Studies of the interaction of the antimicrobial peptide Polymyxin with bacterial membrane models

FEITO, FRANCISCO; MADRID, ROSSANA; DUPUY, FERNANDO

Rosario

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

Sociedad Argentina de Biofísica

Due to the increase of new mechanisms of resistance of sensitive cells to traditional antibiotics, it is necessary to develop novel strategies for the control of microbial growth. In this sense, antimicrobial peptides represent a valuable alternative, due to their broad spectrum of action. Therefore, the study of the mechanism of action of antimicrobial peptides in the interaction with biological membranes is of special interest, since this interaction can affect the properties of the lipid bilayer such as selective permeability and modulate the curvature of the interface. Certain cationic peptides, such as Polymyxin or also known as Colistin B, cause cell death by inserting into the lipid membrane of Gram-negative bacteria by a yet unknown mechanism, acting as antimicrobial agents. To gain knowledge about this interaction and the mechanism of action of this peptide at molecular level, we worked with two different models of bacterial membranes, on the one hand we studied the phospholipid monolayers by means of the Langmuir-Blodgett technique. On the other hand, to determine the degree of order and fluidity of the membranes, lipid bilayer models were studied, using medium-sized unilamellar liposomes or LUVs, in the presence and absence of the peptide by means of fluorescence spectroscopy with polarized light.