Heat-induced inhibition of phosphorylation of the stress-protective transcription factor DREB2A promotes thermotolerance of Arabidopsis thaliana
Heat-induced inhibition of phosphorylation of the stress-protective transcription factor DREB2A promotes thermotolerance of Arabidopsis thaliana
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DOI：
10.1074/jbc.ra118.002662
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发表时间：
2019-01-18
影响因子：
4.8
通讯作者：
Yamaguchi-Shinozaki, Kazuko
中科院分区：
文献类型：
--
作者：
Mizoi, Junya;Kanazawa, Natsumi;Yamaguchi-Shinozaki, Kazuko
植物已经进化出复杂的系统，以迅速应对严重的压力条件，如热、冷和脱水。脱水响应元件结合蛋白2A （DREB2A）是一个关键的转录激活因子，可诱导许多热和干旱响应基因，增加对高温和干旱胁迫的耐受性，并抑制拟南芥的生长。DREB2A的表达是由应激诱导的，但DREB2A蛋白在应激下的稳定对于激活下游应激诱导基因的表达至关重要。在非应激生长条件下，一个积分负调控域（integral negative regulatory domain， NRD）会破坏DREB2A的稳定性，但DREB2A在应激条件下稳定的机制尚不清楚。在这里，基于生物信息学、突变、质谱和生化分析，我们报告了NRD中的丝氨酸/苏氨酸残基在非胁迫生长条件下被磷酸化，并且它们的磷酸化响应于热而降低。此外，我们发现这种磷酸化可能是由酪蛋白激酶1介导的，并且对于非应激条件下nrd依赖性的DREB2A蛋白酶体降解是必不可少的。这些观察结果表明，抑制NRD磷酸化可以稳定和激活DREB2A，以应对热胁迫，增强植物的耐热性。我们的研究揭示了通过胁迫依赖性转录调控调控植物抗逆性和生长协调的分子基础，这可能使植物能够快速响应波动的环境条件。
Plants have evolved complex systems to rapidly respond to severe stress conditions, such as heat, cold, and dehydration. Dehydration-responsive element-binding protein 2A (DREB2A) is a key transcriptional activator that induces many heat- and drought-responsive genes, increases tolerance to both heat and drought stress, and suppresses plant growth in Arabidopsis thaliana. DREB2A expression is induced by stress, but stabilization of the DREB2A protein in response to stress is essential for activating the expression of downstream stress-inducible genes. Under nonstress growth conditions, an integral negative regulatory domain (NRD) destabilizes DREB2A, but the mechanism by which DREB2A is stabilized in response to stress remains unclear. Here, based on bioinformatics, mutational, MS, and biochemical analyses, we report that Ser/Thr residues in the NRD are phosphorylated under nonstress growth conditions and that their phosphorylation decreases in response to heat. Furthermore, we found that this phosphorylation is likely mediated by casein kinase 1 and is essential for the NRD-dependent, proteasomal degradation of DREB2A under nonstress conditions. These observations suggest that inhibition of NRD phosphorylation stabilizes and activates DREB2A in response to heat stress to enhance plant thermotolerance. Our study reveals the molecular basis for the coordination of stress tolerance and plant growth through stress-dependent transcriptional regulation, which may allow the plants to rapidly respond to fluctuating environmental conditions.