Cytochromes P450 CYP94C1 and CYP94B3 Catalyze Two Successive Oxidation Steps of Plant Hormone Jasmonoyl-isoleucine for Catabolic Turnover
Cytochromes P450 CYP94C1 and CYP94B3 Catalyze Two Successive Oxidation Steps of Plant Hormone Jasmonoyl-isoleucine for Catabolic Turnover
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DOI：
10.1074/jbc.m111.316364
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发表时间：
2012-02-24
影响因子：
4.8
通讯作者：
Pinot, Franck
中科院分区：
文献类型：
--
作者：
Heitz, Thierry;Widemann, Emilie;Pinot, Franck
茉莉酸激素途径调节植物重要的防御和发育过程。茉莉酰-异亮氨酸（JA-Ile）已被鉴定为结合COI 1-JAZ共受体的特异性配体，以缓解茉莉酸响应的抑制。两种JA-Ile衍生物，12 OH-JA-Ile和12 COOH-JA-Ile，以COI 1和JAR 1依赖的方式在受伤的拟南芥叶片中积累，并反映激素的分解代谢周转。在这里，我们报告了两个伤口诱导的细胞色素P450，CYP 94 C1和CYP 94 B3，参与JA-Ile氧化的生化和遗传特征。在酵母中表达的两种酶催化具有不同特征的JA-Ile的两个连续氧化步骤。CYP 94 B3有效地进行JA-Ile到12 OH-JA-Ile的初始羟基化，几乎没有转化为12 COOH-JA-Ile，而CYP 94 C1优先催化羧基衍生物的形成。功能丧失和获得的植物系的代谢分析与体外酶性质一致。cyp 94 b3突变体在创伤后12 OH-JA-Ile水平大幅度受损，而12 COOH-JA-Ile水平受损程度较小。相反，cyp 94 c1植物显示野生型12 OH-JA-Ile积累，但损失约60%的12 COOH-JA-Ile。cyp 94 b3 cyp 94 c1双突变体超积累JA-Ile，12 COOH-JA-Ile几乎消失。不同植物基因型中不同的JA-Ile氧化模式与特定的JA-responsive转录谱相关，表明JA-Ile氧化状态影响信号传导。有趣的是，夸张的JA-Ile水平与JAZ阻遏物过度诱导有关，但并没有持久地增强防御基因的诱导，揭示了一种新的负反馈信号环。最后，干扰CYP 94基因表达影响根系生长对外源茉莉酸的敏感性。这些结果确定CYP 94 B3/C1介导的氧化作用是JA-Ile激素转化的主要分解代谢途径。
The jasmonate hormonal pathway regulates important defensive and developmental processes in plants. Jasmonoyl-isoleucine (JA-Ile) has been identified as a specific ligand binding the COI1-JAZ co-receptor to relieve repression of jasmonate responses. Two JA-Ile derivatives, 12OH-JA-Ile and 12COOH-JA-Ile, accumulate in wounded Arabidopsis leaves in a COI1- and JAR1-dependent manner and reflect catabolic turnover of the hormone. Here we report the biochemical and genetic characterization of two wound-inducible cytochromes P450, CYP94C1 and CYP94B3, that are involved in JA-Ile oxidation. Both enzymes expressed in yeast catalyze two successive oxidation steps of JA-Ile with distinct characteristics. CYP94B3 performed efficiently the initial hydroxylation of JA-Ile to 12OH-JA-Ile, with little conversion to 12COOH-JA-Ile, whereas CYP94C1 catalyzed preferentially carboxy-derivative formation. Metabolic analysis of loss-and gain-of-function plant lines were consistent with in vitro enzymatic properties. cyp94b3 mutants were largely impaired in 12OH-JA-Ile levels upon wounding and to a lesser extent in 12COOH-JA-Ile levels. In contrast, cyp94c1 plants showed wild-type 12OH-JA-Ile accumulation but lost about 60% 12COOH-JA-Ile. cyp94b3cyp94c1 double mutants hyperaccumulated JA-Ile with near abolition of 12COOH-JA-Ile. Distinct JA-Ile oxidation patterns in different plant genotypes were correlated with specific JA-responsive transcript profiles, indicating that JA-Ile oxidation status affects signaling. Interestingly, exaggerated JA-Ile levels were associated with JAZ repressor hyperinduction but did not enhance durably defense gene induction, revealing a novel negative feedback signaling loop. Finally, interfering with CYP94 gene expression affected root growth sensitivity to exogenous jasmonic acid. These results identify CYP94B3/C1-mediated oxidation as a major catabolic route for turning over the JA-Ile hormone.