Golgi apparatus-localized synaptotagmin 2 is required for unconventional secretion in Arabidopsis.
Golgi apparatus-localized synaptotagmin 2 is required for unconventional secretion in Arabidopsis.
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拟南芥中非常规分泌所必需的高尔基体 - 定位突触2。
DOI：
10.1371/journal.pone.0026477
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Lin J
中科院分区：
文献类型：
--
作者：
Zhang H;Zhang L;Gao B;Fan H;Jin J;Botella MA;Jiang L;Lin J
大多数分泌蛋白含有信号肽，这些信号肽通过常规的内质网/高尔基转运途径分泌，而一些缺乏信号肽的蛋白已被证明通过内质网/高尔基独立的分泌途径输出。湿霉素B是一种氨基糖苷类抗生素，由吸湿链霉菌产生，对原核和真核细胞都有活性。潮霉素磷酸转移酶（HYGR）可使潮霉素B磷酸化并使其失活，在转基因植物的构建中作为阳性选择标记已被广泛应用。然而，HYGR在植物细胞中的定位和转运尚不清楚。突触塔敏蛋白（SYTs）在动物细胞中作为钙传感器参与控制囊泡内吞和胞吐，而它们在植物细胞中的功能在很大程度上尚不清楚。通过免疫荧光和免疫金标记，我们发现拟南芥synaptotagmin SYT2定位在高尔基体上。令人惊讶的是，SYT2和HYGR的共表达引起了转基因拟南芥对潮霉素b的超敏反应。在HYGR- gfp转基因拟南芥中，缺乏信号序列的HYGR存在于细胞质和胞外空间，其分泌对brefeldin a不敏感，表明其不是通过常规分泌途径分泌的。此外，我们发现HYGR- gfp在合成后不久就在HYGR的羧基端被截断，缺乏SYT2的细胞无法有效截断HYGR- gfp，导致HYGR- gfp在前泡/液泡中积累，表明SYT2参与了HYGR- gfp的运输和分泌。这些发现首次揭示了SYT2定位于高尔基体，并通过细胞质溶胶到细胞外基质的非常规蛋白质运输调节HYGR-GFP的分泌。
Most secretory proteins contain signal peptides that direct their sorting to the ER and secreted via the conventional ER/Golgi transport pathway, while some signal-peptide-lacking proteins have been shown to export through ER/Golgi independent secretory pathways. Hygromycin B is an aminoglycoside antibiotic produced by Streptomyces hygroscopicus that is active against both prokaryotic and eukaryotic cells. The hygromycin phosphotransferase (HYGR) can phosphorylate and inactivate the hygromycin B, and has been widely used as a positive selective marker in the construction of transgenic plants. However, the localization and trafficking of HYGR in plant cells remain unknown. Synaptotagmins (SYTs) are involved in controlling vesicle endocytosis and exocytosis as calcium sensors in animal cells, while their functions in plant cells are largely unclear. We found Arabidopsis synaptotagmin SYT2 was localized on the Golgi apparatus by immunofluorescence and immunogold labeling. Surprisingly, co-expression of SYT2 and HYGR caused hypersensitivity of the transgenic Arabidopsis plants to hygromycin B. HYGR, which lacks a signal sequence, was present in the cytoplasm as well as in the extracellular space in HYGR-GFP transgenic Arabidopsis plants and its secretion is not sensitive to brefeldin A treatment, suggesting it is not secreted via the conventional secretory pathway. Furthermore, we found that HYGR-GFP was truncated at carboxyl terminus of HYGR shortly after its synthesis, and the cells deficient SYT2 failed to efficiently truncate HYGR-GFP,resulting in HYGR-GFP accumulated in prevacuoles/vacuoles, indicating that SYT2 was involved in HYGR-GFP trafficking and secretion. These findings reveal for the first time that SYT2 is localized on the Golgi apparatus and regulates HYGR-GFP secretion via the unconventional protein transport from the cytosol to the extracelluar matrix in plant cells.
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影响因子：
4.9
作者：
McGaha, Susan M.;Champney, W. Scott
通讯作者：
Champney, W. Scott
影响因子：
2
作者：
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通讯作者：
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DOI：
10.1016/j.bbrc.2008.04.174
发表时间：
2008-07-11
影响因子：
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作者：
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影响因子：
4.3
作者：
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作者：
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