The Arabidopsis RING E3 Ubiquitin Ligase AtAIRP2 Plays Combinatory Roles with AtAIRP1 in Abscisic Acid-Mediated Drought Stress Responses
The Arabidopsis RING E3 Ubiquitin Ligase AtAIRP2 Plays Combinatory Roles with AtAIRP1 in Abscisic Acid-Mediated Drought Stress Responses
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DOI：
10.1104/pp.111.185595
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发表时间：
2011-12-01
期刊：
影响因子：
7.4
通讯作者：
Kim, Woo Taek
中科院分区：
文献类型：
--
作者：
Cho, Seok Keun;Ryu, Moon Young;Kim, Woo Taek
泛素(Ub)-26S蛋白酶体途径参与高等植物的多种细胞过程。AtAIRP1是一种c3h2c3型RING (for Really Interesting New Gene) E3 Ub连接酶，是拟南芥（Arabidopsis thaliana）脱落酸（ABA）依赖性干旱响应的正调控因子。本研究鉴定并鉴定了拟南芥aba不敏感环蛋白2 （AtAIRP2）基因。AtAIRP2编码胞质c3hc4型RING E3 Ub连接酶，ABA和脱水胁迫显著诱导其表达。因此，AtAIRP2与AtAIRP1属于不同的RING子类，具有有限的序列同一性。atairp2过表达转基因植株（35S: atairp2 - sgfp）和atairp2功能缺失突变植株在种子萌发、根系生长和气孔运动方面分别表现出对ABA敏感和不敏感的表型。35S: atairp2 - sgfp植物对严重干旱胁迫具有高度的耐受性，atairp2等位基因对水分胁迫的敏感性高于野生型植物。与atairp2植株相比，35S: atairp2 - sgfp植株的干旱诱导过氧化氢产量更高。aba诱导的干旱相关基因在35S: atairp2 - sgfp中上调，在atairp2后代中下调。AtAIRP2对ABA诱导的应激基因的积极作用依赖于snf1相关蛋白激酶，这是ABA信号通路的关键成分。因此，AtAIRP2参与aba依赖性干旱胁迫响应的正调控。为了研究AtAIRP1和AtAIRP2之间的功能关系，FLAG-AtAIRP1和AtAIRP2- sgfp基因分别在AtAIRP2- 2和AtAIRP1植株中异位表达。FLAG-AtAIRP1和AtAIRP2-sGFP分别在atairp2-2和atairp1植株中的组成性表达，在萌发过程中相互挽救了aba不敏感表型的丧失。此外，与atairp1和atairp2-2单敲除植株相比，atairp1/ 35s: AtAIRP2-sGFP和atairp2-2/ 35s: FLAG-AtAIRP1互补系对脱水胁迫的耐受性更强。综上所述，这些结果表明AtAIRP2与AtAIRP1在拟南芥aba介导的干旱胁迫响应中发挥联合作用。
The ubiquitin (Ub)-26S proteasome pathway is implicated in various cellular processes in higher plants. AtAIRP1, a C3H2C3-type RING (for Really Interesting New Gene) E3 Ub ligase, is a positive regulator in the Arabidopsis (Arabidopsis thaliana) abscisic acid (ABA)-dependent drought response. Here, the AtAIRP2 (for Arabidopsis ABA-insensitive RING protein 2) gene was identified and characterized. AtAIRP2 encodes a cytosolic C3HC4-type RING E3 Ub ligase whose expression was markedly induced by ABA and dehydration stress. Thus, AtAIRP2 belongs to a different RING subclass than AtAIRP1 with a limited sequence identity. AtAIRP2-overexpressing transgenic (35S:AtAIRP2-sGFP) and atairp2 loss-of-function mutant plants exhibited hypersensitive and hyposensitive phenotypes, respectively, to ABA in terms of seed germination, root growth, and stomatal movement. 35S: AtAIRP2-sGFP plants were highly tolerant to severe drought stress, and atairp2 alleles were more susceptible to water stress than were wild-type plants. Higher levels of drought-induced hydrogen peroxide production were detected in 35S: AtAIRP2-sGFP as compared with atairp2 plants. ABA-inducible drought-related genes were up-regulated in 35S: AtAIRP2-sGFP and down-regulated in atairp2 progeny. The positive effects of AtAIRP2 on ABA-induced stress genes were dependent on SNF1-related protein kinases, key components of the ABA signaling pathway. Therefore, AtAIRP2 is involved in positive regulation of ABA-dependent drought stress responses. To address the functional relationship between AtAIRP1 and AtAIRP2, FLAG-AtAIRP1 and AtAIRP2-sGFP genes were ectopically expressed in atairp2-2 and atairp1 plants, respectively. Constitutive expression of FLAG-AtAIRP1 and AtAIRP2-sGFP in atairp2-2 and atairp1 plants, respectively, reciprocally rescued the loss-of-function ABA-insensitive phenotypes during germination. Additionally, atairp1/35S: AtAIRP2-sGFP and atairp2-2/35S: FLAG-AtAIRP1 complementation lines were more tolerant to dehydration stress relative to atairp1 and atairp2-2 single knockout plants. Overall, these results suggest that AtAIRP2 plays combinatory roles with AtAIRP1 in Arabidopsis ABA-mediated drought stress responses.