The "pre-assembled state" of magainin 2 lysine-linked dimer determines its enhanced antimicrobial activity

Author(s)

Lorenzon, Esteban N. ; Nobre, Thatyane M. ; Caseli, Luciano ; Cilli, Eduardo M. ; da Hora, Gabriel C. A. ; Soares, Thereza A. ; Oliveira, Osvaldo N., Jr.

• Document type: Journal article
• Source: COLLOIDS AND SURFACES B-BIOINTERFACES; v. 167, p. 9-pg., 2018-07-01.

Abstract

Antimicrobial peptides (AMPs) are alternatives to conventional antibiotics against multi-drug resistant bacteria with low potential for developing microbial resistance. The design of such molecules requires understanding of the mechanisms of action, particularly the interaction with bacteria cell membranes. In this work, we determine the mechanism responsible for the higher activity against Escherichia coil of the C-terminal lysine dimer of magainin 2, (MG2)(2)K, in comparison to the monomeric peptide magainin 2 (MG2). Langmuir monolayers and vesicles made with the E. coli lipid extract were used to address the two possible states for the peptide-membrane interaction, namely the "binding state" and "pore state", respectively. The incorporation of MG2 and (MG2)(2)K in lipid monolayers at the air-water interface caused slight differences in surface pressure isotherms and polarization-modulated infrared reflection absorption (PM-IRRAS) spectra, and therefore the difference in activity is not associated with the binding state. In contrast, large differences were observed in the leakage experiments where (MG2)(2)K was shown to disrupt the large unilamellar vesicles to a much higher extent owing to efficient pore formation. The binding and penetration of MG2 and (MG2)(2)K were also probed with molecular dynamics (MD) simulations for bilayers made with 1-palmitoy1-2-oleoyl-sn-g/ycero-3-phosphoethanolamine:1-palmitoy1-2-oleoyl-snglycero-3-phosphoglycerol (POPE:POPG). (MG2)(2)K forms disordered toroidal pores at a significant lower concentration than for MG2. In summary, the combination of experimental and computational simulation results indicated that the "pre-assembling state" of (MG2)(2)K dimer leads to a reduced number of molecules and shorter time being required to kill E. coli. (C) 2018 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 13/14262-7 - Nanostructured films from biologically-relevant materials
• Grantee: Osvaldo Novais de Oliveira Junior
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 13/07600-3 - CIBFar - Center for Innovation in Biodiversity and Drug Discovery
• Grantee: Glaucius Oliva
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 15/16857-3 - Cell membrane models for investigating the mechanisms of action of antimicrobial peptides and the effects from dimerization and cyclization
• Grantee: Esteban Nicolás Lorenzón
• Support Opportunities: Scholarships in Brazil - Post-Doctoral