GLUTELIN PRECURSOR ACCUMULATION3 Encodes a Regulator of Post-Golgi Vesicular Traffic Essential for Vacuolar Protein Sorting in Rice Endosperm
GLUTELIN PRECURSOR ACCUMULATION3 Encodes a Regulator of Post-Golgi Vesicular Traffic Essential for Vacuolar Protein Sorting in Rice Endosperm
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谷蛋白前体累积3编码对水稻胚乳液泡蛋白分选至关重要的后高尔基体囊泡运输调节因子
DOI：
10.1105/tpc.113.121376
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发表时间：
2014-01-01
期刊：
影响因子：
11.6
通讯作者：
Wan, Jianmin
中科院分区：
文献类型：
--
作者：
Ren, Yulong;Wang, Yihua;Wan, Jianmin
在种子植物中，蛋白质储存泡（PSV）的主要分选途径依赖于高尔基体衍生的致密囊泡（DVs）。然而，调控DV向PSV定向运输的分子机制在很大程度上仍然难以捉摸。在这里，我们报告的功能特性的水稻（Oryza sativa）谷蛋白前体积累3（gpa 3）突变体，表现出面粉胚乳表型和积累过量的proglutelin干种子。细胞学和免疫细胞化学研究表明，在gpa 3突变体中，许多含有谷丙蛋白的DV被错误地发送到质膜，并通过膜融合，将其内容物释放到质外体中，形成一个新的结构，称为壁旁体。定位克隆的GPA 3显示，它编码一种植物特异性的kelch重复蛋白，该蛋白定位于发育中的胚乳中的trans-Golgi网络、DV和PSV。体外和体内实验证实GPA 3与水稻Rab 5a-鸟嘌呤交换因子VPS 9a直接相互作用，并通过VPS 9a与Rab 5a形成调控复合物。此外，我们的遗传数据支持的概念，GPA 3协同作用Rab 5a和VPS 9a调节DV介导的后高尔基体交通在水稻。我们的研究结果提供了深入的了解调节植物特异性PSV途径的分子机制，并扩大了我们的知识真核生物囊泡运输。
In seed plants, a major pathway for sorting of storage proteins to the protein storage vacuole (PSV) depends on the Golgi-derived dense vesicles (DVs). However, the molecular mechanisms regulating the directional trafficking of DVs to PSVs remain largely elusive. Here, we report the functional characterization of the rice (Oryza sativa) glutelin precursor accumulation3 (gpa3) mutant, which exhibits a floury endosperm phenotype and accumulates excess proglutelins in dry seeds. Cytological and immunocytochemistry studies revealed that in the gpa3 mutant, numerous proglutelin-containing DVs are misrouted to the plasma membrane and, via membrane fusion, release their contents into the apoplast to form a new structure named the paramural body. Positional cloning of GPA3 revealed that it encodes a plant-specific kelch-repeat protein that is localized to the trans-Golgi networks, DVs, and PSVs in the developing endosperm. In vitro and in vivo experiments verified that GPA3 directly interacts with the rice Rab5a-guanine exchange factor VPS9a and forms a regulatory complex with Rab5a via VPS9a. Furthermore, our genetic data support the notion that GPA3 acts synergistically with Rab5a and VPS9a to regulate DV-mediated post-Golgi traffic in rice. Our findings provide insights into the molecular mechanisms regulating the plant-specific PSV pathway and expand our knowledge of vesicular trafficking in eukaryotes.