Regulation and antiviral mechanism of a plant ribosome inactivating protein

植物核糖体失活蛋白的调控及抗病毒机制

• 批准号: 249796-2012
• 负责人: Hudak, Katalin
• 金额: $ 2.91万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=547410
• 关键词: Regulation; antiviral; mechanism; plant; ribosome

Plants have evolved several strategies to evade pathogen attack and subsequent disease. One group of proteins generally thought to be involved in defense is the ribosome inactivating proteins. These are enzymes synthesized by many plants that remove a purine base from a conserved region of ribosomal RNA. Early studies showed how this depurination slowed the rate of protein translation, and resulting toxicity was cited to explain a role in defense; that is, localized host cell death would limit pathogen spread. However, little attention has been paid to their mechanisms of action in their native plants. Interestingly, one of these ribosome inactivating proteins was first discovered because of its antiviral, rather than toxic, properties. Namely, pokeweed antiviral protein (PAP), synthesized by the pokeweed plant Phytolacca americana, inhibits the replication of several plant and animal viruses. We were the first to demonstrate that this activity is due to in vivo depurination of the viral genomic RNA; therefore, the enzyme's substrate is not limited to ribosomal RNA. The objectives of our research program will build on this important finding, to determine the molecular mechanisms by which PAP is antiviral in its native pokeweed and when expressed in other, heterologous plants. Our short-term research objectives are two-fold: 1) to determine how PAP targets viral RNAs without causing host cell death. We will co-localize PAP and viral RNAs in cells and identify proteins that may mediate PAP activity. 2) In addition, we want to determine how PAP expression is regulated in pokeweed, to understand its role in its native system. We will investigate the transcriptional and post-transcriptional control of PAP expression by characterizing its promoter and the functions of a PAP-specific small RNA and pseudogene that we have recently identified. Together, results from these studies will provide useful information to improve strategies for crop tolerance to viruses, and will contribute to the long term goal of our research program to expand knowledge of the natural defense strategies of plants.

植物已经进化出多种策略来逃避病原体攻击和随后的疾病。 通常认为参与防御的一组蛋白质是核糖体失活蛋白质。 这些是许多植物合成的酶，可以从核糖体 RNA 的保守区域去除嘌呤碱基。 早期研究表明，这种脱嘌呤如何减慢蛋白质翻译的速度，并且由此产生的毒性被用来解释其防御作用。也就是说，局部宿主细胞死亡将限制病原体的传播。 然而，人们很少关注它们在本土植物中的作用机制。 有趣的是，其中一种核糖体失活蛋白首次被发现是因为其抗病毒特性，而不是毒性特性。 即，商陆抗病毒蛋白（PAP）由商陆植物美洲商陆合成，可抑制多种动植物病毒的复制。 我们是第一个证明这种活性是由于病毒基因组 RNA 体内脱嘌呤所致；因此，该酶的底物不限于核糖体RNA。 我们研究计划的目标将建立在这一重要发现的基础上，以确定 PAP 在其天然美洲商陆中以及在其他异源植物中表达时抗病毒的分子机制。 我们的短期研究目标有两个：1) 确定 PAP 如何在不导致宿主细胞死亡的情况下靶向病毒 RNA。 我们将在细胞中共定位 PAP 和病毒 RNA，并鉴定可能介导 PAP 活性的蛋白质。 2）此外，我们想要确定商陆中PAP表达是如何调节的，以了解其在其天然系统中的作用。 我们将通过表征其启动子以及我们最近鉴定的 PAP 特异性小 RNA 和假基因的功能来研究 PAP 表达的转录和转录后控制。 总之，这些研究的结果将为改善作物对病毒的耐受性策略提供有用的信息，并将有助于我们研究计划的长期目标，即扩大植物自然防御策略的知识。