PDBsum entry 6j6q

Splicing

PDB id: 6j6q

Contents

Protein chains

1913 a.a.

920 a.a.

27 a.a.

357 a.a.

205 a.a.

292 a.a.

261 a.a.

70 a.a.

157 a.a.

447 a.a.

436 a.a.

566 a.a.

102 a.a.

299 a.a.

95 a.a.

722 a.a.

84 a.a.

169 a.a.

156 a.a.

74 a.a.

119 a.a.

75 a.a.

68 a.a.

101 a.a.

100 a.a.

93 a.a.

83 a.a.

108 a.a.

125 a.a.

129 a.a.

161 a.a.

DNA/RNA

Ligands

IHP

GTP

Metals

_MG ×6

_ZN ×7

References listed in PDB file

Key reference

• Title: Structures of the catalytically activated yeast spliceosome reveal the mechanism of branching.
• Authors: R.Wan, R.Bai, C.Yan, J.Lei, Y.Shi.
• Ref.: Cell, 2019, 177, 339. [DOI no: 10.1016/j.cell.2019.02.006]
• PubMed id: 30879786

Abstract

Pre-mRNA splicing is executed by the spliceosome. Structural characterization of the catalytically activated complex (B^∗) is pivotal for understanding the branching reaction. In this study, we assembled the B^∗ complexes on two different pre-mRNAs from Saccharomyces cerevisiae and determined the cryo-EM structures of four distinct B^∗ complexes at overall resolutions of 2.9-3.8 Å. The duplex between U2 small nuclear RNA (snRNA) and the branch point sequence (BPS) is discretely away from the 5'-splice site (5'SS) in the three B^∗ complexes that are devoid of the step I splicing factors Yju2 and Cwc25. Recruitment of Yju2 into the active site brings the U2/BPS duplex into the vicinity of 5'SS, with the BPS nucleophile positioned 4 Å away from the catalytic metal M2. This analysis reveals the functional mechanism of Yju2 and Cwc25 in branching. These structures on different pre-mRNAs reveal substrate-specific conformations of the spliceosome in a major functional state.