Functional Analysis of Rrp7p, an Essential Yeast Protein Involved in Pre-rRNA Processing and Ribosome Assembly

Baudin-Baillieu, Agnès; Tollervey, David; Cullin, Christophe; Lacroute, François

doi:10.1128/mcb.17.9.5023

Cited by 66 publications

(58 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Recent studies have revealed that several factors are required for the correct assembly of a specific ribosomal protein into preribosomal particles. It was suggested that Rrb1p, a yeast homolog of the smallest subunit of chromatin assembly factor 1 (CAF1), forms a direct complex with Rpl3p and assists its interaction with the rRNA precursor as a chaperone (37), and that Rrp7p is required for the correct assembly of Rps27A⁄Bp into pre-40 S ribosomal particles (38). Sqt1p, a protein containing multiple WD repeats, is involved in the assembly of Rpl10p⁄Qsr1p on the 60 S ribosomal protein (39).…”

Section: Discussionmentioning

confidence: 99%

Rpf2p, an Evolutionarily Conserved Protein, Interacts with Ribosomal Protein L11 and Is Essential for the Processing of 27 SB Pre-rRNA to 25 S rRNA and the 60 S Ribosomal Subunit Assembly inSaccharomyces cerevisiae

Morita¹,

Miyoshi²,

Matsui³

et al. 2002

Journal of Biological Chemistry

View full text Add to dashboard Cite

Saccharomyces cerevisiae Rrs1p is a nuclear protein that is essential for the maturation of 25 S rRNA and the 60 S ribosomal subunit assembly. In two-hybrid screening, using RRS1 as bait, we have cloned YKR081c/RPF2. Rpf2p is essential for growth and is mainly localized in the nucleolus. The amino acid sequence of Rpf2p is highly conserved in eukaryotes from yeast to human. Similar to Rrs1p, Rpf2p shows physical interaction with ribosomal protein L11 and appears to associate with preribosomal subunits fairly tightly. Northern, methionine pulse-chase, and sucrose density gradient ultracentrifugation analyses reveal that the depletion of Rpf2p results in a delayed processing of pre-rRNA, a decrease of mature 25 S rRNA, and a shortage of 60 S subunits. An analysis of processing intermediates by primer extension shows that the Rpf2p depletion leads to an accumulation of 27 SB pre-rRNA, suggesting that Rpf2p is required for the processing of 27 SB into 25 S rRNA.

show abstract

Section: Discussionmentioning

confidence: 99%

Rpf2p, an Evolutionarily Conserved Protein, Interacts with Ribosomal Protein L11 and Is Essential for the Processing of 27 SB Pre-rRNA to 25 S rRNA and the 60 S Ribosomal Subunit Assembly inSaccharomyces cerevisiae

Morita¹,

Miyoshi²,

Matsui³

et al. 2002

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…The rest of the 90S particle proteins establish fewer interactions and behave as satellites to different components of the core. These "second-order" interactors include elements proposed to be essential for wrapping up the 35S pre-rRNA (i.e., proteins of the U3 snoRNP and Mpp10p complex) (15,30,37) and other ancillary molecules such as a regulatory GTPase (Bms1p) (20), an RNA helicase (Has1p) (9), the bifunctional protein Rrp5 (10,35), putative chaperone molecules and/or assembly factors for ribosomal proteins (Rrp7p and Krr1p) (2,28), and proteins implicated in the maturation and transport of 40S subunits (Nop14p and Noc4p) (23,24). Taken together, these results suggest that the major stabilization factor for the formation of the 90S particle is the association of its core components with the 35S pre-rRNA precursor, an step that confers the structural stability required for a conformational change of the pre-rRNA precursor that allows the exposure of specific domains and the subsequent incorporation of other 90S proteins with specialized functions in the modification and cleavage of the precursor.…”

Section: Discussionmentioning

confidence: 99%

The 90S Preribosome Is a Multimodular Structure That Is Assembled through a Hierarchical Mechanism

Pérez-Fernández

Román

Rivas

et al. 2007

Molecular and Cellular Biology

158

222

View full text Add to dashboard Cite

The 90S preribosomal particle is required for the production of the 18S rRNA from a pre-rRNA precursor. Despite the identification of the protein components of this particle, its mechanism of assembly and structural design remain unknown. In this work, we have combined biochemical studies, proteomic techniques, and bioinformatic analyses to shed light into the rules of assembly of the yeast 90S preribosome. Our results indicate that several protein subcomplexes work as discrete assembly subunits that bind in defined steps to the 35S pre-rRNA. The assembly of the t-UTP subunit is an essential step for the engagement of at least five additional subunits in two separate, and mutually independent, assembling routes. One of these routes leads to the formation of an assembly intermediate composed of the U3 snoRNP, the Pwp2p/UTP-B, subunit and the Mpp10p complex. The other assembly route involves the stepwise binding of Rrp5p and the UTP-C subunit. We also report the use of a bioinformatic approach that provides a model for the topological arrangement of protein components within the fully assembled particle. Together, our data identify the mechanism of assembly of the 90S preribosome and offer novel information about its internal architecture.The formation of eukaryotic ribosomes involves the production and correct assembly of four rRNAs and Ϸ80 ribosomal proteins. Due to its amenability for genetic and proteomic analyses, Saccharomyces cerevisiae is the organism where the different steps of this pathway have been best characterized (4,11,13,18,32,34). Thus, it is known that three of the four mature rRNAs that form the ribosome structure are generated from a common 35S pre-rRNA polycystronic precursor. After being transcribed in the nucleolus, this precursor is chemically modified and cleaved at three positions (known as the A 0 , A 1 , and A 2 sites) of its 5Ј-terminal end to generate the intermediate 33S, 32S, 27SA 2 , and 20S pre-rRNA precursors (see Fig. S1 in the supplemental material). The 20S and 27SA 2 pre-rRNAs then follow two independent maturation routes that lead to the generation of either the 18S rRNA (a component of the 40S ribosomal subunit) or the 5.8S and 25S rRNAs (two components of the 60S ribosomal subunit), respectively (see Fig. S1 in the supplemental material). These pre-rRNA maturation steps require the involvement of Ϸ170 nonribosomal proteins and 70 small nucleolar ribonucleoproteins (snoRNPs) (4,11,13,32). Different subsets of these molecules form large ribonucleoprotein complexes with specific pre-rRNA precursors that, according to their specific Svedberg coefficients in gradient ultracentrifugation experiments, were initially referred to as 90S, 66S, and 43S preribosomal particles (31, 33). The 90S particle, also known as the "small-subunit processome," contains the 35S pre-rRNA and assembly/processing factors needed for the early cleavage of the 35S pre-rRNA precursor at A 0 , A 1 , and A 2 sites, which is strictly required for the production of 40S ribosomal subunits. The 66S and 43S pa...

show abstract

“…2) (93). This suggests that Rrp7p is required for the correct assembly of Rps27A/Bp into pre-40S ribosomal particles (12).…”

Section: Factors Involved In Ribosome Assembly?mentioning

confidence: 99%

“…This results in a reduction of 18S rRNA synthesis and in a decreased ratio of 40S to 60S ribosomal subunits (12). Interestingly, the lethality of the ⌬rrp7 allele is suppressed by overexpression of the nearly identical proteins Rps27Ap and Rps27Bp (12), which belong to a small group of 40S subunit r-proteins that assemble late into pre-40S ribosomal particles (Fig. 2) (93).…”

Section: Factors Involved In Ribosome Assembly?mentioning

confidence: 99%

“…Moreover, it is often difficult to exclusively attribute an assembly function to a protein trans-acting factor, since ribosome assembly and prerRNA processing are intimately linked. Indeed, mutation in or depletion of r-proteins generally leads to a pre-rRNA processing phenotype (12,128,195). Therefore, we expect that some of the above-mentioned protein trans-acting factors also contribute in one way or another to ribosome assembly.…”

Section: Factors Involved In Ribosome Assembly?mentioning

confidence: 99%

See 1 more Smart Citation

Protein trans-Acting Factors Involved in Ribosome Biogenesis in Saccharomyces cerevisiae

Kressler

Linder

Cruz

1999

Molecular and Cellular Biology

341

343

View full text Add to dashboard Cite

2The synthesis of ribosomes is one of the major cellular activities, and in eukaryotes, it takes place primarily, although not exclusively, in a specialized subnuclear compartment termed the nucleolus (125, 155). There, the rRNA genes are transcribed as precursors (pre-rRNAs), which undergo processing and covalent modification. Maturation of pre-rRNAs is intimately linked to their assembly with the ribosomal proteins (r-proteins). These processes depend on various cis-acting elements (6, 188), and they require a large number of nonribosomal protein trans-acting factors (97,174,193). Experimental evidence suggests that the basic outline of ribosome synthesis is conserved throughout eukaryotes. However, most of our knowledge comes from the combination of molecular genetic and biochemical approaches in the yeast Saccharomyces cerevisiae. This minireview is aimed at giving an insight into the functions of the many protein trans-acting factors involved in ribosome biogenesis in S. cerevisiae. PRE-rRNA PROCESSING AND RIBOSOME ASSEMBLY PATHWAYSIn S. cerevisiae, the large 60S ribosomal subunits are composed of 46 r-proteins and three rRNA species (5S, 5.8S, and 25S) while the small 40S ribosomal subunits contain 32 rproteins and the 18S rRNA (142,201). Three of the four rRNAs (18S, 5.8S, and 25S) are transcribed as a single large pre-rRNA by RNA polymerase I (RNA pol I), whereas the fourth rRNA (5S) is independently transcribed as a pre-rRNA by RNA pol III (201). All four rRNAs are encoded by a 9.1-kb rDNA unit, which is repeated 100 to 200 times on the long arm of chromosome XII (Fig. 1A). In the 35S pre-rRNA, which is the longest detectable precursor, the mature rRNA sequences are separated by two internal transcribed spacer (ITS) sequences, ITS1 and ITS2, and flanked by two external transcribed spacer (ETS) sequences, a 5Ј ETS and a 3Ј ETS (Fig. 1). The 35S pre-rRNA differs from the primary RNA pol I transcript at its 3Ј end because transcription termination maps to nucleotide position ϩ210 relative to the 3Ј end of the mature 25S rRNA, while the 35S pre-rRNA is extended by 7 to 10 nucleotides (78,187,189). Maturation of the 35S pre-rRNA, which contains 10 known processing sites, is a multistep pathway that requires many different trans-acting factors (Fig. 1B and its legend) (97,174,193). Processing of the pre-5S rRNA is independent of 35S pre-rRNA maturation and kinetically faster than formation of mature 18S, 5.8S, and 25S rRNAs (146). The 5Ј end of the mature 5S rRNA corresponds to that of the primary transcript, whereas the 3Ј end is processed from a pre-5S rRNA that is extended by 7 to 13 nucleotides (141). Many specific nucleotides within the rRNA also undergo, mainly shortly after transcription, covalent modification. These modifications include isomerization of uridine to pseudouridine (⌿) by base rotation (45 modified nucleotides), methylation of the 2Ј-hydroxyl group of sugar residues (2Ј-O-ribose methylation; 55 modified nucleotides), and base methylation (about 10 modified nucleotides) (9,21,84,120,135...

show abstract

Functional Analysis of Rrp7p, an Essential Yeast Protein Involved in Pre-rRNA Processing and Ribosome Assembly

Cited by 66 publications

References 36 publications

Rpf2p, an Evolutionarily Conserved Protein, Interacts with Ribosomal Protein L11 and Is Essential for the Processing of 27 SB Pre-rRNA to 25 S rRNA and the 60 S Ribosomal Subunit Assembly inSaccharomyces cerevisiae

Rpf2p, an Evolutionarily Conserved Protein, Interacts with Ribosomal Protein L11 and Is Essential for the Processing of 27 SB Pre-rRNA to 25 S rRNA and the 60 S Ribosomal Subunit Assembly inSaccharomyces cerevisiae

The 90S Preribosome Is a Multimodular Structure That Is Assembled through a Hierarchical Mechanism

Protein trans-Acting Factors Involved in Ribosome Biogenesis in Saccharomyces cerevisiae

Contact Info

Product

Resources

About