Architecture of the 90S Pre-ribosome: A Structural View on the Birth of the Eukaryotic Ribosome
- PMID: 27419870
- DOI: 10.1016/j.cell.2016.06.014
Architecture of the 90S Pre-ribosome: A Structural View on the Birth of the Eukaryotic Ribosome
Abstract
The 90S pre-ribosome is an early biogenesis intermediate formed during co-transcriptional ribosome formation, composed of ∼70 assembly factors and several small nucleolar RNAs (snoRNAs) that associate with nascent pre-rRNA. We report the cryo-EM structure of the Chaetomium thermophilum 90S pre-ribosome, revealing how a network of biogenesis factors including 19 β-propellers and large α-solenoid proteins engulfs the pre-rRNA. Within the 90S pre-ribosome, we identify the UTP-A, UTP-B, Mpp10-Imp3-Imp4, Bms1-Rcl1, and U3 snoRNP modules, which are organized around 5'-ETS and partially folded 18S rRNA. The U3 snoRNP is strategically positioned at the center of the 90S particle to perform its multiple tasks during pre-rRNA folding and processing. The architecture of the elusive 90S pre-ribosome gives unprecedented structural insight into the early steps of pre-rRNA maturation. Nascent rRNA that is co-transcriptionally folded and given a particular shape by encapsulation within a dedicated mold-like structure is reminiscent of how polypeptides use chaperone chambers for their protein folding.
Copyright © 2016 Elsevier Inc. All rights reserved.
Comment in
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Seeing is Believing in Ribosome Assembly.Cell. 2016 Jul 14;166(2):277-278. doi: 10.1016/j.cell.2016.06.055. Cell. 2016. PMID: 27419867
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Structural biology: Moulding the ribosome.Nature. 2016 Sep 1;537(7618):38-40. doi: 10.1038/537038a. Nature. 2016. PMID: 27582216 No abstract available.
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