Bubeck Doryen, Filman David J, Hogle James M
Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, Massachusetts 02138, USA.
Nat Struct Mol Biol. 2005 Jul;12(7):615-8. doi: 10.1038/nsmb955. Epub 2005 Jun 19.
To study non-enveloped virus cell entry, a versatile in vitro model system was developed in which liposomes containing nickel-chelating lipids were decorated with His-tagged poliovirus receptors and bound to virus. This system provides an exciting opportunity for structural characterization of the early steps in cell entry in the context of a membrane. Here we report the three-dimensional structure of a poliovirus-receptor-membrane complex solved by cryo-electron microscopy (cryo-EM) at a resolution of 32 A. Methods were developed to establish the symmetry of the complex objectively. This reconstruction demonstrates that receptor binding brings a viral five-fold axis close to the membrane. Density is clearly defined for the icosahedral virus, for receptors (including known glycosylation sites) and for the membrane bilayer. Apparent perturbations of the bilayer close to the viral five-fold axis may function in subsequent steps of cell entry.
为了研究无包膜病毒进入细胞的过程，开发了一种通用的体外模型系统，其中含有镍螯合脂质的脂质体用带有组氨酸标签的脊髓灰质炎病毒受体进行修饰，并与病毒结合。该系统为在膜的背景下对细胞进入早期步骤进行结构表征提供了一个令人兴奋的机会。在此，我们报告了通过冷冻电子显微镜（cryo-EM）以32埃的分辨率解析的脊髓灰质炎病毒-受体-膜复合物的三维结构。我们开发了一些方法来客观地确定复合物的对称性。该重建结果表明，受体结合使病毒的五重轴靠近膜。二十面体病毒、受体（包括已知的糖基化位点）和膜双层的密度都清晰可辨。靠近病毒五重轴的双层膜的明显扰动可能在细胞进入的后续步骤中发挥作用。
