7AJU

Cryo-EM structure of the 90S-exosome super-complex (state Post-A1-exosome)

This is a non-PDB format compatible entry.

Summary for 7AJU

• Entry DOI: 10.2210/pdb7aju/pdb
• EMDB information: 11808
• Descriptor: rRNA 2'-O-methyltransferase fibrillarin, U3 small nucleolar RNA-associated protein 8, U3 small nucleolar RNA-associated protein 9, ... (78 entities in total)
• Functional Keywords: ribosome, ribosome biogenesis, exosome, 90s pre-ribosome, a1 cleavage, mtr4
• Biological source: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast); More
• Total number of polymer chains: 78
• Total formula weight: 4875600.81

Authors

Cheng, J.,Lau, B.,Flemming, D.,Venuta, G.L.,Berninghausen, O.,Beckmann, R.,Hurt, E. (deposition date: 2020-09-29, release date: 2020-12-30, Last modification date: 2024-05-01)

Primary citation

Lau, B.,Cheng, J.,Flemming, D.,La Venuta, G.,Berninghausen, O.,Beckmann, R.,Hurt, E.
Structure of the Maturing 90S Pre-ribosome in Association with the RNA Exosome.
Mol.Cell, 81:293-, 2021

PubMed Abstract: Ribosome assembly is catalyzed by numerous trans-acting factors and coupled with irreversible pre-rRNA processing, driving the pathway toward mature ribosomal subunits. One decisive step early in this progression is removal of the 5' external transcribed spacer (5'-ETS), an RNA extension at the 18S rRNA that is integrated into the huge 90S pre-ribosome structure. Upon endo-nucleolytic cleavage at an internal site, A, the 5'-ETS is separated from the 18S rRNA and degraded. Here we present biochemical and cryo-electron microscopy analyses that depict the RNA exosome, a major 3'-5' exoribonuclease complex, in a super-complex with the 90S pre-ribosome. The exosome is docked to the 90S through its co-factor Mtr4 helicase, a processive RNA duplex-dismantling helicase, which strategically positions the exosome at the base of 5'-ETS helices H9-H9', which are dislodged in our 90S-exosome structures. These findings suggest a direct role of the exosome in structural remodeling of the 90S pre-ribosome to drive eukaryotic ribosome synthesis.

PubMed: 33326748
DOI: 10.1016/j.molcel.2020.11.009

Experimental method

ELECTRON MICROSCOPY (3.8 Å)