title: Lipid segregation explains selective toxicity of a series of fragments derived from the human cathelicidin LL-37.
abstract: The only human cathelicidin, the 37-residue peptide LL-37, exhibits antimicrobial activity against both gram-positive and gram-negative bacteria. We studied the ability of several fragments of LL-37, exhibiting different antimicrobial activities, to interact with membranes whose compositions mimic the cytoplasmic membranes of gram-positive or of gram-negative bacteria. These fragments are as follows: KR-12, the smallest active segment of LL-37, with the sequence KRIVQRIKDFLR, which exhibits antimicrobial activity only against gram-negative bacteria; a slightly smaller peptide, RI-10, missing the two cationic residues at the N and C termini of KR-12, which has been shown not to have any antimicrobial activity; a longer peptide, GF-17, which shows antimicrobial activity against gram-positive as well as gram-negative bacteria; and GF-17D3, with 3 D-amino-acid residues, which is also selective only for gram-negative bacteria. Those fragments with the capacity to cluster anionic lipids away from zwitterionic lipids in a membrane exhibit selective toxicity toward bacteria containing zwitterionic as well as anionic lipids in their cytoplasmic membranes but not toward bacteria with only anionic lipids. This finding allows for the prediction of the bacterial-species selectivity of certain agents and paves the way for designing new antimicrobials targeted specifically toward gram-negative bacteria.
authors: Department of Biochemistry and Biomedical Sciences, McMaster University Health Sciences Centre, Hamilton, Ontario L8N 3Z5, Canada.
authors: Raquel F
authors: RF
authors: Epand
authors: Guangshun
authors: G
authors: Wang
authors: Bob
authors: B
authors: Berno
authors: Richard M
authors: RM
authors: Epand
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology*; D002152:Calorimetry, Differential Scanning; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins