Biochemical and molecular characterization of a hydroxyjasmonate sulfotransferase from Arabidopsis thaliana
Biochemical and molecular characterization of a hydroxyjasmonate sulfotransferase from Arabidopsis thaliana
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DOI：
10.1074/jbc.m211943200
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发表时间：
2003-05-16
影响因子：
4.8
通讯作者：
Varin, L
中科院分区：
文献类型：
--
作者：
Gidda, SK;Miersch, O;Varin, L
12-羟基茉莉酸，也称为块茎酸，首先从马铃薯中分离出来，并被证明具有块茎诱导特性。它源自普遍存在的茉莉酸，茉莉酸是介导多种发育过程和植物防御反应的重要信号分子。我们在这里报道来自拟南芥的基因AtST2a编码羟基茉莉酸磺基转移酶。重组AtST2a蛋白被发现对11-和12-羟基茉莉酸表现出严格的特异性，Km值分别为50和10μM。此外，12-羟基茉莉酸及其磺化衍生物被证明天然存在于拟南芥中。向拟南芥植物外源施用茉莉酸甲酯导致两种代谢物的水平增加，而用12-羟基茉莉酸处理导致12-羟基茉莉酸硫酸盐的水平增加，而不影响茉莉酸的内源水平。发现用茉莉酸甲酯和12-羟基茉莉酸处理后，AtST2a 表达被诱导。相比之下，茉莉酸甲酯响应基因Thi2.1（植物防御反应中的标记基因）的表达在用12-羟基茉莉酸处理后不被诱导，表明存在响应茉莉酸和12-羟基茉莉酸的独立信号传导途径。综上所述，结果表明羟基化和磺化反应可能是使植物中过量茉莉酸失活的途径的组成部分。或者，AtST2a 的功能可能是控制 12-羟基茉莉酸的生物活性。
12-Hydroxyjasmonate, also known as tuberonic acid, was first isolated from Solanum tuberosum and was shown to have tuber-inducing properties. It is derived from the ubiquitously occurring jasmonic acid, an important signaling molecule mediating diverse developmental processes and plant defense responses. We report here that the gene AtST2a from Arabidopsis thaliana encodes a hydroxyjasmonate sulfotransferase. The recombinant AtST2a protein was found to exhibit strict specificity for 11- and 12-hydroxyjasmonate with Km values of 50 and 10 muM, respectively. Furthermore, 12-hydroxyjasmonate and its sulfonated derivative are shown to be naturally occurring in A. thaliana. The exogenous application of methyljasmonate to A. thaliana plants led to increased levels of both metabolites, whereas treatment with 12-hydroxyjasmonate led to increased level of 12-hydroxyjasmonate sulfate without affecting the endogenous level of jasmonic acid. AtST2a expression was found to be induced following treatment with methyljasmonate and 12-hydroxyjasmonate. In contrast, the expression of the methyljasmonate-responsive gene Thi2.1, a marker gene in plant defense responses, is not induced upon treatment with 12-hydroxyjasmonate indicating the existence of independent signaling pathways responding to jasmonic acid and 12-hydroxyjasmonic acid. Taken together, the results suggest that the hydroxylation and sulfonation reactions might be components of a pathway that inactivates excess jasmonic acid in plants. Alternatively, the function of AtST2a might be to control the biological activity of 12-hydroxyjasmonic acid.