Interaction of the lipopeptide surfactine with model membrane and effect of Cardiolipin content.

Córdoba

Conferencia; XLIX Reunión Anual de la Sociedad Argentina de Biofísica.; 2023

Sociedad Argentina de Biofísica

Is just the cardiolipin content the responsible of the bacteria´s resistance to surfactin? Bacterial cytoplasmic membranes vary widely in phospholipid composition. Phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) are the most common and predominantly components but recently studies shows that Cardiolipin (CL) plays also a key role in determining the extent of the effects produced by lipopeptide on membranes. Surfactin is cyclic heptapeptide antibiotic produced by Bacillus subtilis bearing two negative charges (Asp, Glu) interlinked with a β-hydroxy fatty acid comprising 15 carbon atoms. The amphiphilic nature of surfactin explain their strong surfactant properties and surfaces activity. In a few recent studies, it has been reported that Bacillus subtilis strain alters the proportion of its major membrane phospholipids in response to surfactin exposure and after their production. A resistance mechanism against surfactin include the increment of CL proportion by which the producer prevents killing itself with its own toxic product. Further, a decrease of PG and phosphatidylethanolamine (PE) along with an several increments of phosphatidic acid (PA) was observed. In this study, we investigated the modifications of the membrane lipid moiety in order to estimate the role of not only CL phospholipid but also electrostatic properties of phospholipids during the membrane adaptation. In particular, we focused the on interaction of surfactin with models of bacilus subtitles membranes composed of PG, PE, PA and CL in different ratios to find the answer of how these proportions affect the surfactin interaction/penetration. The critical micellar concentrations of surfactin and their variation with pH was also done.