Toxicity of an α-Pore-forming Toxin Depends on the Assembly Mechanism on the Target Membrane as Revealed by Single Molecule Imaging*
Toxicity of an α-Pore-forming Toxin Depends on the Assembly Mechanism on the Target Membrane as Revealed by Single Molecule Imaging*
复制标题
DOI：
10.1074/jbc.m114.600676
复制
发表时间：
2014-12
期刊：
影响因子：
--
通讯作者：
Yamunadevi Subburaj;Uris Ros;Eduard Hermann;Rudi Tong;A. García-Sáez
中科院分区：
文献类型：
--
作者：
Yamunadevi Subburaj;Uris Ros;Eduard Hermann;Rudi Tong;A. García-Sáez
背景：马奎毒素 II 是一种模型 α-成孔毒素，通过在宿主质膜上打孔来杀死细胞。结果：在膜上，马奎毒素II并没有采取独特的寡聚状态，而是组装成多个与毒性相关的共存物种。结论：马奎毒素II的毒性取决于其组装机制。意义：提出了α-成孔毒素作用的新分子机制。 α-成孔毒素 (α-PFT) 是普遍存在的防御工具，可通过打开靶细胞膜上的孔来杀死细胞。尽管它们与宿主/病原体相互作用相关，但对导致膜透化的孔化学计量和组装途径知之甚少。马奎毒素 II (EqtII) 是一种来自海葵的 α-PFT 模型，它会寡聚并在含有鞘磷脂的膜上形成孔。在这里，我们通过单分子成像确定了活细胞中 EqtII 的时空组织。令人惊讶的是，我们发现在细胞表面EqtII并没有组织成独特的寡聚形式。相反，它以寡聚体的混合物形式存在，主要包括单体、二聚体、四聚体和六聚体。基于我们的数据的数学模型支持了一种新模型，其中毒素聚类在几秒钟内发生，并通过单体缔合时形成的 EqtII 二聚体单元的缩合进行。此外，改变 EqtII 组装途径会强烈影响其毒性活性，这凸显了组装机制与毒性的相关性。
Background: Equinatoxin II is a model α-pore-forming toxin that kills cells by porating the host plasma membrane. Results: On the membrane, equinatoxin II does not adopt a unique oligomeric state, but assembles into multiple coexisting species related to toxicity. Conclusion: Toxicity of Equinatoxin II depends on its assembly mechanism. Significance: A new molecular mechanism is proposed for α-pore-forming toxins action. α-Pore-forming toxins (α-PFTs) are ubiquitous defense tools that kill cells by opening pores in the target cell membrane. Despite their relevance in host/pathogen interactions, very little is known about the pore stoichiometry and assembly pathway leading to membrane permeabilization. Equinatoxin II (EqtII) is a model α-PFT from sea anemone that oligomerizes and forms pores in sphingomyelin-containing membranes. Here, we determined the spatiotemporal organization of EqtII in living cells by single molecule imaging. Surprisingly, we found that on the cell surface EqtII did not organize into a unique oligomeric form. Instead, it existed as a mixture of oligomeric species mostly including monomers, dimers, tetramers, and hexamers. Mathematical modeling based on our data supported a new model in which toxin clustering happened in seconds and proceeded via condensation of EqtII dimer units formed upon monomer association. Furthermore, altering the pathway of EqtII assembly strongly affected its toxic activity, which highlights the relevance of the assembly mechanism on toxicity.