Ohta M, Matsui K, Hiratsu K, Shinshi H, Ohme-Takagi M
Gene Discovery Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, Tsukuba 305-8566, Japan.
Plant Cell. 2001 Aug;13(8):1959-68. doi: 10.1105/tpc.010127.
We reported previously that three ERF transcription factors, tobacco ERF3 (NtERF3) and Arabidopsis AtERF3 and AtERF4, which are categorized as class II ERFs, are active repressors of transcription. To clarify the roles of these repressors in transcriptional regulation in plants, we attempted to identify the functional domains of the ERF repressor that mediates the repression of transcription. Analysis of the results of a series of deletions revealed that the C-terminal 35 amino acids of NtERF3 are sufficient to confer the capacity for repression of transcription on a heterologous DNA binding domain. This repression domain suppressed the intermolecular activities of other transcriptional activators. In addition, fusion of this repression domain to the VP16 activation domain completely inhibited the transactivation function of VP16. Comparison of amino acid sequences of class II ERF repressors revealed the conservation of the sequence motif (L)/(F)DLN(L)/(F)(x)P. This motif was essential for repression because mutations within the motif eliminated the capacity for repression. We designated this motif the ERF-associated amphiphilic repression (EAR) motif, and we identified this motif in a number of zinc-finger proteins from wheat, Arabidopsis, and petunia plants. These zinc finger proteins functioned as repressors, and their repression domains were identified as regions that contained an EAR motif.
我们之前报道过，三种ERF转录因子，即烟草ERF3（NtERF3）以及拟南芥AtERF3和AtERF4，它们被归类为II类ERF，是转录的活性阻遏物。为了阐明这些阻遏物在植物转录调控中的作用，我们试图鉴定介导转录抑制的ERF阻遏物的功能结构域。一系列缺失结果的分析表明，NtERF3的C端35个氨基酸足以赋予异源DNA结合结构域转录抑制能力。该抑制结构域抑制了其他转录激活因子的分子间活性。此外，该抑制结构域与VP16激活结构域的融合完全抑制了VP16的反式激活功能。II类ERF阻遏物氨基酸序列的比较揭示了序列基序（L）/（F）DLN（L）/（F）（x）P的保守性。该基序对于抑制至关重要，因为基序内的突变消除了抑制能力。我们将此基序命名为ERF相关两亲性抑制（EAR）基序，并且我们在来自小麦、拟南芥和矮牵牛植物的许多锌指蛋白中鉴定到了这个基序。这些锌指蛋白作为阻遏物发挥作用，并且它们的抑制结构域被鉴定为包含EAR基序的区域。
