Unravelling the mechanism of action of “de novo” designed peptide P1 with model membranes and gram-positive and gram-negative bacteria

ESPECHE, JUAN CARLOS; MARTÍNEZ, MELINA; MATURANA, PATRICIA; CUTRÓ, ANDREA; SEMORILE, LILIANA; MAFFIA, PAULO C.; HOLLMANN, AXEL

ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS

ELSEVIER SCIENCE INC

Año: 2020 vol. 693

0003-9861

In the last years, the decreasing effectiveness of conventional antimicrobial-drugs has caused serious problemsdue to the rapid emergence of multidrug-resistant pathogens. This situation has brought attention to otherantimicrobial agents like antimicrobial peptides (AMPs), for being considered an alternative to conventionaldrugs. These compounds target bacterial membranes for their activity, which gives them a broad spectrum ofaction and less probable resistance development. That is why the peptide-membrane interaction is a crucialaspect to consider in the study of AMPs. The aim of this work was the characterization of the ?de novo? designedpeptide P1, studying its interactions with model membranes (i.e. liposomes of DMPC:DMPG 5:1) in order toevaluate the final position of the peptide upon interacting with the membrane. Also, we tested the effects of thepeptide in gram-positive and gram-negative bacteria. Later, by spectroscopic methods, the ability of the peptideto permeabilize the inner and outer membrane of E. coli and plasmatic membrane of S. aureus was assessed. Theresults obtained confirmed that P1 can disrupt both membranes, showing some difference in its activity as afunction of the nature of each bacterial cell wall, confirming higher effects on gram-positive S. aureus. Finally, wealso showed the ability of P1 to inhibit biofilms of that gram-positive bacterium.All data obtained in this work allowed us to propose a model, where the first interactions of the peptide withthe bacterial envelope, seem to depend on the gram-negative and gram-positive cell wall structure. After that firstinteraction, the peptide is stabilized by Trp residues depth inserted into the hydrocarbon region, promotingseveral changes in the organization of the lipid bilayer, following a carpet-like mechanism, which results inpermeabilization of the membrane, triggering the antimicrobial activity.