90S pre-ribosome transformation into the primordial 40S subunit
How ribosomes are made - The formation of eukaryotic ribosomes is a complex process that starts with transcription of a large precursor RNA that assembles into a large 90S preribosome, which matures to finally give the 40S small subunit of the ribosome. Cheng et al. and Du et al. give insight into t...
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| Main Authors: | , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
18 Sep 2020
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| In: |
Science
Year: 2020, Volume: 370, Issue: 6150, Pages: 1470-1476 |
| ISSN: | 1095-9203 |
| DOI: | 10.1126/science.abb4119 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1126/science.abb4119 Verlag, lizenzpflichtig, Volltext: https://science.sciencemag.org/content/369/6510/1470 
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| Author Notes: | Jingdong Cheng, Benjamin Lau, Giuseppe La Venuta, Michael Ameismeier, Otto Berninghausen, Ed Hurt, Roland Beckmann |
| Summary: | How ribosomes are made - The formation of eukaryotic ribosomes is a complex process that starts with transcription of a large precursor RNA that assembles into a large 90S preribosome, which matures to finally give the 40S small subunit of the ribosome. Cheng et al. and Du et al. give insight into this process, using cryo-electron microscopy to look at intermediates along the pathway. Together, these studies reveal how a cast of molecular players act to coordinate the compositional and structural changes that transform the 90S preribosome into a pre-40S subunit. - Science, this issue p. 1470, p. 1477 - Production of small ribosomal subunits initially requires the formation of a 90S precursor followed by an enigmatic process of restructuring into the primordial pre-40S subunit. We elucidate this process by biochemical and cryo-electron microscopy analysis of intermediates along this pathway in yeast. First, the remodeling RNA helicase Dhr1 engages the 90S pre-ribosome, followed by Utp24 endonuclease-driven RNA cleavage at site A1, thereby separating the 5′-external transcribed spacer (ETS) from 18S ribosomal RNA. Next, the 5′-ETS and 90S assembly factors become dislodged, but this occurs sequentially, not en bloc. Eventually, the primordial pre-40S emerges, still retaining some 90S factors including Dhr1, now ready to unwind the final small nucleolar U3-18S RNA hybrid. Our data shed light on the elusive 90S to pre-40S transition and clarify the principles of assembly and remodeling of large ribonucleoproteins. - The steps that drive the stepwise dissociation of factors in the transition from the 90S to the 40S ribosome subunit are observed. - The steps that drive the stepwise dissociation of factors in the transition from the 90S to the 40S ribosome subunit are observed. |
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| Item Description: | Gesehen am 27.10.2020 |
| Physical Description: | Online Resource |
| ISSN: | 1095-9203 |
| DOI: | 10.1126/science.abb4119 |