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Parker S, Fraczek MG, Wu J, Shamsah S, Manousaki A, Dungrattanalert K, de Almeida RA, Estrada-Rivadeneyra D, Omara W, Delneri D, O'Keefe RT. A resource for functional profiling of noncoding RNA in the yeast Saccharomyces cerevisiae. RNA (NEW YORK, N.Y.) 2017; 23:1166-1171. [PMID: 28468764 PMCID: PMC5513061 DOI: 10.1261/rna.061564.117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 05/01/2017] [Indexed: 06/07/2023]
Abstract
Eukaryotic genomes are extensively transcribed, generating many different RNAs with no known function. We have constructed 1502 molecular barcoded ncRNA gene deletion strains encompassing 443 ncRNAs in the yeast Saccharomyces cerevisiae as tools for ncRNA functional analysis. This resource includes deletions of small nuclear RNAs (snRNAs), transfer RNAs (tRNAs), small nucleolar RNAs (snoRNAs), and other annotated ncRNAs as well as the more recently identified stable unannotated transcripts (SUTs) and cryptic unstable transcripts (CUTs) whose functions are largely unknown. Specifically, deletions have been constructed for ncRNAs found in the intergenic regions, not overlapping genes or their promoters (i.e., at least 200 bp minimum distance from the closest gene start codon). The deletion strains carry molecular barcodes designed to be complementary with the protein gene deletion collection enabling parallel analysis experiments. These strains will be useful for the numerous genomic and molecular techniques that utilize deletion strains, including genome-wide phenotypic screens under different growth conditions, pooled chemogenomic screens with drugs or chemicals, synthetic genetic array analysis to uncover novel genetic interactions, and synthetic dosage lethality screens to analyze gene dosage. Overall, we created a valuable resource for the RNA community and for future ncRNA research.
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Affiliation(s)
| | | | - Jian Wu
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, United Kingdom
| | - Sara Shamsah
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, United Kingdom
| | | | | | - Rogerio Alves de Almeida
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, United Kingdom
| | - Diego Estrada-Rivadeneyra
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, United Kingdom
| | - Walid Omara
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, United Kingdom
- Department of Microbiology and Immunology, Faculty of Pharmacy, Minia University, Minya 11432, Egypt
| | | | - Raymond T O'Keefe
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, United Kingdom
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2
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Henras AK, Plisson-Chastang C, Humbert O, Romeo Y, Henry Y. Synthesis, Function, and Heterogeneity of snoRNA-Guided Posttranscriptional Nucleoside Modifications in Eukaryotic Ribosomal RNAs. Enzymes 2017; 41:169-213. [PMID: 28601222 DOI: 10.1016/bs.enz.2017.03.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ribosomal RNAs contain numerous 2'-O-methylated nucleosides and pseudouridines. Methylation of the 2' oxygen of ribose moieties and isomerization of uridines into pseudouridines are catalyzed by C/D and H/ACA small nucleolar ribonucleoprotein particles, respectively. We review the composition, structure, and mode of action of archaeal and eukaryotic C/D and H/ACA particles. Most rRNA modifications cluster in functionally crucial regions of the rRNAs, suggesting they play important roles in translation. Some of these modifications promote global translation efficiency or modulate translation fidelity. Strikingly, recent quantitative nucleoside modification profiling methods have revealed that a subset of modification sites is not always fully modified. The finding of such ribosome heterogeneity is in line with the concept of specialized ribosomes that could preferentially translate specific mRNAs. This emerging concept is supported by findings that some human diseases are caused by defects in the rRNA modification machinery correlated with a significant alteration of IRES-dependent translation.
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Affiliation(s)
- Anthony K Henras
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France.
| | - Célia Plisson-Chastang
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Odile Humbert
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Yves Romeo
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Yves Henry
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France.
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3
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Makarova JA, Ivanova SM, Tonevitsky AG, Grigoriev AI. New functions of small nucleolar RNAs. BIOCHEMISTRY (MOSCOW) 2013; 78:638-50. [DOI: 10.1134/s0006297913060096] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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4
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Wang PPS, Ruvinsky I. Family size and turnover rates among several classes of small non-protein-coding RNA genes in Caenorhabditis nematodes. Genome Biol Evol 2012; 4:565-74. [PMID: 22467905 PMCID: PMC3342880 DOI: 10.1093/gbe/evs034] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
It is important to understand the forces that shape the size and evolutionary histories of gene families. Here, we investigated the evolution of non–protein-coding RNA genes in the genomes of Caenorhabditis nematodes. We specifically focused on nested arrangements, that is, cases in which an RNA gene is entirely contained in an intron of another gene. Comparing these arrangements between species simplifies the inference of orthology and, therefore, of evolutionary fates of nested genes. Two distinct patterns are evident in the data. Genes encoding small nuclear RNAs (snRNAs) and transfer RNAs form large families, which have persisted since before the common ancestor of Metazoa. Yet, individual genes die relatively rapidly, with few orthologs having survived since the divergence of Caenorhabditis elegans and Caenorhabditis briggsae. In contrast, genes encoding small nucleolar RNAs (snoRNAs) are either single-copy or form small families. Individual snoRNAs turn over at a relatively slow rate—most C. elegans genes have clearly identifiable orthologs in C. briggsae. We also found that in Drosophila, genes from larger snRNA families die at a faster rate than their counterparts from single-gene families. These results suggest that a relationship between family size and the rate of gene turnover may be a general feature of genome evolution.
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Affiliation(s)
- Paul Po-Shen Wang
- Department of Ecology and Evolution, Institute for Genomics and Systems Biology, The University of Chicago, IL, USA
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5
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Esguerra J, Warringer J, Blomberg A. Functional importance of individual rRNA 2'-O-ribose methylations revealed by high-resolution phenotyping. RNA (NEW YORK, N.Y.) 2008; 14:649-56. [PMID: 18256246 PMCID: PMC2271359 DOI: 10.1261/rna.845808] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 12/13/2007] [Indexed: 05/21/2023]
Abstract
Ribosomal RNAs contain numerous modifications at specific nucleotides. Despite their evolutionary conservation, the functional role of individual 2'-O-ribose methylations in rRNA is not known. A distinct family of small nucleolar RNAs, box C/D snoRNAs, guides the methylating complex to specific rRNA sites. Using a high-resolution phenotyping approach, we characterized 20 box C/D snoRNA gene deletions for altered growth dynamics under a wide array of environmental perturbations, encompassing intraribosomal antibiotics, inhibitors of specific cellular features, as well as general stressors. Ribosome-specific antibiotics generated phenotypes indicating different and long-ranging structural effects of rRNA methylations on the ribosome. For all studied box C/D snoRNA mutants we uncovered phenotypes to extraribosomal growth inhibitors, most frequently reflected in alteration in growth lag (adaptation time). A number of strains were highly pleiotropic and displayed a great number of sensitive phenotypes, e.g., deletion mutants of snR70 and snR71, which both have clear human homologues, and deletion mutants of snR65 and snR68. Our data indicate that individual rRNA ribose methylations can play either distinct or general roles in the workings of the ribosome.
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MESH Headings
- Anti-Bacterial Agents/pharmacology
- Genes, Fungal
- Methylation
- Nucleic Acid Conformation/drug effects
- Phenotype
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Ribosomal/chemistry
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Ribose/chemistry
- Ribosomes/drug effects
- Ribosomes/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Sequence Deletion
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Affiliation(s)
- Jonathan Esguerra
- Department of Cell and Molecular Biology, Göteborg University, 405 30 Göteborg, Sweden
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6
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7
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Normand C, Capeyrou R, Quevillon-Cheruel S, Mougin A, Henry Y, Caizergues-Ferrer M. Analysis of the binding of the N-terminal conserved domain of yeast Cbf5p to a box H/ACA snoRNA. RNA (NEW YORK, N.Y.) 2006; 12:1868-82. [PMID: 16931875 PMCID: PMC1581976 DOI: 10.1261/rna.141206] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
During ribosome biogenesis, the RNA precursor to mature rRNAs undergoes numerous post-transcriptional chemical modifications of bases, including conversions of uridines to pseudouridines. In archaea and eukaryotes, these conversions are performed by box H/ACA small ribonucleoprotein particles (box H/ACA RNPs), which contain a small guide RNA responsible for the selection of substrate uridines and four proteins, including the pseudouridine synthase, Cbf5p. So far, no in vitro reconstitution of eukaryotic box H/ACA RNPs from purified components has been achieved, principally due to difficulties in purifying recombinant eukaryotic Cbf5p. In this study, we present the purification of a truncated derivative of yeast Cbf5p (Cbf5(Delta)p) that retains the highly conserved TRUB and PUA domains. We have used band retardation assays to show that Cbf5(Delta)p on its own binds to box H/ACA small nucleolar (sno)RNAs. We demonstrate that the conserved H and ACA boxes enhance the affinity of the protein for the snoRNA. Furthermore, like its archaeal homologs, Cbf5(Delta)p can bind to a single stem-loop-box ACA RNA. Finally, we report the first enzymatic footprinting analysis of a Cbf5-RNA complex. Our results are compatible with the view that two molecules of Cbf5p interact with a binding platform constituted by the 5' end of the RNA, the single-stranded hinge domain containing the conserved H box, and the 3' end of the molecule, including the conserved ACA box.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Binding Sites/genetics
- Conserved Sequence
- Hydro-Lyases/chemistry
- Hydro-Lyases/genetics
- Hydro-Lyases/metabolism
- Microtubule-Associated Proteins/chemistry
- Microtubule-Associated Proteins/genetics
- Microtubule-Associated Proteins/metabolism
- Molecular Sequence Data
- Nucleic Acid Conformation
- Protein Binding
- Protein Footprinting
- Protein Structure, Tertiary
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Ribonucleases
- Ribonucleoproteins, Small Nuclear/chemistry
- Ribonucleoproteins, Small Nuclear/genetics
- Ribonucleoproteins, Small Nuclear/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/chemistry
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Sequence Homology, Amino Acid
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Affiliation(s)
- Christophe Normand
- Equipe Labellisée Ligue Nationale contre le Cancer, Laboratoire de Biologie Moléculaire Eucaryote, UMR5099, CNRS-Université Paul Sabatier, IFR 109, Toulouse, France, European Union
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8
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Meier UT. The many facets of H/ACA ribonucleoproteins. Chromosoma 2005; 114:1-14. [PMID: 15770508 PMCID: PMC4313906 DOI: 10.1007/s00412-005-0333-9] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 01/31/2005] [Accepted: 02/01/2005] [Indexed: 10/25/2022]
Abstract
The H/ACA ribonucleoproteins (RNPs) are known as one of the two major classes of small nucleolar RNPs. They predominantly guide the site-directed pseudouridylation of target RNAs, such as ribosomal and spliceosomal small nuclear RNAs. In addition, they process ribosomal RNA and stabilize vertebrate telomerase RNA. Taken together, the function of H/ACA RNPs is essential for ribosome biogenesis, pre-mRNA splicing, and telomere maintenance. Every cell contains 100-200 different species of H/ACA RNPs, each consisting of the same four core proteins and one function-specifying H/ACA RNA. Most of these RNPs reside in nucleoli and Cajal bodies and mediate the isomerization of specific uridines to pseudouridines. Catalysis of the reaction is mediated by the putative pseudouridylase NAP57 (dyskerin, Cbf5p). Unexpectedly, mutations in this housekeeping enzyme are the major determinants of the inherited bone marrow failure syndrome dyskeratosis congenita. This review details the many diverse functions of H/ACA RNPs, some yet to be uncovered, with an emphasis on the role of the RNP proteins. The multiple functions of H/ACA RNPs appear to be reflected in the complex phenotype of dyskeratosis congenita.
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Affiliation(s)
- U Thomas Meier
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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9
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Lapeyre B. Conserved ribosomal RNA modification and their putative roles in ribosome biogenesis and translation. ACTA ACUST UNITED AC 2004. [DOI: 10.1007/b105433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
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10
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Lapeyre B, Purushothaman SK. Spb1p-Directed Formation of Gm2922 in the Ribosome Catalytic Center Occurs at a Late Processing Stage. Mol Cell 2004; 16:663-9. [PMID: 15546625 DOI: 10.1016/j.molcel.2004.10.022] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Revised: 08/20/2004] [Accepted: 08/26/2004] [Indexed: 10/25/2022]
Abstract
rRNA molecules undergo extensive posttranscriptional modification, predominantly 2'-O-ribose methylation and pseudouridine formation, both of which are guided by the numerous small nucleolar RNAs in eukaryotes. Here, we describe an exception to this rule. The essential yeast nucleolar protein Spb1p is a site-specific rRNA methyltransferase modifying the universally conserved G2922 that is located within the A loop of the catalytic center of the ribosome. The equivalent position in bacteria is the docking site for aminoacyl-tRNA, and it is critical for translation. In sharp contrast to other 2'-O-methylriboses that are formed on the primary transcript, Gm2922 appears at a late processing stage, during the maturation of the 27S pre-rRNA. Thus, eukaryotes have maintained a site-specific enzyme to catalyze the methylation of a nucleotide that plays a crucial role in ribosome biogenesis and translation.
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Affiliation(s)
- Bruno Lapeyre
- Centre de Recherche de Biochimie Macromoléculaire, 1919 Route de Mende, 34293 Montpellier, France.
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11
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Van Nues RW, Brown JD. Saccharomyces SRP RNA secondary structures: a conserved S-domain and extended Alu-domain. RNA (NEW YORK, N.Y.) 2004; 10:75-89. [PMID: 14681587 PMCID: PMC1370520 DOI: 10.1261/rna.5137904] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Accepted: 09/22/2003] [Indexed: 05/20/2023]
Abstract
The contribution made by the RNA component of signal recognition particle (SRP) to its function in protein targeting is poorly understood. We have generated a complete secondary structure for Saccharomyces cerevisiae SRP RNA, scR1. The structure conforms to that of other eukaryotic SRP RNAs. It is rod-shaped with, at opposite ends, binding sites for proteins required for the SRP functions of signal sequence recognition (S-domain) and translational elongation arrest (Alu-domain). Micrococcal nuclease digestion of purified S. cerevisiae SRP separated the S-domain of the RNA from the Alu-domain as a discrete fragment. The Alu-domain resolved into several stable fragments indicating a compact structure. Comparison of scR1 with SRP RNAs of five yeast species related to S. cerevisiae revealed the S-domain to be the most conserved region of the RNA. Extending data from nuclease digestion with phylogenetic comparison, we built the secondary structure model for scR1. The Alu-domain contains large extensions, including a sequence with hallmarks of an expansion segment. Evolutionarily conserved bases are placed in the Alu- and S-domains as in other SRP RNAs, the exception being an unusual GU(4)A loop closing the helix onto which the signal sequence binding Srp54p assembles (domain IV). Surprisingly, several mutations within the predicted Srp54p binding site failed to disrupt SRP function in vivo. However, the strength of the Srp54p-scR1 and, to a lesser extent, Sec65p-scR1 interaction was decreased in these mutant particles. The availability of a secondary structure for scR1 will facilitate interpretation of data from genetic analysis of the RNA.
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Affiliation(s)
- Rob W Van Nues
- School of Cell and Molecular Biosciences, The Medical School, University of Newcastle, Newcastle Upon Tyne, NE2 4HH, UK
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12
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Olson BL, Siliciano PG. A diverse set of nuclear RNAs transfer between nuclei of yeast heterokaryons. Yeast 2003; 20:893-903. [PMID: 12868058 DOI: 10.1002/yea.1015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Small nuclear RNAs and small nucleolar RNAs function in the nucleus of eukaryotic cells during pre-mRNA splicing and ribosomal RNA processing, respectively. In metazoan cells, the small nuclear RNAs shuttle between the nucleus and the cytoplasm during ribonucleoprotein particle assembly. Nuclear export of these small RNAs in yeast, however, has not been demonstrated. Therefore, we have attempted to visualize internuclear RNA movements by in situ hybridization in heterokaryon yeast cells. Using the kar1Delta15 mutation to block karyogamy, we mated two strains, each expressing a unique allele of U1 snRNA. In these heterokaryons, we observed a time-dependent transfer of U1 snRNA from one nucleus to the other. This transfer was reduced two-fold by the addition of the Crm1p-inhibitor leptomycin B. Interestingly, however, we observed identical transfer of the U2 and U6 snRNAs and SNR4, SNR8, SNR9 and SNR11 snoRNAs. Remarkably, when the U2, U6 or SNR4 RNAs were observed in the same heterokaryon as the U1 snRNA, both RNAs always transferred simultaneously. These data suggest a global leaking or transport of material between nuclei of yeast heterokaryons. Our results suggest that caution must be taken when testing nuclear envelope shuttling in yeast heterokaryons.
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MESH Headings
- Active Transport, Cell Nucleus/genetics
- Active Transport, Cell Nucleus/physiology
- Antifungal Agents/pharmacology
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- DNA, Fungal/genetics
- DNA, Fungal/metabolism
- Fatty Acids, Unsaturated/pharmacology
- Genes, Fungal/genetics
- Genes, Fungal/physiology
- In Situ Hybridization, Fluorescence
- RNA, Small Nuclear/genetics
- RNA, Small Nuclear/metabolism
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Yeasts/genetics
- Yeasts/metabolism
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Affiliation(s)
- Brian L Olson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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13
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King TH, Liu B, McCully RR, Fournier MJ. Ribosome structure and activity are altered in cells lacking snoRNPs that form pseudouridines in the peptidyl transferase center. Mol Cell 2003; 11:425-35. [PMID: 12620230 DOI: 10.1016/s1097-2765(03)00040-6] [Citation(s) in RCA: 207] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
One of the oldest questions in RNA science is the role of nucleotide modification. Here, the importance of pseudouridine formation (Psi) in the peptidyl transferase center of rRNA was examined by depleting yeast cells of 1-5 snoRNAs that guide a total of six Psi modifications. Translation was impaired substantially with loss of a conserved Psi in the A site of tRNA binding. Depletion of other Psis had subtle or no apparent effect on activity; however, synergistic effects were observed in some combinations. Pseudouridines are proposed to enhance ribosome activity by altering rRNA folding and interactions, with some Psis having greater effects than others. The possibility that modifying snoRNPs might affect ribosome structure in other ways is also discussed.
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MESH Headings
- Base Sequence
- Cell Division
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Peptidyl Transferases/chemistry
- Peptidyl Transferases/metabolism
- Protein Biosynthesis
- Protein Structure, Secondary
- Pseudouridine/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Ribonucleoproteins, Small Nucleolar/metabolism
- Ribosomes/chemistry
- Ribosomes/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/metabolism
- RNA, Small Untranslated
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Affiliation(s)
- Thomas H King
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
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14
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Abstract
The synthesis of ribosomes is one of the major metabolic pathways in all cells. In addition to around 75 individual ribosomal proteins and 4 ribosomal RNAs, synthesis of a functional eukaryotic ribosome requires a remarkable number of trans-acting factors. Here, we will discuss the recent, and often surprising, advances in our understanding of ribosome synthesis in the yeast Saccharomyces cerevisiae. These will underscore the unexpected complexity of eukaryotic ribosome synthesis.
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Affiliation(s)
- J Venema
- Department of Biochemistry and Molecular Biology, BioCentrum Amsterdam, Vrije Universiteit, The Netherlands
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15
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Wilkinson BM, Tyson JR, Reid PJ, Stirling CJ. Distinct domains within yeast Sec61p involved in post-translational translocation and protein dislocation. J Biol Chem 2000; 275:521-9. [PMID: 10617647 DOI: 10.1074/jbc.275.1.521] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The translocation of secretory polypeptides into and across the membrane of the endoplasmic reticulum (ER) occurs at the translocon, a pore-forming structure that orchestrates the transport and maturation of polypeptides at the ER membrane. Recent data also suggest that misfolded or unassembled polypeptides exit the ER via the translocon for degradation by the cytosolic ubiquitin/proteasome pathway. Sec61p is a highly conserved multispanning membrane protein that constitutes a core component of the translocon. We have found that the essential function of the Saccharomyces cerevisiae Sec61p is retained upon deletion of either of two internal regions that include transmembrane domains 2 and 3, respectively. However, a deletion mutation encompassing both of these domains was found to be nonfunctional. Characterization of yeast mutants expressing the viable deletion alleles of Sec61p has revealed defects in post-translational translocation. In addition, the transmembrane domain 3 deletion mutant is induced for the unfolded protein response and is defective in the dislocation of a misfolded ER protein. These data demonstrate that the various activities of Sec61p can be functionally dissected. In particular, the transmembrane domain 2 region plays a role in post-translational translocation that is required neither for cotranslational translocation nor for protein dislocation.
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Affiliation(s)
- B M Wilkinson
- School of Biological Sciences, 2.205 Stopford Building, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
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16
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Maden BE, Hughes JM. Eukaryotic ribosomal RNA: the recent excitement in the nucleotide modification problem. Chromosoma 1997; 105:391-400. [PMID: 9211966 DOI: 10.1007/bf02510475] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Eukaryotic ribosomal RNA (rRNA) contains numerous modified nucleotides: about 115 methyl groups and some 95 pseudouridines in vertebrates; about 65 methyl groups and some 45 pseudouridines in Saccharomyces cerevisiae. All but about ten of the methyl groups are ribose methylations. The remaining ten are on heterocyclic bases. The ribose methylations occur very rapidly upon the primary rRNA transcript in the nucleolus, probably on nascent chains, and they appear to play an important role in ribosome maturation, at least in vertebrates. All of the methyl groups occur in the conserved core of rRNA. However, there is no consensus feature of sequence or secondary structure for the methylation sites; thus the nature of the signal(s) for site-specific methylations had until recently remained a mystery. The situation changed dramatically with the discovery that many of the ribose methylation sites are in regions that are precisely complementary to small nucleolar RNA (snoRNA) species. Experimental evidence indicates that structural motifs within the snoRNA species do indeed pinpoint the precise nucleotides to be methylated by the putative 2'-O-methyl transferase(s). Regarding base methylations, the gene DIM1, responsible for modification of the conserved dimethyladenosines near the 3' end of 18S rRNA, has been shown to be essential for viability in S. cerevisiae and is suggested to play a role in the nucleocytoplasmic transport of the small ribosomal subunit. Recently nearly all of the pseudouridines have also been mapped in the rRNA of several eukaryotic species. As is the case for ribose methylations, most pseudouridine modifications occur rapidly upon precursor rRNA, within core sequences, and in a variety of local primary and secondary structure environments. In contrast to ribose methylation, no potentially unifying process has yet been identified for the enzymic recognition of the many pseudouridine modification sites. However, the new data afford the basis for a search for any potential involvement of snoRNAs in the recognition process.
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Affiliation(s)
- B E Maden
- School of Biological Sciences, Life Sciences Building, University of Liverpool, Liverpool L69 7ZB, UK
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17
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Ganot P, Bortolin ML, Kiss T. Site-specific pseudouridine formation in preribosomal RNA is guided by small nucleolar RNAs. Cell 1997; 89:799-809. [PMID: 9182768 DOI: 10.1016/s0092-8674(00)80263-9] [Citation(s) in RCA: 469] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
During the nucleolar maturation of eukaryotic ribosomal RNAs, many selected uridines are converted into pseudouridine by a thus far undefined mechanism. The nucleolus contains a large number of small RNAs (snoRNAs) that share two conserved sequence elements, box H and ACA. In this study, we demonstrate that site-specific pseudouridylation of rRNAs relies on short ribosomal signal sequences that are complementary to sequences in box H/ACA snoRNAs. Genetic depletion and reconstitution studies on yeast snR5 and snR36 snoRNAs demonstrate that box H/ACA snoRNAs function as guide RNAs in rRNA pseudouridylation. These results define a novel function for snoRNAs and further reinforce the idea that base pairing is the most common way to obtain specific substrate-"enzyme" interactions during rRNA maturation.
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Affiliation(s)
- P Ganot
- Laboratoire de Biologie Moléculaire du CNRS, Université Paul Sabatier, Toulouse, France
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18
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Saris N, Holkeri H, Craven RA, Stirling CJ, Makarow M. The Hsp70 homologue Lhs1p is involved in a novel function of the yeast endoplasmic reticulum, refolding and stabilization of heat-denatured protein aggregates. J Cell Biol 1997; 137:813-24. [PMID: 9151684 PMCID: PMC2139846 DOI: 10.1083/jcb.137.4.813] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Heat stress is an obvious hazard, and mechanisms to recover from thermal damage, largely unknown as of yet, have evolved in all organisms. We have recently shown that a marker protein in the ER of Saccharomyces cerevisiae, denatured by exposure of cells to 50 degrees C after preconditioning at 37 degrees C, was reactivated by an ATP-dependent machinery, when the cells were returned to physiological temperature 24 degrees C. Here we show that refolding of the marker enzyme Hsp150Delta-beta-lactamase, inactivated and aggregated by the 50 degrees C treatment, required a novel ER-located homologue of the Hsp70 family, Lhs1p. In the absence of Lhs1p, Hsp150Delta-beta-lactamase failed to be solubilized and reactivated and was slowly degraded. Coimmunoprecipitation experiments suggested that Lhs1p was somehow associated with heat-denatured Hsp150Delta- beta-lactamase, whereas no association with native marker protein molecules could be detected. Similar findings were obtained for a natural glycoprotein of S. cerevisiae, pro-carboxypeptidase Y (pro-CPY). Lhs1p had no significant role in folding or secretion of newly synthesized Hsp150Delta-beta-lactamase or pro-CPY, suggesting that the machinery repairing heat-damaged proteins may have specific features as compared to chaperones assisting de novo folding. After preconditioning and 50 degrees C treatment, cells lacking Lhs1p remained capable of protein synthesis and secretion for several hours at 24 degrees C, but only 10% were able to form colonies, as compared to wild-type cells. We suggest that Lhs1p is involved in a novel function operating in the yeast ER, refolding and stabilization against proteolysis of heatdenatured protein. Lhs1p may be part of a fundamental heat-resistant survival machinery needed for recovery of yeast cells from severe heat stress.
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Affiliation(s)
- N Saris
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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19
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Ni J, Tien AL, Fournier MJ. Small nucleolar RNAs direct site-specific synthesis of pseudouridine in ribosomal RNA. Cell 1997; 89:565-73. [PMID: 9160748 DOI: 10.1016/s0092-8674(00)80238-x] [Citation(s) in RCA: 386] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ten ACA yeast small nucleolar RNAs (snoRNAs) were shown to be required for site-specific synthesis of pseudouridine psi in ribosomal RNA. A common secondary folding motif for the snoRNAs and rRNA target segments predicts that site selection involves: (1) base pairing of the snoRNA with complementary rRNA elements flanking the site of modification, and (2) identification of a uridine located at a near-constant distance from the snoRNA ACA box. The model is supported by mutations showing that: (1) reducing the complementarity between the snoRNA and rRNA disrupts psi formation, and (2) altering the distance between the ACA box and target uridine causes an adjacent uridine to be modified. This discovery implies that most snoRNAs function in targeting nucleotide modification in rRNA: ribose methylation for the box C/D snoRNAs and psi formation for the ACA snoRNAs.
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MESH Headings
- Animals
- Base Sequence
- Cell Nucleolus/metabolism
- Chick Embryo
- Models, Biological
- Molecular Sequence Data
- Molecular Structure
- Mutation
- Nucleic Acid Conformation
- Pseudouridine/biosynthesis
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Ribosomal/chemistry
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Small Nuclear/chemistry
- RNA, Small Nuclear/genetics
- RNA, Small Nuclear/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
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Affiliation(s)
- J Ni
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst 01003, USA
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20
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Abstract
Immuno-detection by 'Midwestern' blotting provides a simple way to identify trimethylguanosine (TMG) capped RNAs. With this technique, over 20 bands are observed when total cellular RNA from Saccharomyces cerevisiae is transferred to a nylon membrane and probed with anti-TMG antibodies. Most, if not all, species known to contain a TMG cap are detected by this method. Only TMG-capped RNAs are detected on Midwestern blots unlike anti-TMG immunoprecipitates. Midwestern blotting is a useful alternative to immunoprecipitation and Northern analysis and may prove to be a better method for determining the relative abundance of capped RNAs. The blots can be reprobed multiple times with labeled antisense oligonucleotides to determine the identity of any TMG-capped species for which the primary sequence or a clone is available. This dual detection capability provides a powerful tool for the analysis of TMG-capped snRNAs and snoRNAs.
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Affiliation(s)
- T P Rasmussen
- Laboratories of Genetics and Molecular Biology, University of Wisconsin, Madison 53706, USA
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21
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Venema J, Tollervey D. RRP5 is required for formation of both 18S and 5.8S rRNA in yeast. EMBO J 1996; 15:5701-14. [PMID: 8896463 PMCID: PMC452314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Three of the four eukaryotic ribosomal RNA molecules (18S, 5.8S and 25-28S) are synthesized as a single precursor which is subsequently processed into the mature rRNAs by a complex series of cleavage and modification reactions. In the yeast Saccharomyces cerevisiae, the early pre-rRNA cleavages at sites A0, A1 and A2, required for the synthesis of 18S rRNA, are inhibited in strains lacking RNA or protein components of the U3, U14, snR10 and snR30 small nucleolar ribonucleoproteins (snoRNPs). The subsequent cleavage at site A3, required for formation of the major, short form of 5.8S rRNA, is carried out by another ribonucleoprotein, RNase MRP. A screen for mutations showing synthetic lethality with deletion of the non-essential snoRNA, snR10, identified a novel gene, RRP5, which is essential for viability and encodes a 193 kDa nucleolar protein. Genetic depletion of Rrp5p inhibits the synthesis of 18S rRNA and, unexpectedly, also of the major short form of 5.8S rRNA. Pre-rRNA processing is concomitantly impaired at sites A0, A1, A2 and A3. This distinctive phenotype makes Rrp5p the first cellular component simultaneously required for the snoRNP-dependent cleavage at sites A0, A1 and A2 and the RNase MRP-dependent cleavage at A3 and provides evidence for a close interconnection between these processing events. Putative RRP5 homologues from Caenorhabditis elegans and humans were also identified, suggesting that the critical function of Rrp5p is evolutionarily conserved.
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Affiliation(s)
- J Venema
- EMBL, Gene Expression Programme, Heidelberg, Germany
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22
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Balakin AG, Smith L, Fournier MJ. The RNA world of the nucleolus: two major families of small RNAs defined by different box elements with related functions. Cell 1996; 86:823-34. [PMID: 8797828 DOI: 10.1016/s0092-8674(00)80156-7] [Citation(s) in RCA: 339] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have discovered that all known yeast and vertebrate small nucleolar RNAs (snoRNAs), except for the MRP/7-2 RNA, fall into two major classes. One class is defined by conserved boxes C and D and the other by a novel element: a consensus ACA triplet positioned 3 nt before the 3' end of the RNA. A role for the ACA box is snoRNA stability has been established by mutational analysis of a yeast ACA snoRNA (snR 11). Full function of the box depends on the integrity of an adjacent upstream stem. All members of the yeast ACA family are associated with the GAR1 protein. Binding of this or another common small nucleolar ribonucleoprotein particle protein is predicted to be a critical entry point to snoRNA posttranscriptional life, including precise formation of the snoRNA 3' end.
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Affiliation(s)
- A G Balakin
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst 01003, USA
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23
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Craven RA, Egerton M, Stirling CJ. A novel Hsp70 of the yeast ER lumen is required for the efficient translocation of a number of protein precursors. EMBO J 1996; 15:2640-50. [PMID: 8654361 PMCID: PMC450199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The yeast genome sequencing project predicts an open reading frame (YKL073) that would encode a novel member of the Hsp70 family of molecular chaperones. We report that this 881 codon reading frame represents a functional gene expressing a 113-119 kDa glycoprotein localized within the lumen of the endoplasmic reticulum (ER). We therefore propose to designate this gene LHS1 (Lumenal Hsp Seventy). Our studies indicate that LHS1 is regulated by the unfolded protein response pathway, as evidenced by its transcriptional induction in cells treated with tunicamycin, and in various mutants defective in precursor processing (sec11-7, sec53-6 and sec59-1). LHS1 is not essential for viability, but an Lhs1 null mutant strain exhibits a coordinated induction of genes regulated by the unfolded protein response indicating a role for Lhs1p in protein folding in the ER. Furthermore, the null mutation is synthetically lethal in combination with (delta)ire1, thus activation of the unfolded protein response pathway is essential for cells to tolerate loss of Lhs1p. Synthetically lethality is also seen with mutations in KAR2, strongly suggesting that Kar2p and Lhs1p have overlapping functions. The Lhs1 null mutant exhibits a severe constitutive defect in the translocation of several secretory preproteins. We therefore propose that Lhs1p is a molecular chaperone of the ER lumen involved in both polypeptide translocation and subsequent protein folding.
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Affiliation(s)
- R A Craven
- School of Biological Sciences, University of Manchester, UK
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24
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Abstract
Post-transcriptional processing of precursor-ribosomal RNA comprises a complex pathway of endonucleolytic cleavages, exonucleolytic digestion and covalent modifications. The general order of the various processing steps is well conserved in eukaryotic cells, but the underlying mechanisms are largely unknown. Recent analysis of pre-rRNA processing, mainly in the yeast Saccharomyces cerevisiae, has significantly improved our understanding of this important cellular activity. Here we will review the data that have led to our current picture of yeast pre-rRNA processing.
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Affiliation(s)
- J Venema
- European Molecular Biology Laboratory (EMBL), Gene Expression Programme, Heidelberg, Germany
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25
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Abstract
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 role 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.
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26
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Amillet JM, Labbe-Bois R. Isolation of the gene HEM4 encoding uroporphyrinogen III synthase in Saccharomyces cerevisiae. Yeast 1995; 11:419-24. [PMID: 7597845 DOI: 10.1002/yea.320110504] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We have isolated a genomic DNA fragment that complements the yeast temperature-sensitive cyt mutation, causing respiratory deficiency and accumulation of porphyrins (Sugimura et al., 1966). Partial DNA sequencing of the complementing region and search for similarity in the DNA and protein databases revealed that (1) the gene had been previously isolated by complementation of the mutation ts2326 (Langgut et al., 1986; accession number X04694), and (2) it encodes a protein with 18-23% identity to uroporphyrinogen III synthases from different sources. This enzyme catalyses the fourth step in the heme biosynthetic pathway and we named its gene HEM4. A hem4 delta disruption mutation was constructed which had phenotypes identical to the cyt mutation. Biochemical analysis confirmed the absence of uroporphyrinogen III synthase activity in both hem4 delta and cyt mutant strains.
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Affiliation(s)
- J M Amillet
- Laboratoire de Biochimie des Porphyrines, Institut Jacques Monod, Université Paris 7, France
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27
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Saccharomyces cerevisiae U14 small nuclear RNA has little secondary structure and appears to be produced by post-transcriptional processing. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)42412-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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28
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29
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Abstract
Despite their early discovery, research into the small RNAs associated with the eukaryotic nucleolus (snoRNAs) has lagged behind that of their cousins, the small nuclear RNAs which are known to function in mRNA splicing (spliceosomal snRNAs). Recent progress has now shown that the snoRNAs also occupy a vital niche in the RNA world, participating in the processing of ribosomal RNA. Like the spliceosomal snRNAs, the snoRNAs exist as ribonucleoprotein (RNP) particles which appear to assemble into a large multi-RNA RNP complex for pre-rRNA maturation.
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Affiliation(s)
- M J Fournier
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst 01003
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30
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Stirling CJ, Hewitt EW. The S. cerevisiae SEC65 gene encodes a component of yeast signal recognition particle with homology to human SRP19. Nature 1992; 356:534-7. [PMID: 1313948 DOI: 10.1038/356534a0] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Translocation of proteins across the endoplasmic reticulum (ER) membrane represents the first step in the eukaryotic secretory pathway. In mammalian cells, the targeting of secretory and membrane protein precursors to the ER is mediated by signal recognition particle (SRP), a cytosolic ribonucleoprotein complex comprising a molecule of 7SL RNA and six polypeptide subunits (relative molecular masses 9, 14, 19, 54, 68 and 72K). In Saccharomyces cerevisiae, a homologue of the 54K subunit (SRP54) co-purifies with a small cytoplasmic RNA, scR1 (refs 4, 5). Genetic data indicate that SRP54 and scR1 are involved in translocation in vivo, suggesting the existence of an SRP-like activity in yeast. Whether this activity requires additional components similar to those found in mammalian SRP is not known. We have recently reported a genetic selection that led to the isolation of a yeast mutant, sec65-1, which is conditionally defective in the insertion of integral membrane proteins into the ER. Here we report the cloning and sequencing of the SEC65 gene, which encodes a 31.2K protein with significant sequence similarity to the 19K subunit of human SRP (SRP19). We also report the cloning of a multicopy suppressor of sec65-1, and its identification as the previously defined SRP54 gene, providing genetic evidence for an interaction between these gene products in vivo.
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Affiliation(s)
- C J Stirling
- Department of Biochemistry and Molecular Biology, Medical School, University of Manchester, UK
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31
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Reddy R, Singh R, Shimba S. Methylated cap structures in eukaryotic RNAs: structure, synthesis and functions. Pharmacol Ther 1992; 54:249-67. [PMID: 1465477 DOI: 10.1016/0163-7258(92)90002-h] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
There are more than twenty capped small nuclear RNAs characterized in eukaryotic cells. All the capped RNAs appear to be involved in the processing of other nuclear premessenger or preribosomal RNAs. These RNAs contain either trimethylguanosine (TMG) cap structure or methylated gamma phosphate (Mppp) cap structure. The TMG capped RNAs are capped with M7G during transcription by RNA polymerase II and trimethylated further post-transcriptionally. The Mppp-capped RNAs are transcribed by RNA polymerase III and also capped post-transcriptionally. The cap structures improve the stability of the RNAs and in some cases TMG cap is required for transport of the ribonucleoproteins from cytoplasm to the nucleus. Where tested, the cap structures were not essential for their function in processing other RNAs.
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Affiliation(s)
- R Reddy
- Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030
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32
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Abstract
We have identified the Saccharomyces cerevisiae homolog of the signal recognition particle (SRP) and characterized its function in vivo. S. cerevisiae SRP is a 16S particle that includes a homolog of the signal sequence-binding protein subunit of SRP (SRP54p) and a small cytoplasmic RNA (scR1). Surprisingly, the genes encoding scR1 and SRP54p are not essential for growth, though SRP-deficient cells grow poorly, suggesting that SRP function can be partially by-passed in vivo. Protein translocation across the ER membrane is impaired in SRP-deficient cells, indicating that yeast SRP, like its mammalian counterpart, functions in this process. Unexpectedly, the degree of the translocation defect varies for different proteins. The ability of some proteins to be efficiently targeted in SRP-deficient cells may explain why previous genetic and biochemical analyses in yeast and bacteria did not reveal components of the SRP-dependent protein targeting pathway.
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Affiliation(s)
- B C Hann
- Department of Biochemistry and Biophysics, University of California, Medical School, San Francisco 94143-0448
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33
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Affiliation(s)
- J L Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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34
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Affiliation(s)
- J Craft
- Yale University School of Medicine, New Haven, Connecticut
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35
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Tollervey D, Hurt EC. The role of small nucleolar ribonucleoproteins in ribosome synthesis. Mol Biol Rep 1990; 14:103-6. [PMID: 2141891 DOI: 10.1007/bf00360433] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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36
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Aramayo R, Adams TH, Timberlake WE. A large cluster of highly expressed genes is dispensable for growth and development in Aspergillus nidulans. Genetics 1989; 122:65-71. [PMID: 2471671 PMCID: PMC1203693 DOI: 10.1093/genetics/122.1.65] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We investigated the functions of the highly expressed, sporulation-specific SpoC1 genes of Aspergillus nidulans by deleting the entire 38-kb SpoC1 gene cluster. The resultant mutant strain did not differ from the wild type in (1) growth rate, (2) morphology of specialized reproductive structures formed during completion of the asexual or sexual life cycles, (3) sporulation efficiency, (4) spore viability or (5) spore resistance to environmental stress. Thus, deletion of the SpoC1 gene cluster, representing 0.15% of the A. nidulans genome, had no readily detectable phenotypic effects. Implications of this result are discussed in the context of major alterations in gene expression that occur during A. nidulans development.
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Affiliation(s)
- R Aramayo
- Department of Genetics, University of Georgia, Athens 30602
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37
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Abstract
Yeast U2 snRNA (1175 nucleotides) is six times larger than its mammalian counterpart (188 nucleotides). Using deletion analysis, we show that the molecule can be divided into three phenotypically distinct domains. As expected, the highly conserved 5' domain (approximately 120 nucleotides) is absolutely essential for viability. Surprisingly, however, deletion of the central 945 nucleotides has no effect on growth rate. In contrast, removal of sequences in the 3' terminal 110 nucleotides results in low numbers of slow-growing colonies; these cells contain U2 with altered 3' ends. This domain can be folded into a secondary structure that strongly resembles the 3' terminal stem-loop IV of human U2. We conclude that yeast U2 contains two functionally important elements. While the 5' domain is known to be directly involved in the splicing reaction, the 3' domain may function primarily in the generation of stable small nuclear ribonucleoprotein particles.
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Affiliation(s)
- E O Shuster
- Department of Biochemistry and Biophysics, University of California, San Francisco 94143
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