title: Molecular architecture of the human U4/U6.U5 tri-snRNP.
abstract: The U4/U6.U5 triple small nuclear ribonucleoprotein (tri-snRNP) is a major spliceosome building block. We obtained a three-dimensional structure of the 1.8-megadalton human tri-snRNP at a resolution of 7 angstroms using single-particle cryo-electron microscopy (cryo-EM). We fit all known high-resolution structures of tri-snRNP components into the EM density map and validated them by protein cross-linking. Our model reveals how the spatial organization of Brr2 RNA helicase prevents premature U4/U6 RNA unwinding in isolated human tri-snRNPs and how the ubiquitin C-terminal hydrolase-like protein Sad1 likely tethers the helicase Brr2 to its preactivation position. Comparison of our model with cryo-EM three-dimensional structures of the Saccharomyces cerevisiae tri-snRNP and Schizosaccharomyces pombe spliceosome indicates that Brr2 undergoes a marked conformational change during spliceosome activation, and that the scaffolding protein Prp8 is also rearranged to accommodate the spliceosome's catalytic RNA network.
authors.affiliation: Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany.
authors.forename: Dmitry E
authors.initials: DE
authors.lastname: Agafonov
authors.affiliation: Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany.
authors.forename: Berthold
authors.initials: B
authors.lastname: Kastner
authors.affiliation: Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany.
authors.forename: Olexandr
authors.initials: O
authors.lastname: Dybkov
authors.affiliation: Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany. Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, D-37075 Göttingen, Germany.
authors.forename: Romina V
authors.initials: RV
authors.lastname: Hofele
authors.affiliation: Department of 3D Electron Cryomicroscopy, Georg-August Universität Göttingen, D-37077 Göttingen, Germany. Department of Structural Dynamics, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany.
authors.forename: Wen-Ti
authors.initials: WT
authors.lastname: Liu
authors.affiliation: Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany. Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, D-37075 Göttingen, Germany. reinhard.luehrmann@mpi-bpc.mpg.de hstark1@gwdg.de henning.urlaub@mpibpc.mpg.de.
authors.forename: Henning
authors.initials: H
authors.lastname: Urlaub
authors.affiliation: Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany. reinhard.luehrmann@mpi-bpc.mpg.de hstark1@gwdg.de henning.urlaub@mpibpc.mpg.de.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Lührmann
authors.affiliation: Department of 3D Electron Cryomicroscopy, Georg-August Universität Göttingen, D-37077 Göttingen, Germany. Department of Structural Dynamics, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany. reinhard.luehrmann@mpi-bpc.mpg.de hstark1@gwdg.de henning.urlaub@mpibpc.mpg.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Stark
mesh_terms: D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D053487:DEAD-box RNA Helicases / Q000737:chemistry; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D010445:Peptide Elongation Factors / Q000737:chemistry; D011487:Protein Conformation; D020365:RNA Helicases / Q000737:chemistry; D016601:RNA-Binding Proteins / Q000737:chemistry; D017414:Ribonucleoprotein, U4-U6 Small Nuclear / Q000737:chemistry*; D017415:Ribonucleoprotein, U5 Small Nuclear / Q000737:chemistry*; D017411:Ribonucleoproteins, Small Nuclear / Q000737:chemistry; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry; D012568:Schizosaccharomyces / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000737:chemistry
chemical_list: C581608:EFTUD2 protein, human; C077018:PRP8 protein, S cerevisiae; C115374:PRPF8 protein, human; D010445:Peptide Elongation Factors; D016601:RNA-Binding Proteins; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017415:Ribonucleoprotein, U5 Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; C545711:SNRNP200 protein, human; D029701:Saccharomyces cerevisiae Proteins; C506012:TXNL4A protein, human; C498290:DDX23 protein, human; D043222:Ubiquitin Thiolesterase; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases