SUMO化修饰调控拟南芥转录因子DREB2A的功能研究

Drought and heat stresses are the main factors that threaten plant growth and crop yield. DREB2A is a key transcription factor responding to drought and heat stresses in Arabidopsis, but the mechanisms of maintaining its protein stability and activating its transcription factor function under stress conditions are unclear. Sumoylation is an important regulating process which functions in plant growth and development as well as abiotic stress. We have recently found that SUMO E2 conjugation enzyme AtSCE1 interacted with DREB2A under stress conditions, and DREB2A can be modified by SUMO, and sumoylation has enhanced its stability under drought and heat conditions. These results suggested that sumoylation may play an important role in regulating the stability and activity of DREB2A protein. Based on these data, we will study the molecular mechanisms of DREB2A stability and transcriptional activity regulated by sumoylation in response to drought and heat stresses using moleculars biology, genetics and biochemical methods. The results from this study will not only clarify the interaction between SUMO pathway and DREB2A pathway, but also improve the transcriptional regulation network of DREB2A in response to drought and heat stresses.

干旱和高温胁迫是威胁植物生长发育及作物产量的主要逆境因子。拟南芥DREB2A是响应干旱及高温胁迫的关键转录因子，但其在胁迫条件下如何维持蛋白质稳定性并被激活其转录活性的机制尚不清楚。SUMO 化是影响植物生长发育和非生物胁迫的重要调控方式。最近我们发现，SUMO E2 结合酶AtSCE1在胁迫条件下能够与DREB2A相互作用，且DREB2A能被SUMO化修饰，SUMO化增强了其在干旱及高温条件下的稳定性。上述结果表明，SUMO化在胁迫条件下对调控DREB2A蛋白的稳定性及活性具有重要的作用。在此基础上，本项目拟利用遗传学、分子生物学及生物化学方法，深入研究SUMO化修饰增强DREB2A稳定性及调控其转录活性来响应胁迫的具体分子机制。通过对SUMO化修饰调控DREB2A功能的阐释，揭示SUMO途径与DREB2A途径之间的关系，进一步完善DREB2A响应干旱及高温胁迫的转录调控网络。

拟南芥DREB2A是响应干旱及高温胁迫的关键转录因子，但其在胁迫条件下如何维持蛋白质稳定性并被激活其转录活性的机制尚不清楚。SUMO 化是影响植物生长发育和非生物胁迫的重要调控方式。本项目通过一系列生化及分子手段证实，拟南芥的DREB2A蛋白在高温等胁迫条件下能够被SUMO化修饰，是SUMO化修饰参与高温胁迫途径中新的底物蛋白。进一步生化数据发现，DREB2A在K163赖氨酸残基处被SUMO化，这是位于与负调控区域（NRD，抑制作用的motif）相邻的保守残基。DREB2A的SUMOylation抑制了其与泛素化连接酶BPM2的相互作用，进而导致DREB2A不能被泛素化修饰而降解，从而提高了DREB2A在高温等胁迫条件下的蛋白质稳定性。对下游与热胁迫相关的标志基因检测发现，SUMO化修饰进一步增强了其转录活性。通过 RNA-seq 研究野生型和 K163R 突变型 DREB2A 过表达植物在高温条件下的基因差异发现，多条信号通路的基因转录水平有所不同。本项目揭示了SUMO化调控DREB2A的功能机制，进一步完善DREB2A响应干旱及高温胁迫的转录调控网络，为下一步创制抗旱、耐高温的新种质奠定基础。