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The regulation of PCNA expression during plant development and geminivirus infection.

机译:植物发育和双生病毒感染过程中PCNA表达的调节。

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摘要

Many aspects of cell cycle control are conserved between animals and plants. Components of the pRb-E2F pathway have been found in a number of plant species. Like the mammalian DNA tumor viruses, the plant geminivirus tomato golden mosaic virus (TGMV) must recreate a replication competent environment to amplify its genome. TGMV does this in part by disrupting the pRb/E2F pathway. TGMV must make extensive use of the host replication machinery for its replication because of its limited coding capacity. TGMV induces accumulation of the DNA polymerase processivity factor proliferating cell nuclear antigen (PCNA) in mature plant tissues that do not normally produce it. The purpose of this project was to examine the mechanism of PCNA induction by TGMV. The PCNA gene from Nicotiana benthamiana was isolated and its expression was examined. TGMV induction was at the level of transcription, with viral infection resulting in a secondary peak of PCNA expression in mature leaves, which correlates with symptom severity and viral DNA levels. The PCNA promoter contains two E2F consensus binding sites that bind to proteins in N. benthamiana nuclear extracts. The roles and interaction of two E2F sites were examined in transgenic plants. In mature leaves, mutation of either site or both sites simultaneously resulted in relief of repression. In young tissues, mutation of the distal E2F site decreased expression, while mutation of the proximal site or both sites together had no effect. Mutation of the E2F sites prevented any detectable effect of TGMV infection. These results demonstrated that both E2F elements contribute to repression of the PCNA promoter in mature leaves whereas the distal E2F site acts as an antirepressor in young leaves to counter the repression activity of the proximal element. The role of E2F in regulation at all stages of plant development is supported by immunohistochemical staining that located both E2F and DP, a protein that associates with E2F to promote efficient DNA binding, in young and mature plant tissues.
机译:细胞周期控制的许多方面在动植物之间是保守的。已经在许多植物物种中发现了pRb-E2F途径的成分。像哺乳动物的DNA肿瘤病毒一样,植物双生病毒番茄金色花叶病毒 TGMV )必须重建能够复制的环境,以扩增其基因组。 TGMV 部分是通过破坏pRb / E2F途径来实现的。 TGMV 由于其复制能力有限,必须广泛使用宿主复制机制进行复制。 TGMV 诱导DNA聚合酶持续性因子增殖细胞核抗原(PCNA)在通常不产生这种作用的成熟植物组织中积累。该项目的目的是研究 TGMV 诱导PCNA的机制。分离了来自的PCNA基因,并检测了其表达。 TGMV 诱导处于转录水平,病毒感染导致成熟叶片中PCNA表达的第二个高峰,这与症状严重程度和病毒DNA水平相关。 PCNA启动子包含两个E2F共有结合位点,可结合的蛋白质。 benthamiana 核提取物。在转基因植物中检查了两个E2F位点的作用和相互作用。在成熟叶片中,任一位点或两个位点的突变同时导致抑制的减轻。在年轻组织中,远端E2F位点的突变降低了表达,而近端位点或两个位点的突变却没有影响。 E2F位点的突变阻止了 TGMV 感染的任何可检测的作用。这些结果表明,两种E2F元件都有助于成熟叶片中PCNA启动子的阻遏,而远端E2F位点在幼叶中充当抗阻抑剂,以抵消近端元件的阻抑活性。 E2F在植物发育各个阶段的调控中的作用得到了免疫组织化学染色的支持,该染色同时定位了E2F和DP(一种与E2F结合以促进有效DNA结合的蛋白质)在年轻和成熟的植物组织中。

著录项

  • 作者

    Egelkrout, Erin Michelle.;

  • 作者单位

    North Carolina State University.;

  • 授予单位 North Carolina State University.;
  • 学科 Chemistry Biochemistry.; Agriculture Plant Pathology.
  • 学位 Ph.D.
  • 年度 2002
  • 页码 174 p.
  • 总页数 174
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物化学;植物病理学;
  • 关键词

  • 入库时间 2022-08-17 11:46:02

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