LOW RESOLUTION VIRUS CRYSTALLOGRAPHY SOLUTION TO PHASE PROBLEM

核酸的选择、包装和递送是重要的 病毒生命周期的各个阶段。 同样的原则 在基因治疗中，通过将外源基因输送到 靶细胞 病毒中核酸的组织有助于 了解它们在病毒组装、稳定性以及 在细胞进入阶段释放核酸。 但 病毒衣壳中的包装核酸在高 与衣壳蛋白亚基不同的是， 核酸不严格符合二十面体对称。 衣壳蛋白的相互作用区域也是如此 与RNA紧密结合。 所谓的“无序区”在高 分辨率，但是，可以在低分辨率（1000-10 E）下检测到， 广泛的密度信封，大约定义的位置， 多肽。 低分辨率衍射数据集， 收集，在SSRL BL 4-2，在真正的羊群之家的晶体 包装病毒RNA和杆状病毒表达的病毒（aFHV）颗粒 包装异源的（合成）鸡群病毒（sFHV）颗粒 RNA。 计算的aFHV和sFHV的电子密度图， 300-14 E分辨率显示了包装核酸的分布 acids. 尽管aFHV和sFHV中的总体RNA分布是相同的， 类似地，由于强加的二十面体对称性， 组织结构的差异：aFHV中的病毒RNA似乎是 结构更紧密，与蛋白质衣壳（RNA）密切相互作用。

Selection, packaging and delivery of nucleic acids are important steps in the virus life cycle. The same principles are being exploited in gene therapy by delivering the foreign genes to the target cells. Organization of nucleic acids in viruses helps to understand their role in virus assembly, stability and perhaps the release of the nucleic acid during the cell entry stage. However, the packaged nucleic acids in the viral capsids can not be seen at high resolution unlike the capsid protein subunits, because the packaged nucleic acid does not strictly conform to the icosahedral symmetry. The same is true with the regions of the capsid protein that interact closely with the RNA. The so called "disordered regions" at high resolution, however, can be detected at low resolution (1000-10 E) as broad envelopes of density that define approximately the location of the polypeptides. Low resolution diffraction data sets were collected, at SSRL BL 4-2, on the crystals of authentic Flock House Virus (aFHV) particles packaging viral RNAs and baculo expressed (synthetic) Flock House Virus (sFHV) particles packaging heterologous RNAs. The electron density maps of aFHV and sFHV calculated between 300-14 E resolution revealed the distribution of the packaged nucleic acids. Although the overall RNA distribution in aFHV and sFHV are similar due to imposed icosahedral symmetry, there are clear differences in their organization: viral RNA in aFHV appeared to be more structured and interacts closely with the protein capsid; RNA.