EMD-4099
Yeast activated spliceosomal B complex
EMD-4099
Single-particle5.8 Å
Deposition: 17/08/2016Map released: 12/10/2016
Last modified: 12/07/2017
Sample Organism:
Saccharomyces cerevisiae
Sample: yeast activated spliceosome (BACT)
Deposition Authors: Stark H, Kastner B, Luehrmann R
Sample: yeast activated spliceosome (BACT)
Deposition Authors: Stark H, Kastner B, Luehrmann R
Molecular architecture of the Saccharomyces cerevisiae activated spliceosome.
Rauhut R,
Fabrizio P,
Dybkov O,
Hartmuth K,
Pena V,
Chari A 
,
Kumar V ,
Lee CT,
Urlaub H,
Kastner B,
Stark H,
Luhrmann R
(2016) Science , 353 , 1399 - 1405
,
Kumar V ,
Lee CT,
Urlaub H,
Kastner B,
Stark H,
Luhrmann R
(2016) Science , 353 , 1399 - 1405
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.
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.