Detection of tBid Oligomerization and Membrane Permeabilization by Graphene-Based Single-Molecule Surface-Induced Fluorescence Attenuation
- Li MaLi MaNational Laboratory of Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaMore by Li Ma
- Shuxin HuShuxin HuNational Laboratory of Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, ChinaMore by Shuxin Hu
- Xiaolong HeXiaolong HeNational Laboratory of Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, ChinaNational Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaMore by Xiaolong He
- Na YangNa YangNational Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaMore by Na Yang
- Licui ChenLicui ChenNational Laboratory of Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, ChinaMore by Licui Chen
- Chenguang YangChenguang YangNational Laboratory of Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaMore by Chenguang Yang
- Fangfu YeFangfu YeNational Laboratory of Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaMore by Fangfu Ye
- Taotao Wei*Taotao Wei*E-mail: [email protected]. Phone: +86-10-64888566.National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaMore by Taotao Wei
- Ming Li*Ming Li*E-mail: [email protected]. Phone: +86-10-82649058.National Laboratory of Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaSongshan Lake Materials Laboratory, Dongguan, Guangdong 523808, ChinaMore by Ming Li
Abstract
The permeabilization of organelle membranes by BCL-2 family proteins is a pivotal step during the regulation of apoptosis; the underlying mechanisms remain unclear. Based on the fluorescence attenuation by graphene oxide, we developed a single-molecule imaging method termed surface-induced fluorescence attenuation (smSIFA), which enabled us to track both vertical and lateral kinetics of singly labeled BCL-2 family protein tBid during membrane permeabilization. We found that tBid monomers lie shallowly on the lipid bilayer, where they self-assemble to form oligomers. During the initiation phase of self-assembly, the two central hydrophobic helices (α6 and α7) of tBid insert halfway into the phospholipid core, while the other helices remain on the surface. In oligomerized tBid clusters, α6 and α7 prefer to float up, and the other helices may sink to the bottom of the membrane and cause the formation of transient two-dimensional, micelle-like pore structures, which are responsible for the permeabilization of membranes and the induction of apoptosis. Our results shed light on the understanding of tBid-induced apoptosis, and this nanotechnology-based smSIFA approach could be used to dissect the kinetic interaction between membrane protein and lipid bilayer at the single-molecule level with subnanometer precision.