Fang Y, Cheley S, Bayley H, Yang J
Department of Physics, University of Vermont, Cook Building, Burlington, Vermont 05405, USA.
Biochemistry. 1997 Aug 5;36(31):9518-22. doi: 10.1021/bi970600j.
We have used atomic force microscopy to study the oligomeric state of a genetically engineered mutant of staphylococcal alpha-hemolysin (alphaHL-H5) that can be arrested as a "prepore" assembly intermediate. AFM images of alphaHL-H5 on supported bilayers of a fluid-phase lipid, egg-yolk phosphatidylcholine (egg-PC), under conditions that lock alphaHL-H5 into the prepore state, clearly show a heptameric structure for many individual oligomers. The central dent of the prepore has a diameter of 3.2 +/- 0.2 nm. The distance between the centers of mass of neighboring subunits is 2.8 +/- 0.3 nm. The heptamer has an average diameter of 8.9 +/- 0.6 nm. These results support a recently proposed pathway for the assembly of alpha-hemolysin.
我们利用原子力显微镜研究了葡萄球菌α-溶血素（αHL-H5）的基因工程突变体的寡聚状态，该突变体可作为“孔前体”组装中间体被捕获。在将αHL-H5锁定为孔前体状态的条件下，在液相脂质蛋黄磷脂酰胆碱（egg-PC）的支撑双层上的αHL-H5的原子力显微镜图像清楚地显示了许多单个寡聚体的七聚体结构。孔前体的中心凹陷直径为3.2±0.2纳米。相邻亚基质心之间的距离为2.8±0.3纳米。七聚体的平均直径为8.9±0.6纳米。这些结果支持了最近提出的α-溶血素组装途径。
