Writers and Erasers of Ubiquitin Moieties in Control of Cell-to-Cell Transport in Plants

项目摘要 也许是大分子生物学中最有趣但研究最少的方面之一， 运输是通过细胞间连接的交通。这些连接称为隧道 哺乳动物中的纳米管和植物中的胞间连丝（Pd）。而哺乳动物和植物 病毒利用细胞到细胞的运输途径，第一个这样的能力被确定为 植物病毒的运动蛋白（MP），其通过Pd的运输代表了一种 大分子细胞间运输的概念范例。而主要的研究 包括我们实验室在内的这一领域的努力一直集中在MP细胞对细胞的机制上 运动，运动机制如何控制的重要问题仍然存在 基本上没有解决。拟议的研究计划旨在开始填补这一空白，在我们的 知识我实验室的研究集中在植物生物学的三个不同方面， 植物-病原体相互作用：（i）模型中运动蛋白（MP）的细胞-细胞转运 植物病毒TMV;（ii）遗传过程中蛋白质和核酸的细菌到植物细胞的转运 通过农杆菌转化;和（iii）基因表达的表观遗传调控，包括 病原体反应基因，通过组蛋白修饰。最近，这三个项目都融合了 泛素书写者（E3连接酶）和清除者（去泛素化酶）在植物中的调节作用 一般来说，在生命周期中，特别是在MP细胞到细胞的运输中。具体来说，我们的发现 表明泛素书写器和擦除器动态地控制MP细胞的两个主要方面- 到电池的运输过程：货物的稳定性/可用性和Pd的组装/拆卸 运输机械拟议的计划利用了丰富的分子工具， 这些实验方法是我们沿着多年来研究细胞间转运的方法 蛋白质泛素化/去泛素化在植物-病原体相互作用中的作用 为了解决一个新的（到目前为止，完全未经研究的）细胞间调节水平， 通过植物细胞的泛素书写器和擦除器的可逆作用通过Pd运输。我们 我认为，这一目标是创新的，也可能是变革性的运输研究， 其他蛋白质，病毒和植物，通过Pd。

PROJECT SUMMARY Perhaps one of the most intriguing, yet least studied, aspects of macromolecular transport is traffic through intercellular connections. These connections are termed tunneling nanotubes in mammals and plasmodesmata (Pd) in plants. Whereas both mammalian and plant viruses utilize cell-to-cell transport pathways, the first such capability was identified for movement proteins (MPs) of plant viruses, the transport of which via Pd represents a conceptual paradigm for intercellular traffic of macromolecules. Whereas the main research effort in the field, including our lab, has been focused on the mechanism of MP cell-to-cell movement, the important question of how the movement mechanism is controlled remained largely unaddressed. The proposed research program aims to begin filing this gap in our knowledge. Research in my laboratory focuses on three diverse aspects of plant biology and plant-pathogen interactions: (i) cell-to-cell transport of the movement protein (MP) of the model plant virus TMV; (ii) bacterium-to-plant cell transport of proteins and nucleic acids during genetic transformation by Agrobacterium; and (iii) epigenetic regulation of gene expression, including the pathogen response genes, by histone modifications. Recently, all three projects converged on the regulatory roles of ubiquitin writers (E3 ligases) and erasers (deubiquitinases) in the plant life cycle in general, and in the MP cell-to-cell transport in particular. Specifically, our findings suggest that ubiquitin writers and erasers dynamically control two major aspects of the MP cell- to-cell transport process: cargo stability/availability and assembly/disassembly of the Pd transport machinery. The proposed program leverages the wealth of molecular tools and experimental approaches that we have developed along the years to study cell-to-cell transport of plant viruses and roles of protein ubiquitylation/deubiquitylation in plant-pathogen interactions to address a new (and, so far, completely unresearched) level of regulation of intercellular transport through Pd by reversible action of ubiquitin writers and erasers of the plant cell. We believe that this goal is innovative and likely to be transformative also for studies of transport of other proteins, viral and plant, through Pd.