SOLUTION STRUCTURE OF CHLORELLA VIRUS DEOXYURIDINE TRIPHOSPHATE

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。这种酶显示了水平基因转移的典型例子，它模拟了癌症的发展阶段。dUTR活性的缺乏引发无胸腺嘧啶的细胞死亡。对该酶的机制和细胞作用的结构见解在调节无胸腺嘧啶细胞凋亡中至关重要。我们已经开始研究的分子机制，影响最佳温度的两个dUTPases的Escherella病毒，每个表现出不同的温度为最佳的催化活性，通过结合溶液结构推导出的溶液X-射线散射和晶体学研究。Moriyama小组最近解决了酶的晶体结构和最适温度与野生型酶不同的突变酶。我们最近进行了初步的解决方案X射线散射实验，并获得了35.5的野生型和39.1的突变体的回转半径。这些值大于晶体结构的预期值，可能是由于存在组氨酸标签以帮助纯化。然而，这些蛋白质的全局结构的实质性差异与我们的晶体学研究所提出的构象差异是一致的。我们正计划将溶液散射研究扩展到更高的结构分辨率，并研究溶液散射与温度依赖性酶活性的相关性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This enzyme shows a typical example of horizontal gene transfer, which mimics a developmental stage of cancers. The lack of dUTPase activity initiates thymine-less cell death. Structural insights on the mechanism and cellular role of the enzyme are crucial in modulating thymine-less apoptosis. We have begun studying the molecular mechanisms which influence optimum temperatures of two dUTPases from the chlorella virus, each exhibiting different temperature for optimum catalytic activity, by combining solution structure deduced by solution x-ray scattering and crystallographic studies. The Moriyama group has recently solved the crystal structure of the enzyme and a mutant enzyme whose optimum temperature differs from that of the wild type enzyme. We recently conducted preliminary solution x-ray scattering experiments and obtained radii of gyration 35.5 ¿¿for the wild type and 39.1¿¿for the mutant. These values are larger than what can be expected from the crystallographic structures possibly due to the presence of a histidine tag to aid purification. However, the substantial difference in global structures for these proteins is consistent with the conformational difference being suggested by our crystallographic studies. We are planning on extending the solution scattering study to higher structural resolution, and examine how solution scattering correlates with the temperature dependent enzyme activity.