Unravel the interactions of ?de novo? antimicrobial peptide P1 with model and bacterial membranes,

ESPECHE, JC; MATURANA P; MARTINEZ, M; MAFFIA, P; CUTRO AC; HOLLMANN A

La Plata

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Biofisica; 2018

Sociedad Argentina de Biofísica

In the present work, we evaluate the interaction of the antimicrobial peptide 1 (P1) with model and bacterial membranes. P1 is a cationic peptide with 21 amino acids (WPKWWKWKRRWGRKKAKKRRG), designed identifying short putative active regions from AMP databases. First, we evaluated the interaction of P1 with model membranes (i.e. liposomes of DMPC:DMPG 5:1) by using Zeta Potential. Then fluorescence quenching was applied to dissect the ability of the peptide to insert into the lipid bilayer. Both experiments confirm the interaction of P1 with this model membrane showing a depth insertion of the Trp residues in the hydrophobic core of the bilayer.In order to evaluate the effect of the peptide in more physiologic scenery, we evaluate also by zeta potential the ability of P1 to interact with Escherichia coli and Staphylococcus aureus. In both cases, zeta potential becomes less negative after peptide incubation confirm the ability of the peptides to bound into the cell envelope. However, the effect becomes more noticeable in S. aureus. Finally, the ability of the peptide to permeabilize the inner and outer membrane of E. coli was assessed. The results obtained confirm that P1 is able to disrupt both membranes, showing a much faster kinetics in the disruption of the outer membrane as expected. All the data put together allows proposing a model where the insertion of the of the peptide, stabilized by Trp residues depth inserted in hydrocarbon region, promotes changes in the lipids organization following a carpet-like mechanism that results in a permeabilization of the membrane triggering the antimicrobial activity.