Czajkowsky D M, Sheng S, Shao Z
Department of Molecular Physiology, University of Virginia School of Medicine, Charlottesville 22908, USA.
J Mol Biol. 1998 Feb 20;276(2):325-30. doi: 10.1006/jmbi.1997.1535.
Atomic force microscopy (AFM) was used to study the structure of the staphylococcal alpha-hemolysin (alpha HL) oligomer formed in supported phospholipid bilayers. In contrast to the recent X-ray crystallographic demonstration of a heptameric stoichiometry for the oligomer formed in deoxycholate (DOC) micelles, the high-resolution unprocessed AFM images unequivocally revealed a hexamer in these phospholipid bilayers. Independent support of this hexameric stoichiometry was obtained from the measurements of the lattice constant in the AFM images and from gel electrophoresis. Therefore, alpha HL can form two different, energetically stable oligomers, which differ in at least stoichiometry but perhaps subunit structure as well. Furthermore, stable, incomplete oligomers were observed in the AFM images, which may be of relevance to the mechanism by which alpha HL damages the cell.
原子力显微镜（AFM）用于研究在支持的磷脂双层中形成的葡萄球菌α-溶血素（αHL）寡聚体的结构。与最近通过X射线晶体学证明在脱氧胆酸盐（DOC）胶束中形成的寡聚体的七聚体化学计量不同，高分辨率未处理的AFM图像明确显示这些磷脂双层中存在六聚体。从AFM图像中的晶格常数测量和凝胶电泳获得了对这种六聚体化学计量的独立支持。因此，αHL可以形成两种不同的、能量稳定的寡聚体，它们至少在化学计量上不同，也许亚基结构也不同。此外，在AFM图像中观察到稳定的、不完整的寡聚体，这可能与αHL损伤细胞的机制有关。
