Department of Chemistry, University of Oxford, Oxford, United Kingdom.
Biophys J. 2011 Dec 7;101(11):2679-83. doi: 10.1016/j.bpj.2011.09.054.
We have observed the assembly of the staphylococcal pore-forming toxin α-hemolysin using single-molecule fluorescence imaging. Surprisingly, assembly from the monomer to the complete heptamer is extremely rapid, occurring in <5 ms. No lower order oligomeric intermediates are detected. Monte Carlo simulation of our experiment shows that assembly is diffusion limited, and pore formation is dependent on the stability of intermediate species. There are close similarities between bacterial pore-forming toxins, such as staphylococcal α-hemolysin, the anthrax protective antigen, and the cholesterol-dependent cytolysins, and their eukaryotic analogs, such as the complement pore membrane attack complex and perforin domain. The assembly mechanism we have observed for α-hemolysin provides a simple model that aids our understanding of these important pore formers.
我们利用单分子荧光成像技术观察了葡萄球菌孔形成毒素 α-溶血素的组装过程。令人惊讶的是，从单体到完整的七聚体的组装非常迅速，<5ms 即可完成。未检测到任何低阶寡聚中间体。我们实验的蒙特卡罗模拟表明，组装是扩散受限的，孔的形成依赖于中间物种的稳定性。细菌孔形成毒素（如葡萄球菌α-溶血素、炭疽保护性抗原和胆固醇依赖性细胞溶素）与其真核类似物（如补体孔膜攻击复合物和穿孔素结构域）之间存在密切相似性。我们观察到的α-溶血素组装机制为我们提供了一个简单的模型，有助于我们理解这些重要的孔形成蛋白。
