scholarly journals Arabidopsis small nucleolar RNA monitors the efficient pre-rRNA processing during ribosome biogenesis

2016 ◽  
Vol 113 (42) ◽  
pp. 11967-11972 ◽  
Author(s):  
Pan Zhu ◽  
Yuqiu Wang ◽  
Nanxun Qin ◽  
Feng Wang ◽  
Jia Wang ◽  
...  
Keyword(s):  
Ribosome Biogenesis ◽  
Higher Plants ◽  
Ribosomal Subunit ◽  
Rrna Processing ◽  
Developmental Defects ◽  
Protein Mutants ◽  
5.8S Rrna ◽  
Important Regulator ◽  
Nucleolar Rna

Ribosome production in eukaryotes requires the complex and precise coordination of several hundred assembly factors, including many small nucleolar RNAs (snoRNAs). However, at present, the distinct role of key snoRNAs in ribosome biogenesis remains poorly understood in higher plants. Here we report that a previously uncharacterized C (RUGAUGA)/D (CUGA) type snoRNA, HIDDEN TREASURE 2 (HID2), acts as an important regulator of ribosome biogenesis through a snoRNA–rRNA interaction. Nucleolus-localized HID2 is actively expressed in Arabidopsis proliferative tissues, whereas defects in HID2 cause a series of developmental defects reminiscent of ribosomal protein mutants. HID2 associates with the precursor 45S rRNA and promotes the efficiency and accuracy of pre-rRNA processing. Intriguingly, disrupting HID2 in Arabidopsis appears to impair the integrity of 27SB, a key pre-rRNA intermediate that generates 25S and 5.8S rRNA and is known to be vital for the synthesis of the 60S large ribosomal subunit and also produces an imbalanced ribosome profile. Finally, we demonstrate that the antisense-box of HID2 is both functionally essential and highly conserved in eukaryotes. Overall, our study reveals the vital and possibly conserved role of a snoRNA in monitoring the efficiency of pre-rRNA processing during ribosome biogenesis.

scholarly journals Recent Advances on the Structure and Function of RNA Acetyltransferase Kre33/NAT10

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1035 ◽  
Author(s):  
Sophie Sleiman ◽  
Francois Dragon
Keyword(s):  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Ribosomal Subunit ◽  
40S Ribosomal Subunit ◽  
Functional Features ◽  
And Function ◽  
Progeria Syndrome ◽  
Hutchinson Gilford Progeria Syndrome ◽  
Nucleolar Rna

Ribosome biogenesis is one of the most energy demanding processes in the cell. In eukaryotes, the main steps of this process occur in the nucleolus and include pre-ribosomal RNA (pre-rRNA) processing, post-transcriptional modifications, and assembly of many non-ribosomal factors and ribosomal proteins in order to form mature and functional ribosomes. In yeast and humans, the nucleolar RNA acetyltransferase Kre33/NAT10 participates in different maturation events, such as acetylation and processing of 18S rRNA, and assembly of the 40S ribosomal subunit. Here, we review the structural and functional features of Kre33/NAT10 RNA acetyltransferase, and we underscore the importance of this enzyme in ribosome biogenesis, as well as in acetylation of non-ribosomal targets. We also report on the role of human NAT10 in Hutchinson–Gilford progeria syndrome.

scholarly journals Structural basis of GTPase-mediated mitochondrial ribosome biogenesis and recycling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hauke S. Hillen ◽  
Elena Lavdovskaia ◽  
Franziska Nadler ◽  
Elisa Hanitsch ◽  
Andreas Linden ◽  
...  
Keyword(s):  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Ribosomal Subunit ◽  
Structural Basis ◽  
Peptidyl Transferase ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
In Vitro Reconstitution

AbstractRibosome biogenesis requires auxiliary factors to promote folding and assembly of ribosomal proteins and RNA. Particularly, maturation of the peptidyl transferase center (PTC) is mediated by conserved GTPases, but the molecular basis is poorly understood. Here, we define the mechanism of GTPase-driven maturation of the human mitochondrial large ribosomal subunit (mtLSU) using endogenous complex purification, in vitro reconstitution and cryo-EM. Structures of transient native mtLSU assembly intermediates that accumulate in GTPBP6-deficient cells reveal how the biogenesis factors GTPBP5, MTERF4 and NSUN4 facilitate PTC folding. Addition of recombinant GTPBP6 reconstitutes late mtLSU biogenesis in vitro and shows that GTPBP6 triggers a molecular switch and progression to a near-mature PTC state. Additionally, cryo-EM analysis of GTPBP6-treated mature mitochondrial ribosomes reveals the structural basis for the dual-role of GTPBP6 in ribosome biogenesis and recycling. Together, these results provide a framework for understanding step-wise PTC folding as a critical conserved quality control checkpoint.

scholarly journals Bop1 Is a Mouse WD40 Repeat Nucleolar Protein Involved in 28S and 5.8S rRNA Processing and 60S Ribosome Biogenesis

2000 ◽  
Vol 20 (15) ◽  
pp. 5516-5528 ◽  
Author(s):  
Žaklina Strezoska ◽  
Dimitri G. Pestov ◽  
Lester F. Lau
Keyword(s):  
Ribosome Biogenesis ◽  
Ribosomal Subunit ◽  
Weight Fraction ◽  
Rnase A ◽  
Mutant Form ◽  
Rrna Processing ◽  
Ribonucleoprotein Complexes ◽  
Nuclear Extracts ◽  
Mouse Tissues ◽  
Mouse Cells

ABSTRACT We have identified and characterized a novel mouse protein, Bop1, which contains WD40 repeats and is highly conserved through evolution. bop1 is ubiquitously expressed in all mouse tissues examined and is upregulated during mid-G1 in serum-stimulated fibroblasts. Immunofluorescence analysis shows that Bop1 is localized predominantly to the nucleolus. In sucrose density gradients, Bop1 from nuclear extracts cosediments with the 50S-80S ribonucleoprotein particles that contain the 32S rRNA precursor. RNase A treatment disrupts these particles and releases Bop1 into a low-molecular-weight fraction. A mutant form of Bop1, Bop1Δ, which lacks 231 amino acids in the N- terminus, is colocalized with wild-type Bop1 in the nucleolus and in ribonucleoprotein complexes. Expression of Bop1Δ leads to cell growth arrest in the G1phase and results in a specific inhibition of the synthesis of the 28S and 5.8S rRNAs without affecting 18S rRNA formation. Pulse-chase analyses show that Bop1Δ expression results in a partial inhibition in the conversion of the 36S to the 32S pre-rRNA and a complete inhibition of the processing of the 32S pre-rRNA to form the mature 28S and 5.8S rRNAs. Concomitant with these defects in rRNA processing, expression of Bop1Δ in mouse cells leads to a deficit in the cytosolic 60S ribosomal subunits. These studies thus identify Bop1 as a novel, nonribosomal mammalian protein that plays a key role in the formation of the mature 28S and 5.8S rRNAs and in the biogenesis of the 60S ribosomal subunit.

Ribosome Biogenesis: Role of Small Nucleolar RNA in Maturation of Eukaryotic rRNA

2001 ◽  
Vol 66 (0) ◽  
pp. 575-590 ◽  
Author(s):  
S.A. GERBI ◽  
A.V. BOROVJAGIN ◽  
M. EZROKHI ◽  
T.S. LANGE
Keyword(s):  
Ribosome Biogenesis ◽  
Small Nucleolar Rna ◽  
Nucleolar Rna

scholarly journals Processing of the Precursors to Small Nucleolar RNAs and rRNAs Requires Common Components

1998 ◽  
Vol 18 (3) ◽  
pp. 1181-1189 ◽  
Author(s):  
Elisabeth Petfalski ◽  
Thomas Dandekar ◽  
Yves Henry ◽  
David Tollervey
Keyword(s):  
Small Nucleolar Rnas ◽  
Rrna Processing ◽  
5.8S Rrna ◽  
Genes Encoding ◽  
Sequences Analysis ◽  
Upstream Processing ◽  
Exonuclease Digestion ◽  
Nucleolar Rna ◽  
Nucleolar Rnas ◽  
Common Components

ABSTRACT The genes encoding the small nucleolar RNA (snoRNA) species snR190 and U14 are located close together in the genome of Saccharomyces cerevisiae. Here we report that these two snoRNAs are synthesized by processing of a larger common transcript. In strains mutant for two 5′→3′ exonucleases, Xrn1p and Rat1p, families of 5′-extended forms of snR190 and U14 accumulate; these have 5′ extensions of up to 42 and 55 nucleotides, respectively. We conclude that the 5′ ends of both snR190 and U14 are generated by exonuclease digestion from upstream processing sites. In contrast to snR190 and U14, the snoRNAs U18 and U24 are excised from the introns of pre-mRNAs which encode proteins in their exonic sequences. Analysis of RNA extracted from a dbr1-Δ strain, which lacks intron lariat-debranching activity, shows that U24 can be synthesized only from the debranched lariat. In contrast, a substantial level of U18 can be synthesized in the absence of debranching activity. The 5′ ends of these snoRNAs are also generated by Xrn1p and Rat1p. The same exonucleases are responsible for the degradation of several excised fragments of the pre-rRNA spacer regions, in addition to generating the 5′ end of the 5.8S rRNA. Processing of the pre-rRNA and both intronic and polycistronic snoRNAs therefore involves common components.

Small nucleolar RNA

1995 ◽  
Vol 73 (11-12) ◽  
pp. 845-858 ◽  
Author(s):  
Susan A. Gerbi
Keyword(s):  
Rna Polymerase Ii ◽  
Binding Sites ◽  
Ribosome Biogenesis ◽  
Internal Transcribed Spacers ◽  
28S Rrna ◽  
Small Nucleolar Rnas ◽  
Rrna Processing ◽  
Conserved Sequence ◽  
Nucleolar Rna ◽  
Nucleolar Rnas

A growing list of small nucleolar RNAs (snoRNAs) has been characterized in eukaryotes. They are transcribed by RNA polymerase II or III; some snoRNAs are encoded in the introns of other genes. The nonintronic polymerase II transcribed snoRNAs receive a trimethylguanosine cap, probably in the nucleus, and move to the nucleolus. snoRNAs are complexed with proteins, sometimes including fibrillarin. Localization and maintenance in the nucleolus of some snoRNAs requires the presence of initial precursor rRNA (pre-rRNA). Many snoRNAs have conserved sequence boxes C and D and a 3′ terminal stem; the roles of these features are discussed. Functional assays done for a few snoRNAs indicate their roles in rRNA processing for cleavage of the external and internal transcribed spacers (ETS and ITS). U3 is the most abundant snoRNA and is needed for cleavage of ETS1 and ITS1; experimental results on U3 binding sites in pre-rRNA are reviewed. 18S rRNA production also needs U14, U22, and snR30 snoRNAs, whereas U8 snoRNA is needed for 5.8S and 28S rRNA production. Other snoRNAs that are complementary to 18S or 28S rRNA might act as chaperones to mediate RNA folding. Whether snoRNAs join together in a large rRNA processing complex (the "processome") is not yet clear. It has been hypothesized that such complexes could anchor the ends of loops in pre-rRNA containing 18S or 28S rRNA, thereby replacing base-paired stems found in pre-rRNA of prokaryotes.Key words: RNA processing, small nucleolar RNAs, nucleolus, ribosome biogenesis, rRNA processing complex.

scholarly journals Sfp1 Plays a Key Role in Yeast Ribosome Biogenesis

2003 ◽  
Vol 2 (5) ◽  
pp. 1061-1068 ◽  
Author(s):  
Ian Fingerman ◽  
Vijayalakshmi Nagaraj ◽  
David Norris ◽  
Andrew K. Vershon
Keyword(s):  
Ribosome Biogenesis ◽  
Zinc Finger Protein ◽  
Ribosomal Subunit ◽  
Rrna Processing ◽  
Reporter Construct ◽  
Promoter Elements ◽  
Translational Machinery ◽  
Finger Protein ◽  
Activation Of Transcription ◽  
Direct Binding

ABSTRACT Sfp1, an unusual zinc finger protein, was previously identified as a gene that, when overexpressed, imparted a nuclear localization defect. sfp1 cells have a reduced size and a slow growth phenotype. In this study we show that SFP1 plays a role in ribosome biogenesis. An sfp1 strain is hypersensitive to drugs that inhibit translational machinery. sfp1 strains also have defects in global translation as well as defects in rRNA processing and 60S ribosomal subunit export. Microarray analysis has previously shown that ectopically expressed SFP1 induces the transcription of a large subset of genes involved in ribosome biogenesis. Many of these induced genes contain conserved promoter elements (RRPE and PAC). Our results show that activation of transcription from a reporter construct containing two RRPE sites flanking a single PAC element is SFP1 dependent. However, we have been unable to detect direct binding of the protein to these elements. This suggests that regulation of genes containing RRPEs is dependent upon Sfp1 but that Sfp1 may not directly bind to these conserved promoter elements; rather, activation may occur through an indirect mechanism.

scholarly journals tRNA Synthetases Are Recruited to Yeast Ribosomes by rRNA Expansion Segment 7L but Do Not Require Association for Functionality

2021 ◽  
Vol 7 (4) ◽  
pp. 73
Author(s):  
Nina Krauer ◽  
Robert Rauscher ◽  
Norbert Polacek
Keyword(s):  
Ribosome Biogenesis ◽  
Protein Biosynthesis ◽  
Ribosomal Subunit ◽  
Trna Synthetase ◽  
Translation Efficiency ◽  
Functional Roles ◽  
Trna Synthetases ◽  
Yeast Ribosomes ◽  
Ribosome Association

Protein biosynthesis is essential for any organism, yet how this process is regulated is not fully understood at the molecular level. During evolution, ribosomal RNA expanded in specific regions, referred to as rRNA expansion segments (ES). First functional roles of these expansions have only recently been discovered. Here we address the role of ES7La located in the large ribosomal subunit for factor recruitment to the yeast ribosome and the potential consequences for translation. Truncation of ES7La has only minor effects on ribosome biogenesis, translation efficiency and cell doubling. Using yeast rRNA deletion strains coupled with ribosome-specific mass spectrometry we analyzed the interactome of ribosomes lacking ES7La. Three aminoacyl-tRNA synthetases showed reduced ribosome association. Synthetase activities however remained unaltered suggesting that the pool of aminoacylated tRNAs is unaffected by the ES deletion. These results demonstrated that aminoacylation activities of tRNA synthetases per se do not rely on ribosome association. These findings suggest a role of ribosome-associated aminoacyl-tRNA synthetase beyond their core enzymatic functions.

scholarly journals Las1L Is a Nucleolar Protein Required for Cell Proliferation and Ribosome Biogenesis

2010 ◽  
Vol 30 (18) ◽  
pp. 4404-4414 ◽  
Author(s):  
Christopher D. Castle ◽  
Erica K. Cassimere ◽  
Jinho Lee ◽  
Catherine Denicourt
Keyword(s):  
Cell Proliferation ◽  
Cell Growth ◽  
Ribosome Biogenesis ◽  
Ribosomal Subunit ◽  
Nucleolar Protein ◽  
28S Rrna ◽  
Rrna Processing ◽  
Tumor Suppressor P53 ◽  
Growth Increase ◽  
Multistep Process

ABSTRACT Ribosome biogenesis is a highly regulated process ensuring that cell growth (increase in biomass) is coordinated with cell proliferation. The formation of eukaryotic ribosomes is a multistep process initiated by the transcription and processing of rRNA in the nucleolus. Concomitant with this, several preribosomal particles, which transiently associate with numerous nonribosomal factors before mature 60S and 40S subunits are formed and exported in the cytoplasm, are generated. Here we identify Las1L as a previously uncharacterized nucleolar protein required for ribosome biogenesis. Depletion of Las1L causes inhibition of cell proliferation characterized by a G1 arrest dependent on the tumor suppressor p53. Moreover, we demonstrate that Las1L is crucial for ribosome biogenesis and that depletion of Las1L leads to inhibition of rRNA processing and failure to synthesize the mature 28S rRNA. Taken together, our data demonstrate that Las1L is essential for cell proliferation and biogenesis of the 60S ribosomal subunit.

scholarly journals Xenopus LSm Proteins Bind U8 snoRNA via an Internal Evolutionarily Conserved Octamer Sequence

2002 ◽  
Vol 22 (12) ◽  
pp. 4101-4112 ◽  
Author(s):  
Nenad Tomasevic ◽  
Brenda A. Peculis
Keyword(s):  
Ribosome Biogenesis ◽  
Rna Binding ◽  
Ribosomal Subunit ◽  
High Specificity ◽  
Sm Proteins ◽  
U6 Snrna ◽  
Evolutionarily Conserved

ABSTRACT U8 snoRNA plays a unique role in ribosome biogenesis: it is the only snoRNA essential for maturation of the large ribosomal subunit RNAs, 5.8S and 28S. To learn the mechanisms behind the in vivo role of U8 snoRNA, we have purified to near homogeneity and characterized a set of proteins responsible for the formation of a specific U8 RNA-binding complex. This 75-kDa complex is stable in the absence of added RNA and binds U8 with high specificity, requiring the conserved octamer sequence present in all U8 homologues. At least two proteins in this complex can be cross-linked directly to U8 RNA. We have identified the proteins as Xenopus homologues of the LSm (like Sm) proteins, which were previously reported to be involved in cytoplasmic degradation of mRNA and nuclear stabilization of U6 snRNA. We have identified LSm2, -3, -4, -6, -7, and -8 in our purified complex and found that this complex associates with U8 RNA in vivo. This purified complex can bind U6 snRNA in vitro but does not bind U3 or U14 snoRNA in vitro, demonstrating that the LSm complex specifically recognizes U8 RNA.

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