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.

中文翻译：

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花椰菜花叶病毒 35S 多聚增强子的基因激活需要 BTB-TAZ 蛋白


拟南芥 (Arabidopsis thaliana) BTB-TAZ 结构域蛋白 2 (BT2) 包含 N 端 BTB 结构域、中心 TAZ 锌指蛋白-蛋白相互作用结构域和 C 端钙调蛋白结合结构域。我们之前证明，BT2 在拟南芥中调节端粒酶活性并介导对营养物质、激素和非生物胁迫的多种反应。在这里，我们描述了 BT2 在多聚化花椰菜花叶病毒 35S (35S) 增强子激活基因中的重要作用。几个特征明确的 35S 增强子激活标记品系中 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转录本丰度的降低有关。核连续分析、mRNA 衰变研究和亚硫酸氢盐测序表明，BT2 是维持多聚化 35S 增强子的转录活性状态所必需的，并且缺乏 BT2 会导致 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 和两个含溴结构域的全局转录因子 E 组蛋白（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 相互作用，调节拟南芥中的 35S 增强子活性。