Arabidopsis DREB2A-interacting proteins function as RING E3 ligases and negatively regulate plant drought stress-responsive gene expression
Arabidopsis DREB2A-interacting proteins function as RING E3 ligases and negatively regulate plant drought stress-responsive gene expression
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DOI：
10.1105/tpc.107.057380
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发表时间：
2008-06-01
期刊：
影响因子：
11.6
通讯作者：
Yamaguchi-Shinozaki, Kazuko
中科院分区：
文献类型：
--
作者：
Qin, Feng;Sakuma, Yoh;Yamaguchi-Shinozaki, Kazuko
脱水反应元件结合蛋白2 A(DREB2 A)转录因子控制缺水诱导基因的表达，需要翻译后修饰才能激活。激活机制尚不清楚，然而，最近发现这种蛋白质在细胞核中的稳定性对其激活很重要。在这里，我们报道了拟南芥DREB2A相互作用蛋白1(DRIP1)和DRIP2，C3HC4环状结构域蛋白的分离，这些蛋白与DREB2A蛋白在细胞核中相互作用。体外泛素化实验表明，它们的功能类似于E3泛素连接酶，能够介导DREB2a的泛素化。DRIP1在拟南芥中的过表达延迟了DREB2A调控的干旱反应基因的表达。在单一的T-DNA突变体Drop1-1和Drop2-1中，干旱诱导基因的表达略有增强。相反，在脱水胁迫下，Drop1、Drop2双突变体的基因表达显著增强。综上所述，这些数据表明DRIP1和DRIP2在植物对干旱胁迫的反应中起着负面作用。此外，全长DREB2A蛋白在Drop1-1中的过表达比在野生型背景中更稳定。这些结果表明，DRIP1和DRIP2通过靶向DREB2A26S蛋白酶体蛋白降解，在干旱响应基因的表达中起到新的负调控作用。
The DEHYDRATION-RESPONSIVE ELEMENT BINDING PROTEIN2A (DREB2A) transcription factor controls water deficit inducible gene expression and requires posttranslational modification for its activation. The activation mechanism is not well understood; however, the stability of this protein in the nucleus was recently found to be important for its activation. Here, we report the isolation of Arabidopsis thaliana DREB2A-INTERACTING PROTEIN1 (DRIP1) and DRIP2, C3HC4 RING domain-containing proteins that interact with the DREB2A protein in the nucleus. An in vitro ubiquitination assay showed that they function as E3 ubiquitin ligases and are capable of mediating DREB2A ubiquitination. Overexpression of DRIP1 in Arabidopsis delayed the expression of DREB2A-regulated drought-responsive genes. Drought-inducible gene expression was slightly enhanced in the single T-DNA mutants of drip1-1 and drip2-1. By contrast, significantly enhanced gene expression was revealed in the drip1 drip2 double mutant under dehydration stress. Collectively, these data imply that DRIP1 and DRIP2 function negatively in the response of plants to drought stress. Moreover, overexpression of full-length DREB2A protein was more stable in drip1-1 than in the wild-type background. These results suggest that DRIP1 and DRIP2 act as novel negative regulators in drought-responsive gene expression by targeting DREB2A to 26S proteasome proteolysis.