title: Membrane interaction and antibacterial properties of chensinin-1, an antimicrobial peptide with atypical structural features from the skin of Rana chensinensis.
abstract: Many antimicrobial peptides from amphibian skin have been purified and structurally characterized and may be developed as therapeutic agents. Here we describe the antibacterial properties and membrane interaction of chensinin-1, a cationic arginine/histidine-rich antimicrobial peptide, from the skin secretions of Rana chensinensis. The amino acid composition, sequence, and atypical structure of chensinin-1 differ from other known antimicrobial peptides from amphibian skin. Chensinin-1 exhibited selective antimicrobial activity against Gram-positive bacteria, was inactive against Gram-negative bacteria, and had no hemolytic activity on human erythrocytes. The CD spectra for chensinin-1 indicated that the peptide adopted an aperiodic structure in water and a conformational structure with 20 % β-strands, 8 % α-helices, and the remaining majority of random coils in the trifluoroethanol or SDS solutions. Time-kill kinetics against Gram-positive Bacillus cereus demonstrated that chensinin-1 was rapidly bactericidal at 2× MIC and PAE was found to be >5 h. Chensinin-1 caused rapid and large dye leakage from negatively charged model vesicles. Furthermore, membrane permeation assays on intact B. cereus indicated that chensinin-1 induced membrane depolarization in less than 1 min and followed to damage the integrity of the cytoplasmic membrane and resulted in efflux of molecules from cytoplasma. Hence, the primary target of chensinin-1 action was the cytoplasmic membrane of bacteria. Chensinin-1 was unable to overcome bacterial resistance imposed by the lipopolysaccharide leaflet, the major constituent of the outer membrane of Gram-negative bacteria. Lipopolysaccharide induced oligomerization of chensinin-1, thus preventing its translocation across the outer membrane.
authors.affiliation: Faculty of Life Science, Liaoning Normal University, Dalian 116081, China. djshang@lnnu.edu.cn
authors.forename: Dejing
authors.initials: D
authors.lastname: Shang
authors.forename: Yue
authors.initials: Y
authors.lastname: Sun
authors.forename: Che
authors.initials: C
authors.lastname: Wang
authors.forename: Shi
authors.initials: S
authors.lastname: Wei
authors.forename: Lijie
authors.initials: L
authors.lastname: Ma
authors.forename: Li
authors.initials: L
authors.lastname: Sun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D002462:Cell Membrane / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011898:Ranidae / Q000235:genetics / Q000378:metabolism*; D012867:Skin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides