title: The evolutionarily conserved core design of the catalytic activation step of the yeast spliceosome.
abstract: Metazoan spliceosomes exhibit an elaborate protein composition required for canonical and alternative splicing. Thus, the minimal set of proteins essential for activation and catalysis remains elusive. We therefore purified in vitro assembled, precatalytic spliceosomal complex B, activated B(act), and step 1 complex C from the simple eukaryote Saccharomyces cerevisiae. Mass spectrometry revealed that yeast spliceosomes contain fewer proteins than metazoans and that each functional stage is very homogeneous. Dramatic compositional changes convert B to B(act), which is composed of approximately 40 evolutionarily conserved proteins that organize the catalytic core. Additional remodeling occurs concomitant with step 1, during which nine proteins are recruited to form complex C. The moderate number of proteins recruited to complex C will allow investigations of the chemical reactions in a fully defined system. Electron microscopy reveals high-quality images of yeast spliceosomes at defined functional stages, indicating that they are well-suited for three-dimensional structure analyses.
authors: Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
authors: Patrizia
authors: P
authors: Fabrizio
authors: Julia
authors: J
authors: Dannenberg
authors: Prakash
authors: P
authors: Dube
authors: Berthold
authors: B
authors: Kastner
authors: Holger
authors: H
authors: Stark
authors: Henning
authors: H
authors: Urlaub
authors: Reinhard
authors: R
authors: Lührmann
mesh_terms: D055162:Biocatalysis; D017124:Conserved Sequence; D019143:Evolution, Molecular; D006801:Humans; D007700:Kinetics; D012326:RNA Splicing; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D029701:Saccharomyces cerevisiae Proteins