Endoplasmic reticulum-directed pex3p routes to peroxisomes and restores peroxisome formation in a Saccharomyces cerevisiae pex3Δ strain
Endoplasmic reticulum-directed pex3p routes to peroxisomes and restores peroxisome formation in a Saccharomyces cerevisiae pex3Δ strain
复制标题
DOI：
10.1074/jbc.m505432200
复制
发表时间：
2005-10-07
影响因子：
4.8
通讯作者：
Distel, B
中科院分区：
文献类型：
--
作者：
Kragt, A;Voorn-Brouwer, T;Distel, B
最近的研究过氧化物酶体膜蛋白的排序挑战了长期以来的模型，其中过氧化物酶体被认为是自主的细胞器，通过生长和分裂繁殖。在这里，我们提出的数据借贷支持的想法，内质网（ER）参与过氧化物酶体膜蛋白Pex 3 p，过氧化物酶体生物发生早期所需的蛋白质的分选。首先，我们表明，引入人工糖基化位点到N末端的Pex 3 p导致部分N-连接的核心糖基化，插入到ER膜的指示。其次，当FLAG标记的Pex 3 p配备有ER靶向信号时，它可以恢复pex 3 Delta细胞中的过氧化物酶体形成。重要的是，特异性识别加工的Pex 3 p的FLAG抗体显示融合蛋白的信号肽被有效地切割掉，并且加工的蛋白质定位于过氧化物酶体。相反，其中信号肽的切割被突变阻断的Pex 3 p构建体定位于ER和胞质溶胶，并且不能补充pex 3Delta细胞。总之，这些结果强烈表明，ER靶向的Pex 3 p确实通过ER途径过氧化物酶体，我们假设这一途径也被内源性Pex 3 p使用。
Recent studies on the sorting of peroxisomal membrane proteins challenge the long-standing model in which peroxisomes are considered to be autonomous organelles that multiply by growth and division. Here, we present data lending support to the idea that the endoplasmic reticulum ( ER) is involved in sorting of the peroxisomal membrane protein Pex3p, a protein required early in peroxisome biogenesis. First, we show that the introduction of an artificial glycosylation site into the N terminus of Pex3p leads to partial N-linked core glycosylation, indicative of insertion into the ER membrane. Second, when FLAG-tagged Pex3p is equipped with an ER targeting signal, it can restore peroxisome formation in pex3 Delta cells. Importantly, FLAG antibodies that specifically recognize the processed Pex3p show that the signal peptide of the fusion protein is efficiently cleaved off and that the processed protein localizes to peroxisomes. In contrast, a Pex3p construct in which cleavage of the signal peptide is blocked by a mutation localizes to the ER and the cytosol and cannot complement pex3 Delta cells. Together, these results strongly suggest that ER-targeted Pex3p indeed routes via the ER to peroxisomes, and we hypothesize that this pathway is also used by endogenous Pex3p.