Texas A&M AgriLife Research and Extension Center, Weslaco, Texas 79596, USA.
Department of Biology, Texas A&M University, College Station, Texas 77843, USA.
Plant Physiol. 2022 Jan 20;188(1):397-410. doi: 10.1093/plphys/kiab450.
The Arabidopsis (Arabidopsis thaliana) BTB-TAZ DOMAIN PROTEIN 2 (BT2) contains an N-terminal BTB domain, a central TAZ zinc-finger protein-protein interaction domain, and a C-terminal calmodulin-binding domain. We previously demonstrated that BT2 regulates telomerase activity and mediates multiple responses to nutrients, hormones, and abiotic stresses in Arabidopsis. Here, we describe the essential role of BT2 in activation of genes by multimerized Cauliflower mosaic virus 35S (35S) enhancers. Loss of BT2 function in several well-characterized 35S enhancer activation-tagged lines resulted in suppression of the activation phenotypes. Suppression of the phenotypes was associated with decreased transcript abundance of the tagged genes. Nuclear run-on assays, mRNA decay studies, and bisulfite sequencing revealed that BT2 is required to maintain the transcriptionally active state of the multimerized 35S enhancers, and lack of BT2 leads to hypermethylation of the 35S enhancers. The TAZ domain and the Ca++/calmodulin-binding domain of BT2 are critical for its function and 35S enhancer activity. We further demonstrate that BT2 requires CULLIN3 and two bromodomain-containing Global Transcription factor group E proteins (GTE9 and GTE11), to regulate 35S enhancer activity. We propose that the BT2-CULLIN3 ubiquitin ligase, through interactions with GTE9 and GTE11, regulates 35S enhancer activity in Arabidopsis.
拟南芥（Arabidopsis thaliana）BTB-TAZ 结构域蛋白 2（BT2）含有一个 N 端 BTB 结构域、一个中央 TAZ 锌指蛋白-蛋白相互作用结构域和一个 C 端钙调蛋白结合结构域。我们之前的研究表明，BT2 调节端粒酶活性，并介导拟南芥对营养物质、激素和非生物胁迫的多种反应。在这里，我们描述了 BT2 在多聚花椰菜花叶病毒 35S（35S）增强子激活基因中的重要作用。在几个经过充分表征的 35S 增强子激活标签线中，BT2 功能的丧失导致激活表型的抑制。表型的抑制与标记基因的转录本丰度降低有关。核运行试验、mRNA 衰减研究和亚硫酸氢盐测序表明，BT2 是维持多聚体 35S 增强子转录活性状态所必需的，并且缺乏 BT2 导致 35S 增强子的过度甲基化。BT2 的 TAZ 结构域和 Ca++/钙调蛋白结合结构域对于其功能和 35S 增强子活性至关重要。我们进一步证明，BT2 需要 CULLIN3 和两个含有溴结构域的全局转录因子组 E 蛋白（GTE9 和 GTE11）来调节 35S 增强子活性。我们提出，BT2-CULLIN3 泛素连接酶通过与 GTE9 和 GTE11 的相互作用，调节拟南芥中 35S 增强子的活性。
