Comparative study of the mechanism of action of the antimicrobial peptide gomesin and its linear analogue: The role of the beta-hairpin structure

Author(s)

Domingues, Tatiana M. ; Perez, Katia R. ; Miranda, Antonio ; Riske, Karin A.

• Document type: Journal article
• Source: BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES; v. 1848, n. 10, p. 8-pg., 2015-10-01.

Abstract

Gomesin (Gm) is an antimicrobial peptide first isolated from the hemolymph of a Brazilian spider. Its powerful antimicrobial activity is, however, accompanied by hemolysis. As an alternative to this issue, a linear analogue (named GmL) lacking the disulfide bonds was designed. Here, CD spectroscopy, a fluorescence-based leakage assay, isothermal titration calorimety (ITC) and light scattering are used to study the interaction of both Gm and GmL with large unilamellar vesicles (LUVs) composed of POPC (palmitoyl oleoyl phosphatidylcholine) with 25 and 50 mol% POPG (palmitoyl oleoyl phosphatidylglycerol). The activities of Gm and GmL in respect to their binding affinity/enthalpy, ability to permeabilize membranes and to induce vesicle aggregation are correlated with peptide secondary structure. Whereas Gm displays a quite stable beta-hairpin motif irrespective of the environment, GmL assumes a random conformation in aqueous solution and in the presence of 25 mol% POPG but adopts a beta-like structure in the presence of 50 mol% POPG. Gm exhibited high lyric activity against both surface charge densities. Instead, the activity of GmL was found to be negligible in the presence of 25 mol% POPG LUVs, but comparable to that of the native peptide against 50 mol% POPG as a consequence of peptide structuring. We conclude that the activity of Gm and its linear analogue is intimately related to the formation of a beta-turn motif, in which the hydrophobic residues form a hydrophobic face able to insert into the membrane and disrupt it. (c) 2015 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 08/57685-7 - NICT of Complex Fluids (IFCx)
• Grantee: Antonio Martins Figueiredo Neto
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 12/10442-8 - Perturbations on charged lipid bilayers induced by electric pulses, antimicrobial peptides and vesicles with opposite charge
• Grantee: Karin Do Amaral Riske
• Support Opportunities: Regular Research Grants