Interacción del polipéptido cargado polymyxina con modelos de membranas bacterianas

FEITO, FRANCISCO; MADRID, ROSSANA E.; FERNANDO, DUPUY

Encuentro; Reunión Anual de la Sociedad Argentina de Biofísica (XLIX SAB 2021); 2021

It is now known that the interaction of peptides with biological membranes is a key process inthe study of the different cellular mechanisms and metabolic pathways necessary for cells tocarry out their function, since this interaction can affect the properties of the lipid bilayer suchas selective permeability and modulate curvature. The biological role of peptides in membraneinteractions is determined by the charge present in the sequence of amino acids that form thesebiomolecules. Certain cationic polypeptides act as antimicrobial agents, altering the cellmembrane of bacteria, due to the binding with the outer membrane in Gram-negative bacteria,finally causing their death, as is the case of the cyclic polypeptide, Polymyxin or also calledColistin B. In this work we seek to gain knowledge about the mechanism of action of thisantimicrobial peptide at the molecular level, as well as its effects on biological membranes, bystudying different models of mimetic membranes using Langmuir- Blodgett phospholipidmonolayers. The effect of pH and lipid composition on the interaction with polymyxin wasstudied by performing fixed-area Gibbs isotherms and Langmuir isotherms, measuring surfacepressure and surface electric potential simultaneously. The results of this work indicate that pHmodulates the surface activity of the peptide at clean interfaces and when interacting withnegatively charged lipid monolayers. The insertion would be through a mechanism not yetelucidated, which is being studied.