Meister Gunter, Fischer Utz
Max-Planck Institute of Biochemistry, Am Klopferspitz 18a, D-82152 Martinsried, Germany.
EMBO J. 2002 Nov 1;21(21):5853-63. doi: 10.1093/emboj/cdf585.
Although spliceosomal Sm proteins can assemble spontaneously onto UsnRNA in vitro, this process requires assisting factors in vivo. SMN, the protein involved in spinal muscular atrophy, is part of a complex that contains the Sm proteins and serves as a critical factor for this reaction. Here, we have reconstituted the SMN-dependent assembly of UsnRNPs in vitro. We demonstrate that the SMN complex is necessary and sufficient for the assembly reaction. The PRMT5 complex, previously implicated in methylation and storage of Sm proteins, interacts with the SMN complex and enhances its activity in an ATP-dependent manner. These data uncover the SMN-PRMT5 complex as a functional entity that promotes the assisted assembly of spliceosomal UsnRNPs, and potentially other, RNA-protein complexes.
尽管剪接体Sm蛋白在体外能够自发地组装到UsnRNA上，但该过程在体内需要辅助因子。与脊髓性肌萎缩症相关的蛋白质SMN是一个包含Sm蛋白的复合物的一部分，并且是此反应的关键因子。在此，我们在体外重建了依赖SMN的UsnRNP组装过程。我们证明，SMN复合物对于组装反应是必需且充分的。先前与Sm蛋白的甲基化和储存有关的PRMT5复合物与SMN复合物相互作用，并以ATP依赖的方式增强其活性。这些数据揭示了SMN-PRMT5复合物是一个功能性实体，它促进剪接体UsnRNP以及可能的其他RNA-蛋白质复合物的辅助组装。
