Interacción de Péptidos antimicrobianos frente a membranas bacterianas

Rosario, Sante Fe

Congreso; L Reunión Anual de la Sociedad Argentina de Biofísica; 2022

Sociedad Argentina de Biofisica

Antimicrobial peptides are biosynthesis by organisms from all kingdoms as part of thedefense mechanism. Their mechanism of action is mainly related to a destabilization ofmembranes, and because of this, bacteria do not acquire resistance as easy as totraditional antibiotics. Therefore, these molecules are currently under studied. Within thisgroup of peptides, the mastopartane MP1, extracted from the venom of the Brazilian waspPolybia Paulista, is of great interest. This molecule has a potent antimicrobial actionagainst a diversity of gram-positive and gram-negative bacteria, without producinghemolysis. Its os a short peptide, 14 amino acid long, with sequence I D W K K L L L D A AK Q I L-NH2 and a low positive net charge (+2). This peptide exhibits a preferentialinteraction with anionic lipids, which could be attributed to electrostatic interactions, ashas been described for other antimicrobial peptides. This may explain why these peptidesare more active against bacterial than mammalian membrane, the former being morenegatively charged. However, the exact mechanism of action and differentiation of thetarget membrane is not known. Therefore, our aim is to study the mechanism by whichMP1 exerts its action against Pseudomona aeruginosa, and what differentiates these cellsfrom mammalian ones. In order to identify changes in the electrostatics due to thepresence of the peptide, zeta potential measurements of the bacteria were performed inthe presence of the peptide. No change in this parameter was observed when the peptidewas added even at concentrations higher than the minimum inhibitory concentration(MIC). In order to check the influence of electrostatics in the mechanism of action of thepeptide, MIC was determined in the presence and absence of salts, finding similar values.Both results indicate that the preferential activity of this peptide against bacterialmembranes would not be driven by electrostatic interactions, which leads us toinvestigate effects related to the mechanical properties of the membrane. We are currentlystudying the effect of the peptide on lateral diffusion in the bacterial membrane.