Ssf1p Prevents Premature Processing of an Early Pre-60S Ribosomal Particle

Fatica, Alessandro; Cronshaw, Andrew D.; Dlakić, Mensur; Tollervey, David

doi:10.1016/s1097-2765(02)00458-6

Cited by 170 publications

(203 citation statements)

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“…The Wnt target c-Myc drives RNA polymerases I-III transcription, which mediates ribosome biogenesis (16,17). Wnt signaling also directly regulates ribosome biogenesis by activating the expression of Peter Pan (PPAN), Pescadillo (PES), and nucleophosmin (NPM/B23), all of which are essential nucleolar components of the ribosome biogenesis machinery (3,18,19). All three factors are up-regulated in cancers with constitutively active Wnt signaling (20 -22).…”

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confidence: 99%

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The Wnt Target Protein Peter Pan Defines a Novel p53-independent Nucleolar Stress-Response Pathway

Pfister

Keil

Kühl

2015

Journal of Biological Chemistry

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Background: Peter Pan (PPAN) localizes to nucleoli and functions in ribosome biogenesis. Results: PPAN localizes also to mitochondria, and PPAN knockdown triggers p53-independent mitochondrial apoptosis and nucleolar stress as observed by de-stabilization of nucleophosmin. Conclusion: PPAN orchestrates a p53-independent stress-response pathway by coupling nucleolar stress induction to the mitochondrial apoptosis. Significance: Novel insight into the anti-apoptotic role of the ribosome processing factor PPAN is provided.

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“…The yeast counterpart of PPAN, Ssf1, was studied in more detail regarding ribosome processing. It was demonstrated that PPAN, together with its interaction partner PES, regulates the maturation of the large ribosomal subunit in the nucleolus (18,25). NPM is a direct binding factor of PES and is required for ribosome formation (19,26).…”

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confidence: 99%

The Wnt Target Protein Peter Pan Defines a Novel p53-independent Nucleolar Stress-Response Pathway

Pfister

Keil

Kühl

2015

Journal of Biological Chemistry

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“…The next nucleolar pre-60S particle, the Ssf1-defined particle, exhibits a complex composition: it contains a 27S pre-rRNA intermediate, more than 30 biogenesis factors, and already around half of the LSU r-proteins [86][87][88]. The following pre-60S ribosomes ([ 4 2 7 _ T D $ D I F F ] Erb1-or Nsa1-associated particles) mainly comprise the 27SB pre-rRNAs and have already lost some early biogenesis factors [86,89] (Figure 2K).…”

Section: Assembly Of the Lsumentioning

confidence: 99%

A Puzzle of Life: Crafting Ribosomal Subunits

Kressler

Hurt

Baßler

2017

Trends in Biochemical Sciences

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127

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The biogenesis of eukaryotic ribosomes is a complicated process during which the transcription, modification, folding, and processing of the rRNA is coupled with the ordered assembly of $80 ribosomal proteins (r-proteins). Ribosome synthesis is catalyzed and coordinated by more than 200 biogenesis factors as the preribosomal subunits acquire maturity on their path from the nucleolus to the cytoplasm. Several biogenesis factors also interconnect the progression of ribosome assembly with quality control of important domains, ensuring that only functional subunits engage in translation. With the recent visualization of several assembly intermediates by cryoelectron microscopy (cryo-EM), a structural view of ribosome assembly begins to emerge. In this review we integrate these first structural insights into an updated overview of the consecutive ribosome assembly steps. Synopsis of Eukaryotic Ribosome AssemblyRibosomes are the molecular machines that translate the genetic information from the intermediary mRNA templates into proteins [1]. Eukaryotic 80S ribosomes comprise two unequal subunits that contain four different rRNAs and around 80 r-proteins ( Figure 1). The small 40S subunit (SSU) comprises the 18S rRNA and 33 r-proteins (referred to as RPS or S). The large 60S subunit (LSU) comprises the 25S/28S, 5.8S, and 5S rRNA and, in most eukaryotic species, 47 r-proteins (RPL or L); a notable exception is budding yeasts, which lack eL28The act of building a ribosome begins in the nucleolus, where the ribosomal DNA (rDNA) is transcribed into a long pre-rRNA precursor (35S pre-rRNA in yeast) and involves the ordered assembly of the r-proteins with the pre-rRNA, which is concomitantly processed into the mature rRNA species [5][6][7][8] (Figure 1 and Box 1). These assembly and processing events are tightly coupled and occur within preribosomal particles (see Glossary) that travel, as maturation progresses, from the nucleus across nuclear pore complexes (NPCs) to the cytoplasm, where they are ultimately converted into translation-competent ribosomal subunits [5,[9][10][11][12][13] (Figure 2, Key Figure). Given the gargantuan complexity of this process, it is unsurprising that the assembly of eukaryotic ribosomes strictly requires the assistance of a plethora (>200) of mostly essential ribosome biogenesis factors, which are also called trans-acting or assembly factors [5,14,15].Our current knowledge has been mainly obtained by studying ribosome biogenesis in the yeast Saccharomyces cerevisiae. Research conducted in the 1970s defined the r-protein composition of ribosomes, revealed the major pre-rRNA processing intermediates, and uncovered the existence of the 90S, 43S, and 66S preribosomal particles. The following 25 years witnessed the identification of numerous biogenesis factors and attributed functional roles TrendsCryoelectron microscopy analyses of the 90S preribosome show that the biogenesis factors create a casting mold that encloses the nascent pre-40S subunit.Structures of nuclear pre-60S particles reveal that a...

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“…In the last few years, the maturation of 40 S and 60 S pre-ribosomes has been extensively analyzed by purification of pre-ribosomal particles (5)(6)(7)(8)(9)(10). Interestingly, a large number of non-ribosomal proteins were identified in pre-60 S particles without an assigned function in RNA metabolism.…”

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Rea1, a Dynein-related Nuclear AAA-ATPase, Is Involved in Late rRNA Processing and Nuclear Export of 60 S Subunits

Galani

Nissan

Petfalski

et al. 2004

Journal of Biological Chemistry

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Rea1, the largest predicted protein in the yeast genome, is a member of the AAA ؉ family of ATPases and is associated with pre-60 S ribosomes. Here we report that Rea1 is required for maturation and nuclear export of the pre-60 S subunit. Rea1 exhibits a predominantly nucleoplasmic localization and is present in a late pre-60 S particle together with members of the Rix1 complex. To study the role of Rea1 in ribosome biogenesis, we generated a repressible GAL::REA1 strain and temperaturesensitive rea1 alleles. In vivo depletion of Rea1 results in the significant reduction of mature 60 S subunits concomitant with defects in pre-rRNA processing and late pre-60 S ribosome stability following ITS2 cleavage and prior to the generation of mature 5.8 S rRNA. Strains depleted of the components of the Rix1 complex (Rix1, Ipi1, and Ipi3) showed similar defects. Using an in vivo 60 S subunit export assay, a strong accumulation of the large subunit reporter Rpl25-GFP (green fluorescent protein) in the nucleus and at the nuclear periphery was seen in rea1 mutants at restrictive conditions.The synthesis of ribosomes is one of the major and most energy-consuming processes in the cell. In Saccharomyces cerevisiae, ribosome biogenesis begins in the nucleolus with the transcription of two rRNA precursors, the 35 S and the pre-5 S RNA, by RNA polymerases I and III, respectively. The 35 S pre-rRNA contains the sequences for the mature 18 S, 5.8 S, and 25 S rRNAs, two external transcribed spacers (ETS) 1 and two internal transcribed spacers (ITS). During the maturation process, the pre-rRNA has to undergo a number of modifications and is subjected to cleavages and trimming events. At least 170 accessory proteins including putative RNA helicases, endo-and exonucleases, and putative GTPases and AAAATPases as well as small nucleolar ribonucleoprotein particles are involved in the maturation of rRNA and its assembly into ribosomal subunits (1, 2).Concomitant with rRNA processing, ribosomal and non-ribosomal proteins are assembled on the pre-35 S rRNA, giving rise to a large 90 S pre-ribosomal particle (see Fig. 6B) (3, 4). The initial cleavages at sites A 0 -A 2 separate the two subunits. The pre-40 S subunit is exported relatively rapidly to the cytoplasm, where it undergoes further processing. In contrast, the maturation of the large subunit continues in the nucleoplasm with recruitment of 60 S-specific biogenesis factors and further processing of the 27 S pre-rRNA. This includes the late cleavage and processing in the ITS2 region, which generates mature 5.8 S and 25 S rRNA.In the last few years, the maturation of 40 S and 60 S pre-ribosomes has been extensively analyzed by purification of pre-ribosomal particles (5-10). Interestingly, a large number of non-ribosomal proteins were identified in pre-60 S particles without an assigned function in RNA metabolism. In contrast to the pre-40 S particles, the nascent 60 S particles contain several putative GTPases and AAA-type ATPases (2, 11).To understand the events of ribosome biogenesis, w...

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Ssf1p Prevents Premature Processing of an Early Pre-60S Ribosomal Particle

Cited by 170 publications

References 42 publications

The Wnt Target Protein Peter Pan Defines a Novel p53-independent Nucleolar Stress-Response Pathway

The Wnt Target Protein Peter Pan Defines a Novel p53-independent Nucleolar Stress-Response Pathway

A Puzzle of Life: Crafting Ribosomal Subunits

Rea1, a Dynein-related Nuclear AAA-ATPase, Is Involved in Late rRNA Processing and Nuclear Export of 60 S Subunits

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