Molecular architecture of the Saccharomyces cerevisiae activated spliceosome

作者：Rauhut Reinhard; Fabrizio Patrizia; Dybkov Olexandr; Hartmuth Klaus; Pena Vladimir; Chari Ashwin; Kumar Vinay; Lee Chung Tien; Urlaub Henning; Kastner Berthold^*; Stark Holger^*; Luehrmann Reinhard

来源：Science, 2016, 353(6306): 1399-1405.

DOI：10.1126/science.aag1906

The activated spliceosome (B-act) 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 B-act complex at 5.8-angstrom resolution. Our model reveals that in B-act, 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.

• 出版日期2016-9-23