Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada.
Biochemistry. 2011 Sep 27;50(38):8226-40. doi: 10.1021/bi200644c. Epub 2011 Aug 29.
Protein arginine N-methyltransferases (PRMTs) act in signaling pathways and gene expression by methylating arginine residues within target proteins. PRMT1 is responsible for most cellular arginine methylation activity and can work independently or in collaboration with other PRMTs. In this study, we demonstrate a direct interaction between PRMT1 and PRMT2 using co-immunoprecipitation, bimolecular fluorescence complementation, and enzymatic assays. As a result of this interaction, PRMT2 stimulated PRMT1 activity, affecting its apparent V(max) and K(M) values in vitro and increasing the production of methylarginines in cells. Active site mutations and regional deletions from PRMT1 and -2 were also investigated, which demonstrated that complex formation required full-length, active PRMT1. Although the inhibition of methylation by adenosine dialdehyde prevented the interaction between PRMT1 and -2, it did not prevent the interaction between PRMT1 and a truncation mutant of PRMT2 lacking its Src homology 3 (SH3) domain. This result suggests that the SH3 domain may mediate an interaction between PRMT1 and -2 in a methylation-dependent fashion. On the basis of our findings, we propose that PRMT1 serves as the major methyltransferase in cells by forming higher-order oligomers with itself, PRMT2, and possibly other PRMTs.
蛋白质精氨酸 N-甲基转移酶（PRMTs）通过在靶蛋白内的精氨酸残基上甲基化来作用于信号通路和基因表达。PRMT1 负责大多数细胞内的精氨酸甲基化活性，可独立或与其他 PRMT 合作发挥作用。在这项研究中，我们通过免疫共沉淀、双分子荧光互补和酶促测定证明了 PRMT1 和 PRMT2 之间的直接相互作用。由于这种相互作用，PRMT2 刺激 PRMT1 活性，影响其体外的表观 Vmax 和 K M 值，并增加细胞中甲基精氨酸的产生。还研究了 PRMT1 和 -2 的活性位点突变和区域缺失，这表明复合物形成需要全长、活性的 PRMT1。尽管腺苷二醛抑制甲基化会阻止 PRMT1 和 -2 之间的相互作用，但它不会阻止 PRMT1 和缺乏其Src 同源 3（SH3）结构域的 PRMT2 截断突变体之间的相互作用。这一结果表明，SH3 结构域可能以依赖甲基化的方式介导 PRMT1 和 -2 之间的相互作用。基于我们的发现，我们提出 PRMT1 通过与自身、PRMT2 以及可能的其他 PRMT 形成更高阶的寡聚体，在细胞中充当主要的甲基转移酶。
