Structural and functional studies of bacterial model membranes and peptide interaction

CAROLINA MEDINA AMADO; GARNICA N; DE MARCO N; OLIVEIRA, R.G.; DUPUY FERNANDO

La Plata

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

Novel antimicrobial therapies are needed as a result of the increasing number of microbials resistant to ordinary antibiotics. In this regard, bacterial membranes represent an important molecular target for new antimicrobials like amphipathic peptides. The bacterial lipid bilayer is typically composed by a higher amount of anionic lipid, compared to eukaryotic membranes. Also, nonbilayer structures can be formed by some of the main bacterial lipids, like phosphatidylethanolamine (PE) or even phosphatidylglycerol (PG) and cardiolipin (CL), when negative charge is screened. In this work, bacterial model membranes were studied by means of x-ray diffraction techniques in order to assess structural rearrangements produced by interaction with antimicrobial peptides. In addition, functional and molecular properties as determined by infrared, fluorescence spectroscopy and Langmuir monolayers were investigated. The results indicate that bilayer composition can modulate the mechanisms by which peptides interact and perturb membrane properties in different ways. Thus, there is none a single mechanism of action of peptide antimicrobial activity, but it rather depends on the intrinsic properties of each particular membrane.