ER-to-Golgi transport by COPII vesicles in Arabidopsis involves a ribosome-excluding scaffold that is transferred with the vesicles to the Golgi matrix
ER-to-Golgi transport by COPII vesicles in Arabidopsis involves a ribosome-excluding scaffold that is transferred with the vesicles to the Golgi matrix
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DOI：
10.1007/s00709-008-0015-6
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发表时间：
2008-12-01
期刊：
影响因子：
2.9
通讯作者：
Staehelin, L. Andrew
中科院分区：
文献类型：
--
作者：
Kang, Byung-Ho;Staehelin, L. Andrew
植物高尔基体是一种移动的细胞器，可以沿着肌动蛋白丝运动。COPII（外壳复合物II）囊泡如何从内质网（ER）出口部位转移到移动的高尔基体堆栈尚不清楚。我们已经研究了COPII囊泡转移高压冷冻/冷冻取代植物细胞的电子断层扫描。每个COPII囊泡的形成伴随着核糖体排除支架层的组装，该支架层延伸超过COPII涂层约40 nm。这些COPII支架可以附着到高尔基体基质的顺式侧，然后COPII囊泡与它们的支架一起转移到高尔基体。当表达Atp 115-GFP（COPII囊泡束缚因子p115的拟南芥同源物的绿色荧光蛋白（GFP）融合蛋白）时，GFP定位于COPII支架和高尔基体基质的顺式侧。在活的根分生组织细胞中的高尔基体堆叠的延时成像表明，高尔基体堆叠在快速、线性、跳跃运动（0.9-1.25 μ m/s）和较慢的摆动运动（< 0.4 μ m/s）之间交替。在根分生组织细胞中，大约70%的高尔基体堆栈连接到ER出口网站通过COPII支架，这些堆栈拥有三倍以上的COPII囊泡比高尔基体不与ER;在柱细胞中，只有15%的高尔基体堆栈位于ER附近。我们假设COPII支架首先结合到高尔基体基质的顺式侧，然后与其融合，将其封闭的COPII囊泡转移到顺式高尔基体。
Plant Golgi stacks are mobile organelles that can travel along actin filaments. How COPII (coat complex II) vesicles are transferred from endoplasmic reticulum (ER) export sites to the moving Golgi stacks is not understood. We have examined COPII vesicle transfer in high-pressure frozen/freeze-substituted plant cells by electron tomography. Formation of each COPII vesicle is accompanied by the assembly of a ribosome-excluding scaffold layer that extends approximately 40 nm beyond the COPII coat. These COPII scaffolds can attach to the cis-side of the Golgi matrix, and the COPII vesicles are then transferred to the Golgi together with their scaffolds. When Atp115-GFP, a green fluorescent protein (GFP) fusion protein of an Arabidopsis thaliana homolog of the COPII vesicle-tethering factor p115, was expressed, the GFP localized to the COPII scaffold and to the cis-side of the Golgi matrix. Time-lapse imaging of Golgi stacks in live root meristem cells demonstrated that the Golgi stacks alternate between phases of fast, linear, saltatory movements (0.9-1.25 mu m/s) and slower, wiggling motions (< 0.4 mu m/s). In root meristem cells, approximately 70% of the Golgi stacks were connected to an ER export site via a COPII scaffold, and these stacks possessed threefold more COPII vesicles than the Golgi not associated with the ER; in columella cells, only 15% of Golgi stacks were located in the vicinity of the ER. We postulate that the COPII scaffold first binds to and then fuses with the cis-side of the Golgi matrix, transferring its enclosed COPII vesicle to the cis-Golgi.