Detection of tBid Oligomerization and Membrane Permeabilization by Graphene-Based Single-Molecule Surface-Induced
Li Ma, Shuxin Hu, Xiaolong He, Na Yang, Licui Chen, Chenguang Yang, Fangfu Ye, Taotao Wei* and Ming Li*
Abstract
The permeabilization of organelle membranes by BCL-2family 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-2family 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 (α6and α7) of tBid insert halfway into the phospholipid core, while the other helices remain on the surface. In oligomerized tBid clusters, α6and α7prefer 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.
附件下载：
Detection of tBid Oligomerization and Membrane Permeabilization by Graphene-Based Single-Molecule Surface-Induced,Nano letters, 09 Oct 2019
Nano letters, 09 October, 2019，DOI：https://doi.org/10.1021/acs.nanolett.9b02223
Detection of tBid Oligomerization and Membrane Permeabilization by Graphene-Based Single-Molecule Surface-Induced
Li Ma, Shuxin Hu, Xiaolong He, Na Yang, Licui Chen, Chenguang Yang, Fangfu Ye, Taotao Wei* and Ming Li*
Abstract
The permeabilization of organelle membranes by BCL-2family 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-2family 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 (α6and α7) of tBid insert halfway into the phospholipid core, while the other helices remain on the surface. In oligomerized tBid clusters, α6and α7prefer 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.
文章链接：https://pubs.acs.org/doi/10.1021/acs.nanolett.9b02223
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