# Turn-engineering tunes the conformational rigidity of β-hairpin AMPs in achieving membrane selectivity and killing drug-resistant ESKAPE pathogens

## TL;DR

This study shows how modifying the structure of antimicrobial peptides can make them selectively attack bacteria while sparing human cells.

## Contribution

Engineering the reverse turn of β-hairpin AMPs to control conformational rigidity and achieve membrane selectivity.

## Key findings

- Modifying the reverse turn with a β-II′ motif increases selectivity for bacterial membranes.
- Engineered peptides effectively kill drug-resistant ESKAPE pathogens in vivo.
- AMPs without disulfide bridges can still achieve membrane selectivity through turn engineering.

## Abstract

Naturally occurring β-hairpin antimicrobial peptides (AMPs) exhibit potent membranolytic activity against bacterial and mammalian cells, limiting their therapeutic development due to the lack of selectivity. This study demonstrates that the reverse turn in these AMPs can be used to dictate their molecular rigidity, which drives their membranolytic action. By fine-tuning the rigidity at the reverse turn by incorporating a moderately rigid β-II′ turn-inducing motif through N-methylation of the amide bond, we achieved selectivity in targeting the bacterial membrane over human red blood cells. The selectivity results from the hairpin-nucleation efficiency of the engineered β-turn within these linear AMPs devoid of disulfide bridges and their interaction with the neutral mammalian and negatively charged bacterial membrane. Such fine-tuning of the structure at the β-turn allowed us to develop molecules derived from naturally occurring toxic AMPs, which displayed selective killing of drug-resistant bacterial pathogens over mammalian cells with in vivo efficacy.

Introducing structural flexibility into naturally occurring β-hairpin antimicrobial peptides through reverse-turn engineering allows selective binding onto bacterial membranes over mammalian membranes and subsequent membranolysis.