Assisted RNP assembly: SMN and PRMT5 complexes cooperate in the formation of spliceosomal UsnRNPs.
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.
Meister
Gunter
G
Max-Planck Institute of Biochemistry, Am Klopferspitz 18a, D-82152 Martinsried, Germany.
Fischer
Utz
U
D000818:Animals; D015153:Blotting, Western; D017362:Cyclic AMP Response Element-Binding Protein; D006367:HeLa Cells; D006801:Humans; D008845:Microinjections; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding; D011496:Protein Methyltransferases / Q000378:metabolism*; D011484:Protein-Arginine N-Methyltransferases; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism*; D055532:SMN Complex Proteins; D017381:Spliceosomes; D014982:Xenopus laevis
D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; D055532:SMN Complex Proteins; D011496:Protein Methyltransferases; C400529:PRMT5 protein, human; D011484:Protein-Arginine N-Methyltransferases