Maymon Tzofia, Eisner Nadav, Bar-Zvi Dudy
Department of Life Sciences, Ben-Gurion University of the Negev, 1 Ben-Gurion Blvd, Beer-Sheva 8410501, Israel.
The Doris and Bertie I. Black Center for Bioenergetics in Life Sciences, Ben-Gurion University of the Negev, 1 Ben-Gurion Blvd, Beer-Sheva 8410501, Israel.
Plants (Basel). 2022 Aug 22;11(16):2179. doi: 10.3390/plants11162179.
The Arabidopsis transcription factor ABSCISIC ACID INSENSITIVE 4 (ABI4) is a key player in the plant hormone abscisic acid (ABA) signaling pathway and is involved in plant response to abiotic stress and development. Expression of the gene is tightly regulated, with low basal expression. Maximal transcript levels occur during the seed maturation and early seed germination stages. Moreover, ABI4 is an unstable, lowly expressed protein. Here, we studied factors affecting the stability of the ABI4 protein using transgenic Arabidopsis plants expressing . Despite the expression of eGFP-tagged ABI4 being driven by the highly active 35S CaMV promoter, low steady-state levels of ABI4 were detected in the roots of seedlings grown under optimal conditions. These levels were markedly enhanced upon exposure of the seedlings to abiotic stress and ABA. ABI4 is degraded rapidly by the 26S proteasome, and we report on the role of phosphorylation of ABI4-serine 114 in regulating ABI4 stability. Our results indicate that ABI4 is tightly regulated both post-transcriptionally and post-translationally. Moreover, abiotic factors and plant hormones have similar effects on ABI4 transcripts and ABI4 protein levels. This double-check mechanism for controlling ABI4 reflects its central role in plant development and cellular metabolism.
拟南芥转录因子脱落酸不敏感4（ABI4）是植物激素脱落酸（ABA）信号通路中的关键因子，参与植物对非生物胁迫的响应及生长发育过程。该基因的表达受到严格调控，基础表达水平较低。在种子成熟和早期种子萌发阶段，转录水平达到最高。此外，ABI4是一种不稳定、低表达的蛋白质。在此，我们利用表达[具体内容缺失]的转基因拟南芥植株，研究了影响ABI4蛋白稳定性的因素。尽管eGFP标签的ABI4由高活性的35S CaMV启动子驱动表达，但在最佳条件下生长的幼苗根中，检测到的ABI4稳态水平较低。当幼苗暴露于非生物胁迫和ABA时，这些水平显著提高。ABI4可被26S蛋白酶体快速降解，我们报道了ABI4丝氨酸114磷酸化在调节ABI4稳定性中的作用。我们的结果表明，ABI4在转录后和翻译后均受到严格调控。此外，非生物因子和植物激素对ABI4转录本和ABI4蛋白水平具有相似的影响。这种控制ABI4的双重检查机制反映了其在植物发育和细胞代谢中的核心作用。
