A novel thiol-reductase activity of Arabidopsis YUC6 confers drought tolerance independently of auxin biosynthesis.
A novel thiol-reductase activity of Arabidopsis YUC6 confers drought tolerance independently of auxin biosynthesis.
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DOI：
10.1038/ncomms9041
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发表时间：
2015-08-28
影响因子：
16.6
通讯作者：
Yun DJ
中科院分区：
文献类型：
--
作者：
Cha JY;Kim WY;Kang SB;Kim JI;Baek D;Jung IJ;Kim MR;Li N;Kim HJ;Nakajima M;Asami T;Sabir JS;Park HC;Lee SY;Bohnert HJ;Bressan RA;Pardo JM;Yun DJ
YUCCA（YUC）蛋白是一个黄素单加氧酶（FMOs）家族，在植物生长素（IAA）的生物合成中起重要作用。在这里，我们报告说，拟南芥植物过表达YUC 6显示增强IAA相关的表型，并表现出改善的干旱胁迫耐受性，水分流失率低，控制ROS积累在干旱和氧化胁迫。共过表达的IAA结合酶降低IAA水平，但干旱胁迫耐受性不受影响，这表明压力相关的表型是不是基于IAA过量生产。YUC 6含有以前未被识别的FAD和NADPH依赖性巯基还原酶活性（TR），其与参与IAA生物合成的FMO结构域重叠。保守的半胱氨酸残基（Cys-85）的突变保留FMO，但抑制TR活性和胁迫耐受性，而突变TR和FMO结构域共有的FAD和NADPH结合位点，则消除所有输出。我们提供了一个范例，一个单一的蛋白质发挥双重作用，调节植物的发育和传达压力防御反应。YUC 6是植物激素生长素合成所需的黄素单加氧酶。Cha等人发现，在拟南芥中，这种酶也通过充当硫醇还原酶在对抗氧化应激中发挥作用，而与生长素生物合成无关。
YUCCA (YUC) proteins constitute a family of flavin monooxygenases (FMOs), with an important role in auxin (IAA) biosynthesis. Here we report that Arabidopsis plants overexpressing YUC6 display enhanced IAA-related phenotypes and exhibit improved drought stress tolerance, low rate of water loss and controlled ROS accumulation under drought and oxidative stresses. Co-overexpression of an IAA-conjugating enzyme reduces IAA levels but drought stress tolerance is unaffected, indicating that the stress-related phenotype is not based on IAA overproduction. YUC6 contains a previously unrecognized FAD- and NADPH-dependent thiol-reductase activity (TR) that overlaps with the FMO domain involved in IAA biosynthesis. Mutation of a conserved cysteine residue (Cys-85) preserves FMO but suppresses TR activity and stress tolerance, whereas mutating the FAD- and NADPH-binding sites, that are common to TR and FMO domains, abolishes all outputs. We provide a paradigm for a single protein playing a dual role, regulating plant development and conveying stress defence responses. YUC6 is a flavin monooxygenase required for the synthesis of the plant hormone auxin. Cha et al. discover that in Arabidopsis, this enzyme also plays a role in combatting oxidative stress independently of auxin biosynthesis, by acting as a thiol-reductase.