DINÂMICA CONFORMACIONAL DO PÉPTIDO TRANSLOCADOR DE CÉLULAS PEP-1 EM SISTEMAS MODELO DE MEMBRANAS: ESTUDOS DE SIMULAÇÃO COMPUTACIONAL E ESPECTROSCÓPICOS

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Interaction of antimicrobial peptides, BP100 and pepR, with model membrane systems as explored by brownian dynamics simulations on a coarse-grained model

Publication . Alves, Carla S.; Kairys, Visvaldas; Castanho, Miguel A. R. B.; Fernandes, Miguel X.

This work focuses on the conformational and dynamic properties of the antimicrobial peptides (AMPs), BP100 and pepR, when confined within model membrane systems. Brownian dynamics (BD) simulations of a coarse-grained model of each respective peptide in an environment reproducing the phospholipid bilayer were carried out. Simple mean-field potentials were used to reproduce three physically different model phosphatidylcholine (PC) membrane systems. Based on the simplicity of the peptide-membrane models used, 1 ls simulations were performed. With the appropriate choice of parameters, the structure and dynamics of each peptide were recovered from each of the simulated BD trajectories. BP100 was observed to adopt a a-helical conformation when confined in each PC membrane. For pepR under the same conditions, the formation of an N-terminal a-helix was detected, whereas the C-terminus appeared to be less ordered. The dynamic properties of each peptide were characterized in terms of local and global motions. BP100 tended to localize with no preferred orientation approximately halfway across each membrane leaflet, whereas pepR localized near the membrane core with no preferred orientation. Overall, the peptide dynamics were found to vary according to the size of the peptide, as well as the width of the membrane environment.

2012Journal article

Open access

Escherichia coli cell surface perturbation and disruption induced by antimicrobial peptides BP100 and pepR

Publication . Alves, Carla S.; Melo, Manuel N.; Franquelim, Henri G.; Ferre, Rafael; Planas, Marta; Feliu, Lidia; Bardají, Eduard; Kowalczyk, Wioleta; Andreu, David; Santos, Nuno C.; Fernandes, Miguel X.; Castanho, Miguel A.R.B.

The potential of antimicrobial peptides (AMPs) as an alter native to conventional therapies is well recognized. Insights into the biological and biophysical properties of AMPs are thus key to understanding their mode of action. In this study, the mech anisms adopted by two AMPs in disrupting the Gram-negative Escherichia coli bacterial envelope were explored. BP100 is a short cecropin A-melittin hybrid peptide known to inhibit the growth of phytopathogenic Gram-negative bacteria. pepR, on the other hand, is a novel AMP derived from the dengue virus capsid protein. Both BP100 and pepR were found to inhibit the growth of E. coli at micromolar concentrations. Zeta potential measurements of E. coli incubated with increasing peptide concentrations allowed for the establishment of a correlation between the minimal inhibitory concentration (MIC) of each AMP and membrane surface charge neutralization. While a neutralization-mediated killing mechanism adopted by either AMP is not necessarily implied, the hypothesis that surface neu tralization occurs close to MIC values was confirmed. Atomic force microscopy (AFM) was then employed to visualize the structural effect of the interaction of each AMP with the E. coli cell envelope. At their MICs, BP100 and pepR progressively destroyed the bacterial envelope, with extensive damage already occurring 2 h after peptide addition to the bacteria. A similar effect was observed for each AMP in the concentration-depen dent studies. At peptide concentrations below MIC values, only minor disruptions of the bacterial surface occurred.

2010Journal article

Open access