title: Structural characterization of the fission yeast U5.U2/U6 spliceosome complex.
abstract: The spliceosome is a dynamic macromolecular machine that catalyzes the excision of introns from pre-mRNA. The megadalton-sized spliceosome is composed of four small nuclear RNPs and additional pre-mRNA splicing factors. The formation of an active spliceosome involves a series of regulated steps that requires the assembly and disassembly of large multiprotein/RNA complexes. The dynamic nature of the pre-mRNA splicing reaction has hampered progress in analyzing the structure of spliceosomal complexes. We have used cryo-electron microscopy to produce a 29-A density map of a stable 37S spliceosomal complex from the genetically tractable fission yeast, Schizosaccharomyces pombe. Containing the U2, U5, and U6 snRNAs, pre-mRNA splicing intermediates, U2 and U5 snRNP proteins, the Nineteen Complex (NTC), and second-step splicing factors, this complex closely resembles in vitro purified mammalian C complex. The density map reveals an asymmetric particle, approximately 30 x 20 x 18 nm in size, which is composed of distinct domains that contact each other at the center of the complex.
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Melanie D
authors.initials: MD
authors.lastname: Ohi
authors.forename: Liping
authors.initials: L
authors.lastname: Ren
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Wall
authors.forename: Kathleen L
authors.initials: KL
authors.lastname: Gould
authors.forename: Thomas
authors.initials: T
authors.lastname: Walz
mesh_terms: D020285:Cryoelectron Microscopy; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012326:RNA Splicing / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017411:Ribonucleoproteins, Small Nuclear / Q000737:chemistry; D012568:Schizosaccharomyces / Q000737:chemistry*; D017381:Spliceosomes / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D046912:Multiprotein Complexes; D017411:Ribonucleoproteins, Small Nuclear