8G1U

Structure of the methylosome-Lsm10/11 complex

Summary for 8G1U

• Entry DOI: 10.2210/pdb8g1u/pdb
• EMDB information: 29677
• Descriptor: Protein arginine N-methyltransferase 5, Methylosome protein 50, Methylosome subunit pICln, ... (5 entities in total)
• Functional Keywords: methylation, gene regulation, transferase
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 16
• Total formula weight: 701611.60

Authors

Lin, M.,Paige, A.,Tong, L. (deposition date: 2023-02-03, release date: 2023-08-23, Last modification date: 2025-05-28)

Primary citation

Yang, X.C.,Desotell, A.,Lin, M.H.,Paige, A.S.,Malinowska, A.,Sun, Y.,Aik, W.S.,Dadlez, M.,Tong, L.,Dominski, Z.
In vitro methylation of the U7 snRNP subunits Lsm11 and SmE by the PRMT5/MEP50/pICln methylosome.
Rna, 29:1673-1690, 2023

PubMed Abstract: U7 snRNP is a multisubunit endonuclease required for 3' end processing of metazoan replication-dependent histone pre-mRNAs. In contrast to the spliceosomal snRNPs, U7 snRNP lacks the Sm subunits D1 and D2 and instead contains two related proteins, Lsm10 and Lsm11. The remaining five subunits of the U7 heptameric Sm ring, SmE, F, G, B, and D3, are shared with the spliceosomal snRNPs. The pathway that assembles the unique ring of U7 snRNP is unknown. Here, we show that a heterodimer of Lsm10 and Lsm11 tightly interacts with the methylosome, a complex of the arginine methyltransferase PRMT5, MEP50, and pICln known to methylate arginines in the carboxy-terminal regions of the Sm proteins B, D1, and D3 during the spliceosomal Sm ring assembly. Both biochemical and cryo-EM structural studies demonstrate that the interaction is mediated by PRMT5, which binds and methylates two arginine residues in the amino-terminal region of Lsm11. Surprisingly, PRMT5 also methylates an amino-terminal arginine in SmE, a subunit that does not undergo this type of modification during the biogenesis of the spliceosomal snRNPs. An intriguing possibility is that the unique methylation pattern of Lsm11 and SmE plays a vital role in the assembly of the U7 snRNP.

PubMed: 37562960
DOI: 10.1261/rna.079709.123

Experimental method

ELECTRON MICROSCOPY (2.83 Å)