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.
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