Three-dimensional structure of a pre-catalytic human spliceosomal complex B.
Major structural changes occur in the spliceosome during its transition from the fully assembled complex B to the catalytically activated spliceosome. To understand the rearrangement, it is necessary to know the detailed three-dimensional structures of these complexes. Here, we have immunoaffinity-purified human spliceosomes (designated B Delta U1) at a stage after U4/U6.U5 tri-snRNP integration but before activation, and have determined the three-dimensional structure of B Delta U1 by single-particle electron cryomicroscopy at a resolution of approximately 40 A. The overall size of the complex is about 370 x 270 x 170 A. The three-dimensional structure features a roughly triangular body linked to a head domain in variable orientations. The body is very similar in size and shape to the isolated U4/U6.U5 tri-snRNP. This provides initial insight into the structural organization of complex B.
Boehringer
Daniel
D
Max Planck Institute for Biophysical Chemistry, Department of Cellular Biochemistry, Am Fassberg 11, 37077 Goettingen, Germany.
Makarov
Evgeny M
EM
Sander
Bjoern
B
Makarova
Olga V
OV
Kastner
Berthold
B
Lührmann
Reinhard
R
Stark
Holger
H
D002384:Catalysis; D006801:Humans; D008854:Microscopy, Electron; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000648:ultrastructure; D017381:Spliceosomes / Q000737:chemistry* / Q000648:ultrastructure
D011506:Proteins