A short peptide derived from zebrafish AP‐2 complex subunit mu‐A AP2M1A354–382 has antimicrobial activity against multi‐drug resistant bacteria

Our previous study shows that the peptide consisting of 29 residues at positions 354–382 of zebrafish AP‐2 complex subunit mu‐A is an antimicrobial peptide (AMP) capable of inhibiting the growth of Escherichia coli and Staphylococcus aureus. Sequence analysis revealed that the N‐terminal 10 amino acids (designated AP10) of the peptide were highly conserved from nematode to humans. On this basis, we designed two AP10 analogs, AP10R and AP10W, by substituting the amino acids at selected positions of AP10 with tryptophan (W), isoleucine (I), and arginine (R). Both AP10 and AP10R as well as AP10W were found to possess the common features of AMPs: a high hydrophobic ratio, a net positive charge, and amphipathicity. Antibacterial activity assay showed that AP10W exhibited the strongest antimicrobial activity against Gram‐negative and Gram‐positive bacteria including MDR bacteria (with MICs ranging from 20 to 25 μg/ml) among the three peptides. In addition, AP10W was able to bind to lipopolysaccharide (LPS), lipoteichoic acid (LTA), and peptidoglycan (PGN), cause depolarization of the bacterial plasma membrane, and stimulate intracellular reactive oxygen species (ROS) production, suggesting it executes antibacterial activity by a combined action of destabilization/destruction of bacterial cell wall through interaction with LPS, LTA, and PGN, disturbance of the usually polarized membrane through depolarization, and apoptosis/necrosis through intracellular ROS production. Importantly, AP10W is not toxic to mammalian cells, and shows tolerance to serum, salt, and pH variation though it is heat labile. These together suggest that AP10W is a promising template for future development of novel peptide antibiotics against MDR bacteria.