The plant 2-Cys peroxiredoxin BAS1 is a nuclear-encoded chloroplast protein: its expressional regulation, phylogenetic origin, and implications for its specific physiological function in plants
The plant 2-Cys peroxiredoxin BAS1 is a nuclear-encoded chloroplast protein: its expressional regulation, phylogenetic origin, and implications for its specific physiological function in plants
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DOI：
10.1046/j.1365-313x.1997.12010179.x
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发表时间：
1997-07-01
期刊：
影响因子：
7.2
通讯作者：
Dietz, KJ
中科院分区：
文献类型：
--
作者：
Baier, M;Dietz, KJ
2-半胱氨酸过氧化物酶是一类催化电子从巯基转移到过氧化物的酶，广泛分布于所有生物体中。本文对高等植物2-Cysperoxiredoxin BAS 1进行了鉴定。(i)过表达BAS 1的大肠杆菌在体内表现出对烷基氢过氧化物的耐受性增加。该结果证实了BAS 1的过氧化物氧还蛋白功能。(ii)BAS 1蛋白与叶肉原生质体的可溶性叶绿体部分相关。进口和处理在体外转录和无细胞翻译的BAS 1蛋白到分离的叶绿体提供了确凿的证据，植物特异性的N-末端延伸的bas 1编码的叶绿体输入信号，其目标的BAS 1的前形式的叶绿体基质，在那里它被切割到其成熟的大小。(iii)基因组分析表明，在拟南芥中，靶向信号由单独的外显子编码。(iv)高等植物的BAS 1核心蛋白的氨基酸序列与蓝绿藻集胞壶菌PCC sp.6803基因组和红藻紫紫菜质体组中的开放阅读框的相似性高于与任何其它核编码的P-Cys过氧化物氧还蛋白的相似性。因此，很容易推测叶绿体输入信号是在植物进化过程中加入到内共生起源的祖先基因中的。(v)bas 1基因表达受细胞氧化还原状态的控制，这与酶的抗氧化功能一致。虽然氧化应激仅略微增加表达，但抗氧化剂如还原硫醇强烈抑制转录水平。这些研究结果的影响进行了讨论，就可能的生理功能的BAS 1。
2-Cys peroxiredoxins constitute a family of enzymes which catalyze the transfer of electrons from sulfhydryl residues to peroxides and are ubiquitously distributed among all organisms. This paper characterizes the higher plant 2-Cysperoxiredoxin BAS1. (i) Escherichia coli over-expressing BAS1 exhibit increased tolerance for alkyl hydroperoxides in vivo. This result substantiates the peroxiredoxin function of BAS1. (ii) BAS1 protein is associated with the soluble chloroplast fraction of mesophyll protoplasts. Import and processing of in vitro-transcribed and cell-free translated BAS1 protein into isolated chloroplasts provides conclusive evidence that the plant-specific N-terminal extension of bas1 encodes the chloroplast import signal which targets the pre-form of BAS1 to the chloroplast stroma where it is cleaved to its mature size. (iii) Genomic analysis reveals that the targeting signal is encoded by a separate exon in Arabidopsis thaliana. (iv) The amino acid sequence of the BAS1 core protein of higher plants has a higher degree of similarity to open reading frames in the genome of the bluegreen algae Synechochystis PCC sp. 6803 and in the plastome of the red algae Porphyra purpurea than to any other nuclear-encoded P-Cys peroxiredoxin. Therefore, it is tempting to speculate that the chloroplast import signal was added to an ancestor gene of endosymbiotic origin in the course of plant evolution. (v) The bas1 gene expression is regulated under the control of the cellular redox state which is in accordance with the anti-oxidant function of the enzyme. While oxidative stressors increased expression only slightly, antioxidants such as reduced thiols strongly suppressed the transcript level. The implications of these findings are discussed with respect to the possible physiological functions of BAS1.