of a physiological Na+/K+ gradient their minimal inhibitory concentrations for influenza virus M2 protein were 100, 400 and 500 microM, polyamine levels reported to exist in oocytes. In conditions depleted for Na+, polyamines inhibited M2 at concentrations two to three orders of magnitude lower. The data suggest that influenza virus M2 protein possesses a binding site for polyamines, distinct from the amantadine binding site, which is normally masked by Na+ and which could be targeted by selective antiviral inhibitors.
authors.affiliation: Institut für Medizinische Virologie, Universitätsklinikum Charité, Humboldt-Universität zu Berlin, Germany.
authors.forename: T I
authors.initials: TI
authors.lastname: Lin
authors.forename: H
authors.initials: H
authors.lastname: Heider
authors.forename: C
authors.initials: C
authors.lastname: Schroeder
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives / Q000494:pharmacology*; D007473:Ion Channels / Q000037:antagonists & inhibitors*; D017136:Ion Transport / Q000187:drug effects; D009975:Orthomyxoviridae / Q000378:metabolism*; D011073:Polyamines / Q000494:pharmacology*; D014763:Viral Matrix Proteins / Q000037:antagonists & inhibitors*; D000086082:Viroporin Proteins
chemical_list: D000218:Adamantane; D007473:Ion Channels; D011073:Polyamines; D014763:Viral Matrix Proteins; C031540:M-protein, influenza virus; C488937:M2 protein, Influenza A virus; D000086082:Viroporin Proteins