Characterizing the structure–function relationship reveals the mode of action of a novel antimicrobial peptide, P1, from jumper ant Myrmecia pilosula

Abstract

Microbial infections of antibiotic-resistant strains cause serious diseases and have a significant impact on public health worldwide, so novel antimicrobial drugs are urgently needed. Insect venoms, a rich source of bioactive components containing antimicrobial peptides (AMPs), are attractive candidates for new therapeutic agents against microbes. Recently, a novel peptide, P1, identified from the venom of the Australian jumper ant Myrmecia pilosula, showed potent antimicrobial activities against both Gram-negative and Gram-positive bacteria, but its structure-function relationship is unknown. Here, we used biochemical and biophysical techniques coupled with computational simulations to explore the mode of action of P1 interaction with dodecylphosphocholine (DPC) micelles as a model membrane system. Our circular dichroism (CD) and NMR studies revealed an amphipathic α-helical structure for P1 upon interaction with DPC micelles. A paramagnetic relaxation enhancement approach revealed that P1 orients its α-helix segment (F6-G14) into DPC micelles. In addition, the α-helix segment could be essential for membrane permeabilization and antimicrobial activity. Moreover, the arginine residues R8, R11, and R15 significantly contribute to helix formation and membrane-binding affinity. The lysine residue K19 of the C-terminus functionally guides P1 to interact with DPC micelles in the early interaction stage. Our study provides insights into the mode of action of P1, which is valuable in modifying and developing potent AMPs as antibiotic drugs.

Heterodimeric Insecticidal Peptide Provides New Insights into the Molecular and Functional Diversity of Ant Venoms

“…These features are also shared with membrane-active peptides from ant venom that display insecticidal, cytotoxic, and antimicrobial activities. Cell membranes are the common molecular target of linear, polycationic, and amphiphilic ant venom peptides. ,,, Among ant venoms, the biological activity and the molecular target have been described for very few dimeric peptides. Nevertheless, Et1a and Mp1a, are pore-forming peptides that induce the formation of nonselective cationic channels in cell membranes, increasing cell permeability with resultant ion leakage and finally cell death. , Similar interactions with lipid bilayers were also observed with the homodimeric MIITX 1 -Mg2a peptide isolated from the venom of Myrmecia gulosa , which produces pain in vertebrates via the formation of pores in the membranes of peripheral sensory neurons .…”

Nanofibrous dressing: Potential alternative for fighting against antibiotic‐resistance wound infections

“…In general, AMPs can be divided into four types according to their secondary structure: α‐helix, β‐sheet, loop, and extension structure 38 . The N‐terminal and C‐terminal of α‐helix AMPs are hydrophilic and hydrophobic, respectively, forming a positively charged amphiphilic structure, which plays an extremely important role in the destruction of bacterial cell membranes 41 . Specifically, since the amino acid residue is positively charged, AMPs can be electrically adsorbed with anionic lipopolysaccharide (Gram‐negative bacteria) or ester teichoic acid (Gram‐positive bacteria) 42 .…”

Molecular simulations of venom peptide‐membrane interactions: Progress and challenges

“…An alternative approach is to start with a random mixture of water, lipids and peptide(s) and allow the lipid bilayer to self‐assemble . Other simulation studies have used pre‐formed micelles to match the experimental conditions of NMR or CD experiments . While micelles can mimic some of the essential features of lipid bilayers the effect of the membrane curvature has to be taken into account when interpreting results.…”