Yo1082p, a novel CVT protein involved in the selective targeting of aminopeptidase I to the yeast vacuole
Yo1082p, a novel CVT protein involved in the selective targeting of aminopeptidase I to the yeast vacuole
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DOI：
10.1074/jbc.m101438200
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发表时间：
2001-08-03
影响因子：
4.8
通讯作者：
Mazón, MJ
中科院分区：
文献类型：
--
作者：
Leber, R;Silles, E;Mazón, MJ
酵母液泡酶氨肽酶I（API）在细胞质中合成为前体（pAPI）。在其组装成十二聚体后，pAPI被双膜囊状结构包裹，用于其在囊泡内的进一步运输，所述囊泡与液泡膜融合并在液泡腔中释放其内容物。API靶向液泡通过两种替代的运输途径发生，cvt和自噬途径，尽管它们在机制上相似，但分别在营养生长或氮饥饿条件下特异性地起作用。我们已经研究了Yol 082 p的作用，Yol 082 p是一种通过其与API相互作用的能力而鉴定的蛋白质，在其前体向液泡的运输中。我们表明Yol 082 p与成熟的API相互作用，这种相互作用通过API蛋白的氨基延伸而加强。在生长和短期氮饥饿条件下，将pAPI靶向液泡需要Yol 082 p。Yol 082 p的不存在不妨碍pAPI组装成十二聚体，但排除了pAPI在转运囊泡内的封闭。显微镜研究表明，在营养生长Yol 082 p分布在细胞质池和可变数量的0.13-0.27-妈妈圆，移动的结构，这是不再观察到氮饥饿的条件下，并成为更大的细胞表达失活Yol 082三角洲C32 p，或缺乏Apg 12 p。与参与API转运的自噬突变体相反，Delta yol 082菌株在氮饥饿条件下不丧失活力，表明自噬途径的正常功能。数据与Yol 082 p在其组装成十二聚体后在API转运的早期步骤中的作用一致。由于Yo 1082 p满足定义CVT蛋白的功能性要求，我们建议将其命名为Cvt 19。
The yeast vacuolar enzyme aminopeptidase I (API) is synthesized in the cytoplasm as a precursor (pAPI). Upon its assembly into dodecamers, pAPI is wrapped by double-membrane saccular structures for its further transport within vesicles that fuse with the vacuolar membrane and release their content in the vacuolar lumen. Targeting of API to the vacuole occurs by two alternative transport routes, the cvt and the autophagy pathways, which although mechanistically similar specifically operate under vegetative growth or nitrogen starvation conditions, respectively. We have studied the role of Yol082p, a protein identified by its ability to interact with API, in the transport of its precursor to the vacuole. We show that Yol082p, interacts with mature API, an interaction that is strengthened by the amino extension of the API protein. Yol082p is required for targeting of pAPI to the vacuole, both under growing and short term nitrogen starvation conditions. Absence of Yol082p does not impede the assembly of pAPI into dodecamers, but precludes the enclosure of pAPI within transport vesicles. Microscopy studies show that during vegetative growth Yol082p is distributed between a cytoplasmic pool and a variable number of 0.13-0.27-mum round, mobile structures, which are no longer observed under conditions of nitrogen starvation, and become larger in cells expressing the inactive Yol082 Delta C32p, or lacking Apg12p. In contrast to the autophagy mutants involved in API transport, a Delta yol082 strain does not lose viability under nitrogen starvation conditions, indicating normal function of the autophagy pathway. The data are consistent with a role of Yol082p in an early step of the API transport, after its assembly into dodecamers. Because Yo1082p fulfills the functional requisites that define the CVT proteins, we propose to name it Cvt19.