Protein disulfide isomerase-2 of Arabidopsis mediates protein folding and localizes to both the secretory pathway and nucleus, where it interacts with maternal effect embryo arrest factor
Protein disulfide isomerase-2 of Arabidopsis mediates protein folding and localizes to both the secretory pathway and nucleus, where it interacts with maternal effect embryo arrest factor
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DOI：
10.1007/s10059-011-0150-3
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发表时间：
2011-11-01
影响因子：
3.8
通讯作者：
Christopher, David A.
中科院分区：
文献类型：
--
作者：
Cho, Eun Ju;Yuen, Christen Y. L.;Christopher, David A.
蛋白质二硫键异构酶（PDI）是一种硫代二硫键氧化还原酶，催化真核生物蛋白质中二硫键的形成、还原和重排。经典的 PDI 具有信号肽、两个含有 CXXC 的硫氧还蛋白催化位点 (a,a')、两个非催化硫氧还蛋白折叠结构域 (b,b')、一个酸性结构域 (c) 和一个 C 端内质网 (ER) 保留信号。尽管PDI存在于内质网中，介导分泌途径新生多肽的折叠，但我们最近发现，拟南芥的PDI5在发育种子中内皮程序性细胞死亡之前运输到液泡的过程中作为分子伴侣并抑制半胱氨酸蛋白酶。在这里，我们描述了拟南芥 PDI2，它具有与经典 PDI 相似的一级结构。重组 PDI2 被导入 ER 衍生的微粒体中，并补充大肠杆菌蛋白折叠突变体 dsbA。 PDI2 与 ER 和细胞核中的蛋白质相互作用，包括 ER 驻留蛋白折叠伴侣 BiP1 和核胚胎转录因子 MEE8。 PDI2-MEE8 相互作用已被证实在体外和体内发生。 PDI2-GFP 融合体在叶肉原生质体中的瞬时表达导致 ER、细胞核和液泡的标记。 PDI2在多种组织中表达，其中在种子和根尖中表达量较高。在转基因种子 (PDI2-GFP) 和野生型根上使用 GFP 和 PDI2 特异性抗血清进行的免疫电子显微镜检查表明，在分泌途径（内质网、高尔基体、液泡、细胞壁）和细胞核中发现了 PDI2。我们的结果表明，PDI2 介导内质网中的蛋白质折叠，并在细胞核中具有新的功能作用。
Protein disulfide isomerase (PDI) is a thiodisulfide oxidoreductase that catalyzes the formation, reduction and rearrangement of disulfide bonds in proteins of eukaryotes. The classical PDI has a signal peptide, two CXXCcontaining thioredoxin catalytic sites (a,a'), two noncatalytic thioredoxin fold domains (b,b'), an acidic domain (c) and a C-terminal endoplasmic reticulum (ER) retention signal. Although PDI resides in the ER where it mediates the folding of nascent polypeptides of the secretory pathway, we recently showed that PDI5 of Arabidopsis thaliana chaperones and inhibits cysteine proteases during trafficking to vacuoles prior to programmed cell death of the endothelium in developing seeds. Here we describe Arabidopsis PDI2, which shares a primary structure similar to that of classical PDI. Recombinant PDI2 is imported into ER-derived microsomes and complements the E. coli protein-folding mutant, dsbA. PDI2 interacted with proteins in both the ER and nucleus, including ER-resident protein folding chaperone, BiP1, and nuclear embryo transcription factor, MEE8. The PDI2-MEE8 interaction was confirmed to occur in vitro and in vivo. Transient expression of PDI2-GFP fusions in mesophyll protoplasts resulted in labeling of the ER, nucleus and vacuole. PDI2 is expressed in multiple tissues, with relatively high expression in seeds and root tips. Immunoelectron microscopy with GFP- and PDI2-specific antisera on transgenic seeds (PDI2-GFP) and wild type roots demonstrated that PDI2 was found in the secretory pathway (ER, Golgi, vacuole, cell wall) and the nuclei. Our results indicate that PDI2 mediates protein folding in the ER and has new functional roles in the nucleus.