Restructuring of Lipid Membranes by an Arginine-Capped Peptide Bolaamphiphile

Abstract

We study the self-assembly of arginine-capped bolaamphiphile peptide RAR (A: alanine, R: arginine) together with its binding to model membranes and its cytotoxicity and antimicrobial activity. Anionic 2-oleoyl-1-palmitoyl- sn-glycero-3-phospho-rac-(1-glycerol) sodium salt/2-oleoyl-1-palmitoyl- sn-glycero-3-phosphoethanolamine (POPG/POPE) vesicles and zwitterionic 1,2-dioleoyl- sn-glycero-3-phosphocholine/2-oleoyl-1-palmitoyl- sn-glycero-3-phosphocholine (POPC/DOPC) vesicles are used as model membranes to mimic bacterial and mammalian cell membranes, respectively. We show that RAR adopts a polyproline-II collagen-like conformation in water. Binding of RAR to POPG/POPE vesicles induces a strong correlation between the lipid bilayers, driven by RAR/POPG attractive electrostatic interaction together with a shift of the intramolecular POPE zwitterionic interaction toward an attractive electrostatic interaction with the RAR. Populations of RAR/POPG/POPE vesicles comprise different bilayer spacings, d and d, controlled by the conformation of the lipid chains corresponding to the L (gel-like) and L (liquid-crystal) phases, respectively. Cryo-TEM images reveal the presence of vesicles with no internal structure, compartmentalized thin-wall vesicles, or multilayer vesicles with uncorrelated layers and compartmentalization depending on the RAR/POPG/POPE composition. In contrast, the interaction of RAR with multilamellar POPC/DOPC vesicles leads to the decorrelation of the lipid bilayers. RAR was tolerated by skin fibroblast cells for a concentration up to 0.01 wt %, while 0.25 wt % RAR proved to be an efficient antibacterial agent against Gram-positive bacteria L. monocytogenes. Our results highlight the ability of RAR to distinguish between bacterial and mammalian cells and establish this peptide as a candidate to reduce the proliferation of L. monocytogenes bacteria.

Self-Assembly, Antimicrobial Activity, and Membrane Interactions of Arginine-Capped Peptide Bola-Amphiphiles

“…For RA 6 R acting against both E. coli and P. aeruginosa and RA 9 R acting against E. coli , the main reduction in the number of CFUs occurs in the first 2 h after treatment with the peptide. However, in terms of RA 9 R activity against S. aureus , this seems to occur steadily over the course of 24 h. The antimicrobial activity of these peptides is significantly lower than previously studied peptide RA 3 R, 20 which in part may be due to the decreased concentrations used in this study, which were selected to correspond to concentrations where there is no substantial cytotoxicity. It can be seen that RA 9 R displays little antimicrobial activity under these conditions.…”

“…A similar peptide RA 3 R also interacts with lipid membranes in the form of unassociated molecules due to interactions between the arginine residues and anionic or lipid head groups. 20 The cytotoxicity of RA 9 R is higher than that of RA 6 R at a given concentration, likely in some part due to the self-assembly of the fibrils, in which the arginine motif is presented at high density on the fibril surface. A further factor may be the increased hydrophobicity of RA 9 R due to the increase in alanine sequence length.…”

“…17,18 In another example, the self-assembly ability of arginine based bola-amphiphile RFL 4 FR was investigated and it was found to form nanosheets through lateral association of the backbone and dried films were compatible with human corneal stromal fibroblast cells. 19 Recently our group studied the self-assembly, antimicrobial activity, and membrane interaction of a short bola-amphiphile consisting of arginine and alanine residues, RA 3 R. 20 RA 3 R was found to form a polyproline II (collagen-like) secondary structure, but it does not assemble in water probably due the solubility imparted by the R residues. RA 3 R was found to induce strong correlation between anionic lipid bilayers through electrostatic interactions with POPG and demonstrates strong activity against the Gram-positive foodborne pathogen L. monocytogenes .…”

Molecular dynamic simulations, GIAO‐NMR and TD‐DFT spectroscopy analyze for zwitterionic isoleucine (ILE)N, 1 ≤ N ≤ 6, in water solution

“…In recent years, there has been an increase in interest for biological molecules especially amino acids, which has had great appeal for the manufacture of new nanomaterials and applications. In this regard, the determination of spectroscopic properties and the possible dependence of these properties on amino acid chain growth becomes an important point for applications of these new nanomaterials whether in the membranes research [1][2][3][4] or self-assemble properties [5][6][7][8] , energy storage 9 or even pharmaceutical applications [10][11][12] . In this article, we focus on the amino acid Isoleucine (ILE) which has a characteristic hydrophobic structure and has a high β-sheet formation potential compared to the other amino acids.…”

Enhancing the Potency of Antimicrobial Peptides through Molecular Engineering and Self-Assembly

“…2 ) (Figure 1, green-turquoise-brown); the Page of ACS Paragon Plus EnvironmentBiomacromolecules aliphatic residues provide a hydrophobic moiety to drive self-assembly [47][48]. However, this sequence was unable to aggregate at various concentrations and pHs, suggesting that alanines are not sufficient to promote the aggregation.…”