Role of Pex21p for Piggyback Import of Gpd1p and Pnc1p into Peroxisomes of Saccharomyces cerevisiae
Role of Pex21p for Piggyback Import of Gpd1p and Pnc1p into Peroxisomes of Saccharomyces cerevisiae
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DOI：
10.1074/jbc.m115.653451
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发表时间：
2015-10-16
影响因子：
4.8
通讯作者：
Erdmann, Ralf
中科院分区：
文献类型：
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作者：
Effelsberg, Daniel;Cruz-Zaragoza, Luis Daniel;Erdmann, Ralf
指定用于过氧化物酶体蛋白输入的蛋白质具有两种常见的过氧化物酶体靶向信号（PTS）之一。在酵母酿酒酵母中，通过可溶性输入受体Pex 7 p与辅助Pex 18 p（两种推测冗余的PTS 2共受体之一）合作，进行由茶氨酸诱导的PTS 2依赖性硫解酶Fox 3 p输入过氧化物酶体。在这里，我们报告了一个新的功能的共同受体Pex 21 p，这是不能实现的Pex 18 p。这些数据确立了Pex 21 p作为PTS 2依赖性蛋白质输入中的一般共受体，而Pex 18 p对于油酸诱导的PTS 2蛋白输入尤其重要。生产甘油的PTS 2蛋白甘油-3-磷酸脱氢酶Gpd 1 p显示在过氧化物酶体中，在细胞质中，和在渗透胁迫条件下的细胞核中的三方定位。我们显示以下内容：（i）Pex 21 p是Gpd 1 p和NAD（+）补救途径的关键酶Pnc 1 p的过氧化物酶体输入所必需的;（ii）Pnc 1 p是一种没有功能性PTS 2的烟酰胺酶，通过Gpd 1 p的背驮运输共同输入过氧化物酶体。此外，这两种酶到过氧化物酶体的特异性运输表明过氧化物酶体在各种胁迫条件下具有新的调节作用。
Proteins designated for peroxisomal protein import harbor one of two common peroxisomal targeting signals (PTS). In the yeast Saccharomyces cerevisiae, theoleate-induced PTS2-dependent import of the thiolase Fox3p into peroxisomes is conducted by the soluble import receptor Pex7p in cooperation with the auxiliary Pex18p, one of two supposedly redundant PTS2 co-receptors. Here, we report on a novel function for the co-receptor Pex21p, which cannot be fulfilled by Pex18p. The data establish Pex21p as a general co-receptor in PTS2-dependent protein import, whereas Pex18p is especially important for oleate-induced import of PTS2 proteins. The glycerol-producing PTS2 protein glycerol-3-phosphate dehydrogenase Gpd1p shows a tripartite localization in peroxisomes, in the cytosol, and in the nucleus under osmotic stress conditions. We show the following: (i) Pex21p is required for peroxisomal import of Gpd1p as well as a key enzyme of the NAD(+) salvage pathway, Pnc1p; (ii) Pnc1p, a nicotinamidase without functional PTS2, is co-imported into peroxisomes by piggyback transport via Gpd1p. Moreover, the specific transport of these two enzymes into peroxisomes suggests a novel regulatory role for peroxisomes under various stress conditions.