Secondary structure and membrane interaction of PR-39, a Pro+Arg-rich antibacterial peptide.
PR-39 is a 4719-Da peptide isolated from pig intestine and belonging to the recently discovered family of Pro+Arg-rich antibacterial peptides. PR-39 does not lyse Escherichia coli, instead the lethal action is probably linked to the termination of DNA and protein synthesis [Boman, H. G., Agerberth, B. & Boman, A. (1993) Infect. Immun. 61, 2978-2984]. Circular dichroism and Fourier-transform infrared spectroscopy have been used to investigate the secondary structure of PR-39 in the absence or presence of lipids. According to the circular dichroic data, this structure is not altered upon incubation of PR-39 with negatively charged vesicles, although the infrared spectra suggest that the hydrogen bond pattern is modified upon the peptide-lipid interaction. This is detected by a shift in the maximum wavelength of absorption of PR-39 from 1636 cm-1 in the absence of lipids to 1645 cm-1 in the presence of lipids. We have further addressed the question of the possible mechanism of interaction of PR-39 with model membranes (liposomes and planar lipid bilayers) whose lipid compositions mimick that of the E. coli inner membrane. PR-39 induced a calcein release from large unilamellar vesicles, which is dependent upon the peptide concentration and upon the presence of negatively charged lipid (glycerophosphoglycerol) in the membrane. The binding study of PR-39 to dioleoylglycerophosphoglycerol vesicles suggests that nearly 100% of the added peptide is membrane-bound. Addition of PR-39 to a planar lipid bilayer induced a linear increase in the current but no channel formation was observed since no discrete steps of conductance occurred.
Cabiaux
V
V
Université Libre de Bruxelles, Laboratoire des Macromolécules aux Interfaces, Belgium.
Agerberth
B
B
Johansson
J
J
Homblé
F
F
Goormaghtigh
E
E
Ruysschaert
J M
JM
D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry*; D023181:Antimicrobial Cationic Peptides; D001120:Arginine / Q000032:analysis*; D002942:Circular Dichroism; D005452:Fluoresceins / Q000378:metabolism; D007202:Indicators and Reagents; D008051:Lipid Bilayers; D010455:Peptides / Q000737:chemistry*; D011392:Proline / Q000032:analysis*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D013552:Swine
D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D005452:Fluoresceins; D007202:Indicators and Reagents; D008051:Lipid Bilayers; D010455:Peptides; C072212:PR 39; D001120:Arginine; D011392:Proline; C007740:fluorexon