ABI5相互作用蛋白AFP4与AFP5激活/介导ABI5转录活性的机理研究

ABI5 subfamily is a class of leucine zipper transcription factors. They participated in gene expression and regulation during the late embryogenesis, and in responding ABA and stress signal transduction. AFP4 and AFP5 are two ABI5-interacting proteins, they can activate or mediate transcriptional activity of the transcription factor ABI5 in yeast cells. With smaller molecular weight, AFP4 and AFP5 have neither kinase activity nor structural similarity with various types of kinases found to date. Expression of AFP4 gene is induced by ABA in Arabidopsis. It would play as a negative regulator to ABA signal transduction. It is unclear how AFP4 and AFP5 activate / mediate transcriptional activity of ABI5. This project intends to study in depth the interacting sites between AFP4/5 and ABI5 in yeast cells, and which parts of AFP4 and AFP5 are responsible for activating or mediating transcriptional activity of ABI5. In addition, effects of ABI5 phosphorylation by SnRK2 on its transcriptional activity will be investgated and compared to the role of AFP4/5 to ABI5. Transgenic Arabidopsis will be constructed with the AFP5 promoter-driven reporter gene and then assayed for AFP5 spatiotemporal characteristics as well as ABA and stress signal responses. All of these studies are trying to provide new insights into the molecular mechanisms of AFP4 and AFP5 roles.

ABI5亚家族是一类亮氨酸拉链类转录因子,它们参与了植物种子胚胎发育晚期的基因表达调控以及ABA信号转导等生理过程。AFP4与AFP5是2个ABI5相互作用蛋白,它们可在酵母细胞中激活/介导ABI5的转录活性。AFP4与AFP5分子量较小,无激酶活性,也与目前已发现的各类激酶无结构相似性。AFP4在拟南芥中的表达受ABA诱导,可能是ABI5信号转导的负调节子。目前尚不清楚AFP4与AFP5如何激活/介导了ABI5蛋白的转录活性。本项目拟在酵母细胞中深入研究AFP4与AFP5和ABI5相互作用的部位、AFP4与AFP5的哪个区域负责激活/介导ABI5的转录活性、SnRK2磷酸化ABI5蛋白对其转录活性的影响并和AFP4与AFP5的作用相比对、构建AFP5启动子驱动的报告基因转拟南芥植株以了解AFP5的时空表达特性以及对ABA和逆境信号的响应模式。以此了解AFP4与AFP5发挥作用的分子机制。