8QPA
Cryo-EM Structure of Pre-B+5'ssLNG Complex (core part)
Summary for 8QPA
Entry DOI | 10.2210/pdb8qpa/pdb |
EMDB information | 18546 |
Descriptor | U5 small nuclear ribonucleoprotein 200 kDa helicase, 116 kDa U5 small nuclear ribonucleoprotein component, NHP2-like protein 1, N-terminally processed, ... (18 entities in total) |
Functional Keywords | spliceosome, splicing |
Biological source | Homo sapiens (human) More |
Total number of polymer chains | 17 |
Total formula weight | 1422807.38 |
Authors | Zhang, Z.,Kumar, V.,Dybkov, O.,Will, C.L.,Zhong, J.,Ludwig, S.,Urlaub, H.,Kastner, B.,Stark, H.,Luehrmann, R. (deposition date: 2023-10-01, release date: 2024-05-22, Last modification date: 2024-07-10) |
Primary citation | Zhang, Z.,Kumar, V.,Dybkov, O.,Will, C.L.,Zhong, J.,Ludwig, S.E.J.,Urlaub, H.,Kastner, B.,Stark, H.,Luhrmann, R. Structural insights into the cross-exon to cross-intron spliceosome switch. Nature, 630:1012-1019, 2024 Cited by PubMed Abstract: Early spliceosome assembly can occur through an intron-defined pathway, whereby U1 and U2 small nuclear ribonucleoprotein particles (snRNPs) assemble across the intron. Alternatively, it can occur through an exon-defined pathway, whereby U2 binds the branch site located upstream of the defined exon and U1 snRNP interacts with the 5' splice site located directly downstream of it. The U4/U6.U5 tri-snRNP subsequently binds to produce a cross-intron (CI) or cross-exon (CE) pre-B complex, which is then converted to the spliceosomal B complex. Exon definition promotes the splicing of upstream introns and plays a key part in alternative splicing regulation. However, the three-dimensional structure of exon-defined spliceosomal complexes and the molecular mechanism of the conversion from a CE-organized to a CI-organized spliceosome, a pre-requisite for splicing catalysis, remain poorly understood. Here cryo-electron microscopy analyses of human CE pre-B complex and B-like complexes reveal extensive structural similarities with their CI counterparts. The results indicate that the CE and CI spliceosome assembly pathways converge already at the pre-B stage. Add-back experiments using purified CE pre-B complexes, coupled with cryo-electron microscopy, elucidate the order of the extensive remodelling events that accompany the formation of B complexes and B-like complexes. The molecular triggers and roles of B-specific proteins in these rearrangements are also identified. We show that CE pre-B complexes can productively bind in trans to a U1 snRNP-bound 5' splice site. Together, our studies provide new mechanistic insights into the CE to CI switch during spliceosome assembly and its effect on pre-mRNA splice site pairing at this stage. PubMed: 38778104DOI: 10.1038/s41586-024-07458-1 PDB entries with the same primary citation |
Experimental method | ELECTRON MICROSCOPY (3.7 Å) |
Structure validation
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