GPA5 Encodes a Rab5a Effector Required for Post-Golgi Trafficking of Rice Storage Proteins
GPA5 Encodes a Rab5a Effector Required for Post-Golgi Trafficking of Rice Storage Proteins
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GPA5 编码高尔基体后水稻储存蛋白运输所需的 Rab5a 效应子
DOI：
10.1105/tpc.19.00863
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发表时间：
2020-03-01
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
致密囊泡（DVS）是植物特有的囊泡载体，介导种子中贮藏蛋白质在高尔基体后向蛋白质贮藏液泡（PSV）的运输。然而，调控DVs定向靶向PSV的分子机制仍然难以捉摸。在这里，我们表明，水稻（水稻）谷蛋白前体积累5（gpa 5）突变体是有缺陷的定向靶向DVs的PSV，导致其货物蛋白排放到细胞外空间。分子克隆表明，GPA 5编码一个植物特有的phox同源结构域，与拟南芥（Arabidopsis thaliana）的具有PX结构域的内体RAB受体同源。我们表明，GPA 5是一种膜相关蛋白能够形成同源二聚体，它是专门定位于DV在发育胚乳。共定位，生物化学和遗传学证据表明，GPA 5与Rab 5a和VPS 9a协同作用，调节DV介导的高尔基体后运输到PSV。此外，我们证明，GPA 5物理相互作用的C类核心液泡/内体拴系复合物和种子植物特异性VAMP 727含有R-可溶性N-乙基马来酰亚胺敏感因子附着蛋白受体复合物。这些结果表明，GPA 5是Rab 5a的植物特异性效应子，介导水稻胚乳DVs与PSV的系留和膜融合; GPA 5是Rab 5a的植物特异性效应子，介导水稻胚乳致密囊泡与蛋白质贮藏泡的系留和膜融合。
Dense vesicles (DVs) are vesicular carriers, unique to plants, that mediate post-Golgi trafficking of storage proteins to protein storage vacuoles (PSVs) in seeds. However, the molecular mechanisms regulating the directional targeting of DVs to PSVs remain elusive. Here, we show that the rice (Oryza sativa) glutelin precursor accumulation5 (gpa5) mutant is defective in directional targeting of DVs to PSVs, resulting in discharge of its cargo proteins into the extracellular space. Molecular cloning revealed that GPA5 encodes a plant-unique phox-homology domain-containing protein homologous to Arabidopsis (Arabidopsis thaliana) ENDOSOMAL RAB EFFECTOR WITH PX-DOMAIN. We show that GPA5 is a membrane-associated protein capable of forming homodimers and that it is specifically localized to DVs in developing endosperm. Colocalization, biochemical, and genetic evidence demonstrates that GPA5 acts in concert with Rab5a and VPS9a to regulate DV-mediated post-Golgi trafficking to PSVs. Furthermore, we demonstrated that GPA5 physically interacts with a class C core vacuole/endosome tethering complex and a seed plant-specific VAMP727-containing R-soluble N-ethylmaleimide sensitive factor attachment protein receptor complex. Collectively, our results suggest that GPA5 functions as a plant-specific effector of Rab5a required for mediating tethering and membrane fusion of DVs with PSVs in rice endosperm.GPA5 functions as a plant-specific effector of Rab5a required for mediating tethering and membrane fusion of dense vesicles with protein storage vacuoles in rice endosperm cells.