Plant SET- and RING-associated domain proteins in heterochromatinization
Plant SET- and RING-associated domain proteins in heterochromatinization
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DOI：
10.1111/j.1365-313x.2007.03286.x
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发表时间：
2007-12-01
期刊：
影响因子：
7.2
通讯作者：
Shen, Wen-Hui
中科院分区：
文献类型：
--
作者：
Liu, Shiming;Yu, Yu;Shen, Wen-Hui
许多真核生物的异染色质由组蛋白H3赖氨酸9（H3 K9）甲基化和DNA胞嘧啶甲基化两者标记。一些研究揭示了这两个表观遗传标记之间的联系。然而，建立这些联系的分子机制在很大程度上仍然未知。在植物中，H3 K9甲基化主要由包含SET和SRA（SET-和RING-相关）结构域的高度保守的蛋白质家族进行。在这里，我们表明，SRA-SET域H3 K9甲基转移酶NtSET 1，以及像异染色质蛋白1，结合异染色质DNA重复。在酵母双杂交试验中，NtSET 1结合DNA甲基胞嘧啶结合蛋白甲基化变异体1（VIM 1），该蛋白含有保守的PHD、SRA和RING结构域。这种结合需要含有SRA结构域的NtSET 1的N-末端或含有SET结构域和VIM 1的PHD结构域的NtSET 1的C-末端。与细胞分裂期间染色质结构的建立/维持中的作用一致，VIM 1转录物在活跃分裂的细胞中丰富，并且VIM 1蛋白定位于细胞核中。vim 1无效突变体植物表现出正常的生长表型，而过表达VIM 1的转基因拟南芥植物表现出根生长抑制和开花延迟。我们提出SRA-SET结构域H3 K9甲基转移酶与PHD-SRA-RING结构域蛋白VIM 1相关联，在异染色质化中相互加强H3 K9和DNA甲基化。
The heterochromatin of many eukaryotes is marked by both histone H3 lysine 9 (H3K9) methylation and DNA cytosine methylation. Several studies have revealed links between these two epigenetic markers. The molecular mechanisms involved in establishment of these links, however, remain largely unknown. In plants, H3K9 methylation is primarily carried out by a highly conserved family of proteins that contain SET and SRA (SET- and RING-associated) domains. Here, we show that the SRA-SET domain H3K9 methyltransferase NtSET1, as well as LIKE HETEROCHROMATIN PROTEIN1, binds heterochromatin DNA repeats. In the yeast two-hybrid assay, NtSET1 binds the DNA methylcytosine-binding protein VARIANT IN METHYLATION1 (VIM1), which contains conserved PHD, SRA and RING domains. This binding requires either the N-terminus of NtSET1 containing the SRA domain or the C-terminus of NtSET1 containing the SET domain and the PHD domain of VIM1. Consistent with a role in the establishment/maintenance of chromatin structure during cell division, VIM1 transcripts are abundant in actively dividing cells and the VIM1 protein is localized in the nucleus. While null vim1 mutant plants show a normal growth phenotype, transgenic Arabidopsis plants over-expressing VIM1 show inhibition in root growth and delay in flowering. We propose that SRA-SET domain H3K9 methyltransferases associate with the PHD-SRA-RING domain protein VIM1, mutually reinforcing H3K9 and DNA methylation in heterochromatinization.