Structure, Antimicrobial Activities and Mode of Interaction with Membranes of Bovel Phylloseptins from the Painted-Belly Leaf Frog, Phyllomedusa sauvagii

Abstract

Transcriptomic and peptidomic analysis of skin secretions from the Painted-belly leaf frog Phyllomedusa sauvagii led to the identification of 5 novel phylloseptins (PLS-S2 to -S6) and also of phylloseptin-1 (PSN-1, here renamed PLS-S1), the only member of this family previously isolated in this frog. Synthesis and characterization of these phylloseptins revealed differences in their antimicrobial activities. PLS-S1, -S2, and -S4 (79–95% amino acid sequence identity; net charge = +2) were highly potent and cidal against Gram-positive bacteria, including multidrug resistant S. aureus strains, and killed the promastigote stage of Leishmania infantum, L. braziliensis and L. major. By contrast, PLS-S3 (95% amino acid identity with PLS-S2; net charge = +1) and -S5 (net charge = +2) were found to be almost inactive against bacteria and protozoa. PLS-S6 was not studied as this peptide was closely related to PLS-S1. Differential scanning calorimetry on anionic and zwitterionic multilamellar vesicles combined with circular dichroism spectroscopy and membrane permeabilization assays on bacterial cells indicated that PLS-S1, -S2, and -S4 are structured in an amphipathic α-helix that disrupts the acyl chain packing of anionic lipid bilayers. As a result, regions of two coexisting phases could be formed, one phase rich in peptide and the other lipid-rich. After reaching a threshold peptide concentration, the disruption of lipid packing within the bilayer may lead to local cracks and disintegration of the microbial membrane. Differences in the net charge, α-helical folding propensity, and/or degree of amphipathicity between PLS-S1, -S2 and -S4, and between PLS-S3 and -S5 appear to be responsible for their marked differences in their antimicrobial activities. In addition to the detailed characterization of novel phylloseptins from P. sauvagii, our study provides additional data on the previously isolated PLS-S1 and on the mechanism of action of phylloseptins.

Insight into the mechanism of action of temporin-SHa, a new broad-spectrum antiparasitic and antibacterial agent

“…The homogeneity and identity of the synthetic peptides were assessed by analytical reversed-phase high-performance liquid chromatography (RP-HPLC) on a C18 analytical column (Modulo-cart QS Uptisphere 5 ODB, 5 mm, 250 x 4.6 mm, Interchim, Montluçon, France) and by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry carried out on a Voyager-DE PRO (Applied Biosystems, Foster City, CA, USA) under the same conditions as described previously (Mass Spectrometry and Proteomics Platform, IBPS, FR 3631 UPMC-CNRS, UPMC, Paris, France) [77]. …”

Resurrecting Inactive Antimicrobial Peptides from the Lipopolysaccharide Trap

“…It has also been realized that the cell wall components of bacteria play important roles in insertion and translocation of AMPs toward cytosolic membrane (33)(34)(35). Several studies have demonstrated higher MICs of AMPs for Gram-negative bacteria compared to Gram-positive organisms (36)(37)(38)(39)(40). In particular, LPS of the outer membrane of Gram-negative bacteria has been found to be actively involved in the mode of action of AMPs (5,(41)(42)(43)(44)(45)(46).…”

MD simulations and multivariate studies for modeling the antileishmanial activity of peptides

“…However, the generated model had a poor statistical quality ( q 2 = 0.142 and r 2 = 0.787, 14 PCs). Analyzing the complete dataset, we tested the exclusion of two peptides, phylloseptin 3 and phylloseptin 5 due to the uncertainty in their respective IC 50 values, which were reported as >60 μ m and not as 60 μ m , as we initially had considered. A new model was obtained showing better results ( q 2 = 0.561 and r 2 = 0.932, 8 PCs).…”