{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"submitter":["Paul T"],"funding":["National Institutes of Health","NIH HHS","NIGMS NIH HHS"],"pagination":["e5117"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC11255866"],"repository":["biostudies-literature"],"omics_type":["Unknown"],"volume":["33(8)"],"pubmed_abstract":["In eukaryotes, pre-mRNA splicing is vital for RNA processing and orchestrated by the spliceosome, whose assembly starts with the interaction between U1-70K and SR proteins. Despite the significance of the U1-70K/SR interaction, the dynamic nature of the complex and the challenges in obtaining soluble U1-70K have impeded a comprehensive understanding of the interaction at the structural level for decades. We overcome the U1-70K solubility issues, enabling us to characterize the interaction between U1-70K and SRSF1, a representative SR protein. We unveil specific interactions: phosphorylated SRSF1 RS with U1-70K BAD1, and SRSF1 RRM1 with U1-70K RRM. The RS/BAD1 interaction plays a dominant role, whereas the interaction between the RRM domains further enhances the stability of the U1-70K/SRSF1 complex. The RRM interaction involves the C-terminal extension of U1-70K RRM and the conserved acid patches on SRSF1 RRM1 that is involved in SRSF1 phase separation. Our circular dichroism spectra reveal that BAD1 adapts an α-helical conformation and RS is intrinsically disordered. Intriguingly, BAD1 undergoes a conformation switch from α-helix to β-strand and random coil upon RS binding. In addition to the regulatory mechanism via SRSF1 phosphorylation, the U1-70K/SRSF1 interaction is also regulated by U1-70K BAD1 phosphorylation. We find that U1-70K phosphorylation inhibits the U1-70K and SRSF1 interaction. Our structural findings are validated through in vitro splicing assays and in-cell saturated domain scanning using the CRISPR method, providing new insights into the intricate regulatory mechanisms of pre-mRNA splicing."],"journal":["Protein science : a publication of the Protein Society"],"pubmed_title":["The U1-70K and SRSF1 interaction is modulated by phosphorylation during the early stages of spliceosome assembly."],"pmcid":["PMC11255866"],"funding_grant_id":["R35 GM147091","R35GM147091"],"pubmed_authors":["Ekpenyong E","Prevelige P","Jamal S","Zhang Z","Zhang J","Powell E","De Silva NIU","Fargason T","Paul T","Zhang P","Yu Y","Lu R"],"additional_accession":[]},"is_claimable":false,"name":"The U1-70K and SRSF1 interaction is modulated by phosphorylation during the early stages of spliceosome assembly.","description":"In eukaryotes, pre-mRNA splicing is vital for RNA processing and orchestrated by the spliceosome, whose assembly starts with the interaction between U1-70K and SR proteins. Despite the significance of the U1-70K/SR interaction, the dynamic nature of the complex and the challenges in obtaining soluble U1-70K have impeded a comprehensive understanding of the interaction at the structural level for decades. We overcome the U1-70K solubility issues, enabling us to characterize the interaction between U1-70K and SRSF1, a representative SR protein. We unveil specific interactions: phosphorylated SRSF1 RS with U1-70K BAD1, and SRSF1 RRM1 with U1-70K RRM. The RS/BAD1 interaction plays a dominant role, whereas the interaction between the RRM domains further enhances the stability of the U1-70K/SRSF1 complex. The RRM interaction involves the C-terminal extension of U1-70K RRM and the conserved acid patches on SRSF1 RRM1 that is involved in SRSF1 phase separation. Our circular dichroism spectra reveal that BAD1 adapts an α-helical conformation and RS is intrinsically disordered. Intriguingly, BAD1 undergoes a conformation switch from α-helix to β-strand and random coil upon RS binding. In addition to the regulatory mechanism via SRSF1 phosphorylation, the U1-70K/SRSF1 interaction is also regulated by U1-70K BAD1 phosphorylation. We find that U1-70K phosphorylation inhibits the U1-70K and SRSF1 interaction. Our structural findings are validated through in vitro splicing assays and in-cell saturated domain scanning using the CRISPR method, providing new insights into the intricate regulatory mechanisms of pre-mRNA splicing.","dates":{"release":"2024-01-01T00:00:00Z","publication":"2024 Aug","modification":"2026-06-01T13:21:09.216Z","creation":"2025-04-06T17:12:13.28Z"},"accession":"S-EPMC11255866","cross_references":{"pubmed":["39023093"],"doi":["10.1002/pro.5117"]}}