BPS2026 – Evaluation of membrane disruption and drug resistance in β-hairpin antimicrobial peptides

Membrane-disruptive antimicrobial peptides (AMPs) are expected to be unique antibacterial agents due to their minimal propensity to develop resistance. Although the secondary structures of AMPs are considered important and β-hairpin AMPs may have low ability to develop resistance, the study on β-hairpin AMPs remains limited. To elucidate their activities and reveal the correlation between activities and resistance, we performed electrophysiological measurement and laboratory evolution of E. coli in the presence of drugs. Moreover, we attempted to design and evaluate a β-hairpin peptide referring SVG28, which is a de novo designed nanopore-forming β-hairpin peptide. Electrophysiological measurement enables us to observe the molecular level of the membrane-disruptive activities. A planar lipid bilayer for measurement was easily constructed by the droplet contact method on the microdevice. We detected the mode of action of AMPs in the membrane as current signals. We classified the signals based on the shapes and assigned them into four groups of peptide structures. As a result, we estimated the activity of each AMP as membrane-disruption or membrane-penetration. We hypothesize that the long length of taking secondary structure may contribute to the activities. In addition, we evaluated the membrane-disruptive activities by analyzing ion current and estimating the AMPs’ activity to form pores and the pore property, such as pore stability and pore size. About drug resistance, not all β-hairpin AMPs in this study showed the low ability to develop resistance. The membrane-disruptive activity and AMPs’ activity frequency to the membrane may be important for developing resistance. A de novo designed β-hairpin peptide showed moderate membrane-disruptive activity with low frequency. This research elucidated the correlation between peptides’ activities and resistance. In the next step, we plan to compare and analyze these results with the characteristics of the peptides.