title: Membrane-binding properties of gating modifier and pore-blocking toxins: Membrane interaction is not a prerequisite for modification of channel gating.
abstract: Many venom peptides are potent and selective inhibitors of voltage-gated ion channels, including channels that are validated therapeutic targets for treatment of a wide range of human diseases. However, the development of novel venom-peptide-based therapeutics requires an understanding of their mechanism of action. In the case of voltage-gated ion channels, venom peptides act either as pore blockers that bind to the extracellular side of the channel pore or gating modifiers that bind to one or more of the membrane-embedded voltage sensor domains. In the case of gating modifiers, it has been debated whether the peptide must partition into the membrane to reach its binding site. In this study, we used surface plasmon resonance, fluorescence spectroscopy and molecular dynamics to directly compare the lipid-binding properties of two gating modifiers (μ-TRTX-Hd1a and ProTx-I) and two pore blockers (ShK and KIIIA). Only ProTx-I was found to bind to model membranes. Our results provide further evidence that the ability to insert into the lipid bilayer is not a requirement to be a gating modifier. In addition, we characterised the surface of ProTx-I that mediates its interaction with neutral and anionic phospholipid membranes and show that it preferentially interacts with anionic lipids.
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia; School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia. Electronic address: e.deplazes@uq.edu.au.
authors: Evelyne
authors: E
authors: Deplazes
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Sónia Troeira
authors: ST
authors: Henriques
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Jennifer J
authors: JJ
authors: Smith
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Glenn F
authors: GF
authors: King
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: David J
authors: DJ
authors: Craik
authors: School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Alan E
authors: AE
authors: Mark
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia. Electronic address: c.schroeder@imb.uq.edu.au.
authors: Christina I
authors: CI
authors: Schroeder
mesh_terms: D001665:Binding Sites / Q000187:drug effects; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D008566:Membranes / Q000737:chemistry / Q000187:drug effects*; D010455:Peptides / Q000737:chemistry* / Q000633:toxicity; D013111:Spider Venoms / Q000737:chemistry* / Q000633:toxicity
chemical_list: D010455:Peptides; D013111:Spider Venoms
keywords: Gating modifier; Lipid binding; Molecular dynamics simulations; Phospholipid membrane; Pore blocker; Surface plasmon resonance; Toxin; Venom peptide; Voltage-gated ion channel