Initiation of Geminivirus DNA Replication

9506038 Hanley-Bowdoin双生病毒是一个独特的真核脱氧核糖核酸病毒家族，具有单链基因组，通过滚环机制在受感染的植物细胞的细胞核中复制。它们的基因组很小，编码一种对它们的复制至关重要的蛋白质，并招募宿主的复制机器。这些特征使双生病毒成为研究真核DNA复制的极佳模型系统，这是一个在植物系统中尚未广泛研究的领域。对植物DNA复制及其整合到细胞分裂周期的研究将为所有生物体中这些过程的普遍机制提供有价值的见解，并可能揭示导致植物和动物根本不同的发育途径的重要差异。这项研究将研究导致双生病毒复制启动的事件，并将提供一个难得的机会来研究真核系统中滚环复制的机制。这也将从我们的长期研究目标的基础上，识别和了解宿主蛋白在双生病毒和植物核DNA复制中的功能。具有良好特性的双生病毒--番茄黄金花叶病毒(TGMV)将用于这些实验。TGMV复制起点已被定位到一个89bp的序列。TGMV编码两种蛋白质用于其复制，一种是绝对必需的(AL1)，另一种(AL3)影响病毒DNA的积累。本研究的目的是检测双生病毒最小复制起点的功能的序列和结构要求，鉴定双生病毒复制蛋白的功能，鉴定导致双生病毒复制启动的步骤。双生病毒是一个独特的真核DNA病毒家族，具有单链基因组，通过滚环机制在受感染的植物细胞的细胞核中复制。它们的基因组很小，编码一种对它们的复制至关重要的蛋白质，并招募宿主的复制机器。这些特征使双生病毒成为研究真核DNA复制的极佳模型系统，这是一个在植物系统中尚未广泛研究的领域。这项研究的目的是了解介导双生病毒复制的分子过程，并将这些事件与植物核DNA复制联系起来。对植物DNA复制及其整合到细胞分裂周期的研究将为所有生物体中这些过程的普遍机制提供有价值的见解，并可能揭示导致植物和动物根本不同的发育途径的重要差异。***

9506038 Hanley-Bowdoin Geminiviruses constitute a unique family of eucaryotic DNA viruses with single-stranded genomes that replicate through a rolling circle mechanism in the nuclei of infected plant cells. They have small genomes, encode one protein that is essential for their replicatoin, and recruit the replication machineryof their hosts. These features make geminiviruses excellent model systems for studying eucaryotic DNA replication, an area of study that has not been pursued extensively in plant systems. Study of plant DNA replication and its integration into the cell division cycle will provide valuable insight into the universal mechanisms that underlie these processes in all organisms and may reveal important differences that are responsible for the fundamentally different developmental pathways of plants and animals. This research will study the events that lead to initiation of geminivirus replication, and will provide a rare opportunity to examine the mechanism of rolling circle replication in a eucaryotic system. It will also from the foundation of our long term research goals to identify and understand the functions of host proteins in geminivirus and plant nuclear DNA replication. The well-characterized geminivirus, tomato golden mosaic virus (TGMV), will be used for these experiments. The TGMV replication origin has been mapped to an 89-bp sequence. TGMV encodes two proteins for its replication one (AL1) that is absolutely required and a second (AL3) that impacts viral DNA accumulation. The objectives of this research are to examine the sequence and structural requirements for function of a geminivirus minimal origin of replication, to characterize the functions of an essential geminivirus replication protein, to characterize the steps leading to initiation of geminivirus replication. %%% Geminiviruses constitute a unique family of eucaryotic DNA viruses with single-stranded genomes that replicate through a rolling circle mechanism in the nuclei of infected plant ce lls. They have small genomes, encode one protein that is essential for their replicatoin, and recruit the replication machineryof their hosts. These features make geminiviruses excellent model systems for studying eucaryotic DNA replication, an area of study that has not been pursued extensively in plant systems. The goal of this research is to understand the molecular processes that mediate geminivirus replication and to relate these events to plant nuclear DNA replication. Study of plant DNA replication and its integration into the cell division cycle will provide valuable insight into the universal mechanisms that underlie these processes in all organisms and may reveal important differences that are responsible for the fundamentally different developmental pathways of plants and animals. ***