Two plant-viral movement proteins traffic in the endocytic recycling pathway
Two plant-viral movement proteins traffic in the endocytic recycling pathway
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DOI：
10.1105/tpc.104.027821
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发表时间：
2005-01-01
期刊：
影响因子：
11.6
通讯作者：
Torrance, L
中科院分区：
文献类型：
--
作者：
Haupt, S;Cowan, GH;Torrance, L
许多植物病毒利用一组被称为三重基因块（TGB）的保守蛋白进行细胞间运动。在这里，我们研究了马铃薯马铃薯顶病毒（PMTV）的两个TGB蛋白（TGB2和TGB3）与分泌和内吞途径的组分在以n端融合表达到绿色荧光蛋白或单体红色荧光蛋白（mRFP）时的相互作用。我们的研究表明，荧光团标记的TGB2和TGB3显示出与内质网（ER）的早期关联，并在利用内质网肌动蛋白网络进行细胞内运动的运动颗粒中共定位。两种蛋白均增加了胞间连丝的大小排斥极限，TGB3在缺乏TGB2的情况下积聚在胞间连丝上。TGB3含有一个假定的基于tyrs的分类基序，其突变消除了内质网定位和胞间连丝靶向。在表达周期的后期，两种融合蛋白都被整合到囊泡结构中。TGB2本身与这些结构相关，但在没有TGB2的情况下，TGB3不能被纳入囊泡。此外，除了定位于内质网和运动颗粒外，mRFP-TGB3在pmtv感染的表皮细胞中表达时被纳入囊泡，这表明病毒表达的TGB2参与了招募。用FM4-64标记含TGB融合蛋白的囊泡，FM4-64是质膜内化的标记物和内吞途径的组成部分。TGB2也与Ara7（一种标记早期核内体的Rab5同源物）共定位于囊泡中。蛋白相互作用分析显示，重组TGB2与烟草j结构域伴侣蛋白RME-8家族的一个高度保守的蛋白相互作用，该蛋白被证明对线虫和黑腹果蝇的内吞运输至关重要。总的来说，这些数据表明内吞途径参与了病毒的细胞内运动，并讨论了其含义。
Many plant viruses exploit a conserved group of proteins known as the triple gene block (TGB) for cell-to-cell movement. Here, we investigated the interaction of two TGB proteins (TGB2 and TGB3) of Potato mop-top virus (PMTV), with components of the secretory and endocytic pathways when expressed as N-terminal fusions to green fluorescent protein or monomeric red fluorescent protein (mRFP). Our studies revealed that fluorophore-labeled TGB2 and TGB3 showed an early association with the endoplasmic reticulum (ER) and colocalized in motile granules that used the ER-actin network for intracellular movement. Both proteins increased the size exclusion limit of plasmodesmata, and TGB3 accumulated at plasmodesmata in the absence of TGB2. TGB3 contains a putative Tyr-based sorting motif, mutations in which abolished ER localization and plasmodesmatal targeting. Later in the expression cycle, both fusion proteins were incorporated into vesicular structures. TGB2 associated with these structures on its own, but TGB3 could not be incorporated into the vesicles in the absence of TGB2. Moreover, in addition to localization to the ER and motile granules, mRFP-TGB3 was incorporated into vesicles when expressed in PMTV-infected epidermal cells, indicating recruitment by virus-expressed TGB2. The TGB fusion protein-containing vesicles were labeled with FM4-64, a marker for plasma membrane internalization and components of the endocytic pathway. TGB2 also colocalized in vesicles with Ara7, a Rab5 ortholog that marks the early endosome. Protein interaction analysis revealed that recombinant TGB2 interacted with a tobacco protein belonging to the highly conserved RME-8 family of J-domain chaperones, shown to be essential for endocytic trafficking in Caenorhabditis elegans and Drosophila melanogaster. Collectively, the data indicate the involvement of the endocytic pathway in viral intracellular movement, the implications of which are discussed.