Peptidomimetic analogues of an Arg-Trp-x-x-Trp motif responsible for interaction of translocase MraY with bacteriophage φX174 lysis protein E

Translocase MraY is the target for bacteriophage phi X174 lysis protein E, which interacts via a protein-protein interaction mediated by Phe-288 and Glu-287 of E. coli MraY, and an Arg-Trp-x-x-Trp motif on protein E, also found in several cationic antimicrobial peptides. Analogues of Arg-Trp-octyl ester, found previously to show antimicrobial activity, were tested for antimicrobial activity, with Lys-Trp-oct (MIC50 P. fluorescens 5 mu g/mL) and Arg-Trp-decyl ester (MIC50 P. fluorescens 3 mu g/mL) showing enhanced antimicrobial activity. Synthesis and testing of alpha-helix peptidomimetic analogues for this motif revealed improved antibacterial activity (MIC50 E. coli 4-7 mu g/mL) for analogues containing two aromatic substituents, mimicking the Arg-Trp-x-x-Trp motif, and MraY inhibition (IC50 140 mu M) by one such peptidomimetic. Investigation of mechanism of action using the Alamar Blue membrane permeabilisation assay revealed bacteriostatic and bacteriocidal mechanisms in different members of this set of compounds, raising the possibility of more than one biological target. The observed antimicrobial activity and MraY inhibition shown by peptidomimetic compounds confirms that this site could be targeted by drug-like molecules.

Automated summary

The study revealed that MraY protein is the target for bacteriophage, with antimicrobial activity shown by analogues and improved antibacterial activity demonstrated by alpha-helix peptidomimetic analogues. The compounds exhibited bacteriostatic and bacteriocidal mechanisms, suggesting the potential of multiple biological targets. The observed antimicrobial activity and MraY inhibition indicate that this site could be targeted by drug-like molecules.