Multisubunit viral ATPases that couple ATP-hydrolysis to genome translocation

描述（由申请人提供）：病毒基因组的包装是生物学中的基本过程。在许多DNA病毒中，这种反应是由一个大的（M.W. ~1.5MDa）基因组包装马达，由末端酶全酶组装成十二聚体门蛋白。这种大分子复合物的功能就像一个化学马达，它水解ATP，以每秒2000个碱基的速度在预先形成的衣壳内转移病毒基因组的拷贝。除了是自然界中最快和最强大的引擎之外，基因组包装马达也是一种有趣的分子机器，其结构和催化机制都很差。在这项资助中，我们将结合使用晶体学和生物化学技术来表征噬菌体P22基因组包装马达的结构。在我实验室最近确定的P22门蛋白结构的基础上，我们的工作将集中在P22末端酶的化学上，P22末端酶是马达中的功能性ATP酶。与门户蛋白复合的P22末端酶的结构表征将提供一个结构框架来解释在包装马达内，末端酶如何将ATP水解与病毒基因组的易位偶联。此外，由于终止酶在疱疹病毒中高度保守，因此该资助中提出的工作也将提供一个逻辑框架，以开始对致病性人类病毒中的包装马达进行结构表征。我们工作的具体目标是：（1）。以确定在门蛋白顶点处组装的P22末端酶全酶的结构; 2.）以确定在基因组包装过程中小末端酶亚基如何刺激大末端酶ATP酶活性。

DESCRIPTION (provided by applicant): Packaging of viral genomes is a fundamental process in biology. In many DNA viruses this reaction is powered by a large (M.W. ~1.5MDa) genome-packaging motor, which is formed by a terminase holoenzyme assembled to a dodecameric portal protein. This macromolecular complex functions like a chemical motor, which hydrolyzes ATP to translocate a copy of the viral genome inside a preformed capsid, at rates as high as 2000 bases per second. In addition to being the fastest and most powerful engine in nature, the genome-packaging motor is also an intriguing molecular machine, which is poorly characterized both in structure and catalytic mechanisms. In this grant, we will use a combination of crystallographic and biochemical techniques to characterize the structure of the bacteriophage P22 genome-packaging motor. Building upon the structure of P22 portal protein, which was recently determined in my laboratory, our work will focus on the chemistry of P22 terminase that is a functional ATPase in the motor. The structural characterization of P22 terminase in complex with portal protein will provide a structural framework to decipher how, within the packaging motor, terminase couples ATP hydrolysis to translocation of viral genomes. In addition, since terminases are highly conserved in herpesviruses, the work proposed in this grant will also provide a logical framework to begin structural characterization of packaging motors in pathogenic human viruses. Specific aims of our work are: 1.) to determine the structure of the P22 terminase holoenzyme assembled at the portal protein vertex; 2.) to define how small terminase subunit stimulates large terminase ATPase activity during genome-packaging.