Determining the Mechanism of Action of the Antimicrobial Peptide DASamP2 by Characterization

Due to the proliferation of drug-resistant strains of pathogenic bacteria, there is an urgent need for alternatives to traditional antibiotics. Intriguingly, most organisms produce a variety of antimicrobial peptides (AMPs) as part of their innate immune response to infection. Previous research has demonstrated that these small peptides can be remarkably potent and, in some cases, possess broad-spectrum activity against both Gram-positive and Gram-negative bacterial species. Using structures inspired by these natural defensive tools, human-engineered AMPs have shown promise as novel antibacterial agents. DASamP2, an AMP developed by the Wang lab at UNMC, has demonstrated effectiveness against Pseudomonas aeruginosa. An opportunistic pathogen, the WHO has recently classified the need for novel drugs targeting P. aeruginosa as ‘critical’ due to its inherent adaptability and rapid acquisition of drug resistance. However, the mechanism by which DASamP2 is able to kill this pathogen is not understood. In an attempt to illuminate the mechanism of action of DASampP2 and to identify proteins that affect the susceptibility of bacteria to this AMP, the lab has previously isolated eleven mutant strains of P. aeruginosa that showed increased resistance to DASamP2. Next, we sought to determine the precise mutation responsible for DASamP2 resistance in these mutant strains through the use of inverse PCR and DNA sequencing. Here I will report the results of my efforts to identify the gene mutated in two of these mutants and discuss what our findings have revealed about the mechanism of action of DASamP2