New Insight into the Mechanism of Action of Wasp Mastoparan Peptides: Lytic Activity and Clustering Observed with Giant Vesicles

New Insight into the Mechanism of Action of Wasp Mastoparan Peptides: Lytic Activity and Clustering Observed with Giant Vesicles

Author Santos Cabrera, Marcia P. dos Google Scholar
Alvares, Dayane S. Google Scholar
Leite, Natalia B. Google Scholar
Souza, Bibiana Monson de Google Scholar
Palma, Mario S. Google Scholar
Riske, Karin A. Autor UNIFESP Google Scholar
Neto, Joao Ruggiero Google Scholar
Institution UNESP São Paulo State Univ
Universidade Federal de São Paulo (UNIFESP)
Abstract Antimicrobial peptides of the mastoparans family exert their bactericidal activity by binding to lipid membranes, inducing pores or defects and leaking the internal contents of vesicles and cells. However, this does not seem to be the only mechanism at play, and they might be important in the search for improved peptides with lower undesirable side effects. This work deals with three mastoparans peptides, Polybia-MP-1(MP-1), N2-Polybia-MP-1 (N-MP-1), and Mastoparan X (MPX), which exhibit high sequence homology. They all have three lysine residues and amidated C termini, but because of the presence of two, one, and no aspartic acid residues, respectively, they have +2, +3, and +4 net charges at physiological pH. Here we focus on the effects of these mastoparans peptides on anionic model membranes made of palmitoleyoilphosphatidylcholine (POPC) and palmitoleyoilphosphatidylglycerol (POPG) at 1:1 and 3:1 molar ratios in the presence and in the absence of saline buffer. Zeta potential experiments were carried out to measure the extent of the peptides' binding and accumulation at the vesicle surface, and CD spectra were acquired to quantify the helical structuring of the peptides upon binding. Giant unilamellar vesicles were observed under phase contrast and fluorescence microscopy. We found that the three peptides induced the leakage of GUVs at a gradual rate with many characteristics of the graded mode. This process was faster in the absence of saline buffer. Additionally, we observed that the peptides induced the formation of dense regions of phospholipids and peptides on the GUV surface. This phenomenon was easily observable for the more charged peptides.(MPX > N-MP-1 > MP-1) and in the absence of added salt. Our data suggest that these mastoparans accumulate on the bilayer surface and induce a transient interruption to its barrier properties, leaking the vesicle contents. Next, the bilayer recovers its continuity, but this happens in an inhomogeneous way, forming a kind of ply with peptides sandwiched between two juxtaposed membranes. Eventually, a peptide-lipid aggregate forming a lump is formed at high peptide-to-lipid ratios.
Language English
Sponsor Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Grant number CNPq: 477507/2008-5
FAPESP: 2010/11823-0
FAPESP: 06/57122-7
FAPESP: 07/03657-0
Date 2011-09-06
Published in Langmuir. Washington: Amer Chemical Soc, v. 27, n. 17, p. 10805-10813, 2011.
ISSN 0743-7463 (Sherpa/Romeo, impact factor)
Publisher Amer Chemical Soc
Extent 10805-10813
Access rights Closed access
Type Article
Web of Science ID WOS:000294373300059

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