Regulation of the activity of an antimicrobial peptide by the presence of a sterol or a hopanoid

RUGGIERO NETO J.; MONTI MARIELA R.,; ALVARES DAYA S.; WILKE NATALIA

Congreso; 20th Annual Meeting of the International Union for Pure and Applied Biophysics (IUPAB), the 49th Annual Metting of the Brazilian Society for Biochemistry and Molecular Biology (SBBq) and the 45th Annual Meeting of the Brazilian Biophysical Society (SBBf); 2019

Hopanoids are sterol-surrogates present in membranes of sterol-lacking bacteria. Our aim was to inquire about the impact of the antimicrobial tetradecapeptide Polybia-MP1 on membranes containing the sterol-cholesterol (CHO), or the hopanoid-diplopterol (DP), using in vitro and in vivo assays. We found that, despite DP induced similar properties to lipid membranes than CHO, the effect of MP1 on membranes with CHO or DP was significantly different.DP did not prevent dye release from LUVs, and the insertion of MP1 into DP-enriched monolayers, as well as its affinity to bilayers was higher than in the presence of CHO. Zeta potential (ζ) measurements in LUVs with DP showed a complex behavior with increasing MP1 concentration. A decrease in ζwas observed at low peptide concentrations, with a subsequent increase at higher concentrations. The effect of the peptide on the membrane elasticity was investigatedby generating nanotubes from single giant vesicles using optical tweezers. Analysis of the nanotube refraction showed that the membrane rigidity decreased with time following the order: POPC