Cellular and Molecular Studies of Tobamovirus Movement Proteins

大多数植物病毒，包括烟草花叶病毒（TMV），利用胞间连丝（近端细胞之间的细胞质桥梁）向邻近细胞传播。大多数植物病毒编码一种或两种蛋白质，这些蛋白质是病毒通过胞间连丝运动所必需的。这些蛋白质被称为运动蛋白（MP）。后者显然是通过改变胞间连丝的大小排除界限而起作用的。PI构建了MP的突变体，将MP与Aequorea victoria的绿色荧光蛋白（GFP）融合，以研究MP的细胞分布和作用方式。本提案的总体目标是：确定原生质体和叶片感染过程中GFP-MP细胞分布的时间过程；在MP中产生突变，导致GFP-MP在特定细胞结构中积累，而不是在其他细胞结构中积累；分离含有GFP-MP的细胞结构，确定与GFP-MP相关的细胞成分；以及包括细胞中GFP-MP的详细分析的研究。这些研究将大大增加我们对TMV在细胞内和细胞间分布的认识，以及我们对细胞骨架在胞间连丝蛋白靶向和运输中的作用的认识。大多数植物病毒已经进化出利用宿主细胞中的成分进行病毒基因组复制、翻译病毒蛋白、分类和包装病毒成分、输出和传播到近端细胞的能力。对于后一个过程，大多数病毒编码的蛋白质可以改变胞间连丝的大小排除限制。这些蛋白质被称为运动蛋白（MP）。目前对MP的分子机制知之甚少。提出的研究将探讨烟草花叶病毒（TMV） MP的细胞定位和作用方式。这些研究将大大增加我们对TMV细胞分布的认识，以及细胞骨架在t靶向中的作用，并可能在MP到胞间连丝的运输中发挥作用。* * *

96-31124 Beachy Most plant viruses, including tobacco mosaic virus (TMV), use plasmodesmata, the cytoplasmic bridges between proximal cells, to spread to adjacent cells. Most plant viruses encode one or two proteins that are required for virus movement through the plasmodesmata. These proteins are termed movement proteins (MP). The latter apparently functions by modifying the size exclusion limits of plasmodesmata. The PI has constructed mutants of MP in which the latter is fused to the green fluorescent protein (GFP) of Aequorea victoria to study cellular distribution and mode of action of the MP. The general goals of this proposal are: to determine the time course of GFP-MP cellular distribution during the course of infection in protoplasts and in leaves; to create mutations in the MP that leads to accumulation of GFP-MP in specific cellular structures, but not in other; to isolate cellular structures that contain GFP-MP, to determine what cellular components are associated with GFP-MP; as well as studies that include detailed analyses of GFP-MP in cells. These studies will add significantly to our knowledge about the intra- and inter-cellular distribution of TMV, as well as our knowledge of the role of the cytoskeleton in the targeting and transport of proteins in plasmodesmata. %%% Most plant viruses have evolved the capacity to use components in host cells for viral genome replication, for translation of viral proteins, for sorting and packaging of viral components, for export, and for spreading to proximal cells. For the latter process, most viruses encode proteins that modify the size exclusion limit of plasmodesmata. These proteins are termed movement proteins (MP). Little is known about the molecular mechanism of the MP. The proposed studies will investigate the cellular localization and mode of action of the tobacco mosaic virus (TMV) MP. These studies will increase significantly our knowledge about the cellular distribution of TMV as well as the role of the cytoskeleton in the t argeting and, possibly, in the transport of MP to plasmodesmata. ***