CLONING AND CHARACTERIZATION OF A GLUTATHIONE-S-TRANSFERASE THAT CAN BE PHOTOLABELED WITH 5-AZIDO-INDOLE-3-ACETIC ACID
CLONING AND CHARACTERIZATION OF A GLUTATHIONE-S-TRANSFERASE THAT CAN BE PHOTOLABELED WITH 5-AZIDO-INDOLE-3-ACETIC ACID
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DOI：
10.1104/pp.109.1.253
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发表时间：
1995-09-01
期刊：
影响因子：
7.4
通讯作者：
STURM, A
中科院分区：
文献类型：
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作者：
BILANG, J;STURM, A
此前，我们从Hyoscyamos moticus中鉴定了一种可被5-叠氮基-吲哚-3-乙酸光标记的蛋白质。该蛋白被确定为谷胱甘肽S转移酶(CST；J.Bilang，H.Macdonald，P.J.King，and A.Sturm[1993]Factory Physiol102：29-34)。我们研究了生长素对该H.muticus CST活性的影响。生长素仅在高浓度下降低酶活性，其中2，4-二氯苯氧基乙酸(2，4-D)和2，4，5-三氯苯氧基乙酸(2，4-D)比吲哚-3-乙酸(IAA)和萘乙酸更有效。IAA是一种非竞争性抑制剂，而2，4-D对1-氯-2，4-二硝基苯的抑制是竞争性的。我们还给出了编码CST的全长cDNA克隆的序列，该克隆包含纯化蛋白的全部氨基酸序列。与生长素结合的CST在根和茎中含量较高，在叶和花蕾中含量较低。而2，4-D和2，3-二氯苯氧基乙酸可增加细胞内的mRNA水平。我们提出了一个模型，其中2，4-D是CST的底物，而IAA结合在第二个位置，称为连接蛋白结合部位，用于细胞内转运。
Previously, we identified a soluble protein from Hyoscyamos moticus that was photolabeled by 5-azido-indole-3-acetic acid. This protein was determined to be a glutathione S-transferase (CST; J. Bilang, H. Macdonald, P.J. King, and A. Sturm [1993] Plant Physiol 102: 29-34). We have examined the effect of auxin on the activity of this H. muticus CST. Auxins reduced enzyme activity only at high concentrations, with 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid being more effective than indole-3-acetic acid (IAA) and naphthylacetic acid. IAA was a noncompetitive inhibitor, whereas inhibition by 2,4-D was competitive with respect to 1-chloro-2,4-dinitro-benzene. We also present the sequence of a full-length cDNA clone that codes for a CST and contains all partial amino acid sequences of the purified protein. The auxin-binding CST was found in high amounts in roots and stems and low amounts in leaves and flower buds. The steady-state mRNA level was not regulated by IAA or naphthylacetic acid, whereas 2,4-D and 2,3-dichlorophenoxyacetic acid increased mRNA levels. We propose a model in which 2,4-D is a substrate for CST, whereas IAA binds at a second site, known as a ligandin-binding site for the purpose of intracellular transport.