Functional analysis of an Arabidopsis transcription factor, DREB2A, involved in drought-responsive gene expression
Functional analysis of an Arabidopsis transcription factor, DREB2A, involved in drought-responsive gene expression
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DOI：
10.1105/tpc.105.035881
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发表时间：
2006-05-01
期刊：
影响因子：
11.6
通讯作者：
Yamaguchi-Shinozaki, K
中科院分区：
文献类型：
--
作者：
Sakuma, Y;Maruyama, K;Yamaguchi-Shinozaki, K
转录因子 DREB1A/CBF3 和 DREB2A 与参与拟南芥寒冷和干旱胁迫响应基因表达的顺式脱水响应元件/C 重复序列 (DRE/CRT) 特异性相互作用。完整的DREB2A表达在正常生长条件下不会激活下游基因，表明DREB2A需要翻译后修饰才能激活，但激活机制尚未阐明。使用拟南芥原生质体的 DREB2A 结构域分析鉴定了残基 254 和 335 之间的转录激活结构域，并且残基 136 和 165 之间区域的缺失将 DREB2A 转化为组成型活性形式。组成型活性 DREB2A 的过度表达导致转基因拟南芥植物具有显着的干旱胁迫耐受性，但仅具有轻微的冷冻耐受性。微阵列和 RNA 凝胶印迹分析表明 DREB2A 调节许多水分胁迫诱导基因的表达。然而，DREB2A下游的一些基因不是DREB1A的下游，DREB1A也识别DRE/CRT，但在冷应激反应基因表达中发挥作用。当合成的绿色荧光蛋白与组成型活性 DREB2A 融合时，在无应激控制条件下在细胞核中发出强信号，但当与全长 DREB2A 融合时仅发出微弱信号。 DREB2A 残基 136 和 165 之间的区域对该蛋白在细胞核中的稳定性起着重要作用，这对于蛋白激活很重要。
Transcription factors DREB1A/CBF3 and DREB2A specifically interact with cis-acting dehydration-responsive element/C-repeat (DRE/CRT) involved in cold and drought stress-responsive gene expression in Arabidopsis thaliana. Intact DREB2A expression does not activate downstream genes under normal growth conditions, suggesting that DREB2A requires posttranslational modification for activation, but the activation mechanism has not been clarified. DREB2A domain analysis using Arabidopsis protoplasts identified a transcriptional activation domain between residues 254 and 335, and deletion of a region between residues 136 and 165 transforms DREB2A to a constitutive active form. Overexpression of constitutive active DREB2A resulted in significant drought stress tolerance but only slight freezing tolerance in transgenic Arabidopsis plants. Microarray and RNA gel blot analyses revealed that DREB2A regulates expression of many water stress inducible genes. However, some genes downstream of DREB2A are not downstream of DREB1A, which also recognizes DRE/CRT but functions in cold stress-responsive gene expression. Synthetic green fluorescent protein gave a strong signal in the nucleus under unstressed control conditions when fused to constitutive active DREB2A but only a weak signal when fused to full-length DREB2A. The region between DREB2A residues 136 and 165 plays a role in the stability of this protein in the nucleus, which is important for protein activation.