The Influence of Isoleucine and Arginine on Biological Activity and Peptide-Membrane Interactions of Antimicrobial Peptides from the Bactericidal Domain of AvBD4

In this study, the influence of isoleucine and arginine on the biological activity and peptide-membrane interactions of linear avian beta-defensin-4 (RL38) analogs was investigated. Results of biological activities showed that the antimicrobial activities of AvBD-4 analogs were closely related to hydrophobicity and amphipathicity. The peptide GLI19 with high hydrophobicity value and amphipathicity displayed broad spectrum antimicrobial activity against both gram-negative and gram-positive, whereas GLR19 with increasing multiple charges only exhibited activity against gram-negative. The interaction between peptides and the liposome membrane demonstrated that the peptides preferentially bound to negatively charged phospholipids over zwitterionic phospholipids, which supported the antimicrobial activity data. The outer membranes assay further demonstrated that GLI19 had a greater capacity than the other tested peptides to penetrate the cell membrane at a low concentration. Collectively, the peptides derived from the bactericidal domain of linear defensins by truncation and hydrophobic amino acid substitution may be effective high-potential antibacterial agents.