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Effect of the interaction of antimicrobial peptides on the structuring of the lipid bilayer

Grant number: 20/03998-6
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): September 01, 2020
Effective date (End): February 28, 2022
Field of knowledge:Biological Sciences - Biophysics - Molecular Biophysics
Principal researcher:Karin Do Amaral Riske
Grantee:Lucas Pinheiro Dias
Home Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
Associated research grant:16/13368-4 - Nanostructured systems: from membrane biomimetic models to carriers of bioactives, AP.TEM

Abstract

The selection of microorganisms resistant to conventional drugs, caused mainly by the indiscriminate use of antibiotics, is a problem in the world health scenario, which has led the scientific community to seek new therapeutic strategies. Antimicrobial Peptides (AMPs) are naturally modulators of the innate immune system of several organisms and have been shown to be a promising alternative for the treatment of several infectious diseases becoming potential candidates to assist in the treatment against resistant microorganisms. PAMs are relatively small (less than 60 amino acid residues) and most of them are amphiphilic with a high content of basic amino acids giving it a polycation character. These properties, associated with the conformational characteristics of these peptides, allow them to bind and insert themselves in the membrane of microorganisms. Studying the interactions of antimicrobial peptides with pure phospholipids or mixtures of lipids in membrane models may be relevant to determine the type of cell damage induced by the peptides. In this project, the interaction of anitmicrobial peptides of interest, such as ocellatin PT7 and PT8, which have been purified, identified and characterized from the secretion of the skin of a Leptodactylus pustulatus, with membranes of different lipid compositions will be studied. These peptides were chosen because they showed a good action against S. choleraesuis, K. pneumoniae, S. aureus and E. coli, being more efficient against this last strain, and also for having low hemolytic activity. The insertion and orientation of peptides in the membranes, as well as the integrity and structure of the lipid bilayer can be determined by biophysical techniques such as FTIR, EPR, SAXS, fluorescence, CD, calorimetry and electrophysiology of flat bilayers. These methods, therefore, can show definite relationships between the composition of the membrane and the activity of these peptides. These data can contribute to the design and synthesis of antimicrobial peptides for therapeutic use. (AU)