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Science. 2016 Sep 23;353(6306):1399-1405. Epub 2016 Aug 25.

Molecular architecture of the Saccharomyces cerevisiae activated spliceosome.

Author information

1
Department of Cellular Biochemistry, Max Planck Institute (MPI) for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.
2
Research Group Macromolecular Crystallography, MPI for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
3
3D Electron Cryomicroscopy Group, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.
4
Bioanalytical Mass Spectrometry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany. Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center, Göttingen, Robert-Koch-Straße 40, D-37075 Göttingen, Germany.
5
Department of Cellular Biochemistry, Max Planck Institute (MPI) for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany. b.kastner@mpi-bpc.mpg.de hstark1@gwdg.de reinhard.luehrmann@mpi-bpc.mpg.de.
6
3D Electron Cryomicroscopy Group, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany. Department of 3D Electron Cryomicroscopy, Georg-August Universität, Göttingen, Justus von-Liebig-Weg 11, D-37077 Germany. b.kastner@mpi-bpc.mpg.de hstark1@gwdg.de reinhard.luehrmann@mpi-bpc.mpg.de.

Abstract

The activated spliceosome (Bact) is in a catalytically inactive state and is remodeled into a catalytically active machine by the RNA helicase Prp2, but the mechanism is unclear. Here, we describe a 3D electron cryomicroscopy structure of the Saccharomyces cerevisiae Bact complex at 5.8-angstrom resolution. Our model reveals that in Bact, the catalytic U2/U6 RNA-Prp8 ribonucleoprotein core is already established, and the 5' splice site (ss) is oriented for step 1 catalysis but occluded by protein. The first-step nucleophile-the branchsite adenosine-is sequestered within the Hsh155 HEAT domain and is held 50 angstroms away from the 5'ss. Our structure suggests that Prp2 adenosine triphosphatase-mediated remodeling leads to conformational changes in Hsh155's HEAT domain that liberate the first-step reactants for catalysis.

PMID:
27562955
DOI:
10.1126/science.aag1906
[Indexed for MEDLINE]
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