Nano-viscosimetry analysis of the membrane disrupting action of the bee venom peptide melittin

Abstract

Melittin is one of the most studied α-helical cationic membrane disrupting peptides. It is the main component of bee venom, however it is considered an antimicrobial peptide for its ability to kill bacteria. Melittin is believed to act by opening large toroidal pores in the plasma membrane of the targeted cells/bacteria, although this is questioned by some authors. Little is known, however, about the molecular mechanism leading to this activity. In this study the mechanism of action of melittin was studied by dye leakage and quartz crystal microbalance fingerprinting analysis in biomimetic model membranes. The results revealed the existence of multiple stages in the membrane disrupting action with characteristic differences between different membrane types. In bacterial-mimetic (charged) lipid mixtures the viscoelastic fingerprints suggest a surface-acting mechanism, whereas in mammalian-mimetic (neutral) membranes melittin appears to penetrate the bilayer already at low concentrations. In domain-forming mixed membranes melittin shows a preference for the domain containing predominantly zwitterionic lipids. The results confirm membrane poration but are inconsistent with the insertion-to-toroidal pore pathway. Therefore hypotheses of the two membrane disrupting pathways were developed, describing the membrane disruption as either surface tension modulation leading to toroidal pore formation, or linear aggregation leading to fissure formation in the membrane.

Hybrid bilayer membranes on metallurgical polished aluminum

“…The hBLMs in our study are sufficiently fluid to allow a biologically relevant response to the membrane damaging agent, melittin from bee venom. The response was found to be dependent on cholesterol content in the hBLMs, with cholesterol acting as a moderate inhibitor of melittin damage, consistent with earlier studies on vesicles 74 , 75 , 81 . The melittin effect was reproducible and concentration dependent which suggests utility of the hBLMs on metallurgical Al as a robust platform for biosensor design.…”

Mechanism of Action of the Antimicrobial Peptide Caerin1.1

“…The QCM fingerprint data above is consistent with peptide penetration into the membrane. Yet, while membrane disruption is a multistage process, the fingerprints suggest a much simpler process, consistent with membrane penetration without disruption; however it should be noted that the fingerprints are different from the trends recorded for proline‐rich peptides that could reversibly enter and exit the membrane . Temperature‐ramping analysis has shown that caerin1.1 is dominantly present in two states, that is consistent with distinct surface bound and membrane inserted states.…”

Lipid Headgroup Charge Controls Melittin Oligomerization in Membranes: Implications in Membrane Lysis

“…Since melittin is a cationic peptide at physiological pH, it is known to show preferential binding to negatively charged membranes. − However, negatively charged lipids confer protection to lipid vesicles against melittin-induced lysis. ,− This apparently paradoxical behavior has been attributed to differential melittin orientation in negatively charged membranes , relative to zwitterionic membranes. Biophysical investigations utilizing fluorescence signatures of melittin , have highlighted the role of negatively charged membranes in modulating the organization and dynamics of membrane-bound melittin.…”