MADS transcription factors are master regulators of plant reproduction and flower development. The SEPALLATA (SEP) subfamily of MADS transcription factors is required for the development of floral organs and plays roles in inflorescence architecture and development of the floral meristem. SEPALLATAs act as organizers of MADS complexes, forming both heterodimers and heterotetramers in vitro. To date, the MADS complexes characterized in angiosperm floral organ development contain at least one SEPALLATA protein. Whether DNA-binding by SEPALLATA-containing dimeric MADS complexes is sufficient for launching floral organ identity programs, however, is not clear as only defects in floral meristem determinacy were observed in tetramerization--impaired SEPALLATA mutant proteins. Here, we used a combination of genome-wide binding studies, high resolution structural studies of the SEP3/AGAMOUS (AG) tetramerization domain, structure-based mutagenesis and complementation experiments in Arabidopsis (Arabidopsis thaliana) sep1 sep2 sep3 and sep1 sep2 sep3 ag-4 plants transformed with versions of SEP3 encoding tetramerization mutants. We demonstrate that while SEP3 heterodimers can bind DNA both in vitro and in vivo and recognize the majority of SEP3 wild-type binding sites genome-wide, tetramerization is required not only for floral meristem determinacy, but also for floral organ identity in the second, third and fourth whorls.

中文翻译：

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SEPALLATA 驱动的 MADS 转录因子四聚化是内轮花器官发育所必需的


MADS 转录因子是植物繁殖和花卉发育的主要调节因子。 MADS 转录因子的 SEPALLATA (SEP) 亚家族是花器官发育所必需的，并且在花序结构和花分生组织的发育中发挥作用。 SEPALLATA 作为 MADS 复合物的组织者，在体外形成异二聚体和异四聚体。迄今为止，被子植物花器官发育的 MADS 复合体含有至少一种 SEPALLATA 蛋白。然而，含 SEPALLATA 的二聚体 MADS 复合物的 DNA 结合是否足以启动花器官识别程序尚不清楚，因为在四聚化受损的 SEPALLATA 突变蛋白中仅观察到花分生组织决定性的缺陷。在这里，我们结合了全基因组结合研究、SEP3/AGAMOUS (AG) 四聚化结构域的高分辨率结构研究、拟南芥 (Arabidopsis thaliana) sep1 sep2 sep3 和 sep1 sep2 sep3 ag-中基于结构的诱变和互补实验。 4株植物用编码四聚化突变体的SEP3版本进行转化。我们证明，虽然 SEP3 异​​二聚体可以在体外和体内结合 DNA，并识别全基因组范围内的大多数 SEP3 野生型结合位点，但四聚化不仅对于花分生组织的确定性是必需的，而且对于花器官的同一性也是必需的。第三和第四轮。