3JCM
Cryo-EM structure of the spliceosomal U4/U6.U5 tri-snRNP
Summary for 3JCM
| Entry DOI | 10.2210/pdb3jcm/pdb |
| EMDB information | 6561 |
| Descriptor | Pre-mRNA-splicing factor 8, Small nuclear ribonucleoprotein Sm D3, Small nuclear ribonucleoprotein-associated protein B, ... (29 entities in total) |
| Functional Keywords | u4/u6.u5 tri-snrnp, pre-mrna, transcription |
| Biological source | Saccharomyces cerevisiae S288c More |
| Total number of polymer chains | 34 |
| Total formula weight | 1373832.70 |
| Authors | |
| Primary citation | Wan, R.,Yan, C.,Bai, R.,Wang, L.,Huang, M.,Wong, C.C.,Shi, Y. The 3.8 angstrom structure of the U4/U6.U5 tri-snRNP: Insights into spliceosome assembly and catalysis Science, 351:466-475, 2016 Cited by PubMed Abstract: Splicing of precursor messenger RNA is accomplished by a dynamic megacomplex known as the spliceosome. Assembly of a functional spliceosome requires a preassembled U4/U6.U5 tri-snRNP complex, which comprises the U5 small nuclear ribonucleoprotein (snRNP), the U4 and U6 small nuclear RNA (snRNA) duplex, and a number of protein factors. Here we report the three-dimensional structure of a Saccharomyces cerevisiae U4/U6.U5 tri-snRNP at an overall resolution of 3.8 angstroms by single-particle electron cryomicroscopy. The local resolution for the core regions of the tri-snRNP reaches 3.0 to 3.5 angstroms, allowing construction of a refined atomic model. Our structure contains U5 snRNA, the extensively base-paired U4/U6 snRNA, and 30 proteins including Prp8 and Snu114, which amount to 8495 amino acids and 263 nucleotides with a combined molecular mass of ~1 megadalton. The catalytic nucleotide U80 from U6 snRNA exists in an inactive conformation, stabilized by its base-pairing interactions with U4 snRNA and protected by Prp3. Pre-messenger RNA is bound in the tri-snRNP through base-pairing interactions with U6 snRNA and loop I of U5 snRNA. This structure, together with that of the spliceosome, reveals the molecular choreography of the snRNAs in the activation process of the spliceosomal ribozyme. PubMed: 26743623DOI: 10.1126/science.aad6466 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (3.8 Å) |
Structure validation
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