Single channel planar lipid bilayer recordings of the melittin variant MelP5

Abstract

MelP5 is a 26 amino acid peptide derived from melittin, the main active constituent of bee venom, with five amino acid replacements. The pore-forming activity of MelP5 in lipid membranes is attracting attention because MelP5 forms larger pores and induces dye leakage through liposome membranes at a lower concentration than melittin. Studies of MelP5 have so far focused on ensemble measurements of membrane leakage and impedance; here we extend this characterization with an electrophysiological comparison between MelP5 and melittin using planar lipid bilayer recordings. These experiments reveal that MelP5 pores in lipid membranes composed of 3:1 phosphatidylcholine:cholesterol consist of an average of 10 to 12 monomers compared to an average of 3 to 9 monomers for melittin. Both peptides form transient pores with dynamically varying conductance values similar to previous findings for melittin, but MelP5 occasionally also forms stable, well-defined pores with single channel conductance values that vary greatly and range from 50 to 3000pS in an electrolyte solution containing 100mM KCl.

Nanopore‐Based, Rapid Characterization of Individual Amyloid Particles in Solution: Concepts, Challenges, and Prospects

“…Biological nanopores range from ion channels to assemblies of pore‐forming toxins and their biological function is to facilitate or regulate the passage of polar molecules, ions, or peptides across cell membranes . With regard to resistive pulse sensing, biological nanopores are appealing as their sensing volumes are often defined with atomic precision and they can be produced in large quantities through bacteria fermentation or cell culture followed by purification .…”

It's Not a Bug, It's a Feature: Functional Materials in Insects

“…[486] The venom of bees in particular contains a compound called melittin, an amphiphilic peptide that self-assembles into oligomeric pores in enemy lipid membranes to induce cell death. [494][495][496] A number of mechanisms exist that allow sting removal. Vespid stylets are wider than their lancets, allowing the lancets to retreat and shield their serrated barbs before extraction ( Figure 22A-D).…”

Investigating pore-forming peptides using the atomic force microscope

“…Many papers using other methods dispute the idea that melittin creates a stable, transmembrane pore 17 . Fennouri, et al, investigated the effects of Melp5, a mutant peptide synthetically evolved from melittin, in comparison with melittin in POPC/Cholesterol bilayers using single ion channel recordings 18 . 18 .…”

“…Fennouri, et al, investigated the effects of Melp5, a mutant peptide synthetically evolved from melittin, in comparison with melittin in POPC/Cholesterol bilayers using single ion channel recordings 18 . 18 .…”

“…Melittin is widely known to affect cell membranes by forming pores, but its effect is short-lived, owing to the inherent instability of the pores. 17,[32][33][34] Wild-type melittin is known to have a bimodal interaction with a lipid bilayer; it can exist either in a surface-bound state, with its backbone approximately parallel to the membrane surface, or in an inserted state, forming pores that span the membrane. An amphipathic helix arises when melittin contacts the membrane.…”