Synaptotagmin SYTA forms ER-plasma membrane junctions that are recruited to plasmodesmata for plant virus movement.
Synaptotagmin SYTA forms ER-plasma membrane junctions that are recruited to plasmodesmata for plant virus movement.
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DOI：
10.1016/j.cub.2015.06.015
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发表时间：
2015-08-03
期刊：
影响因子：
--
通讯作者：
Lazarowitz SG
中科院分区：
文献类型：
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作者：
Levy A;Zheng JY;Lazarowitz SG
后生动物突触素是一种钙离子感受器，调节各种细胞类型的胞吐和内吞作用，特别是神经和神经内分泌细胞[1，2]。最近，结构上相关的延伸突触素被证明在人和酵母细胞中将皮质内质网拴在质膜上，以维持内质网的形态，并稳定细胞内脂质和钙信号的ER-PM接触部位[3，4]。拟南芥突触素SYTA调节内吞作用和植物病毒运动蛋白(MPS)改变胞间连丝以促进病毒细胞间运输的能力[5，6]。然而，MPS如何修饰胞间连丝，SYTA的细胞功能，以及这些如何帮助MP活性，以及形成植物细胞ER-PM接触部位所必需的蛋白质，仍然是未知的。我们使用拟南芥SYTA击倒株yta-1和烟草病毒运动蛋白MPTVCV[5，7]来解决这些问题。我们在此报告SYTA本地化到ER-PM联系人站点。在SYTA-1中，这些站点被耗尽，ER网络崩溃，在SYTA的营救下，两者都进行了改革。在Syta-1中，胞间连丝中MPTVV的积累也受到抑制，但分泌转运没有受到抑制。在感染过程中，MPTVCV将SYTA聚集到胞间连丝，SYTA和皮质ER随后被重塑，形成与胞间连丝相邻的病毒复制部位，MPTVCV和SYTA直接相互作用于ER膜内。在MPTVCV转运过程中，SYTA也在胞间连丝中积累。我们的发现表明，SYTA对形成ER-PM接触位点是必不可少的，并提示MPS与SYTA相互作用，招募这些部位来改变胞间连丝，以便病毒细胞到细胞之间的运动。
Metazoan synaptotagmins are Ca2+sensors that regulate exocytosis and endocytosis in various cell types, notably in nerve and neuroendocrine cells [1, 2]. Recently, the structurally related extended synaptotagmins were shown to tether the cortical ER to the plasma membrane in human and yeast cells to maintain ER morphology and stabilize ER-plasma membrane (ER-PM) contact sites for intracellular lipid and Ca2+signaling [3, 4]. TheArabidopsissynaptotagmin SYTA regulates endocytosis and the ability of plant virus movement proteins (MPs) to alter plasmodesmata to promote virus cell-to-cell transport [5, 6]. Yet how MPs modify plasmodesmata, the cellular functions of SYTA and how these aid MP activity, and the proteins essential to form plant cell ER-PM contact sites remain unknown. We addressed these questions using anArabidopsisSYTA knockdown linesyta-1and a Tobamovirus movement protein MPTVCV[5, 7]. We report here that SYTA localized to ER-PM contact sites. These sites were depleted and the ER network collapsed insyta-1, and both reformed upon rescue with SYTA. MPTVCVaccumulation in plasmodesmata, but not secretory trafficking, was also inhibited insyta-1. During infection, MPTVCVrecruited SYTA to plasmodesmata, and SYTA and the cortical ER were subsequently remodeled to form viral replication sites adjacent to plasmodesmata in which MPTVCVand SYTA directly interacted caged within ER membrane. SYTA also accumulated in plasmodesmata active in MPTVCVtransport. Our findings show that SYTA is essential to form ER-PM contact sites and suggest that MPs interact with SYTA to recruit these sites to alter plasmodesmata for virus cell-to-cell movement.