Single-molecule visualization of dynamic transitions of pore-forming peptides among multiple transmembrane positions

• Published in: Nature communications Vol. 7; no. 1; p. 12906
• Main Authors: Li, Ying, Qian, Zhenyu, Ma, Li, Hu, Shuxin, Nong, Daguan, Xu, Chunhua, Ye, Fangfu, Lu, Ying, Wei, Guanghong, Li, Ming
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.09.2016; Nature Publishing Group; Nature Portfolio
• Subjects: 14/33; 631/45/612/1237; 631/57/2265; 631/57/2282; Dyes; Humanities and Social Sciences; Laboratories; Lipids; Membranes; multidisciplinary; Peptides; Physical sciences; Physics; Proteins; Science; Science (multidisciplinary); Visualization; Beijing China; China
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms12906

Research on the dynamics of single-membrane proteins remains underdeveloped due to the lack of proper approaches that can probe in real time the protein’s insertion depth in lipid bilayers. Here we report a single-molecule visualization method to track both vertical insertion and lateral diffusion of membrane proteins in supported lipid bilayers by exploiting the surface-induced fluorescence attenuation (SIFA) of fluorophores. The attenuation follows a d −4 dependency, where d is the fluorophore-to-surface distance. The method is validated by observing the antimicrobial peptide LL-37 to transfer among five transmembrane positions: the surface, the upper leaflet, the centre, the lower leaflet and the bottom of the lipid bilayer. These results demonstrate the power of SIFA to study protein-membrane interactions and provide unprecedented in-depth understanding of molecular mechanisms of the insertion and translocation of membrane proteins. Assessing protein localization within lipid membranes is problematic. Here, the authors describe a single molecule visualization method based on surface-induced fluorescence attenuation (SIFA) to determine the insertion depth and lateral diffusion of a peptide in a lipid bilayer.