State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
Protein Cell. 2012 Jun;3(6):450-9. doi: 10.1007/s13238-012-2935-3. Epub 2012 Jun 22.
Arabidopsis AtPRMT10 is a plant-specific type I protein arginine methyltransferase that can asymmetrically dimethylate arginine 3 of histone H4 with auto-methylation activity. Mutations of AtPRMT10 derepress FLOWERING LOCUS C (FLC) expression resulting in a late-flowering phenotype. Here, to further investigate the biochemical characteristics of AtPRMT10, we analyzed a series of mutated forms of the AtPRMT10 protein. We demonstrate that the conserved "VLD" residues and "double-E loop" are essential for enzymatic activity of AtPRMT10. In addition, we show that Arg54 and Cys259 of AtPRMT10, two residues unreported in animals, are also important for its enzymatic activity. We find that Arg13 of AtPRMT10 is the auto-methylation site. However, substitution of Arg13 to Lys13 does not affect its enzymatic activity. In vivo complementation assays reveal that plants expressing AtPRMT10 with VLD-AAA, E143Q or E152Q mutations retain high levels of FLC expression and fail to rescue the late-flowering phenotype of atprmt10 plants. Taken together, we conclude that the methyltransferase activity of AtPRMT10 is essential for repressing FLC expression and promoting flowering in Arabidopsis.
拟南芥 AtPRMT10 是一种植物特异性的 I 型蛋白精氨酸甲基转移酶，具有自我甲基化活性，可不对称地二甲基化组蛋白 H4 的精氨酸 3。AtPRMT10 的突变会解除 FLOWERING LOCUS C（FLC）的表达抑制，导致晚花表型。在这里，为了进一步研究 AtPRMT10 的生化特性，我们分析了一系列 AtPRMT10 蛋白的突变形式。我们证明了保守的“VLD”残基和“双-E 环”对于 AtPRMT10 的酶活性是必不可少的。此外，我们还表明，Arg54 和 Cys259 这两个在动物中未报道的残基对于其酶活性也很重要。我们发现 AtPRMT10 的 Arg13 是自我甲基化位点。然而，Arg13 突变为 Lys13 并不影响其酶活性。体内互补实验表明，表达 AtPRMT10 蛋白 VLD-AAA、E143Q 或 E152Q 突变的植物仍然保持高水平的 FLC 表达，并且不能挽救 atprmt10 植物的晚花表型。综上所述，我们得出结论，AtPRMT10 的甲基转移酶活性对于抑制 FLC 的表达和促进拟南芥开花是必不可少的。
