The MADS transcription factors (TF) constitute an ancient family of TF found in all eukaryotes that bind DNA as obligate dimers. Plants have dramatically expanded the functional diversity of the MADS family during evolution by adding protein–protein interaction domains to the core DNA-binding domain, allowing the formation of heterotetrameric complexes. Tetramerization of plant MADS TFs is believed to play a central role in the evolution of higher plants by acting as one of the main determinants of flower formation and floral organ specification. The MADS TF, SEPALLATA3 (SEP3), functions as a central protein–protein interaction hub, driving tetramerization with other MADS TFs. Here, we use a SEP3 splice variant, SEP3^Δtet, which has dramatically abrogated tetramerization capacity to decouple SEP3 tetramerization and DNA-binding activities. We unexpectedly demonstrate that SEP3 heterotetramer formation is required for correct termination of the floral meristem, but plays a lesser role in floral organogenesis. The heterotetramer formed by SEP3 and the MADS protein, AGAMOUS, is necessary to activate two target genes, KNUCKLES and CRABSCLAW, which are required for meristem determinacy. These studies reveal unique and highly specific roles of tetramerization in flower development and suggest tetramerization may be required to activate only a subset of target genes in closed chromatin regions.

中文翻译：

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拟南芥中花分生组织确定性需要MADS家族转录因子SEPALLATA3和AGAMOUS的四聚化

MADS转录因子（TF）构成了一个古老的TF家族，存在于所有将DNA结合为专性二聚体的真核生物中。植物在进化过程中通过向核心DNA结合结构域添加蛋白质-蛋白质相互作用域，从而形成异四聚体复合物，极大地扩展了MADS家族的功能多样性。据信，植物MADS TFs的四聚体通过充当花形成和花器官规格的主要决定因素之一，在高等植物的进化中发挥核心作用。MADS TF，SEPALLATA3（SEP3），起着蛋白质-蛋白质相互作用的中心作用，与其他MADS TFs发生四聚作用。在这里，我们使用^SEP3剪接变体^SEP3Δtet，它具有极大的消除四聚作用的能力，从而使SEP3四聚作用与DNA结合活性脱钩。我们意外地证明，SEP3异四聚体的形成对于花分生组织的正确终止是必需的，但在花器官发生中的作用较小。由SEP3和MADS蛋白AGAMOUS形成的异四聚体对于激活两个目标基因，即分生组织确定性必需的KNUCKLES和CRABSCLAW是必需的。这些研究揭示了四聚体在花发育中的独特且高度特异性的作用，并暗示可能需要四聚体才能激活封闭染色质区域中的靶基因的一个子集。