Download MendeleyStructure of the Maturing 90S Pre-ribosome in Association with the RNA Exosome.
Lau, B., Cheng, J., Flemming, D., La Venuta, G., Berninghausen, O., Beckmann, R., Hurt, E.(2021) Mol Cell 81: 293
- PubMed: 33326748 Search on PubMed
- DOI: https://doi.org/10.1016/j.molcel.2020.11.009
- Primary Citation Related Structures:
7AJT, 7AJU - 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 1 , 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.
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
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