title: Probing membrane topology of the antimicrobial peptide distinctin by solid-state NMR spectroscopy in zwitterionic and charged lipid bilayers.
abstract: Distinctin is a 47-residue antimicrobial peptide, which interacts with negatively charged membranes and is active against Gram-positive and Gram-negative bacteria. Its primary sequence comprises two linear chains of 22 (chain 1) and 25 (chain 2) residues, linked by a disulfide bridge between Cys19 of chain 1 and Cys23 of chain 2. Unlike other antimicrobial peptides, distinctin in the absence of the lipid membrane has a well-defined three-dimensional structure, which protects it from protease degradation. Here, we used static solid-state NMR spectroscopy in mechanically aligned lipid bilayers (charged or zwitterionic) to study the topology of distinctin in lipid bilayers. We found that this heterodimeric peptide adopts an ordered conformation absorbed on the surface of the membrane, with the long helix (chain 2), approximately parallel to the lipid bilayer (~5° from the membrane plane) and the short helix (chain 1) forming a ~24° angle with respect to the bilayer plane. Since the peptide does not disrupt the macroscopic alignment of charged or zwitterionic lipid bilayers at lipid-to-protein molar ratio of 50:1, it is possible that higher peptide concentrations might be needed for pore formation, or alternatively, distinctin elicits its cell disruption action by another mechanism.
authors: Departments of Chemistry and Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
authors: Raffaello
authors: R
authors: Verardi
authors: Nathaniel J
authors: NJ
authors: Traaseth
authors: Lei
authors: L
authors: Shi
authors: Fernando
authors: F
authors: Porcelli
authors: Luca
authors: L
authors: Monfregola
authors: Stefania
authors: S
authors: De Luca
authors: Pietro
authors: P
authors: Amodeo
authors: Gianluigi
authors: G
authors: Veglia
authors: Andrea
authors: A
authors: Scaloni
mesh_terms: D029845:Amphibian Proteins / Q000737:chemistry*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D001419:Bacteria / Q000378:metabolism; D001671:Biochemistry / Q000379:methods; D001703:Biophysics / Q000379:methods; D002462:Cell Membrane / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008826:Microbial Sensitivity Tests; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry*; D013696:Temperature
chemical_list: D029845:Amphibian Proteins; D023181:Antimicrobial Cationic Peptides; D004220:Disulfides; D008051:Lipid Bilayers; D010455:Peptides; C531945:distinctin; D003545:Cysteine