Abstract 1754 Hybrids of translocating antimicrobial peptides exhibit enhanced activity and permeabilize membranes

Due to increasing rates of antibiotic resistance in bacteria, there is a pressing need for alternative treatments to conventional antibiotics. Antimicrobial peptides (AMPs) are considered strong candidates as they can target viruses and fungi in addition to bacteria. They also have more generalized targets in the cell, which allows them to have a broader effect and makes it more difficult for bacteria to develop resistance. One strategy for enhancing the potency of AMPs has been to covalently link two individual peptides into one hybrid peptide through a peptide bond, either directly to each other or with an amino acid linker. It is hypothesized that such hybrids are not only more active but also have increased selectivity for bacteria over eukaryotic cells. Most work on hybrid peptides has focused on AMPs that permeabilize cell membranes. However, here we investigate hybrids made from two peptides that translocate across the bacterial cell membrane and target internal nucleic acids, buforin II (BF2) and DesHDAP1 (Des1). Propidium iodide (PI) uptake assays and confocal microscopy revealed that BF2-Des1 hybrids gain significant permeabilizing character. Using microbroth dilution and radial diffusion assays we measured the activity of parent peptides (BF2 and Des1), hybrids, and 1:1 mixtures of BF2 and Des1 against B. subtilis and E. coli. Results indicate that all hybrids have a lower minimum inhibitory concentration than parent peptides against B. subtilis and E. coli. Preliminary results also indicate that this enhancement is similar to that of 1:1 mixtures of BF2 and Des1. MTS assays found no cytotoxicity of parent peptides, hybrids, or peptide mixtures against human embryonic kidney (HEK) 293 cells. Considering the efficacy of the BF2 and Des1 mixture, ongoing work is evaluating the synergy between different permutations of other histone-derived peptides. This work was supported by NIH/NIAID award 1R15AI169210.