A Geminivirus DNA Replication Protein - Programming Its Plant Host

双生病毒 DNA 复制蛋白 - 对其植物宿主进行编程

• 批准号: 9809953
• 负责人: Linda Hanley-Bowdoin
• 金额: $ 33万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-15 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9809953&HistoricalAwards=false
• 关键词: Geminivirus; DNA; Replication; Protein; Programming

9809953 Hanley-Bowdoin Geminiviruses are a family of eukaryotic DNA viruses with single-stranded genomes that replicate through a rolling circle mechanism in nuclei of infected plant cells. They have small genomes, encode one protein that is essential for their replication, and rely on the replication machinery of their hosts. The overall goal of this research is to determine the mechanisms whereby geminiviruses recruit host DNA replication machinery. The investigator showed that geminivirus infection induces the accumulation of the host DNA synthesis protein, proliferating cell nuclear antigen (PCNA), in terminally differentiated plant cells. PCNA RNA levels and promoter activity are also elevated in infected tissue, demonstrating that geminiviruses can activate transcription of genes encoding DNA synthesis proteins in quiescent plant cells. The essential viral replication protein, AL1, is sufficient to induce the accumulation of PCNA in differentiated cells of transgenic plants, and thus may be analogous to the tumor antigen proteins of mammalian DNA viruses. In animal systems, DNA tumor viruses induce replication machinery in their host through a combination of common mechanisms. They encode proteins that directly activate transcription of genes encoding DNA synthesis proteins and/or interact with cell cycle regulatory factors to render quiescent cells competent for DNA replication. The investigator will determine whether AL1 uses similar or different mechanisms to induce PCNA transcription in differentiated plant cells by 1) determining whether interaction between AL1 and the cell cycle regulatory factor, retinoblastoma protein, is required for PCNA transcription, 2) asking whether multiple domains of AL1 contribute to PCNA transcriptional activation, and 3) identifying other plant proteins that interact with AL1 for PCNA induction. Geminiviruses are excellent model systems for studying eukaryotic DNA replication and cell cycle regulation, areas of study that have not been pursued extensively in plant systems. The ultimate g oals of the project are to elucidate the pathway whereby geminiviruses modify and maintain their host plants in an optimal state for viral DNA replication and to relate this pathway to plant cell cycle and transcriptional regulatory processes. The research will identify and begin to characterize components of the geminivirus/host regulatory network. The long term objectives are to understand how each component functions during geminivirus infection and in normal cellular processes. These experiments, which are based entirely on plant virus and host components, afford a rare opportunity to study plant cell cycle regulation directly. They will also increase our understanding of the basic mechanisms whereby eukaryotic viruses modify cellular processes and may illustrate fundamental similarities and/or differences between plants and animals.

9809953 Hanley-Bowdoin 双生病毒是一个真核 DNA 病毒家族，具有单链基因组，通过滚环机制在受感染植物细胞的细胞核中复制。 它们的基因组很小，编码一种对其复制至关重要的蛋白质，并依赖于宿主的复制机制。 这项研究的总体目标是确定双生病毒招募宿主 DNA 复制机制的机制。 研究人员表明，双生病毒感染会诱导宿主 DNA 合成蛋白、增殖细胞核抗原 (PCNA) 在终末分化的植物细胞中积累。 感染组织中 PCNA RNA 水平和启动子活性也升高，表明双生病毒可以激活静止植物细胞中编码 DNA 合成蛋白的基因转录。 病毒复制所必需的蛋白AL1足以诱导转基因植物分化细胞中PCNA的积累，因此可能类似于哺乳动物DNA病毒的肿瘤抗原蛋白。 在动物系统中，DNA 肿瘤病毒通过常见机制的组合在宿主体内诱导复制机制。 它们编码的蛋白质可直接激活编码 DNA 合成蛋白的基因转录和/或与细胞周期调节因子相互作用，使静止细胞能够进行 DNA 复制。 研究人员将通过以下方式确定 AL1 是否使用相似或不同的机制在分化的植物细胞中诱导 PCNA 转录：1) 确定 PCNA 转录是否需要 AL1 和细胞周期调节因子视网膜母细胞瘤蛋白之间的相互作用；2) 询问 AL1 的多个结构域是否有助于 PCNA 转录激活；3) 识别与 AL1 相互作用以诱导 PCNA 的其他植物蛋白。 双生病毒是研究真核 DNA 复制和细胞周期调控的优秀模型系统，这些研究领域在植物系统中尚未得到广泛研究。 该项目的最终目标是阐明双生病毒修改宿主植物并将其维持在病毒 DNA 复制的最佳状态的途径，并将该途径与植物细胞周期和转录调控过程联系起来。 该研究将识别并开始表征双生病毒/宿主调控网络的组成部分。 长期目标是了解每个成分在双生病毒感染期间和正常细胞过程中如何发挥作用。 这些完全基于植物病毒和宿主成分的实验为直接研究植物细胞周期调控提供了难得的机会。 它们还将增加我们对真核病毒改变细胞过程的基本机制的理解，并可能说明植物和动物之间的基本相似性和/或差异。