RDS3 complex subunit 10 / Pre-mRNA-splicing factor PRP9 / Pre-mRNA-processing ATP-dependent RNA helicase PRP5 / Pre-mRNA-splicing factor PRP21 / Small nuclear ribonucleoprotein-associated protein B / Small nuclear ribonucleoprotein G / U2 small nuclear ribonucleoprotein B'' / Small nuclear ribonucleoprotein Sm D3 / U2 snRNP component HSH155 / Small nuclear ribonucleoprotein F ...RDS3 complex subunit 10 / Pre-mRNA-splicing factor PRP9 / Pre-mRNA-processing ATP-dependent RNA helicase PRP5 / Pre-mRNA-splicing factor PRP21 / Small nuclear ribonucleoprotein-associated protein B / Small nuclear ribonucleoprotein G / U2 small nuclear ribonucleoprotein B'' / Small nuclear ribonucleoprotein Sm D3 / U2 snRNP component HSH155 / Small nuclear ribonucleoprotein F / Small nuclear ribonucleoprotein Sm D1 / Cold sensitive U2 snRNA suppressor 1 / Pre-mRNA-splicing factor RSE1 / Small nuclear ribonucleoprotein Sm D2 / Pre-mRNA-splicing factor RDS3 / Pre-mRNA-splicing factor PRP11 / U2 small nuclear ribonucleoprotein A' / Small nuclear ribonucleoprotein E / Protein HSH49 類似検索 - 構成要素
ジャーナル: Nature / 年: 2021 タイトル: Structural insights into how Prp5 proofreads the pre-mRNA branch site. 著者: Zhenwei Zhang / Norbert Rigo / Olexandr Dybkov / Jean-Baptiste Fourmann / Cindy L Will / Vinay Kumar / Henning Urlaub / Holger Stark / Reinhard Lührmann / 要旨: During the splicing of introns from precursor messenger RNAs (pre-mRNAs), the U2 small nuclear ribonucleoprotein (snRNP) must undergo stable integration into the spliceosomal A complex-a poorly ...During the splicing of introns from precursor messenger RNAs (pre-mRNAs), the U2 small nuclear ribonucleoprotein (snRNP) must undergo stable integration into the spliceosomal A complex-a poorly understood, multistep process that is facilitated by the DEAD-box helicase Prp5 (refs. ). During this process, the U2 small nuclear RNA (snRNA) forms an RNA duplex with the pre-mRNA branch site (the U2-BS helix), which is proofread by Prp5 at this stage through an unclear mechanism. Here, by deleting the branch-site adenosine (BS-A) or mutating the branch-site sequence of an actin pre-mRNA, we stall the assembly of spliceosomes in extracts from the yeast Saccharomyces cerevisiae directly before the A complex is formed. We then determine the three-dimensional structure of this newly identified assembly intermediate by cryo-electron microscopy. Our structure indicates that the U2-BS helix has formed in this pre-A complex, but is not yet clamped by the HEAT domain of the Hsh155 protein (Hsh155), which exhibits an open conformation. The structure further reveals a large-scale remodelling/repositioning of the U1 and U2 snRNPs during the formation of the A complex that is required to allow subsequent binding of the U4/U6.U5 tri-snRNP, but that this repositioning is blocked in the pre-A complex by the presence of Prp5. Our data suggest that binding of Hsh155 to the bulged BS-A of the U2-BS helix triggers closure of Hsh155, which in turn destabilizes Prp5 binding. Thus, Prp5 proofreads the branch site indirectly, hindering spliceosome assembly if branch-site mutations prevent the remodelling of Hsh155. Our data provide structural insights into how a spliceosomal helicase enhances the fidelity of pre-mRNA splicing.