SDIR1 is a RING finger E3 ligase that positively regulates stress-responsive abscisic acid signaling in Arabidopsis
SDIR1 is a RING finger E3 ligase that positively regulates stress-responsive abscisic acid signaling in Arabidopsis
复制标题
SDIR1 是一种环指 E3 连接酶，可正向调节拟南芥中的应激响应性脱落酸信号传导
DOI：
10.1105/tpc.106.048488
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发表时间：
2007-06-01
期刊：
影响因子：
11.6
通讯作者：
Xie, Qi
中科院分区：
文献类型：
--
作者：
Zhang, Yiyue;Yang, Chengwei;Xie, Qi
泛素化在植物激素信号转导中起着重要作用。我们发现，环指E3连接酶，拟南芥盐和干旱诱导的环FINGER1(SDIR1)，参与了与脱落酸(ABA)相关的胁迫信号转导。SDIR1在拟南芥的所有组织中都有表达，并且在干旱和盐胁迫下表达上调，但不受ABA的上调。表达ProSDIR1-β-葡萄糖醛酸苷酶(GUS)报告基因的植物构建证实了干旱胁迫下GUS在气孔保卫细胞和叶肉细胞中的强烈诱导表达。绿色荧光蛋白-SDIR1融合蛋白与胞内膜共定位。我们证明了SDIR1是一种E3泛素连接酶，其活性需要环指保守区。SDIR1的过表达导致了ABA敏感和ABA相关的表型，如萌发过程中的盐敏感，增强了ABA诱导的气孔关闭，增强了抗旱性。在SDIR1过表达和sdir1-1突变植株中，许多关键的ABA和胁迫标记基因的表达水平都发生了变化。交叉互补实验表明，ABA-INSENSITIVE5(ABI5)、AbRE结合因子3(ABF3)和ABF4基因可以挽救sdir1-1突变体对ABA不敏感的表型，而SDIR1不能挽救abi5-1突变体。这表明SDIR1在那些基本的亮氨酸拉链家族基因的上游起作用。我们的结果表明，SDIR1是ABA信号的正向调节因子。
Ubiquitination plays important roles in plant hormone signal transduction. We show that the RING finger E3 ligase, Arabidopsis thaliana SALT- AND DROUGHT-INDUCED RING FINGER1 (SDIR1), is involved in abscisic acid (ABA)-related stress signal transduction. SDIR1 is expressed in all tissues of Arabidopsis and is upregulated by drought and salt stress, but not by ABA. Plants expressing the ProSDIR1-beta-glucuronidase (GUS) reporter construct confirmed strong induction of GUS expression in stomatal guard cells and leaf mesophyll cells under drought stress. The green fluorescent protein-SDIR1 fusion protein is colocalized with intracellular membranes. We demonstrate that SDIR1 is an E3 ubiquitin ligase and that the RING finger conservation region is required for its activity. Overexpression of SDIR1 leads to ABA hypersensitivity and ABA-associated phenotypes, such as salt hypersensitivity in germination, enhanced ABA-induced stomatal closing, and enhanced drought tolerance. The expression levels of a number of key ABA and stress marker genes are altered both in SDIR1 overexpression and sdir1-1 mutant plants. Cross-complementation experiments showed that the ABA-INSENSITIVE5 (ABI5), ABRE BINDING FACTOR3 (ABF3), and ABF4 genes can rescue the ABA-insensitive phenotype of the sdir1-1 mutant, whereas SDIR1 could not rescue the abi5-1 mutant. This suggests that SDIR1 acts upstream of those basic leucine zipper family genes. Our results indicate that SDIR1 is a positive regulator of ABA signaling.