Journal Article

Cryo-EM structure of the yeast U4/U6.U5 tri-snRNP at 3.7 Å resolution

Galej, Wojciech P., Bai, Xiao-chen, Oubridge, Chris, Nguyen, Thi Hoang Duong, Newman, Andrew J., Scheres, Sjors H. W., Nagai, Kiyoshi

2016

Overview

U4/U6.U5 tri-snRNP represents a substantial part of the spliceosome before activation. A cryo-electron microscopy structure of Saccharomyces cerevisiae U4/U6.U5 tri-snRNP at 3.7 Å resolution led to an essentially complete atomic model comprising 30 proteins plus U4/U6 and U5 small nuclear RNAs (snRNAs). The structure reveals striking interweaving interactions of the protein and RNA components, including extended polypeptides penetrating into subunit interfaces. The invariant ACAGAGA sequence of U6 snRNA, which base-pairs with the 5′-splice site during catalytic activation, forms a hairpin stabilized by Dib1 and Prp8 while the adjacent nucleotides interact with the exon binding loop 1 of U5 snRNA. Snu114 harbours GTP, but its putative catalytic histidine is held away from the γ-phosphate by hydrogen bonding to a tyrosine in the amino-terminal domain of Prp8. Mutation of this histidine to alanine has no detectable effect on yeast growth. The structure provides important new insights into the spliceosome activation process leading to the formation of the catalytic centre. A 3.7 Å resolution structure for the yeast U4/U6.U5 tri-snRNP, a complex involved in splicing, allows a better appreciation of the architecture of the tri-snRNP, and offers new functional insights into the activation of the spliceosome and the assembly of the catalytic core. Yeast U4/U6.U5 tri-snRNP structure Following up on their 5.9 Å cryo-electron microscopy structure published less than a year ago, Kiyoshi Nagai and colleagues have now achieved a resolution of 3.7 Å for the yeast U4/U6.U5 tri-snRNP, a complex involved in splicing of messenger RNA. The improved resolution allows a better appreciation of the architecture of the tri-snRNP, and offers new functional insights into the activation of the spliceosome and the assembly of the catalytic core.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/337/1645/1792 / 631/45/500 / 631/535/1258/1259 / Base Pairing / Catalytic Domain / Cryoelectron Microscopy / DNA Helicases - metabolism / Exons - genetics / Guanosine Triphosphate - metabolism / Histidine / Humanities and Social Sciences / Hydrogen Bonding / Influence / Messenger RNA / Microscopy / Models, Molecular / Molecular structure / multidisciplinary / Nucleic Acid Conformation / Physiological aspects / Polypeptides / Proteins / Ribonucleic acid / Ribonucleoprotein, U4-U6 Small Nuclear - chemistry / Ribonucleoprotein, U4-U6 Small Nuclear - metabolism / Ribonucleoprotein, U5 Small Nuclear - chemistry / Ribonucleoprotein, U5 Small Nuclear - metabolism / Ribonucleoproteins, Small Nuclear - chemistry / Ribonucleoproteins, Small Nuclear - genetics / Ribonucleoproteins, Small Nuclear - metabolism / Ribonucleoproteins, Small Nuclear - ultrastructure / RNA / RNA Splice Sites / RNA, Small Nuclear - chemistry / RNA, Small Nuclear - genetics / RNA, Small Nuclear - metabolism / Saccharomyces cerevisiae - chemistry / Saccharomyces cerevisiae - genetics / Saccharomyces cerevisiae - growth & development / Saccharomyces cerevisiae - ultrastructure / Saccharomyces cerevisiae Proteins - chemistry / Saccharomyces cerevisiae Proteins - genetics / Saccharomyces cerevisiae Proteins - metabolism / Saccharomyces cerevisiae Proteins - ultrastructure / Science / Spliceosomes - metabolism / Yeast / Yeast fungi / Yeasts