Lipid Nanodisc Formation using Pxt-5 Peptide Isolated from Amphibian (<i>Xenopus tropicalis</i>) Skin, and its Altered Form, Modify-Pxt-5

Abstract

Nanodiscs are self-assembled discoidal nanoparticles composed of amphiphilic α-helical scaffold proteins or peptides that accumulate around the circumference of a lipid bilayer. In this study, Pxt-5, which is an antimicrobial peptide isolated from the skin of Xenopus tropicalis, and its modified peptide (Modify-Pxt-5) were synthesized by solid-phase peptide synthesis (SPPS).Their surface properties, which are an important factor in inducing nanodisc formation, were investigated by circular dichroism (CD) spectroscopy, surface tension measurement, phospholipid vesicle clearance assay, and negative-staining transmission electron microscopy (NS-TEM). The α-helicity of Pxt-5 (8.4%) improved drastically to 45.6% by four amino-acid substitutions (Modify-Pxt-5). Both the peptides, having hydrophobic and hydrophilic faces, behaved like general surfactants, and the surface activity of Modify-Pxt-5 (CAC: 9.5×10 M, γ: 30.3 mN·m) was much higher than that of Pxt-5 (CAC: 7.9×10 M, γ: 38.1 mN·m). A turbid L-α-dimyristoylphosphatidylcholine (DMPC) vesicle solution (T = 0.3%) quickly turned transparent upon addition of Pxt-5 or Modify-Pxt-5. After twelve hours, the transmittance of vesicle solution with Modify-Pxt-5 (T = 96.2%) was found to be higher than that of vesicle solution with Pxt-5 (T = 83.5%), and then the micro-solubilized solutions were observed by NS-TEM. Interestingly, nanodisc structures were found in the vicinity of DMPC vesicles in both the images, and the average diameter of the nanodiscs was 11.2 ± 6.0 nm for those containing Pxt-5 and 10.8 ± 5.8 nm for those containing Modify-Pxt-5. It was also found that Modify-Pxt-5 effectively self-assembles into nanodiscs compared to Pxt-5 without any substitutions.

Nanodiscoidal Nucleic Acids for Gene Regulation

“…ND 2, which displayed Cys at the peptide C-terminus afforded 16 ± 1 DNA strands per ND. These values are consistent with our simple calculations , that estimate that there are 4-fold more thiol groups on peptides compared to that of the phospholipids. Unsurprisingly, ND 3 displayed 25 ± 7 DNA strands per ND which suggests that DNA coupling can efficiently proceed on both the phospholipid and peptide with minimal steric clash.…”

Designing nanodiscs as versatile platforms for on-demand therapy

“…Through experiments, it was demonstrated that these antimicrobial peptides could be efficiently incorporated into NDs, highlighting the potential for their application in antimicrobial therapies. 76 In conclusion, NDs offer substantial potential as versatile platforms for antibacterial and antiviral therapies. Their capability to deliver antimicrobial agents, induce specific immune responses, and be modified with various components significantly enhances the immunogenicity, specificity, and effectiveness of these therapeutic approaches.…”

“…Through experiments, it was demonstrated that these antimicrobial peptides could be efficiently incorporated into NDs, highlighting the potential for their application in antimicrobial therapies. 76…”

Solubilization of Phospholipid by Surfactin Leading to Lipid Nanodisc and Fibrous Architecture Formation

“…This technique involves the spontaneous structural conversion of phospholipid vesicles (liposomes) into nanodiscs through the straightforward addition of amphiphilic peptides. These amphiphilic helical peptides function as a surfactant, adeptly solubilizing the phospholipid bilayer while stabilizing the edge of the bilayer’s rim [ 16 , 17 , 18 ]. Owing to their amphiphilic nature, these self-assembled structures prevent the exposure of the hydrophobic lipid core to aqueous media, thus providing relative stability and monodispersity.…”