Interaction of antimicrobial peptide protegrin with biomembranes

Abstract

The antimicrobial peptide protegrin-1 (PG-1) interacts with membranes in a manner that strongly depends on membrane lipid composition. In this research we use an approach representing the outer layers of bacterial and red blood cell membranes with lipid monolayers and using a combination of insertion assay, epifluorescence microscopy, and surface x-ray scattering to gain a better understanding of antimicrobial peptide's mechanism of action. We find that PG-1 inserts readily into anionic dipalmitoyl-phosphatidylglycerol, palmitoyl-oleoyl-phosphatidylglycerol, and lipid A films, but significantly less so into zwitterionic dipalmitoyl-phosphatidylcholine, palmitoyl-oleoyl-phosphatidylcholine, and dipalmitoyl-phosphatidylethanolamine monolayers under similar experimental conditions. Epifluorescence microscopy shows that the insertion of PG-1 into the lipid layer results in the disordering of lipid packing; this disordering effect is corroborated by grazing incidence x-ray diffraction data. X-ray reflectivity measurements further point to the location of the peptide in the lipid matrix. In a pathologically relevant example we show that PG-1 completely destabilizes monolayer composed of lipid A, the major component in the outer membrane of Gram-negative bacteria, which is likely to be the mechanism by which PG-1 disrupts the outer membrane, thus allowing it to reach the target inner membrane.

TheNeisseria meningitidisCapsule Is Important for Intracellular Survival in Human Cells

“…One of the mechanisms by which the capsule may protect the meningococci in the intracellular environment is an increased resistance to CAMPs (Fig. 4) that kill gram-negative bacteria by destabilizing the inner and outer membranes (8,18,23,39,40,46). Mechanistically, the capsule may protect the bacteria by impairing the interaction of CAMPs with the surface, as shown in K. pneumoniae (3).…”

Antibacterial Properties and Mode of Action of a Short Acyl-Lysyl Oligomer

“…Insertion experiments were carried out to quantify the interactions of NC 12 -2␤ 12 with membrane mimics as previously described (9,20). Initially, Langmuir monolayers of dipalmitoyl-sn-glycero-3 phosphocholine (DPPC)-cholesterol (9:1) were deposited at the air-liquid interface from chloroform (high-performance liquid chromatography grade; Fisher Scientific), whereas 1,2-dipalmitoyl-sn-glycero-3 phosphoglycerol (DPPG) and DPPG-1,2-dipalmitoyl-sn-glycero-3 phosphoethanolamine (DPPE) (ratio, 1/4) (Avanti Polar Lipids, Inc.) were from 9%/1% (vol/vol) chloroform-methanol solution (highperformance liquid chromatography grade; Fisher Scientific).…”

Mechanisms of Selective Antimicrobial Activity of Gaegurin 4

“…In addition, the abundance of cholesterol in RBC membranes and its absence in bacterial cells may underlie the different hemolytic activity of the peptides (Ames, 1968;Cronan & Roy, 1972;Gennis, 1991). For the antimicrobial peptides, it has been suggested that the selective activity of antimicrobial peptides is due to the differences in membrane lipid compositions of target cells (Matsuzaki et al, 1989;Zasloff, 2002;Gidalevitz et al, 2003; see for review Matsuzaki, 2009).…”