拟南芥中酪氨酰蛋白磺基转移酶的鉴定。,Proceedings of the National Academy of Sciences of the United States of America

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拟南芥中酪氨酰蛋白磺基转移酶的鉴定。
Proceedings of the National Academy of Sciences of the United States of America ( IF 9.4 ) Pub Date : 2009 Sep 1 , DOI: 10.1073/pnas.0902801106
Ryota Komori ₁ , Yukari Amano , Mari Ogawa-Ohnishi , Yoshikatsu Matsubayashi

Affiliation

酪氨酸硫酸化是大多数真核生物分泌途径合成的肽和蛋白质中常见的翻译后修饰。在植物中，这种修饰对于部分肽激素（如 PSK 和 PSY1）的生物活性至关重要。在动物中，酪氨酸硫酸化由高尔基体定位的 II 型跨膜蛋白催化，称为酪氨酸蛋白磺基转移酶 (TPST)。然而，在植物中没有发现动物 TPST 基因的直向同源物，这表明植物已经进化出植物特异性 TPST，在结构上不同于它们的动物对应物。为了研究植物中酪氨酸硫酸化的机制，我们从拟南芥 MM2d 细胞的微粒体部分纯化了 TPST 活性，并鉴定了一种 62-kDa 的蛋白质，该蛋白质与 PSY1 前体肽的硫酸化基序特异性相互作用。这种蛋白质是一种 500-aa 的 I 型跨膜蛋白质，与动物 TPST 没有序列相似性。在酵母中表达的该蛋白质的重组版本在体外催化 PSY1 和 PSK 前体多肽的酪氨酸硫酸化，表明新鉴定的蛋白质确实是拟南芥 (At)TPST。AtTPST 在整个植物体中表达，在根尖分生组织中表达水平最高。AtTPST 的功能丧失突变体表现出明显的矮化表型，伴随着根发育不良、淡绿色叶子、高阶脉减少、早衰以及花和长角果数量减少。我们的研究结果表明，植物和动物通过趋同进化独立获得酪氨酸硫酸化酶。

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Identification of tyrosylprotein sulfotransferase in Arabidopsis.

Tyrosine sulfation is a posttranslational modification common in peptides and proteins synthesized by the secretory pathway in most eukaryotes. In plants, this modification is critical for the biological activities of a subset of peptide hormones such as PSK and PSY1. In animals, tyrosine sulfation is catalyzed by Golgi-localized type II transmembrane proteins called tyrosylprotein sulfotransferases (TPSTs). However, no orthologs of animal TPST genes have been found in plants, suggesting that plants have evolved plant-specific TPSTs structurally distinct from their animal counterparts. To investigate the mechanisms of tyrosine sulfation in plants, we purified TPST activity from microsomal fractions of Arabidopsis MM2d cells, and identified a 62-kDa protein that specifically interacts with the sulfation motif of PSY1 precursor peptide. This protein is a 500-aa type I transmembrane protein that shows no sequence similarity to animal TPSTs. A recombinant version of this protein expressed in yeast catalyzed tyrosine sulfation of both PSY1 and PSK precursor polypeptide in vitro, indicating that the newly identified protein is indeed an Arabidopsis (At)TPST. AtTPST is expressed throughout the plant body, and the highest levels of expression are in the root apical meristem. A loss-of-function mutant of AtTPST displayed a marked dwarf phenotype accompanied by stunted roots, pale green leaves, reduction in higher order veins, early senescence, and a reduced number of flowers and siliques. Our results indicate that plants and animals independently acquired tyrosine sulfation enzymes through convergent evolution.

更新日期：2017-01-31

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