Mechanism of Lipid Bilayer Disruption by the Human Antimicrobial Peptide, LL-37†

Katherine A. Henzler Wildman, Dong-Kuk Lee, A. Ramamoorthy
2003 Biochemistry  
LL-37 is an amphipathic, R-helical, antimicrobial peptide. 15 N chemical shift and 15 N dipolarshift spectroscopy of site-specifically labeled LL-37 in oriented lipid bilayers indicate that the amphipathic helix is oriented parallel to the surface of the bilayer. This surface orientation is maintained in both anionic and zwitterionic bilayers and at different temperatures and peptide concentrations, ruling out a barrelstave mechanism for bilayer disruption by LL-37. In contrast, electrostatic
more » ... st, electrostatic factors, the type of lipid, and the presence of cholesterol do affect the extent to which LL-37 perturbs the lipids in the bilayer as observed with 31 P NMR. The 31 P spectra also show that micelles or other small, rapidly tumbling membrane fragments are not formed in the presence of LL-37, excluding a detergent-like mechanism. LL-37 does increase the lamellar to inverted hexagonal phase transition temperature of both PE model lipid systems and Escherichia coli lipids, demonstrating that it induces positive curvature strain in these environments. These results support a toroidal pore mechanism of lipid bilayer disruption by LL-37.
doi:10.1021/bi0273563 pmid:12767238 fatcat:gsodfhdzqvde7hqwvyrcvdiada