title: Alamethicin Supramolecular Organization in Lipid Membranes from19F Solid-State NMR.
abstract: Alamethicins (ALMs) are antimicrobial peptides of fungal origin. Their sequences are rich in hydrophobic amino acids and strongly interact with lipid membranes, where they cause a well-defined increase in conductivity. Therefore, the peptides are thought to form transmembrane helical bundles in which the more hydrophilic residues line a water-filled pore. Whereas the peptide has been well characterized in terms of secondary structure, membrane topology, and interactions, much fewer data are available regarding the quaternary arrangement of the helices within lipid bilayers. A new, to our knowledge, fluorine-labeled ALM derivative was prepared and characterized when reconstituted into phospholipid bilayers. As a part of these studies, C19F3-labeled compounds were characterized and calibrated for the first time, to our knowledge, for19F solid-state NMR distance and oligomerization measurements by centerband-only detection of exchange (CODEX) experiments, which opens up a large range of potential labeling schemes. The19F-19F CODEX solid-state NMR experiments performed with ALM in POPC lipid bilayers and at peptide/lipid ratios of 1:13 are in excellent agreement with molecular-dynamics calculations of dynamic pentameric assemblies. When the peptide/lipid ratio was lowered to 1:30, ALM was found in the dimeric form, indicating that the supramolecular organization is tuned by equilibria that can be shifted by changes in environmental conditions.
authors.affiliation: Institute of Chemistry, University of Strasbourg/CNRS, UMR7177, Strasbourg, France.
authors.forename: Evgeniy S
authors.initials: ES
authors.lastname: Salnikov
authors.affiliation: Institute of Chemistry, University of Strasbourg/CNRS, UMR7177, Strasbourg, France.
authors.forename: Jesus
authors.initials: J
authors.lastname: Raya
authors.affiliation: ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: De Zotti
authors.affiliation: Department of Membrane Physiology and Technology, Institute of Physiology, University of Freiburg, Freiburg, Germany.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Zaitseva
authors.affiliation: ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Peggion
authors.affiliation: ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova, Italy.
authors.forename: Gema
authors.initials: G
authors.lastname: Ballano
authors.affiliation: ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Toniolo
authors.affiliation: Leiden Institute of Chemistry, Gorlaeus Laboratories, University of Leiden, Leiden, the Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Raap
authors.affiliation: Institute of Chemistry, University of Strasbourg/CNRS, UMR7177, Strasbourg, France. Electronic address: bechinge@unistra.fr.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Bechinger
mesh_terms: D000408:Alamethicin / Q000737:chemistry*; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D055724:Electrophysiological Phenomena; D009682:Magnetic Resonance Spectroscopy; D010713:Phosphatidylcholines / Q000378:metabolism; D055503:Protein Multimerization
chemical_list: D000900:Anti-Bacterial Agents; D010713:Phosphatidylcholines; D000408:Alamethicin; C028694:1-palmitoyl-2-oleoylphosphatidylcholine