Designed Trp-Cage Proteins with Antimicrobial Activity and Enhanced Stability

α-Helical antimicrobial
peptides (αAMPs) are among
the potential candidates for new anti-infectives to tackle the global
crisis in antibiotic resistance, but they suffer from low bioavailability
due to high susceptibility to enzymatic degradation. Here, we describe
a strategy to increase the resistance of αAMPs against proteases.
Fusing the 12-residue αAMP KR-12 with a Trp-cage domain induces
an α-helical structure in the otherwise unfolded KR-12 moiety
in solution. The resulting antimicrobial Trp-cage exhibits higher
proteolytic resistance due to its stable fold as evidenced by correlating
sequence-resolved digest data with structural analyses. In addition,
the antimicrobial Trp-cage displays increased activity against bacteria
in the presence of physiologically relevant concentrations of NaCl,
while the hemolytic activity remains negligible. In contrast to previous
strategies, the presented approach is not reliant on artificial amino
acids and is therefore applicable to biosynthetic procedures. Our
study aims to improve the pharmacokinetics of αAMPs to facilitate
their use as therapeutics.