Plant Physiol.:水稻泛素連接酶調控乾旱脅迫信號轉導研究獲進展

乾旱脅迫嚴重影響農作物的產量和質量，在當前人口日益增長和糧食缺乏的情況下，對其調控機制進行研究顯得極為迫切和重要。泛素介導的蛋白酶體途徑是植物體內蛋白質修飾最重要的調控機制之一，其功能涉及植物細胞周期和光周期調控、激素信號轉導、新陳代謝調控和DNA修復等多個過程。目前擬南芥中一系列研究表明泛素介導的蛋白酶體途徑也參與對植物乾旱脅迫響應過程的調控，但泛素蛋白酶體途徑是否同樣參與水稻乾旱響應過程調控還不清楚。

中科院遺傳與發育生物學研究所謝旗實驗室等通過生物化學、分子生物學和遺傳學相結合的方法，研究鑑定出SINA類型泛素連接酶OsDIS1負調控水稻乾旱脅迫響應過程。OsDIS1過量表達削弱了水稻對乾旱的抗耐性，而RNAi幹擾抑制表達卻增強了水稻對乾旱的抗耐性。全基因組表達分析結果表明，OsDIS1基因在轉錄水平上主要通過抑制一系列乾旱正調控因子和誘導一系列乾旱負調控因子的表達，來負調控水稻的乾旱脅迫響應過程。

酵母雙雜交發現，OsDIS1與一個絲氨酸/蘇氨酸類激酶OsNek6相互作用，而且OsDIS1可通過泛素化促進OsNek6的降解，OsNek6可能是OsDIS1泛素化的底物。以上結果表明，OsDIS1在轉錄水平上通過調節一系列逆境相關基因的表達，翻譯後修飾水平上通過和OsNek6互作調控水稻的乾旱脅迫響應過程。

該項研究對進一步深入研究泛素蛋白酶體途徑參與水稻乾旱響應過程的分子機制提供了新線索，也對水稻抗旱分子育種提供了理論基礎。

該研究結果已於6月30在線發表於Plant Physiology。謝旗實驗室與王國梁教授實驗室聯合培養博士生寧約瑟為該論文的第一作者，謝旗研究員和王國梁教授為該論文共同通訊作者。該研究得到了科技部和國家自然科學基金委的資助。寧約瑟獲得中國科學院「西部之光」項目資助。(生物谷 Bioon.com)

生物谷推薦原文出處：

Plant Physiology   DOI: 10.1104/pp.111.180893

The SINA E3 ligase OsDIS1 Negatively Regulates Drought Response in Rice

Yuese Ning, Chat Jantasuriyarat, Qingzhen Zhao, Huawei Zhang, Songbiao Chen, Jinling Liu, Lijing Liu, Sanyan Tang, Chan Ho park, Xuejun Wang, Xionglun Liu1 , Liangying Dai, Qi Xie and Guo-Liang Wang

Ubiquitin-regulated protein degradation is a critical regulatory mechanism that controls a wide range of biological processes in plants. Here, we report that OsDIS1 (O. sativa drought-induced SINA protein 1), a C3HC4 RING finger E3 ligase, is involved in drought-stress signal transduction in rice. The expression of OsDIS1 was up-regulated by drought treatment. In vitro ubiquitination assays showed that OsDIS1 possessed E3 ubiquitin ligase activity, and that the conserved region of the RING finger was required for the activity. Transient expression assays in Nicotiana benthamiana leaves and rice protoplasts indicated that OsDIS1 was localized predominantly in the nucleus. Overexpression of OsDIS1 reduced drought tolerance in transgenic rice plants while RNAi silencing of OsDIS1 enhanced drought tolerance. Microarray analysis revealed that a large number of drought-responsive genes were induced or suppressed in the OsDIS1 overexpression plants under normal and drought conditions. Yeast two-hybrid screening showed that OsDIS1 interacted with OsNek6, a tubulin complex-related serine/threonine protein kinase. Co-expression assays in N. benthamiana leaves indicated that OsNek6 was degraded by OsDIS1 via the 26S proteosome-dependent pathway, and that this degradation was abolished by the OsDIS1(H71Y) mutation, which is essential for its E3 ligase activity. Together, these results demonstrate that OsDIS1 plays a negative role in drought stress tolerance through transcriptional regulation of diverse stress-related genes and possibly through post-translational regulation of OsNek6 in rice.

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