Cryo-Electron Microscopy and Image Analysis of Cauliflower Mosiac Virus

利用最新发展的低温电子显微镜和图像分析技术研究花椰菜花叶病毒(CaMV)的天然三维结构。CaMV是研究最广泛的植物病毒之一，部分原因是它是第一个发现双链DNA基因组的植物病毒。然而，人们对DNA和蛋白质成分的组织和组装细节知之甚少。由此产生的结构模型将提供关于衣壳中蛋白质亚单位的对称性和堆积排列的新见解，并可能揭示关于结构内蛋白质-DNA相互作用的新细节。CaMV是杆状病毒家族的典型成员，该家族是已知的唯一一组包裹双链DNA基因组的植物病毒。在真核生物的小DNA病毒中，CaulimoVirus的独特之处在于它组装在细胞质中，而不是宿主细胞的细胞核中。它们可以作为研究植物基因组织、表达和复制的模型系统，也可以作为基因载体用于高等植物的遗传操作。此外，CaMV与某些动物病毒有惊人的相似之处。例如，CaMV和逆转录病毒都通过逆转录进行复制，这是植物细胞中第一个这种现象的例子。为了充分了解CaMV的功能，对其结构的详细了解是必不可少的。

The native three-dimensional structure of cauliflower mosaic virus (CaMV) will be studied using recently developed cryo-electron microscopy and image analysis techniques. CaMV is one of the most extensively studied plant viruses, in part, because it was the first plant virus in which a double-stranded DNA genome was discovered. However, little is known about the details of the organization and assembly of the DNA and protein components. The resulting structural model will provide new insights about the symmetry and packing arrangement of the protein subunits in the capsid and may reveal new details concerning protein-DNA interactions within the structure. CaMV is the type member of the caulimovirus family, the only group of plant viruses known to encapsidate a genome of double-stranded DNA. Caulimoviruses are unique among small DNA viruses of eukaryotes in being assembled in the cytoplasm rather than the nucleus of their host cells. They serve as a suitable model system for studying plant gene organization, expression and replication and they also are potentially useful as gene vectors for the genetic manipulation of higher plants. In addition, there are striking similarities between CaMV and certain animal viruses. For example, CaMV and the retroviruses both replicate by reverse transcription and this represents the first such example of this phenomenon in plant cells. To fully understand how CaMV functions, detailed knowledge of its structure is essential.