The Plasmodesmal Localization Signal of TMV MP Is Recognized by Plant Synaptotagmin SYTA.
The Plasmodesmal Localization Signal of TMV MP Is Recognized by Plant Synaptotagmin SYTA.
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DOI：
10.1128/mbio.01314-18
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发表时间：
2018-07-10
期刊：
影响因子：
6.4
通讯作者：
Citovsky V
中科院分区：
文献类型：
--
作者：
Yuan C;Lazarowitz SG;Citovsky V
植物病毒通过称为胞间连丝的细胞间通道穿过植物细胞壁的屏障侵入其宿主。它们通过编码运动蛋白（MP）来实现这一点，运动蛋白的作用是改变胞间连丝门控。MP如何靶向胞间连丝还不清楚。我们最近鉴定的第一个胞间连丝定位信号（PLS）中确定的病毒MP，即烟草花叶病毒（TMV）编码的MP，现在提供了机会，以确定宿主蛋白，识别这种PLS，并可能是重要的胞间连丝靶向。一种这样的候选蛋白是拟南芥突触结合蛋白A（SYTA），其是形成内质网（ER）-质膜接触位点所需的，并调节MP介导的菜豆花叶病毒、菜豆花叶病毒和马铃薯Y病毒的运输。特别地，SYTA与TMV MP和由烟草花叶病毒芜菁脉透明病毒（TVCV）编码的MP相互作用，并调节TMV MP和由烟草花叶病毒芜菁脉透明病毒（TVCV）编码的MP两者的细胞到细胞转运。利用植物双分子荧光互补（BiFC）和酵母双杂交试验，我们在这里表明，TMV PLS与SYTA相互作用。该PLS序列对于与SYTA的相互作用是必要的和充分的，并且在拟南芥SYTA敲除系中TMV PLS的胞间连丝靶向活性显著降低。我们的研究结果表明，SYTA是一个主机因子，可以识别TMV PLS，并建议这种相互作用可能会稳定与胞间连丝的关联TMV MP。植物病毒利用其运动蛋白（MP）通过宿主细胞间连接（胞间连丝）移动。也许最有趣的，但研究最少，这种运输的方面是MP信号序列和它们的宿主识别因子。最近，我们描述了烟草花叶病毒（TMV）MP的胞间连丝定位信号（PLS）。在这里，我们确定了拟南芥synaptotagmin A（SYTA）作为一个主机的因素，承认TMV MP PLS和促进其协会与胞间连丝膜。这些发现的意义是双重的：（i）我们鉴定了TMV MP在胞间连丝处与细胞膜的缔合作为胞间连丝靶向中的重要PLS依赖性步骤，以及（ii）我们鉴定了特异性识别PLS的植物SYTA蛋白作为参与该步骤的宿主因子。
Plant viruses cross the barrier of the plant cell wall by moving through intercellular channels, termed plasmodesmata, to invade their hosts. They accomplish this by encoding movement proteins (MPs), which act to alter plasmodesmal gating. How MPs target to plasmodesmata is not well understood. Our recent characterization of the first plasmodesmal localization signal (PLS) identified in a viral MP, namely, the MP encoded by the Tobamovirus Tobacco mosaic virus (TMV), now provides the opportunity to identify host proteins that recognize this PLS and may be important for its plasmodesmal targeting. One such candidate protein is Arabidopsis synaptotagmin A (SYTA), which is required to form endoplasmic reticulum (ER)-plasma membrane contact sites and regulates the MP-mediated trafficking of begomoviruses, tobamoviruses, and potyviruses. In particular, SYTA interacts with, and regulates the cell-to-cell transport of, both TMV MP and the MP encoded by the Tobamovirus Turnip vein clearing virus (TVCV). Using in planta bimolecular fluorescence complementation (BiFC) and yeast two-hybrid assays, we show here that the TMV PLS interacted with SYTA. This PLS sequence was both necessary and sufficient for interaction with SYTA, and the plasmodesmal targeting activity of the TMV PLS was substantially reduced in an Arabidopsis syta knockdown line. Our findings show that SYTA is one host factor that can recognize the TMV PLS and suggest that this interaction may stabilize the association of TMV MP with plasmodesmata. Plant viruses use their movement proteins (MPs) to move through host intercellular connections, plasmodesmata. Perhaps one of the most intriguing, yet least studied, aspects of this transport is the MP signal sequences and their host recognition factors. Recently, we have described the plasmodesmal localization signal (PLS) of the Tobacco mosaic virus (TMV) MP. Here, we identified the Arabidopsis synaptotagmin A (SYTA) as a host factor that recognizes TMV MP PLS and promotes its association with the plasmodesmal membrane. The significance of these findings is two-fold: (i) we identified the TMV MP association with the cell membrane at plasmodesmata as an important PLS-dependent step in plasmodesmal targeting, and (ii) we identified the plant SYTA protein that specifically recognizes PLS as a host factor involved in this step.