Cell Wall Polysaccharides are Mislocalized to the Vacuole in echidna Mutants
Cell Wall Polysaccharides are Mislocalized to the Vacuole in echidna Mutants
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DOI：
10.1093/pcp/pct129
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发表时间：
2013-11-01
影响因子：
4.9
通讯作者：
Samuels, Lacey
中科院分区：
文献类型：
--
作者：
McFarlane, Heather E.;Watanabe, Yoichiro;Samuels, Lacey
在细胞壁生物合成过程中，高尔基体是细胞壁基质生物合成的平台，也是将基质多糖和蛋白质包装成具有正确靶向信息的分泌囊泡的位点。本研究的目的是解剖后高尔基体运输的细胞壁多糖作为模式系统的模式系统，针鼹鼠作为小泡交通突变体的拟南芥和果胶分泌细胞的种皮。ECHIDNA编码一种跨高尔基体网络（TGN）定位的蛋白质，该蛋白质先前被证明是分泌途径的适当结构和功能所必需的。在针鼹鼠突变体中，一些细胞壁基质多糖在细胞内积累，而不是分泌到质外体。在这项研究中，荧光蛋白标记物的活细胞成像以及冷冻固定的种皮细胞的透射电子显微镜（TEM）/免疫TEM被用来检查的后果TGN解体在针鼹鼠突变体的条件下，高多糖的生产和分泌。而在野生型种皮细胞中，果胶被分泌到顶端表面，在针鼹鼠中，多糖积累在高尔基体后囊泡、中央裂解泡和内质网衍生体中。相反，针鼹鼠的蛋白质部分错误定位于内部多层膜。这些结果表明，虽然分泌的细胞壁多糖和蛋白质在TGN需要ECHIDNA，不同的囊泡运输组件可能介导的下游事件，在他们的分泌从TGN。
During cell wall biosynthesis, the Golgi apparatus is the platform for cell wall matrix biosynthesis and the site of packaging, of both matrix polysaccharides and proteins, into secretory vesicles with the correct targeting information. The objective of this study was to dissect the post-Golgi trafficking of cell wall polysaccharides using echidna as a vesicle traffic mutant of Arabidopsis thaliana and the pectin-secreting cells of the seed coat as a model system. ECHIDNA encodes a trans-Golgi network (TGN)-localized protein, which was previously shown to be required for proper structure and function of the secretory pathway. In echidna mutants, some cell wall matrix polysaccharides accumulate inside cells, rather than being secreted to the apoplast. In this study, live cell imaging of fluorescent protein markers as well as transmission electron microscopy (TEM)/immunoTEM of cryofixed seed coat cells were used to examine the consequences of TGN disorganization in echidna mutants under conditions of high polysaccharide production and secretion. While in wild-type seed coat cells, pectin is secreted to the apical surface, in echidna, polysaccharides accumulate in post-Golgi vesicles, the central lytic vacuole and endoplasmic reticulum-derived bodies. In contrast, proteins were partially mistargeted to internal multilamellar membranes in echidna. These results suggest that while secretion of both cell wall polysaccharides and proteins at the TGN requires ECHIDNA, different vesicle trafficking components may mediate downstream events in their secretion from the TGN.