Tang J, Frankel A, Cook R J, Kim S, Paik W K, Williams K R, Clarke S, Herschman H R
Molecular Biology Institute, UCLA, Los Angeles, California 90095, USA.
J Biol Chem. 2000 Mar 17;275(11):7723-30. doi: 10.1074/jbc.275.11.7723.
Type I protein arginine methyltransferases catalyze the formation of asymmetric omega-N(G),N(G)-dimethylarginine residues by transferring methyl groups from S-adenosyl-L-methionine to guanidino groups of arginine residues in a variety of eucaryotic proteins. The predominant type I enzyme activity is found in mammalian cells as a high molecular weight complex (300-400 kDa). In a previous study, this protein arginine methyltransferase activity was identified as an additional activity of 10-formyltetrahydrofolate dehydrogenase (FDH) protein. However, immunodepletion of FDH activity in RAT1 cells and in murine tissue extracts with antibody to FDH does not diminish type I methyltransferase activity toward the methyl-accepting substrates glutathione S-transferase fibrillarin glycine arginine domain fusion protein or heterogeneous nuclear ribonucleoprotein A1. Similarly, immunodepletion with anti-FDH antibody does not remove the endogenous methylating activity for hypomethylated proteins present in extracts from adenosine dialdehyde-treated RAT1 cells. In contrast, anti-PRMT1 antibody can remove PRMT1 activity from RAT1 extracts, murine tissue extracts, and purified rat liver FDH preparations. Tissue extracts from FDH(+/+), FDH(+/-), and FDH(-/-) mice have similar protein arginine methyltransferase activities but high, intermediate, and undetectable FDH activities, respectively. Recombinant glutathione S-transferase-PRMT1, but not purified FDH, can be cross-linked to the methyl-donor substrate S-adenosyl-L-methionine. We conclude that PRMT1 contributes the major type I protein arginine methyltransferase enzyme activity present in mammalian cells and tissues.
I 型蛋白质精氨酸甲基转移酶通过将 S-腺苷-L-甲硫氨酸的甲基转移到多种真核蛋白质中精氨酸残基的胍基上，催化不对称 ω-N(G),N(G)-二甲基精氨酸残基的形成。I 型酶的主要活性以高分子量复合物（300-400 kDa）的形式存在于哺乳动物细胞中。在先前的一项研究中，这种蛋白质精氨酸甲基转移酶活性被鉴定为 10-甲酰四氢叶酸脱氢酶（FDH）蛋白的一种额外活性。然而，用抗 FDH 抗体对 RAT1 细胞和小鼠组织提取物中的 FDH 活性进行免疫去除，并不会降低 I 型甲基转移酶对甲基接受底物谷胱甘肽 S-转移酶原纤维蛋白甘氨酸精氨酸结构域融合蛋白或不均一核核糖核蛋白 A1 的活性。同样，用抗 FDH 抗体进行免疫去除并不能消除来自腺苷二醛处理的 RAT1 细胞提取物中存在的低甲基化蛋白质的内源性甲基化活性。相比之下，抗 PRMT1 抗体可以从 RAT1 提取物、小鼠组织提取物和纯化的大鼠肝脏 FDH 制剂中去除 PRMT1 活性。来自 FDH(+/+)、FDH(+/-)和 FDH(-/-)小鼠的组织提取物具有相似的蛋白质精氨酸甲基转移酶活性，但分别具有高、中、不可检测的 FDH 活性。重组谷胱甘肽 S-转移酶-PRMT1，而不是纯化的 FDH，可以与甲基供体底物 S-腺苷-L-甲硫氨酸交联。我们得出结论，PRMT1 贡献了哺乳动物细胞和组织中存在的主要 I 型蛋白质精氨酸甲基转移酶活性。
