Emergence of the primordial pre-60S from the 90S pre-ribosome.
Synthesis of ribosomes begins in the nucleolus with formation of the 90S pre-ribosome, during which the pre-40S and pre-60S pathways diverge by pre-rRNA cleavage. However, it remains unclear how, after this uncoupling, the earliest pre-60S subunit continues to develop. Here, we reveal a large-subunit intermediate at the beginning of its ... construction when still linked to the 90S, the precursor to the 40S subunit. This primordial pre-60S is characterized by the SPOUT domain methyltransferase Upa1-Upa2, large ?-solenoid scaffolds, Mak5, one of several RNA helicases, and two small nucleolar RNA (snoRNAs), C/D box snR190 and H/ACA box snR37. The emerging pre-60S does not efficiently disconnect from the 90S pre-ribosome in a dominant mak5 helicase mutant, allowing a 70-nm 90S-pre-60S bipartite particle to be visualized by electron microscopy. Our study provides insight into the assembly pathway when the still-connected nascent 40S and 60S subunits are beginning to separate.
Mesh Terms:
DEAD-box RNA Helicases, RNA Precursors, RNA, Ribosomal, RNA, Small Nucleolar, Ribosome Subunits, Large, Eukaryotic, Ribosomes, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
DEAD-box RNA Helicases, RNA Precursors, RNA, Ribosomal, RNA, Small Nucleolar, Ribosome Subunits, Large, Eukaryotic, Ribosomes, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Cell Rep
Date: Dec. 05, 2021
PubMed ID: 35385737
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