Genome packaging in DNA viruses

描述（由申请方提供）：基因组包装是大双链DNA（dsDNA）病毒（包括加尾双链DNA噬菌体和疱疹病毒）形态发生的关键步骤，并且对于感染性子代病毒体的组装至关重要。基因组包装是一种精确协调的分子协同作用，其中来自DNA多联体的一定量的病毒DNA插入到预先形成的原衣壳中，然后将另外的病毒蛋白结合到衣壳以保留包装的DNA。这个DNA插入过程是由一个强大的分子机器完成的，该机器由末端酶和门户组成。入口在衣壳的单个顶点处形成管道，允许病毒DNA在病毒组装期间进入并在感染期间离开。末端酶复合物包含特异性结合病毒DNA的DNA识别亚基和为包装反应提供能量并从多联体切割基因组长度DNA的催化亚基。由于异常的复杂性和缺乏高分辨率的结构数据，这些大型病毒基因组包装的分子机制还没有得到很好的理解。特别是，这些基因组包装蛋白必须形成高阶分子组装才能发挥作用。门户蛋白形成包埋在衣壳中的环状十二聚体。然而，人们对末端酶如何组装、它如何与门户组装以及门户如何嵌入衣壳知之甚少。我们的目标是了解DNA病毒基因组包装的分子机制，通过分析组装的基因组包装蛋白质使用结构的方法。我们特别感兴趣的一般性问题是，大量的蛋白质和其他生物分子，每一个都以多个拷贝存在，如何分层组装成一个复杂的系统，以完成一个复杂的生物过程。在本提案中，我们试图：（i）阐明一个完整的，感染性的细菌病毒的高分辨率结构;（ii）阐明的终止酶的组成蛋白的结构;（iii）阐明的模式的DNA结合的终止酶的DNA识别蛋白;和（iv）探讨在体外组装的终止酶复合物。疱疹病毒是重要的人类病原体，其引起从水痘到各种形式的癌症的疾病。该提案预计将通过确定新的抗病毒靶点来控制和预防疱疹病毒引起的感染和疾病，从而为公共卫生做出贡献。 公共卫生相关性：人类疱疹病毒与从水痘到危及生命的癌症等重要人类疾病有关。大多数人类群体中的大多数个体被几种疱疹病毒感染。我们试图研究疱疹病毒和许多其他大的双链DNA病毒的生命周期中的共同分子机制，以寻找控制和预防这些病毒病原体引起的感染和疾病的新措施。

DESCRIPTION (provided by applicant): Genome packaging is a key step in morphogenesis of large double-stranded DNA (dsDNA) viruses including tailed double-stranded DNA bacteriophages and herpesviruses, and is essential for assembly of infectious progeny virions. Genome packaging is a precisely coordinated molecular synergy, in which a certain amount of viral DNA from a DNA concatemer is inserted into a preformed procapsid, followed by binding of additional viral proteins to the capsid to retain the packaged DNA. This DNA insertion process is fulfilled by a powerful molecular machine consisting of the terminase and the portal. The portal forms a conduit at a single vertex of the capsid that allows viral DNA to enter during virus assembly and exit during infection. The terminase complex contains a DNA-recognition subunit that specifically binds to the viral DNA, and a catalytic subunit that provides the energy for the packaging reaction and cleaves the genome-length DNA from the concatemer. Molecular mechanisms of genome packaging in these large viruses are not well understood, owing to unusual complexity and lack of high resolution structural data. In particular, these genome-packaging proteins have to form high-order molecular assemblies in order to function. The portal protein forms a ring-like dodecamer embedded in the capsid. However, little is known about how the terminase assembles, how it assembles with the portal, and how the portal is embedded in the capsid. Our goal is to understand molecular mechanisms of genome packaging in DNA viruses by analyzing assemblies of genome-packaging proteins using structural approaches. We are particularly interested in the general question of how numerous proteins and other biological molecules, each present in multiple copies, assemble hierarchically into a sophisticated system to fulfill a complex biological process. In the present proposal, we seek to: (i) elucidate the high resolution structure of a complete, infectious bacterial virus; (ii) elucidate structures of component proteins of the terminase; (iii) elucidate the mode of DNA-binding for a terminase DNA-recognition protein; and (iv) explore the assembly of the terminase complex in vitro. Herpes viruses are important human pathogens that cause diseases ranging from chickenpox to various forms of cancer. This proposal is anticipated to contribute to public health by identification of novel targets of antiviral to control and prevent infection and diseases caused by herpes viruses. PUBLIC HEALTH RELEVANCE: Human herpes viruses are linked to important human diseases ranging from chickenpox to life-threatening cancer. The majority of individuals in most human populations are infected by several herpes viruses. We seek to investigate a common molecular mechanism in life cycles of herpes virus and many other large double- stranded DNA viruses, in search of new measures to control and prevent infection and diseases caused by these viral pathogens.