Mammalian Protein Arginine Methyltransferase 7 (PRMT7) Specifically Targets RXR Sites in Lysine- and Arginine-rich Regions
Mammalian Protein Arginine Methyltransferase 7 (PRMT7) Specifically Targets RXR Sites in Lysine- and Arginine-rich Regions
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DOI：
10.1074/jbc.m113.525345
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发表时间：
2013-12-27
影响因子：
4.8
通讯作者：
Clarke, Steven G.
中科院分区：
文献类型：
--
作者：
Feng, You;Maity, Ranjan;Clarke, Steven G.
哺乳动物蛋白精氨酸甲基转移酶7 （PRMT7）参与转录调控、DNA损伤修复、RNA剪接、细胞分化和转移。然而，它催化的反应类型及其底物特异性仍然存在争议。在这项研究中，我们纯化了在昆虫细胞中表达的重组小鼠PRMT7，显示出强大的甲基转移酶活性。使用多种底物，我们证明该酶仅催化-单甲基精氨酸残基的形成，并证实其活性为原型III型蛋白精氨酸甲基转移酶。该酶在所有重组人核心组蛋白上都有活性，但组蛋白H2B是高度优选的底物。对完整组蛋白H2B、H2B和H4肽内的特异性甲基化位点的分析揭示了新的翻译后修饰位点和PRMT7对赖氨酸和精氨酸丰富区域的精氨酸残基甲基化的独特特异性。我们证明了一个突出的底物识别基序由一对由一个残基（RXR基序）分开的精氨酸残基组成。这些发现将显著加快PRMT7的底物分析、生物学功能研究和抑制剂的发现。
The mammalian protein arginine methyltransferase 7 (PRMT7) has been implicated in roles of transcriptional regulation, DNA damage repair, RNA splicing, cell differentiation, and metastasis. However, the type of reaction that it catalyzes and its substrate specificity remain controversial. In this study, we purified a recombinant mouse PRMT7 expressed in insect cells that demonstrates a robust methyltransferase activity. Using a variety of substrates, we demonstrate that the enzyme only catalyzes the formation of -monomethylarginine residues, and we confirm its activity as the prototype type III protein arginine methyltransferase. This enzyme is active on all recombinant human core histones, but histone H2B is a highly preferred substrate. Analysis of the specific methylation sites within intact histone H2B and within H2B and H4 peptides revealed novel post-translational modification sites and a unique specificity of PRMT7 for methylating arginine residues in lysine- and arginine-rich regions. We demonstrate that a prominent substrate recognition motif consists of a pair of arginine residues separated by one residue (RXR motif). These findings will significantly accelerate substrate profile analysis, biological function study, and inhibitor discovery for PRMT7.