Unconventional Secretion of AcbA in Dictyostelium discoideum through a Vesicular Intermediate
Unconventional Secretion of AcbA in Dictyostelium discoideum through a Vesicular Intermediate
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DOI：
10.1128/ec.00337-09
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发表时间：
2010-07-01
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影响因子：
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通讯作者：
Kuspa, Adam
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文献类型：
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作者：
Cabral, Matthew;Anjard, Christophe;Kuspa, Adam
酰基辅酶A（CoA）结合蛋白AcbA以非常规方式分泌并加工成孢子分化因子2（SDF-2），这是一种协调盘基网柄菌孢子形成的肽。我们报告说，AcbA是本地化的囊泡，积累在前孢子细胞的皮层孢子形成之前。这些囊泡在细胞被刺激释放AcbA后没有观察到，但在缺乏高尔基体重组堆积蛋白（GRASP）的细胞中刺激后仍然可见。酰基辅酶A的结合是包含在这些囊泡中的AcbA所必需的，并且AcbA的分泌需要N-乙基马来酰亚胺敏感因子（NSF）。约1%的细胞AcbA可以在膜结合囊泡内纯化。当从被刺激释放AcbA的野生型细胞中纯化时，囊泡的产量急剧下降，而从GRASP突变体细胞中纯化的产量仅被刺激适度改变。我们认为，这些含AcbA的囊泡是分泌中间体，GRASP功能在后期步骤导致这些囊泡在细胞表面的对接/融合。
The acyl coenzyme A (CoA) binding protein AcbA is secreted unconventionally and processed into spore differentiation factor 2 (SDF-2), a peptide that coordinates sporulation in Dictyostelium discoideum. We report that AcbA is localized in vesicles that accumulate in the cortex of prespore cells just prior to sporulation. These vesicles are not observed after cells are stimulated to release AcbA but remain visible after stimulation in cells lacking the Golgi reassembly stacking protein (GRASP). Acyl-CoA binding is required for the inclusion of AcbA in these vesicles, and the secretion of AcbA requires N-ethylmaleimide-sensitive factor (NSF). About 1% of the total cellular AcbA can be purified within membrane-bound vesicles. The yield of vesicles decreases dramatically when purified from wild-type cells that were stimulated to release AcbA, whereas the yield from GRASP mutant cells was only modestly altered by stimulation. We suggest that these AcbA-containing vesicles are secretion intermediates and that GRASP functions at a late step leading to the docking/fusion of these vesicles at the cell surface.