Characterization of phytochelatin synthase-like protein encoded by alr0975 from a prokaryote, Nostoc sp PCC 7120
Characterization of phytochelatin synthase-like protein encoded by alr0975 from a prokaryote, Nostoc sp PCC 7120
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DOI：
10.1016/j.bbrc.2004.01.122
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发表时间：
2004-03-12
影响因子：
3.1
通讯作者：
Miyamoto, K
中科院分区：
文献类型：
--
作者：
Tsuji, N;Nishikori, S;Miyamoto, K
众所周知，植物螯合素（PC）是高等植物、真核藻类、真菌和线虫中的重金属解毒肽。相比之下，PC 和 PC 合酶基因都尚未在任何原核生物中被发现。蓝藻发菜属的基因组序列。 PCC 7120 最近完成，使我们能够识别编码 PC 合酶样蛋白的基因，称为 alr0975。 alr0975 的预测产物包含保守的 N 末端结构域，但不包含真核 PC 合酶中的可变 C 末端结构域。重组alr0975蛋白强烈催化PC合成的第一步，其中谷胱甘肽（GSH）转化为γ-谷氨酰半胱氨酸（γ-EC），尽管该蛋白仅弱催化PC合成的第二步，即γ-EC部分转移到受体GSH分子形成PC2。这些结果表明alr0975 蛋白可能是真核生物中发现的PC 合酶的更原始形式。 (C) 2004 Elsevier Inc. 保留所有权利。
Phytochelatins (PCs) are well known as the heavy metal-detoxifying peptides in higher plants, eukaryotic algae, fungi, and nematode. In contrast, neither PCs nor PC synthase genes have ever been identified in any prokaryotes. The genome sequences for the cyanobacterium Nostoc sp. PCC 7120 were recently completed and allowed us to identify a gene encoding a PC synthase-like protein, termed alr0975. The predicted product of alr0975 contains the conserved N-terminal domain but not the variable C-terinitial domain found in eukaryotic PC synthases. The recombinant alr0975 protein strongly catalyzed the first step of PC synthesis, in which glutathione (GSH) is converted to gamma-glutamylcysteine (gamma-EC), although the protein only weakly catalyzed the second step of PC synthesis, namely the transfer of gamma-EC moiety to an acceptor GSH molecule to form PC2. These results suggest alr0975 protein may be a more primitive form of the PC synthases found in eukaryotes. (C) 2004 Elsevier Inc. All rights reserved.