Immature small ribosomal subunits can engage in translation initiation in Saccharomyces cerevisiae

Soudet, Julien; Gélugne, Jean‐Paul; Belhabich-Baumas, Kamila; Caizergues‐Ferrer, Michèle; Mougin, Annie

doi:10.1038/emboj.2009.307

Cited by 62 publications

(75 citation statements)

References 50 publications

(88 reference statements)

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“…2A). It is reported that the immature small ribosomal subunits can engage in translation initiation and the putative endonuclease Nob1, which is specific to late pre-40S particles can interact with polysomes (35,36). This is one possible reason why Nob1 was detected in polysome fractions.…”

Section: Resultsmentioning

confidence: 99%

The von Hippel-Lindau Protein pVHL Inhibits Ribosome Biogenesis and Protein Synthesis

Zhao

Zhou

et al. 2013

Journal of Biological Chemistry

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Background: pVHL, a tumor suppressor, functions as the substrate recognition component of an E3-ligase complex that targets hypoxia inducible factor (HIF) 1␣ for destruction. Results: pVHL binds ribosomal protein RPS3, interferes with ribosome assembly, and inhibits protein synthesis. Conclusion: pVHL suppresses ribosome biogenesis and protein synthesis. Significance: The findings disclose a novel function of pVHL and provide insight into the regulation of ribosome biogenesis.

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Section: Resultsmentioning

confidence: 99%

The von Hippel-Lindau Protein pVHL Inhibits Ribosome Biogenesis and Protein Synthesis

Zhao

Zhou

et al. 2013

Journal of Biological Chemistry

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“…However, a recent study reached the opposite conclusion: Immature 40S subunits containing 20S pre-rRNA can bind translation factors and engage in translation initiation in S. cerevisiae, although the resulting 80S is less efficient in translation and rapidly destroyed by a specialized mRNA 2 These authors contributed equally to this work. (Soudet et al 2010). In a similar vein, two very recent studies have concluded that processing of S. cerevisiae 20S pre-rRNA in fact requires the pre-40S particle to associate in the cytoplasm with both the translation initiation factor eIF5b and 60S subunit; it was suggested that this might represent the final proofreading step before 40S engages in translation (Lebaron et al 2012;Strunk et al 2012).…”

Section: Introductionmentioning

confidence: 91%

Visualization of the joining of ribosomal subunits reveals the presence of 80S ribosomes in the nucleus

Al-Jubran

Wen

Abdullahi

et al. 2013

RNA

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In eukaryotes the 40S and 60S ribosomal subunits are assembled in the nucleolus, but there appear to be mechanisms preventing mRNA binding, 80S formation, and initiation of translation in the nucleus. To visualize association between ribosomal subunits, we tagged pairs of Drosophila ribosomal proteins (RPs) located in different subunits with mutually complementing halves of fluorescent proteins. Pairs of tagged RPs expected to interact, or be adjacent in the 80S structure, showed strong fluorescence, while pairs that were not in close proximity did not. Moreover, the complementation signal is found in ribosomal fractions and it was enhanced by translation elongation inhibitors and reduced by initiation inhibitors. Our technique achieved 80S visualization both in cultured cells and in fly tissues in vivo. Notably, while the main 80S signal was in the cytoplasm, clear signals were also seen in the nucleolus and at other nuclear sites. Furthermore, we detected rapid puromycin incorporation in the nucleolus and at transcription sites, providing an independent indication of functional 80S in the nucleolus and 80S association with nascent transcripts.

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“…6, data not shown and Ref. 28). In cells lacking Dim2, some Nob1 is found free at the top of the gradient, not associated with preribosomal particles.…”

Section: Mutations In the Central Kh-like Domain Of Dim2 Reduce Nob1 mentioning

confidence: 99%

Roles of Dim2 in Ribosome Assembly

Woolls¹,

Lamanna

Karbstein

2011

Journal of Biological Chemistry

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In eukaryotes, ribosome assembly requires hundreds of conserved essential proteins not present in the mature particle. Despite their importance, the function of most factors remains unknown. This is because protein deletion often affects the composition of the entire particle. Additionally, many proteins are present in assembling ribosomes for extended times, which makes it difficult to pinpoint their role to a particular step. Here we have combined classical yeast biochemistry with experiments using recombinant proteins and RNA to study the role of Dim2 and its interaction with Nob1, the nuclease that generates the 3-end of 18 S rRNA. Analysis of Dim2 mutants in which the interaction with Nob1 is disrupted demonstrates that this interaction between Dim2 and Nob1 is essential for optimal growth, and RNA binding experiments show that Dim2 increases Nob1 RNA affinity. Furthermore, our data indicate that Dim2 helps regulate Nob1 cleavage activity at the 3-end of 18 S rRNA, as point mutants where this interaction is abolished in vitro accumulate pre-ribosomes containing Nob1 and 20 S rRNA in vivo. Interestingly, the site of interaction with Nob1 is mapped to the canonical RNA binding surface of a KH-like domain in Dim2, providing another example where an RNA-binding domain can be repurposed for protein interactions.Ribosome assembly in eukaryotes is a complex and highly regulated process that consumes much of the energy of an actively growing cell (1). Ribosome assembly begins with the transcription of the ribosomal RNAs (rRNAs), 3 three of which (18 S, 5.8 S, and 25 S) are produced as a single transcript (Fig. 1). During transcription, this RNA is extensively methylated at 2Ј-OH groups (2), and initial cleavages separate the rRNAs destined for the small and large ribosomal subunit (3). Data in the literature indicate that 18 S rRNA processing is initiated in the nucleolus by a non-essential cleavage step (termed A 0 ) in the region 5Ј to 18 S rRNA (5Ј-ETS), followed by the essential cleavages at sites A 1 (to generate the 5Ј-end of 18 S rRNA) and A 2 (to separate 18 S rRNA from 5.8 S and 25 S rRNA (4), Fig. 1). The final step of 18 S rRNA maturation is the cytoplasmic cleavage at site D to form the mature 3Ј-end of 18 S rRNA. This cleavage step is carried out by the PIN-domaincontaining nuclease Nob1 (5-8).Modification and cleavage of pre-rRNAs is integrated with rRNA folding and binding of ribosomal proteins via a large machinery. In yeast, this essential machinery comprises ϳ200 proteins, assembly factors that bind transiently to pre-ribosomal complexes. Despite their importance for assembling this essential biomolecule, in many cases their specific roles in ribosome biogenesis remain unknown. The function of enzymes can be dissected relatively easily, resulting in the identification of all rRNA-modifying enzymes as well as many of the nucleolytic enzymes, particularly in the 60 S pathway. In contrast, the function of the majority of the assembly factors is harder to study, as by sequence analysis many proteins ...

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Immature small ribosomal subunits can engage in translation initiation in Saccharomyces cerevisiae

Cited by 62 publications

References 50 publications

The von Hippel-Lindau Protein pVHL Inhibits Ribosome Biogenesis and Protein Synthesis

The von Hippel-Lindau Protein pVHL Inhibits Ribosome Biogenesis and Protein Synthesis

Visualization of the joining of ribosomal subunits reveals the presence of 80S ribosomes in the nucleus

Roles of Dim2 in Ribosome Assembly

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