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Abstract：
Protein arginine N-methyltransferases are a family of epigenetic enzymes responsible for monomethylation or dimethylation of arginine residues on histones. Dysregulation of protein arginine N-methyltransferase activity can lead to aberrant gene expression and cancer. Recent studies have shown that PRMT2 expression and histone H3 methylation at arginine 8 are correlated with disease severity in glioblastoma multiforme, hepatocellular carcinoma, and renal cell carcinoma. In this study, we explore a noncatalytic mechanistic role for PRMT2 in histone methylation by investigating interactions between PRMT2, histone peptides and proteins, and other PRMTs using analytical and enzymatic approaches. We quantify interactions between PRMT2, peptide ligands, and PRMT1 in a cofactor- and domain-dependent manner using differential scanning fluorimetry. We found that PRMT2 modulates the substrate specificity of PRMT1. Using calf thymus histones as substrates, we saw that a 10-fold excess of PRMT2 promotes PRMT1 methylation of both histone H4 and histone H2A. We found equimolar or a 10-fold excess of PRMT2 to PRMT1 can improve the catalytic efficiency of PRMT1 towards individual histone substrates H2A, H3, and H4. We further evaluated the effects of PRMT2 towards PRMT1 on unmodified histone octamers and mononucleosomes and found marginal PRMT1 activity improvements in histone octamers but significantly greater methylation of mononucleosomes in the presence of 10-fold excess of PRMT2. This work reveals the ability of PRMT2 to serve a noncatalytic role through its SH3 domain in driving site-specific histone methylation marks.
摘要：
蛋白质精氨酸N-甲基转移酶是负责组蛋白上精氨酸残基的单甲基化或二甲基化的表观遗传酶家族。蛋白质精氨酸N-甲基转移酶活性的失调可导致异常基因表达和癌症。最近的研究表明，在多形性胶质母细胞瘤中，PRMT2的表达和精氨酸8处的组蛋白H3甲基化与疾病的严重程度相关。肝细胞癌，和肾细胞癌。在这项研究中,我们通过研究PRMT2，组蛋白肽和蛋白质之间的相互作用，探索了PRMT2在组蛋白甲基化中的非催化机制作用，和其他使用分析和酶促方法的PRMT。我们量化了PRMT2，肽配体，和PRMT1以辅因子和结构域依赖的方式使用差示扫描荧光测定法。我们发现PRMT2调节PRMT1的底物特异性。用小牛胸腺组蛋白作为底物,我们发现10倍过量的PRMT2促进组蛋白H4和组蛋白H2A的PRMT1甲基化。我们发现PRMT2与PRMT1等摩尔或10倍过量可以提高PRMT1对单个组蛋白底物H2A的催化效率，H3，和H4。我们进一步评估了PRMT2对PRMT1对未修饰的组蛋白八聚体和单核体的影响，发现组蛋白八聚体中PRMT1活性的边缘改善，但在存在10倍过量的PRMT2的情况下，单核体的甲基化显着增加。这项工作揭示了PRMT2通过其SH3结构域在驱动位点特异性组蛋白甲基化标记中发挥非催化作用的能力。
