Exploring Peptide Membrane Interaction Using Surface Plasmon Resonance:  Differentiation between Pore Formation versus Membrane Disruption by Lytic Peptides

Abstract

Lytic peptides comprise a large group of membrane-active peptides used in the defensive and offensive systems of all organisms. Differentiating between their modes of interaction with membranes is crucial for understanding how these peptides select their target cells. Here we utilized SPR to study the interaction between lytic peptides and lipid bilayers (L1 sensor chip). Using studies also on hybrid monolayers (HPA sensor chip) revealed that SPR is a powerful tool for obtaining a real-time monitoring of the steps involved in the mode of action of membrane-active peptides, some of which previously could not be detected directly by other techniques and reported here for the first time. We investigated the mode of action of peptides that represent two major families: (i) the bee venom, melittin, as a model of a non-cell-selective peptide that forms transmembrane pores and (ii) magainin and a diastereomer of melittin (four amino acids were replaced by their D enantiomers), as models of bacteria-selective non-pore-forming peptides. Fitting the SPR data to different interaction models allows differentiating between two major steps: membrane binding and membrane insertion. Melittin binds to PC/cholesterol approximately 450-fold better than its diastereomer and magainin, mainly because it is inserted into the inner leaflet (2/3 of the binding energy), whereas the other two are not. In contrast, there is only a slight difference in the binding of all the peptides to negatively charged PE/PG mono- and bilayer membranes (in the first and second steps), indicating that the inner leaflet contributes only slightly to their binding to PE/PG bilayers. Furthermore, the 100-fold stronger binding of the cell-selective peptides to PE/PG as compared with PC/cholesterol resulted only from electrostatic attraction to the negatively charged headgroups of the outer leaflet. These results clearly differentiate between the two general mechanisms: pore formation by melittin only in zwitterionic membranes and a detergent-like effect (carpet mechanism) for all the peptides in negatively charged membranes, in agreement with their biological function.

The Presence of a Single N-terminal Histidine Residue Enhances the Fusogenic Properties of a Membranotropic Peptide Derived from Herpes Simplex Virus Type 1 Glycoprotein H

“…We employed numerical integration analysis that uses nonlinear analysis to fit an integrated rate equation directly to the sensorgrams (61). When fitting the peptide sensorgrams globally (using different concentrations of the peptides) with the simplest 1:1 Langmuir binding model, a poor fit was obtained (X 2 Ͼ 100), confirming that this model does not represent the lipid binding mechanism of the peptide.…”

Evaluation of the Membrane-binding Properties of the Proximal Region of the Angiotensin II Receptor (AT1A) Carboxyl Terminus by Surface Plasmon Resonance

“…This model was chosen based on previous studies of peptides-membrane interaction. [9][10][11][12][13][14][15][24][25][26][27] …”

Dendrimers as Antibacterial Agents

“…They are an important part of the innate defense system, possessing a high potency and broad spectrum of activity against prokaryotic cells with only a minor impact on eukaryotic cells. Such properties raised some hope that natural antimicrobial peptides and their synthetic analogs may be adaptable for use in vivo as new generation antibiotics (Lequin et al, 2003;Papo & Shai, 2003;Powers & Hancock, 2003).…”