title: Antimicrobial activity and membrane-active mechanism of tryptophan zipper-like β-hairpin antimicrobial peptides.
abstract: Antimicrobial peptides (AMPs) with amphipathic β-hairpin structures have been demonstrated to possess potent antimicrobial activities and great cell selectivities. However, our understanding of β-hairpin antimicrobial peptides lags behind that of α-helices, mainly because it is difficult for short peptides to form robust β-hairpin structures. Tryptophan zipper (trpzip) peptides are among the most stable β-hairpin peptides known to fold spontaneously without requiring covalent disulfide constraint or metal binding. To develop model β-hairpin AMPs with small size and remarkable stability, a series of amphiphilic linear peptides were designed based on the trpzip motif. The sequence of designed peptides is (WK) n (D) PG(KW) n -NH2 (n = 1, 2, 3, 4, 5), and the antimicrobial activity and membrane interaction mechanism of the peptides were evaluated. The results showed that these peptides readily fold into β-hairpin structures in aqueous and membrane-mimicking environments and exhibit broad-spectrum antimicrobial activities against both gram-positive and gram-negative bacteria. The antibacterial potency of the peptides initially increased and then decreased with increasing chain length. WK3, a 14-residue peptide, displayed excellent antimicrobial activity with minimal hemolytic activity and cytotoxicity, suggesting that it possesses great cell selectivity. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), fluorescence spectroscopy, and flow cytometry indicated that representative peptides WK3 and WK4 exert their activities by permeabilizing the microbial membrane and damaging cell membrane integrity. This study reveals the application potential of the designed peptides as promising antimicrobial agents for the control of infectious diseases, and it also provides new insights into the design and optimization of highly stable β-hairpin AMPs with great antimicrobial activities and cell selectivities.
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, 59 Mucai Street, Harbin, 150030, China.|Heilongjiang Polytechnic, 5 Xuefu Road, Harbin, 150080, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Xu
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, 59 Mucai Street, Harbin, 150030, China.
authors.forename: Shuli
authors.initials: S
authors.lastname: Chou
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, 59 Mucai Street, Harbin, 150030, China.
authors.forename: Jiajun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, 59 Mucai Street, Harbin, 150030, China.
authors.forename: Changxuan
authors.initials: C
authors.lastname: Shao
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, 59 Mucai Street, Harbin, 150030, China.
authors.forename: Weizhong
authors.initials: W
authors.lastname: Li
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, 59 Mucai Street, Harbin, 150030, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, 59 Mucai Street, Harbin, 150030, China. asshan@neau.edu.cn.
authors.forename: Anshan
authors.initials: A
authors.lastname: Shan
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D001419:Bacteria / Q000254:growth & development*; D017433:Protein Structure, Secondary; D014364:Tryptophan / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D014364:Tryptophan
keywords: Antimicrobial peptides; Bactericidal mechanism; Cell selectivity; Tryptophan zipper; β-Hairpin