Novel Design of Short Antimicrobial Peptides Derived from the Bactericidal Domain of Avian β-defensin-4

Abstract

Short antimicrobial peptides were designed and synthesized by C-terminal truncation and residue substitution of avian β-defensin-4. The biological activity of these peptides was examined to elucidate the quantitative structure-activity relationships and find a lead peptide for the development of a novel antimicrobial peptide. The results showed that the truncation of the avian β-defensin-4 eliminated the hemolysis of the peptide. The GLI13 derivative, developed by substituting the Cys of the truncated peptide with Ile, led to increased antimicrobial activity. These results suggest that the peptides with antimicrobial activity can be derived by truncating the avian β-defensin-4. We further developed the GLI13 derivative with an increased net charge by residue substitution. The results showed that the GLI13-5 with 5 net charges had the highest cell selectivty. An increase in the net charge from 6 to 8 did not result in the improvement of antimicrobial potency. Membrane-simulating experiments showed that the peptides preferentially bound to negatively charged phospholipids over zwitterionic phospholipids, which led to greater cell selectivity. A membrane depolarization assay showed that GLI13-5 killed bacteria by targeting the cytoplasmic membrane. These results suggest that the short peptide developed by truncation of linear β-defensin may be a promising candidate for future antibacterial agents.

Tissue expression and antibacterial activity of host defense peptides in chicken

“…Increased cationicity also helps to enhance antibacterial activity [ 9 ]. Cationicity is important for killing bacteria [ 47 ], but simply increasing the net charge does not result in the improvement of antimicrobial potency [ 48 ]. Hydrophobicity also requires an optimal range to enhance antibacterial activity [ 45 ].…”

Antimicrobial Properties and Membrane-Active Mechanism of a Potential α-Helical Antimicrobial Derived from Cathelicidin PMAP-36

“…Recently, Paulsen et al reported that the N-terminal fragment arasin 1(1–23) was almost equally active to the full length peptide arasin 1(a 37-residue peptide) [14]. We have previously shown that the truncation of the C-terminal region of linear chicken-defensin-4 (AvBD-4) retained the antimicrobial activity and eliminated its hemolytic activity [15], [16].…”

Antitumor effect of the antimicrobial peptide GLI13-8 derived from domain of the avian β-defensin-4

“…We previously demonstrated that the GLI13-8 peptide derived from the linear AvBD-4 (RL38) exerted antimicrobial activities against Gram-positive and Gram-negative bacteria and showed a low hemolytic activity towards human erythrocytes [21]. In this study, it was shown that the peptide GLI13-8 rapidly initiated cytotoxicity and significantly inhibited the viability of three tumor cell lines, especially HepG2 cells in a dose-dependent manner.…”

“…Previous studies reported that most AMPs, including magainin II and defensins, induced pore formation in cellular membranes [22,25,32]. We previously reported that GLI13-8 contained high net positive charges [21]. The positive charges interact electrostatically with the negative charges on the cancer cell surface and the amphipathicity favors the peptide to insert into the membrane.…”

“…We previously found that avian b-defensin-4 (AvBD-4) induced hemolysis of human red blood cells [21]. However, GLI13-8, the 13-mer peptide (RLIRRKRRIIRWL-NH 2 ) derived from AvBD-4, was found to preferentially permeabilize bacterial membranes rich in anionic phospholipids and exhibit high cell selectivity between bacteria and mammalian cells [21].…”