Interaction of protegrin-1 with lipid bilayers: membrane thinning effect.

ABSTRACT: Protegrins (PG) are important in defending host tissues, preventing infection via an attack on the membrane surface of invading microorganisms. Protegrins have powerful antibiotic abilities, but the molecular-level mechanisms underlying the interactions of their beta-sheet motifs with the membrane are not known. Protegrin-1 (PG-1) is composed of 18 amino acids with a high content of basic residues and two disulfide bonds. Here we focused on the stability of PG-1 at the amphipathic interface in lipid bilayers and on the details of the peptide-membrane interactions. We simulated all-atom models of the PG-1 monomer with explicit water and lipid bilayers composed of both homogeneous POPC (palmitoyl-oleyl-phosphatidylcholine) lipids and a mixture of POPC/POPG (palmitoyl-oleyl-phosphatidylglycerol) (4:1) lipids. We observed that local thinning of the lipid bilayers mediated by the peptide is enhanced in the lipid bilayer containing POPG, consistent with experimental results of selective membrane targeting. The beta-hairpin motif of PG-1 is conserved in both lipid settings, whereas it is highly bent in aqueous solution. The conformational dynamics of PG-1, especially the highly charged beta-hairpin turn region, are found to be mostly responsible for disturbing the membrane. Even though the eventual membrane disruption requires PG-1 oligomers, our simulations clearly show the first step of the monomeric effects. The thinning effects in the bilayer should relate to pore/channel formation in the lipid bilayer and thus be responsible for further defects in the membrane caused by oligomer.

SUBMITTER: Jang H 

PROVIDER: S-EPMC1578484 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature