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.

The C‐terminal sequences of porcine thrombin are active as antimicrobial peptides

“…In addition, T‐4, T‐6, T‐7 and T‐8 showed stronger antimicrobial potency, and the antimicrobial activities of the other four peptides with lower hydrophobicity were weak. Peptide length is positively correlated with antibacterial activity within a certain threshold, which was consistent with our results. This positive relationship may associate with the hydrophobicity and cationicity (Table ), which are features required for killing bacteria.…”

Expression, purification and characterization of the recombinant cysteine-rich antimicrobial peptide snakin-1 in Pichia pastoris

“…In order to determine how cysteine-rich cationic SN-1 exerts its microbicidal action on target cells, we selected E. coli ML35 as a model organism. The outer membrane of Gram-negative bacteria acts as a permeability barrier which is composed of negatively charged phospholipids [45]. Generally, cationic AMPs having positive charges are electrostatically attracted to the negatively charged outer microbial membrane and subsequently cause a disruption of the inner membrane through pore formation, resulting in release of the cellular contents and cell death [10].…”

Antibacterial activities and molecular mechanism of amino‐terminal fragments from pig nematode antimicrobial peptide CP‐1

“…Recently, tandem amino acid sequences have been developed as a prevailing method for generating peptides with stronger antimicrobial activity and application potential. [42] Considering the poor performance of natural peptides against broad spectrum microbes and their weak stability in various complicated physiological environments, this strategy is the most efficient way to optimize antimicrobial behavior compared to others. Therefore, in the current study, the initial repeat unit in the N-terminus of Cecropin P1 was truncated, duplicated, and linked.…”