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

项目总结 也许是大分子中最耐人寻味但研究最少的方面之一 传输是通过蜂窝间连接的流量。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 病毒利用细胞间的运输途径，第一次发现这种能力是为了 植物病毒的运动蛋白(MPS)，其通过PD的运输代表一种 大分子细胞间交通的概念范例。鉴于主要研究 这一领域的努力，包括我们的实验室，一直集中在MP细胞到细胞的机制上 移动，如何控制移动机制这一重要问题仍然存在 很大程度上没有得到解决。拟议的研究计划旨在开始在我们的 知识。我实验室的研究集中在植物生物学和 植物-病原菌的相互作用：(I)模型中运动蛋白的细胞间运输 植物病毒TMV；(Ii)细菌与植物细胞之间的蛋白质和核酸运输 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，这三个项目都汇聚在一起。 泛素编写体(E3连接酶)和擦除器(脱泛素酶)在植物中的调节作用 一般的生命周期，特别是在MP细胞到细胞的运输中。具体地说，我们的发现 提示泛素编写器和擦除器动态控制MP细胞的两个主要方面- 到细胞的运输过程：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和 我们多年来发展起来的研究细胞间运输的实验方法 植物病毒及其蛋白泛素化/去泛素化在植物-病原物相互作用中的作用 为了解决一个新的(而且到目前为止完全没有研究过的)细胞间调节水平 通过植物细胞的泛素编写器和擦除器的可逆作用通过PD进行运输。我们 我相信这个目标是创新的，可能也会对运输研究产生革命性的影响 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.