Instituto Biologia Molecular y Celular de Plantas, Universidad Politécnica, Universidad Politécnica de Valencia-CSIC, Avenida de los Naranjos s/n, 46022 Valencia, Spain.
Mol Plant Microbe Interact. 2010 Mar;23(3):263-72. doi: 10.1094/MPMI-23-3-0263.
Plant viruses hijack endogenous host transport machinery to aid their intracellular spread. Here, we study the localization of the p7B, the membrane-associated viral movement protein (MP) of the Melon necrotic spot virus (MNSV), and also the potential involvement of the secretory pathway on the p7B targeting and intra- and intercellular virus movements. p7B fused to fluorescent proteins was located throughout the endoplasmic reticulum (ER) at motile Golgi apparatus (GA) stacks that actively tracked the actin microfilaments, and at the plasmodesmata (PD). Hence, the secretory pathway inhibitor, Brefeldin A (BFA), and the overexpression of the GTPase-defective mutant of Sar1p, Sar1[H74L], fully retained the p7B within the ER, revealing that the protein is delivered to PD in a BFA-sensitive and COPII-dependent manner. Disruption of the actin cytoskeleton with latrunculin B led to the accumulation of p7B in the ER, which strongly suggests that p7B is also targeted to the cell periphery in an actin-dependent manner. Remarkably, the local spread of the viral infection was significantly restricted either with the presence of BFA or under the overexpression of Sar1[H74L], thus revealing the involvement of an active secretory pathway in the intracellular movement of MNSV. Overall, these findings support a novel route for the intracellular transport of a plant virus led by the GA.
植物病毒劫持内源性宿主运输机制来辅助其在细胞内的扩散。在这里，我们研究了 Melon necrotic spot virus (MNSV) 的膜相关运动蛋白 (MP) p7B 的定位，以及分泌途径在 p7B 靶向和细胞内及细胞间病毒运动中的潜在参与。融合到荧光蛋白的 p7B 定位于活跃追踪肌动蛋白微丝的运动性高尔基体 (GA) 堆栈的内质网 (ER) 中，以及质膜结构域 (PD) 中。因此，分泌途径抑制剂布雷菲德菌素 A (BFA) 和 Sar1p 的 GTPase 缺陷突变体 Sar1[H74L]的过表达完全将 p7B 保留在内质网中，表明该蛋白以 BFA 敏感和 COPII 依赖的方式被递送到 PD。用拉他环素 B 破坏肌动蛋白细胞骨架导致 p7B 在 ER 中的积累，这强烈表明 p7B 也以依赖肌动蛋白的方式被靶向到细胞边缘。值得注意的是，BFA 的存在或 Sar1[H74L]的过表达显著限制了病毒感染的局部扩散，从而揭示了活跃的分泌途径在 MNSV 的细胞内运动中的参与。总的来说，这些发现支持了 GA 介导的植物病毒细胞内运输的新途径。
