Arabidopsis ING and Alfin1-like protein families localize to the nucleus and bind to H3K4me3/2 via plant homeodomain fingers
Arabidopsis ING and Alfin1-like protein families localize to the nucleus and bind to H3K4me3/2 via plant homeodomain fingers
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DOI：
10.1111/j.1365-313x.2009.03795.x
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发表时间：
2009-05-01
期刊：
影响因子：
7.2
通讯作者：
Kwon, Chang Seob
中科院分区：
文献类型：
--
作者：
Lee, Woo Yong;Lee, Daeyoup;Kwon, Chang Seob
在酵母和动物中，赖氨酸4 （H3K4me3/2）组蛋白H3的三甲基化和二甲基化是转录活性基因的标记，这些基因最近被证明是植物同源结构域（PHD）手指的主要配体。然而，在植物中尚未发现能够与H3K4me3/2结合的PHD指。在这里，我们在拟南芥蛋白质组数据库中确定了83个典型的PHD手指，这些手指得到了SMART和Pfam预测的支持。其中，基于预测的三层结构，我们重点研究了与人类ING2和bromodomain PHD指转录因子（BPTF）高度相似的ING（生长抑制剂）同源物（AtING）和alfin1样（AL）蛋白中的PHD指。ING蛋白存在于酵母、动物和植物中，而AL蛋白只存在于植物中。体外结合实验表明拟南芥中atin和AL蛋白中的PHD指可以与H3K4me3结合，与H3K4me2结合的程度较低。此外，突变分析证实，预测的芳香笼和特定的保守酸性残基都是与H3K4me3/2结合的关键。最后，我们证明了atin和AL蛋白是在拟南芥多种组织中表达的核蛋白。因此，我们提出ING和AL蛋白是核蛋白，通过与植物中活性组蛋白标记H3K4me3/2结合参与染色质调节。
In yeast and animals, tri- and dimethylation of histone H3 at lysine 4 (H3K4me3/2) are markers of transcriptionally active genes that have recently been shown to be primary ligands for the plant homeodomain (PHD) finger. However, PHD fingers able to bind to H3K4me3/2 have not been identified in plants. Here, we identify 83 canonical PHD fingers in the Arabidopsis proteome database that are supported by both SMART and Pfam prediction. Among these, we focus on PHD fingers in ING (inhibitor of growth) homologues (AtING) and Alfin1-like (AL) proteins, which are highly similar to those in human ING2 and bromodomain PHD finger transcription factor (BPTF), based on predicted tertiary structures. ING proteins are found in yeast, animals and plants, whereas AL proteins exist only in plants. In vitro binding experiments indicated that PHD fingers in AtING and AL proteins in Arabidopsis can bind to H3K4me3, and, to a lesser extent, to H3K4me2. In addition, mutational analysis confirmed that a predicted aromatic cage and a specific conserved acidic residue are both crucial for binding to H3K4me3/2. Finally, we demonstrate that AtING and AL proteins are nuclear proteins that are expressed in various tissues of the Arabidopsis plant. Thus, we propose that ING and AL proteins are nuclear proteins that are involved in chromatin regulation by binding to H3K4me3/2, the active histone markers, in plants.