title: Structural dissection of a highly knotted peptide reveals minimal motif with antimicrobial activity.
abstract: The increasing occurrence of bacterial resistance to antibiotics is driving a renewed interest on antimicrobial peptides, in the hope that understanding the structural features responsible for their activity will provide leads into new anti-infective drug candidates. Most chemical studies in this field have focused on linear peptides of various eukaryotic origins, rather than on structures with complex folding patterns found also in nature. We have undertaken the structural dissection of a highly knotted, cysteine-rich plant thionin, with the aim of defining a minimal, synthetically accessible, structure that preserves the bioactive properties of the parent peptide. Using efficient strategies for directed disulfide bond formation, we have prepared a substantially simplified (45% size reduction) version with undiminished antimicrobial activity against a representative panel of pathogens. Analysis by circular dichroism shows that the downsized peptide preserves the central double alpha-helix of the parent form as an essential bioactive motif. Membrane permeability and surface plasmon resonance studies confirm that the mechanism of action remains unchanged.
authors.affiliation: Department of Experimental and Health Sciences, Pompeu Fabra University, Dr. Aiguader, 80, E-08003 Barcelona, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: Vila-Perelló
authors.forename: Andrea
authors.initials: A
authors.lastname: Sánchez-Vallet
authors.forename: Francisco
authors.initials: F
authors.lastname: García-Olmedo
authors.forename: Antonio
authors.initials: A
authors.lastname: Molina
authors.forename: David
authors.initials: D
authors.lastname: Andreu
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D000935:Antifungal Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D002021:Buffers; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D015195:Drug Design; D025301:Hyphae / Q000187:drug effects / Q000378:metabolism; D013058:Mass Spectrometry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides; D010935:Plant Diseases / Q000382:microbiology / Q000821:virology; D017433:Protein Structure, Secondary; D020349:Surface Plasmon Resonance
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D002021:Buffers; D004220:Disulfides; D010455:Peptides