title: Investigating the role of GXXXG motifs in helical folding and self-association of plasticins, Gly/Leu-rich antimicrobial peptides.
abstract: Plasticins (PTC) are dermaseptin-related antimicrobial peptides characterized by a large number of leucine and glycine residues arranged in GXXXG motifs that are often described to promote helix association within biological membranes. We report the structure and interaction properties of two plasticins, PTC-B1 from Phyllomedusa bicolor and a cationic analog of PTC-DA1 from Pachymedusa dacnicolor, which exhibit membrane-lytic activities on a broad range of microorganisms. Despite a high number of glycine, CD and NMR spectroscopy show that the two plasticins adopt mainly alpha-helical conformations in a wide variety of environments such as trifluoroethanol, detergent micelles and lipid vesicles. In DPC and SDS, plasticins adopt well-defined helices that lie parallel to the micelle surface, all glycine residues being located on the solvent-exposed face. Spectroscopic data and cross-linking experiments indicate that the GXXXG repeats in these amphipathic helices do not provide a strong oligomerization interface, suggesting a different role from GXXXG motifs found in transmembrane helices.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, Ecole Normale Supérieure-PSL Research University, Département de chimie, CNRS UMR 7203 Laboratoire des Biomolécules, 4 place Jussieu, F-75005 Paris, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: Carlier
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, IBPS, Biogenèse des Signaux Peptidiques, 7 quai St Bernard, F-75005 Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Joanne
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, Ecole Normale Supérieure-PSL Research University, Département de chimie, CNRS UMR 7203 Laboratoire des Biomolécules, 4 place Jussieu, F-75005 Paris, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Khemtémourian
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, Ecole Normale Supérieure-PSL Research University, Département de chimie, CNRS UMR 7203 Laboratoire des Biomolécules, 4 place Jussieu, F-75005 Paris, France; Faculté des Sciences et Technologie, Université Paris Est Créteil-Val de Marne, 61 avenue du Général de Gaulle, F-94010 Créteil CEDEX, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Lacombe
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, IBPS, Biogenèse des Signaux Peptidiques, 7 quai St Bernard, F-75005 Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Nicolas
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, IBPS, Biogenèse des Signaux Peptidiques, 7 quai St Bernard, F-75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 8256, B2A, Biological Adaptation and Ageing, Integrated Cellular Ageing and Inflammation, Molecular & Functional Enzymology, 7 quai St Bernard, F-75005 Paris, France. Electronic address: chahrazade.el_amri@upmc.fr.
authors.forename: Chahrazade
authors.initials: C
authors.lastname: El Amri
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, Ecole Normale Supérieure-PSL Research University, Département de chimie, CNRS UMR 7203 Laboratoire des Biomolécules, 4 place Jussieu, F-75005 Paris, France. Electronic address: olivier.lequin@upmc.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Lequin
mesh_terms: D020816:Amino Acid Motifs; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D002151:Calorimetry; D002942:Circular Dichroism; D004058:Diffusion; D005136:Eye Proteins / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D005998:Glycine / Q000737:chemistry; D007930:Leucine / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013816:Thermodynamics
chemical_list: D023181:Antimicrobial Cationic Peptides; D005136:Eye Proteins; D008081:Liposomes; D009419:Nerve Tissue Proteins; C076104:plasticin; D007930:Leucine; D005998:Glycine
keywords: Antimicrobial peptide; CD; Cross-linking reaction; ITC; Liquid-state NMR; Membrane mimetics