Chang Juan, Weigele Peter, King Jonathan, Chiu Wah, Jiang Wen
Graduate Program in Structural and Computational Biology and Molecular Biophysics, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
Structure. 2006 Jun;14(6):1073-82. doi: 10.1016/j.str.2006.05.007. Epub 2006 May 25.
The mechanisms by which most double-stranded DNA viruses package and release their genomic DNA are not fully understood. Single particle cryo-electron microscopy and asymmetric 3D reconstruction reveal the organization of the complete bacteriophage P22 virion, including the protein channel through which DNA is first packaged and later ejected. This channel is formed by a dodecamer of portal proteins and sealed by a tail hub consisting of two stacked barrels capped by a protein needle. Six trimeric tailspikes attached around this tail hub are kinked, suggesting a functional hinge that may be used to trigger DNA release. Inside the capsid, the portal's central channel is plugged by densities interpreted as pilot/injection proteins. A short rod-like density near these proteins may be the terminal segment of the dsDNA genome. The coaxially packed DNA genome is encapsidated by the icosahedral shell. This complete structure unifies various biochemical, genetic, and crystallographic data of its components from the past several decades.
大多数双链DNA病毒包装和释放其基因组DNA的机制尚未完全明了。单颗粒冷冻电子显微镜和非对称三维重建揭示了完整的噬菌体P22病毒体的结构，包括DNA最初被包装以及随后被排出所通过的蛋白质通道。该通道由一个由门蛋白组成的十二聚体形成，并由一个由两个堆叠桶状物组成的尾枢纽密封，尾枢纽顶部有一个蛋白质针。围绕这个尾枢纽附着的六个三聚体尾刺呈弯曲状，表明存在一个可能用于触发DNA释放的功能性铰链。在衣壳内部，门的中央通道被解释为先导/注射蛋白的密度所堵塞。这些蛋白附近的一个短棒状密度可能是双链DNA基因组的末端片段。同轴包装的DNA基因组被二十面体壳包裹。这一完整结构整合了过去几十年中其各个组分的各种生化、遗传和晶体学数据。
