探究SnRK2在渗透胁迫诱导的B-RAF激酶快速强烈激活过程中的作用

干旱、高盐等诱导植物产生渗透胁迫并抑制植物的正常生长发育过程，植物需要及时地感知并快速响应环境胁迫以更好地生存。近年来多项研究均发现B RAF-SnRK2激酶级联反应在植物渗透胁迫通路中起着重要作用，但渗透胁迫如何在2分钟内快速激活B RAF蛋白激酶仍不清楚。拟南芥SnRK2突变体中渗透胁迫激活B RAF的激活程度部分降低，结合我们新发现的SnRK2.4可以强烈磷酸化B RAF的激酶结构域，我们推测SnRK2以反馈调节方式参与渗透胁迫通路中B RAF的活性调控。为验证这一假说，我们将通过生化实验检测SnRK2是否通过磷酸化增强B RAF的激酶活性，体内验证磷酸化位点在胁迫前后的磷酸化水平变化以及该位点点突变对B RAF活性及渗透胁迫应答的影响，阐明SnRK2通过磷酸化B RAF的正反馈调节途径介导渗透胁迫下B RAF快速强烈激活的分子机制。

Drought and high salinity induced osmotic stress and inhibited plant growth and development. To survive, plants need to rapidly sense and respond to environmental stress. Recent Studies found B RAF-SnRK2 kinase cascade plays an important role in plant osmotic stress pathways, but it is still unclear how B RAF kinase was rapidly activated by osmotic stress within 2 minutes. The activation of B RAF activated by osmotic stress in Arabidopsis SnRK2 mutant was partially reduced, and our newly found SnRK2.4 can strongly phosphorylate the kinase domain of B RAF, so we speculate that SnRK2 participates in the regulation of B RAF kinase activity through feedback. To verify this hypothesis, we will test whether SnRK2 enhances the kinase activity of B RAF through phosphorylation by biochemical experiments, detect the phosphorylation level changes of B RAF after stress in plant, and the effect of site mutation on the B RAF activation and osmotic stress response in plant, clarify the molecular mechanism of rapid and strong activation of B RAF under osmotic stress mediated by SnRK2 through the positive feedback pathway.