Real-time quantitative analysis of lipid disordering by aurein 1.2 during membrane adsorption, destabilisation and lysis

Tzong-Hsien Lee, Christine Heng, Marcus J Swann, Johh D Gehman, Frances Separovic, Marie Isabel Aguilar

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Effective antimicrobial peptides (AMPs) distinguish between the host and microbial cells, show selective antimicrobial activity and exhibit a fast killing mechanism. Although understanding the structure-function characteristics of AMPs is important, the impact of the peptides on the architecture of membranes with different lipid compositions is also critical in understanding the molecular mechanism and specificity of membrane destabilisation. In this study, the destabilisation of supported lipid bilayers (SLBs) by the AMP, aurein 1.2 was quantitatively analysed by dual polarisation interferometry. The lipid bilayers were formed on a planar silicon oxynitride chip, and composed of mixed synthetic lipids, or E. coli lipid extract. The molecular events leading sequentially from peptide adsorption to membrane lysis were examined in real time by changes in bilayer birefringence (lipid molecular ordering) as a function of membrane-bound peptide mass. Aurein 1.2 bound weakly without any change in membrane ordering at low peptide concentration (5 I?M), indicating a surface-associated state without significant perturbation in membrane structure. At 10 I?M peptide, marked reversible changes in molecular ordering were observed for all membranes except MPE/DMPG. However, at 20 I?M aurein 1.2, removal of lipid molecules, as determined by mass loss with a concomitant decrease in birefringence during the association phase, was observed for DMPC, and ...
Original languageEnglish
Pages (from-to)1977 - 1986
Number of pages10
JournalBiochimica et Biophysica Acta - Biomembranes
Issue number10
Publication statusPublished - 2010

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