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Terenin IM, Smirnova VV, Andreev DE, Dmitriev SE, Shatsky IN. A researcher's guide to the galaxy of IRESs. Cell Mol Life Sci 2017; 74:1431-1455. [PMID: 27853833 PMCID: PMC11107752 DOI: 10.1007/s00018-016-2409-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 12/25/2022]
Abstract
The idea of internal initiation is frequently exploited to explain the peculiar translation properties or unusual features of some eukaryotic mRNAs. In this review, we summarize the methods and arguments most commonly used to address cases of translation governed by internal ribosome entry sites (IRESs). Frequent mistakes are revealed. We explain why "cap-independent" does not readily mean "IRES-dependent" and why the presence of a long and highly structured 5' untranslated region (5'UTR) or translation under stress conditions cannot be regarded as an argument for appealing to internal initiation. We carefully describe the known pitfalls and limitations of the bicistronic assay and artefacts of some commercially available in vitro translation systems. We explain why plasmid DNA transfection should not be used in IRES studies and which control experiments are unavoidable if someone decides to use it anyway. Finally, we propose a workflow for the validation of IRES activity, including fast and simple experiments based on a single genetic construct with a sequence of interest.
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Affiliation(s)
- Ilya M Terenin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia.
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
| | - Victoria V Smirnova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
- Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Dmitri E Andreev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Sergey E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119334, Russia
- Department of Biochemistry, Biological Faculty, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Ivan N Shatsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia.
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2
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Hodgman CE, Jewett MC. Characterizing IGR IRES-mediated translation initiation for use in yeast cell-free protein synthesis. N Biotechnol 2014; 31:499-505. [PMID: 25017988 DOI: 10.1016/j.nbt.2014.07.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Revised: 06/02/2014] [Accepted: 07/02/2014] [Indexed: 12/27/2022]
Abstract
Eukaryotic cell-free protein synthesis (CFPS) systems are limited, in part, by inefficient translation initiation. Here, we report three internal ribosome entry site (IRES) sequences from the Dicistroviridae family that are highly active in yeast CFPS. These include the intergenic region (IGR) IRES from cricket paralysis virus (CrPV), plautia stali intestine virus (PSIV) and Solenopsis invicta virus 1 (SINV1). Optimization of combined transcription and translation (Tx/Tl) CFPS reactions primed with linear DNA containing the CrPV IGR IRES resulted in batch synthesis yields of 0.92 ± 0.17 μg/mL luciferase. Further template engineering, such as including the first 12 nt of native CrPV gene, increased yields to 2.33 ± 0.11 μg/mL. We next observed that the inclusion of a 50 nt poly(A) to the 3' end of the IGR IRES-mediated message increased yields an additional 81% to 4.33 ± 0.37 μg/mL, without any effect on mRNA stability or copy number. This was surprising because the CrPV IGR IRES requires no known translation initiation factors. Lastly, we investigated a method to inhibit background expression through competitive inhibition by supplying the reaction with 5' cap structure analog. This study highlights the crucial role translation initiation plays in yeast CFPS and offers a simple platform to study IRES sequences.
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Affiliation(s)
- C Eric Hodgman
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Technological Institute, E136, Evanston, IL 60208-3120, USA; Chemistry of Life Processes Institute, Northwestern University, 2170 Campus Drive, Evanston, IL 60208-3120, USA
| | - Michael C Jewett
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Technological Institute, E136, Evanston, IL 60208-3120, USA; Chemistry of Life Processes Institute, Northwestern University, 2170 Campus Drive, Evanston, IL 60208-3120, USA; Member, Robert H. Lurie Comprehensive Cancer Center, Northwestern University, 676 North St Clair Street, Suite 1200, Chicago, IL 60611-3068, USA; Institute for BioNanotechnology in Medicine, Northwestern University, 303 East Superior Street, Suite 11-131, Chicago, IL 60611-2875, USA.
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3
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Tomo N, Goto T, Morikawa Y. Trans-packaging of human immunodeficiency virus type 1 genome into Gag virus-like particles in Saccharomyces cerevisiae. Microb Cell Fact 2013; 12:28. [PMID: 23530915 PMCID: PMC3623794 DOI: 10.1186/1475-2859-12-28] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 03/15/2013] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Yeast is recognized as a generally safe microorganism and is utilized for the production of pharmaceutical products, including vaccines. We previously showed that expression of human immunodeficiency virus type 1 (HIV-1) Gag protein in Saccharomyces cerevisiae spheroplasts released Gag virus-like particles (VLPs) extracellularly, suggesting that the production system could be used in vaccine development. In this study, we further establish HIV-1 genome packaging into Gag VLPs in a yeast cell system. RESULTS The nearly full-length HIV-1 genome containing the entire 5' long terminal repeat, U3-R-U5, did not transcribe gag mRNA in yeast. Co-expression of HIV-1 Tat, a transcription activator, did not support the transcription. When the HIV-1 promoter U3 was replaced with the promoter for the yeast glyceraldehyde-3-phosphate dehydrogenase gene, gag mRNA transcription was restored, but no Gag protein expression was observed. Co-expression of HIV-1 Rev, a factor that facilitates nuclear export of gag mRNA, did not support the protein synthesis. Progressive deletions of R-U5 and its downstream stem-loop-rich region (SL) to the gag start ATG codon restored Gag protein expression, suggesting that a highly structured noncoding RNA generated from the R-U5-SL region had an inhibitory effect on gag mRNA translation. When a plasmid containing the HIV-1 genome with the R-U5-SL region was coexpressed with an expression plasmid for Gag protein, the HIV-1 genomic RNA was transcribed and incorporated into Gag VLPs formed by Gag protein assembly, indicative of the trans-packaging of HIV-1 genomic RNA into Gag VLPs in a yeast cell system. The concentration of HIV-1 genomic RNA in Gag VLPs released from yeast was approximately 500-fold higher than that in yeast cytoplasm. The deletion of R-U5 to the gag gene resulted in the failure of HIV-1 RNA packaging into Gag VLPs, indicating that the packaging signal of HIV-1 genomic RNA present in the R-U5 to gag region functions similarly in yeast cells. CONCLUSIONS Our data indicate that selective trans-packaging of HIV-1 genomic RNA into Gag VLPs occurs in a yeast cell system, analogous to a mammalian cell system, suggesting that yeast may provide an alternative packaging system for lentiviral RNA.
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Affiliation(s)
- Naoki Tomo
- Kitasato Institute for Life Sciences and Graduate School for Infection Control, Kitasato University, Shirokane 5-9-1, Minato-ku, Tokyo, 108-8641, Japan
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4
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Morikawa Y. [Study of animal viruses in yeast]. Uirusu 2006; 56:9-16. [PMID: 17038807 DOI: 10.2222/jsv.56.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Yeast is often considered to be a model eukaryotic organism, in a manner analogous to E. coli as a model prokaryotic organism. Yeast has been extensively characterized and the genomes completely sequenced. Despite the small genome size, yeast displays most of features of higher eukaryotes. The facts that most of cellular machinery is conserved among different eukaryotes and that the powerful technologies of genetics and molecular biology are available have made yeast model eukaryotic cells in biological and biomedical sciences including virology. Cumulative data indicate that yeast can be a host for animal viruses. I briefly describe yeast gene expression and review viral replication in yeast. Great discovery include complete replication of animal viruses and production of virus-like particle vaccines in yeast. Current studies on yeast focus on identification of host factors and machinery used for viral replication. The studies are based on traditional yeast genetics and genome-wide identification using a complete set of yeast deletion strains.
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Affiliation(s)
- Yuko Morikawa
- Kitasato Unversity, Shirokane 5-9-1, Minato-ku, Tokyo 108-8641, Japan.
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5
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Dasgupta A, Das S, Izumi R, Venkatesan A, Barat B. Targeting internal ribosome entry site (IRES)-mediated translation to block hepatitis C and other RNA viruses. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09533.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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Izumi RE, Das S, Barat B, Raychaudhuri S, Dasgupta A. A peptide from autoantigen La blocks poliovirus and hepatitis C virus cap-independent translation and reveals a single tyrosine critical for La RNA binding and translation stimulation. J Virol 2004; 78:3763-76. [PMID: 15016896 PMCID: PMC371053 DOI: 10.1128/jvi.78.7.3763-3776.2004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Accepted: 11/25/2003] [Indexed: 02/05/2023] Open
Abstract
La, a 52-kDa autoantigen in patients with systemic lupus erythematosus, was one of the first cellular proteins identified to interact with viral internal ribosome entry site (IRES) elements and stimulate poliovirus (PV) and hepatitis C virus (HCV) IRES-mediated translation. Previous results from our laboratory have shown that a small, yeast RNA (IRNA) could selectively inhibit PV and HCV IRES-mediated translation by sequestering the La protein. Here we have identified an 18-amino-acid-long sequence from the N-terminal "La motif" which is required for efficient interaction of La with IRNA and viral 5' untranslated region (5'-UTR) elements. A synthetic peptide (called LAP, for La peptide) corresponding to this sequence (amino acids 11 to 28) of La was found to efficiently inhibit viral IRES-mediated translation in vitro. The LAP efficiently enters Huh-7 cells and preferentially inhibits HCV IRES-mediated translation programmed by a bicistronic RNA in vivo. The LAP does not bind RNA directly but appears to block La binding to IRNA and PV 5'-UTR. Competition UV cross-link and translation rescue experiments suggested that LAP inhibits IRES-mediated translation by interacting with proteins rather than RNA. Mutagenesis of LAP demonstrates that single amino acid changes in a highly conserved sequence within LAP are sufficient to eliminate the translation-inhibitory activity of LAP. When one of these mutations (Y23Q) is introduced into full-length La, the mutant protein is severely defective in interacting with the PV IRES element and consequently unable to stimulate IRES-mediated translation. However, the La protein with a mutation of the next tyrosine moiety (Y24Q) could still interact with PV 5'-UTR and stimulate viral IRES-mediated translation significantly. These results underscore the importance of the La N-terminal amino acids in RNA binding and viral RNA translation. The possible role of the LAP sequence in La-RNA binding and stimulation of viral IRES-mediated translation is discussed.
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Affiliation(s)
- Raquel E Izumi
- Department of Microbiology, Immunology and Molecular Genetics, UCLA School of Medicine, University of California-Los Angeles, Los Angeles, California 90095, USA
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7
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Jan E, Thompson SR, Wilson JE, Pestova TV, Hellen CU, Sarnow P. Initiator Met-tRNA-independent translation mediated by an internal ribosome entry site element in cricket paralysis virus-like insect viruses. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 66:285-92. [PMID: 12762030 DOI: 10.1101/sqb.2001.66.285] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- E Jan
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305, USA
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Dorokhov YL, Skulachev MV, Ivanov PA, Zvereva SD, Tjulkina LG, Merits A, Gleba YY, Hohn T, Atabekov JG. Polypurine (A)-rich sequences promote cross-kingdom conservation of internal ribosome entry. Proc Natl Acad Sci U S A 2002; 99:5301-6. [PMID: 11959981 PMCID: PMC122764 DOI: 10.1073/pnas.082107599] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2001] [Accepted: 02/22/2002] [Indexed: 11/18/2022] Open
Abstract
The internal ribosome entry sites (IRES), IRES(CP,148)(CR) and IRES(MP,75)(CR), precede the coat protein (CP) and movement protein (MP) genes of crucifer-infecting tobamovirus (crTMV), respectively. In the present work, we analyzed the activity of these elements in transgenic plants and other organisms. Comparison of the relative activities of the crTMV IRES elements and the IRES from an animal virus--encephalomyocarditis virus--in plant, yeast, and HeLa cells identified the 148-nt IRES(CP,148)(CR) as the strongest element that also displayed IRES activity across all kingdoms. Deletion analysis suggested that the polypurine (A)-rich sequences (PARSs) contained in IRES(CP,148)(CR) are responsible for these features. On the basis of those findings, we designed artificial PARS-containing elements and showed that they, too, promote internal translation from dicistronic transcripts in vitro, in tobacco protoplasts and in HeLa cells. The maximum IRES activity was obtained from multiple copies of either (A)(4)G(A)(2)(G)(2) or G(A)(2-5) as contained in IRES(CP,148)(CR). Remarkably, even homopolymeric poly(A) was moderately active, whereas a poly(G) homopolymer was not active. Furthermore, a database search for existing PARS sequences in 5'-untranslated regions (5'UTR) of genes in tobacco genome allowed the easy identification of a number of IRES candidates, in particular in the 5'UTR of the gene encoding Nicotiana tabacum heat-shock factor 1 (NtHSF1). Consistent with our prediction, the 5'UTR of NtHSF1 turned out to be an IRES element active in vitro, in plant protoplasts and HeLa cells. We predict that PARS elements, when found in other mRNAs, will show a similar activity.
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Affiliation(s)
- Yuri L Dorokhov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119899 Moscow, Russia
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9
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Thompson SR, Gulyas KD, Sarnow P. Internal initiation in Saccharomyces cerevisiae mediated by an initiator tRNA/eIF2-independent internal ribosome entry site element. Proc Natl Acad Sci U S A 2001; 98:12972-7. [PMID: 11687653 PMCID: PMC60809 DOI: 10.1073/pnas.241286698] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Internal initiation of translation can be mediated by specific internal ribosome entry site (IRES) elements that are located in certain mammalian and viral mRNA molecules. Thus far, these mammalian cellular and viral IRES elements have not been shown to function in the yeast Saccharomyces cerevisiae. We report here that a recently discovered IRES located in the genome of cricket paralysis virus can direct the efficient translation of a second URA3 cistron in dicistronic mRNAs in S. cerevisiae, thereby conferring uracil-independent growth. Curiously, the IRES functions poorly in wild-type yeast but functions efficiently either in the presence of constitutive expression of the eIF2 kinase GCN2 or in cells that have two initiator tRNA(met) genes disrupted. Both of these conditions have been shown to lower the amounts of ternary eIF2-GTP/initiator tRNA(met) complexes. Furthermore, tRNA(met)-independent initiation was also observed in translation-competent extracts prepared from S. cerevisiae in the presence of edeine, a compound that has been shown to interfere with start codon recognition by ribosomal subunits carrying ternary complexes. Therefore, the cricket paralysis virus IRES is likely to recruit ribosomes by internal initiation in S. cerevisiae in the absence of eIF2 and initiator tRNA(met), by the same mechanism of factor-independent ribosome recruitment used in mammalian cells. These findings will allow the use of yeast genetics to determine the mechanism of internal ribosome entry.
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Affiliation(s)
- S R Thompson
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
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Izumi RE, Valdez B, Banerjee R, Srivastava M, Dasgupta A. Nucleolin stimulates viral internal ribosome entry site-mediated translation. Virus Res 2001; 76:17-29. [PMID: 11376843 DOI: 10.1016/s0168-1702(01)00240-4] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Previous results from our laboratory have identified a small (60 nt) RNA from the yeast S. cerevisiae that specifically inhibits internal ribosome entry site (IRES)-mediated translation programmed by poliovirus (PV) and hepatitis C virus (HCV) 5'-untranslated region (5'UTR). The yeast inhibitor RNA (called IRNA) was found to efficiently compete with viral 5'UTR for binding of several cellular polypeptides that presumably play important roles in IRES-mediated translation. One such IRNA (and 5'UTR)-binding protein has previously been identified as the La autoantigen. In this report, we have identified a 110-kDa IRNA-binding protein (which also interacts with viral 5'UTR) as nucleolin, a nucleolar RNA binding protein that was previously shown to translocate into the cytoplasm following infection of cells with poliovirus. We demonstrate that nucleolin (called C23) stimulates viral IRES-mediated translation both in vitro and in vivo. We also show that nucleolin mutants containing the carboxy-terminal RNA binding domains but lacking the amino terminal domain inhibit IRES-mediated translation in vitro. The translation inhibitory activity of these mutants correlates with their ability to bind the 5'UTR sequence. These results suggest a role of nucleolin/C23 in viral IRES-mediated translation.
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Affiliation(s)
- R E Izumi
- Department of Microbiology Immunology and Molecular Genetics, UCLA School of Medicine, 10833 Le Conte Avenue, 90095, Los Angeles, CA, USA
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11
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Zhou W, Edelman GM, Mauro VP. Transcript leader regions of two Saccharomyces cerevisiae mRNAs contain internal ribosome entry sites that function in living cells. Proc Natl Acad Sci U S A 2001; 98:1531-6. [PMID: 11171985 PMCID: PMC29291 DOI: 10.1073/pnas.98.4.1531] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In higher eukaryotes, translation of some mRNAs occurs by internal initiation. It is not known, however, whether this mechanism is used to initiate the translation of any yeast mRNAs. In this report, we identify naturally occurring nucleotide sequences that function as internal ribosome entry sites (IRESes) within the 5' leader sequences of Saccharomyces cerevisiae YAP1 and p150 mRNAs. When tested in the 5' untranslated regions of monocistronic reporter genes, both leader sequences enhanced translation efficiency in vegetatively growing yeast cells. Moreover, when tested in the intercistronic region of dicistronic mRNAs, both sequences were shown to contain IRESes that functioned in living cells. The activity of the p150 leader was much greater than that of the YAP1 leader. The second cistron was not expressed in control dicistronic constructs that lacked these sequences or contained the 5' leader sequence of the CLN3 mRNA in the intercistronic region. Further analyses of the p150 IRES revealed that it contained several nonoverlapping segments that were able independently to mediate internal initiation. These results suggested a modular composition for the p150 IRES that resembled the composition of IRESes contained within some cellular mRNAs of higher eukaryotes. Both YAP1 and p150 leaders contain several complementary sequence matches to yeast 18S rRNA. The findings are discussed in terms of our understanding of internal initiation in higher eukaryotes.
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Affiliation(s)
- W Zhou
- Department of Neurobiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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12
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Urwin P, Yi L, Martin H, Atkinson H, Gilmartin PM. Functional characterization of the EMCV IRES in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2000; 24:583-9. [PMID: 11123797 DOI: 10.1046/j.1365-313x.2000.00904.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The translation of eukaryotic messenger RNA is typically dependent upon the presence of an m7GpppN cap structure at the 5' end of the transcript. However, several animal viruses, including the Picorna viruses, have been shown to exhibit cap-independent translation through the presence of an internal ribosome entry site or IRES. This IRES-mediated cap-independent internal translation initiation has been exploited to generate bicistronic transcripts that function in animal cells. Recently IRES elements have also been identified in a small number of vertebrate, insect and yeast cellular messenger RNAs although no such sequences have been identified in endogenous plant genes and there are no reports of animal virus derived IRES activity in plant cells. Here we have constructed a bicistronic gene containing both green fluorescent protein and luciferase open-reading frames separated by the encephalomyocarditis IRES element under the control of the CaMV 35S promoter. Northern analysis reveals expression of the bicistronic transcript and in vivo imaging of GFP and luciferase activities demonstrates the functional presence of both proteins. Western blot analysis confirms the independent translation of both reporter proteins. These data suggest that insertion of the encephalomyocarditis virus (EMCV) IRES element between two open-reading frames of a plant bicistronic transcript can mediate translation of the second open-reading frame. This activity is more apparent in the leaves, than in the roots, of transgenic seedlings carrying the bicistronic reporter gene construct.
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Affiliation(s)
- P Urwin
- Centre for Plant Sciences, Leeds Institute for Plant Biotechnology and Agriculture, University of Leeds, Leeds LS2 9JT, UK
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13
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Isoyama T, Kamoshita N, Yasui K, Iwai A, Shiroki K, Toyoda H, Yamada A, Takasaki Y, Nomoto A. Lower concentration of La protein required for internal ribosome entry on hepatitis C virus RNA than on poliovirus RNA. J Gen Virol 1999; 80 ( Pt 9):2319-2327. [PMID: 10501483 DOI: 10.1099/0022-1317-80-9-2319] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Translation initiation of poliovirus and hepatitis C virus (HCV) RNA occurs by entry of ribosomes to the internal RNA sequence, called the internal ribosomal entry site (IRES). Both IRES bind to the La protein and are thought to require the protein for their translation initiation activity, although they are greatly different in both the primary and predicted secondary structures. To compare the La protein requirement for these IRES, we took advantage of I-RNA from the yeast Saccharomyces cerevisiae, which has been reported to bind to La protein and block poliovirus IRES-mediated translation initiation. In a cell-free translation system prepared from HeLa cells, yeast I-RNA inhibited translation initiation on poliovirus RNA as expected, but did not significantly inhibit translation initiation on HCV RNA. However, the translation initiation directed by either IRES was apparently inhibited by I-RNA in rabbit reticulocyte lysates, in which La protein is limiting. I-RNA-mediated inhibition of HCV IRES-dependent translation in rabbit reticulocyte lysates was reversed by exogenous addition of purified recombinant La protein of smaller amounts than necessary to reverse poliovirus IRES-dependent translation. These results suggest that HCV IRES requires lower concentrations of La protein for its function than does poliovirus IRES. Immunofluorescence studies showed that HCV infection appeared not to affect the subcellular localization of La protein, which exists mainly in the nucleus, although La protein redistributed to the cytoplasm after poliovirus infection. The data are compatible with the low requirement of La protein for HCV IRES activity.
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Affiliation(s)
- Takeshi Isoyama
- Department of Microbiology, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan1
| | - Nobuhiko Kamoshita
- Department of Microbiology, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan1
| | - Kotaro Yasui
- Department of Microbiology and Immunology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu-shi, Tokyo 183-8526, Japan2
| | - Atsushi Iwai
- Department of Microbiology, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan1
| | - Kazuko Shiroki
- Department of Microbiology, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan1
| | - Haruka Toyoda
- Department of Microbiology, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan1
| | - Akio Yamada
- Department of Internal Medicine, Sagamihara National Hospital, 18-1 Sakuradai, Sagamihara, Kanagawa 228-0815, Japan3
| | - Yoshinari Takasaki
- Division of Rheumatology, Department of Medicine, Juntendo University, School of Medicine, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan4
| | - Akio Nomoto
- Department of Microbiology, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan1
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14
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Paz I, Abramovitz L, Choder M. Starved Saccharomyces cerevisiae cells have the capacity to support internal initiation of translation. J Biol Chem 1999; 274:21741-5. [PMID: 10419487 DOI: 10.1074/jbc.274.31.21741] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Internal initiation of translation, whereby ribosomes are directed to internal AUG codon independently of the 5' end of the mRNA, has been observed rarely in higher eucaryotes and has not been demonstrated in living yeast. We report here that starved yeast cells are capable of initiating translation of a dicistronic message internally. The studied element that functions as an internal ribosome entry site (IRES) is hardly functional or not functional at all in logarithmically growing cells. Moreover, during the logarithmic growth phase, this element seems to inhibit translation reinitiation when placed as an intercistronic spacer or to inhibit translation when placed in the 5'-untranslated region of a monocistronic message. Inhibition of translation is likely due to the putative strong secondary structure of the IRES that interferes with the cap-dependent scanning process. When cells exit the logarithmic growth phase, or when artificially starved for carbon source, translation of the IRES-containing messages is substantially induced. Our findings imply that the capacity to translate internally is a characteristic of starved rather than vegetatively growing yeast cells.
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Affiliation(s)
- I Paz
- Department of Molecular Microbiology and Biotechnology, Tel-Aviv University, Ramat Aviv 69978, Israel
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15
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Venkatesan A, Das S, Dasgupta A. Structure and function of a small RNA that selectively inhibits internal ribosome entry site-mediated translation. Nucleic Acids Res 1999; 27:562-72. [PMID: 9862981 PMCID: PMC148216 DOI: 10.1093/nar/27.2.562] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A 60 nt long RNA termed IRNA, isolated from the yeast Saccharomyces cerevesiae, was previously shown to selectively block internal ribosome entry site (IRES)-mediated translation without interfering with cap-dependent translation of cellular mRNAs both in vivo and in vitro. IRNA specifically bound cellular proteins believed to be important for IRES-mediated translation. We demonstrate here that a complementary copy of IRNA (cIRNA) is also active in blocking IRES-mediated translation and that it binds many of the same cellular proteins that IRNA does. We have probed the secondary structure of both IRNA and cIRNA using single-strand- and double-strand-specific nucleases as well as using oligonucleotide hybridization followed by RNase H digestion. Both IRNA and cIRNA share secondary structural homology, although distinct differences do exist between the two structures. Mutational analysis of IRNA shows that sequences that form both the main stem and one loop are critical for its translation inhibitory activity. Maintenance of the established secondary structure appears to be required for both IRNA's ability to bind cellular trans -acting proteins believed to be required for IRES-mediated translation and its ability to block IRES-mediated translation.
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Affiliation(s)
- A Venkatesan
- Molecular Biology Institute, University of California, Los Angeles, CA 90095-1747, USA and Department of Microbiology, Molecular Genetics and Immunology, UCLA School of Medicine, Los Angeles, CA 90095-1747, USA
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Abstract
Studies of the budding yeast Saccharomyces cerevisiae have greatly advanced our understanding of the posttranscriptional steps of eukaryotic gene expression. Given the wide range of experimental tools applicable to S. cerevisiae and the recent determination of its complete genomic sequence, many of the key challenges of the posttranscriptional control field can be tackled particularly effectively by using this organism. This article reviews the current knowledge of the cellular components and mechanisms related to translation and mRNA decay, with the emphasis on the molecular basis for rate control and gene regulation. Recent progress in characterizing translation factors and their protein-protein and RNA-protein interactions has been rapid. Against the background of a growing body of structural information, the review discusses the thermodynamic and kinetic principles that govern the translation process. As in prokaryotic systems, translational initiation is a key point of control. Modulation of the activities of translational initiation factors imposes global regulation in the cell, while structural features of particular 5' untranslated regions, such as upstream open reading frames and effector binding sites, allow for gene-specific regulation. Recent data have revealed many new details of the molecular mechanisms involved while providing insight into the functional overlaps and molecular networking that are apparently a key feature of evolving cellular systems. An overall picture of the mechanisms governing mRNA decay has only very recently begun to develop. The latest work has revealed new information about the mRNA decay pathways, the components of the mRNA degradation machinery, and the way in which these might relate to the translation apparatus. Overall, major challenges still to be addressed include the task of relating principles of posttranscriptional control to cellular compartmentalization and polysome structure and the role of molecular channelling in these highly complex expression systems.
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Affiliation(s)
- J E McCarthy
- Posttranscriptional Control Group, Department of Biomolecular Sciences, University of Manchester Institute of Science and Technology (UMIST), Manchester M60 1QD, United Kingdom.
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17
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Das S, Ott M, Yamane A, Tsai W, Gromeier M, Lahser F, Gupta S, Dasgupta A. A small yeast RNA blocks hepatitis C virus internal ribosome entry site (HCV IRES)-mediated translation and inhibits replication of a chimeric poliovirus under translational control of the HCV IRES element. J Virol 1998; 72:5638-47. [PMID: 9621022 PMCID: PMC110227 DOI: 10.1128/jvi.72.7.5638-5647.1998] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/1997] [Accepted: 03/30/1998] [Indexed: 02/07/2023] Open
Abstract
Hepatitis C virus (HCV) infection frequently leads to chronic hepatitis and cirrhosis of the liver and has been linked to development of hepatocellular carcinoma. We previously identified a small yeast RNA (IRNA) capable of specifically inhibiting poliovirus (PV) internal ribosome entry site (IRES)-mediated translation. Here we report that IRNA specifically inhibits HCV IRES-mediated translation both in vivo and in vitro. A number of human hepatoma (Huh-7) cell lines expressing IRNA were prepared and characterized. Constitutive expression of IRNA was not detrimental to cell growth. HCV IRES-mediated cap-independent translation was markedly inhibited in cells constitutively expressing IRNA compared to control hepatoma cells. However, cap-dependent translation was not significantly affected in these cell lines. Additionally, Huh-7 cells constitutively expressing IRNA became refractory to infection by a PV-HCV chimera in which the PV IRES is replaced by the HCV IRES. In contrast, replication of a PV-encephalomyocarditis virus (EMCV) chimera containing the EMCV IRES element was not affected significantly in the IRNA-producing cell line. Finally, the binding of the La autoantigen to the HCV IRES element was specifically and efficiently competed by IRNA. These results provide a basis for development of novel drugs effective against HCV infection.
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Affiliation(s)
- S Das
- Department of Microbiology and Immunology and Jonsson Comprehensive Cancer Center, School of Medicine, University of California, Los Angeles, California 90095, USA
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18
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Das S, Kenan DJ, Bocskai D, Keene JD, Dasgupta A. Sequences within a small yeast RNA required for inhibition of internal initiation of translation: interaction with La and other cellular proteins influences its inhibitory activity. J Virol 1996; 70:1624-32. [PMID: 8627683 PMCID: PMC189986 DOI: 10.1128/jvi.70.3.1624-1632.1996] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We recently reported purification, determination of the nucleotide sequence, and cloning of a 60-nucleotide RNA (I-RNA) from the yeast Saccharomyces cerevisiae which preferentially blocked cap-independent, internal ribosome entry site (IRES)-mediated translation programmed by the poliovirus (PV) 5' untranslated region (UTR). The I-RNA appeared to inhibit IRES-mediated translation by virtue of its ability to bind a 52-kDa polypeptide which interacts with the 5' UTR of viral RNA. We demonstrate here that the HeLa 52-kDa I-RNA-binding protein is immunologically identical to human La autoantigen. Moreover, I-RNA-mediated purified La protein. By using I-RNAs with defined deletions, we have identified sequences of I-RNA required for inhibition of internal initiation of translation. Two smaller fragments of I-RNA (16 and 25 nucleotides) inhibited PV UTR-mediated translation from both monocistronic and bicistronic RNAs. When transfected into HeLa cells, these derivatives of I-RNA inhibited translation of PV RNA. A comparison of protein binding by active and inactive I-RNA mutants demonstrates that in addition to the La protein, three other polypeptides with apparent molecular masses of 80, 70, and 37 kDa may influence the translation-inhibitory activity of I-RNA.
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Affiliation(s)
- S Das
- Department of Microbiology and Immunology, UCLA School of Medicine 90024-1747, USA
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19
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Barco A, Carrasco L. Cloning and inducible synthesis of poliovirus non-structural proteins in Saccharomyces cerevisiae. Gene 1995; 156:19-25. [PMID: 7737511 DOI: 10.1016/0378-1119(94)00872-p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Several coding regions of the poliovirus (PV) genome were cloned in the yeast Saccharomyces cerevisiae, and placed under the control of the inducible hybrid promoter pGAL/CYC, such that expression was triggered by incubating the cells in galactose (Gal)-containing medium. A number of PV genes encoding non-structural proteins, including 2Apro, 2B, 2C, 3A, 3AB and 3Cpro, were cloned and expressed in this eukaryotic system. The presence of these proteins after induction was detected by immunoblot analysis using specific antisera against each protein. The levels and the kinetics of protein synthesis after induction varied according to the PV protein analyzed. Thus, 2C was detected soon after Gal addition (3-5 h) and was one of the major polypeptides synthesized by yeast cells after 16 h of induction. In contrast, only low levels of synthesis were observed for 3A or 3AB, and then only after several hours of growth in Gal. The induction of the PV protease, 2Apro, was highly toxic for the cells such that growth was arrested after 5 h of induction and cell survival sharply declined.
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Affiliation(s)
- A Barco
- Centro de Biología Molecular, Universidad Autónoma de Madrid, Spain
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Iizuka N, Chen C, Yang Q, Johannes G, Sarnow P. Cap-independent translation and internal initiation of translation in eukaryotic cellular mRNA molecules. Curr Top Microbiol Immunol 1995; 203:155-77. [PMID: 7555089 DOI: 10.1007/978-3-642-79663-0_8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- N Iizuka
- Department of Biochemistry, Biophysics and Genetics, University of Colorado Health Sciences Center, Denver, CO 80262, USA
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21
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Cap-dependent and cap-independent translation by internal initiation of mRNAs in cell extracts prepared from Saccharomyces cerevisiae. Mol Cell Biol 1994. [PMID: 7935446 DOI: 10.1128/mcb.14.11.7322] [Citation(s) in RCA: 147] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Translation extracts were prepared from various strains of Saccharomyces cerevisiae. The translation of mRNA molecules in these extracts were cooperatively enhanced by the presence of 5'-terminal cap structures and 3'-terminal poly(A) sequences. These cooperative effects could not be observed in other translation systems such as those prepared from rabbit reticulocytes, wheat germ, and human HeLa cells. Because the yeast translation system mimicked the effects of the cap structure and poly(A) tail on translational efficiency seen in vivo, this system was used to study cap-dependent and cap-independent translation of viral and cellular mRNA molecules. Both the 5' noncoding regions of hepatitis C virus and those of coxsackievirus B1 conferred cap-independent translation to a reporter coding region during translation in the yeast extracts; thus, the yeast translational apparatus is capable of initiating cap-independent translation. Although the translation of most yeast mRNAs was cap dependent, the unusually long 5' noncoding regions of mRNAs encoding cellular transcription factors TFIID and HAP4 were shown to mediate cap-independent translation in these extracts. Furthermore, both TFIID and HAP4 5' noncoding regions mediated translation of a second cistron when placed into the intercistronic spacer region of a dicistronic mRNA, indicating that these leader sequences can initiate translation by an internal ribosome binding mechanism in this in vitro translation system. This finding raises the possibility that an internal translation initiation mechanism exists in yeast cells for regulated translation of endogenous mRNAs.
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22
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Iizuka N, Najita L, Franzusoff A, Sarnow P. Cap-dependent and cap-independent translation by internal initiation of mRNAs in cell extracts prepared from Saccharomyces cerevisiae. Mol Cell Biol 1994; 14:7322-30. [PMID: 7935446 PMCID: PMC359267 DOI: 10.1128/mcb.14.11.7322-7330.1994] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Translation extracts were prepared from various strains of Saccharomyces cerevisiae. The translation of mRNA molecules in these extracts were cooperatively enhanced by the presence of 5'-terminal cap structures and 3'-terminal poly(A) sequences. These cooperative effects could not be observed in other translation systems such as those prepared from rabbit reticulocytes, wheat germ, and human HeLa cells. Because the yeast translation system mimicked the effects of the cap structure and poly(A) tail on translational efficiency seen in vivo, this system was used to study cap-dependent and cap-independent translation of viral and cellular mRNA molecules. Both the 5' noncoding regions of hepatitis C virus and those of coxsackievirus B1 conferred cap-independent translation to a reporter coding region during translation in the yeast extracts; thus, the yeast translational apparatus is capable of initiating cap-independent translation. Although the translation of most yeast mRNAs was cap dependent, the unusually long 5' noncoding regions of mRNAs encoding cellular transcription factors TFIID and HAP4 were shown to mediate cap-independent translation in these extracts. Furthermore, both TFIID and HAP4 5' noncoding regions mediated translation of a second cistron when placed into the intercistronic spacer region of a dicistronic mRNA, indicating that these leader sequences can initiate translation by an internal ribosome binding mechanism in this in vitro translation system. This finding raises the possibility that an internal translation initiation mechanism exists in yeast cells for regulated translation of endogenous mRNAs.
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Affiliation(s)
- N Iizuka
- Department of Biochemistry, Biophysics and Genetics, University of Colorado Health Sciences Center, Denver 80262
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23
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Das S, Coward P, Dasgupta A. A small yeast RNA selectively inhibits internal initiation of translation programmed by poliovirus RNA: specific interaction with cellular proteins that bind to the viral 5'-untranslated region. J Virol 1994; 68:7200-11. [PMID: 7933102 PMCID: PMC237159 DOI: 10.1128/jvi.68.11.7200-7211.1994] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We have purified, sequenced, and prepared a synthetic clone of a small (60-nucleotide) RNA molecule from the yeast Saccharomyces cerevisiae that had previously been isolated on the basis of its ability to selectively block the translation of poliovirus mRNA. RNA derived from the clone by transcription with T7 RNA polymerase appears to block translation initiation by internal ribosome entry (cap independent) but does not significantly affect cap-dependent translation. Deletion analysis of the poliovirus 5'-untranslated region (5'-UTR) has shown that yeast inhibitor RNA (I-RNA) requires internal ribosome entry site sequences to inhibit the translation of poliovirus RNA in vitro. Using a bicistronic RNA construct, we show that I-RNA preferentially inhibits translation by internal ribosome entry. Gel retardation and UV cross-linking studies demonstrate that I-RNA specifically binds proteins which interact with RNA secondary structures within the poliovirus 5'-UTR presumably involved in internal initiation. Specifically, purified I-RNA competes with virus RNA structures within the 5'-UTR which bind a cellular protein with an approximate molecular mass of 52 kDa. Finally, when transfected into HeLa cells, I-RNA efficiently inhibits the replication of poliovirus RNA presumably by inhibiting translation of the input virus RNA.
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Affiliation(s)
- S Das
- Department of Microbiology and Immunology, UCLA School of Medicine 90024-1747
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Svitkin YV, Pause A, Sonenberg N. La autoantigen alleviates translational repression by the 5' leader sequence of the human immunodeficiency virus type 1 mRNA. J Virol 1994; 68:7001-7. [PMID: 7933082 PMCID: PMC237137 DOI: 10.1128/jvi.68.11.7001-7007.1994] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The trans-activation response element (TAR) at the 5' end of the human immunodeficiency virus type 1 (HIV-1) mRNAs forms a stable hairpin structure which is a target for binding of the virally encoded protein Tat, which activates viral gene expression, as well as several cellular factors. TAR is also inhibitory to translation. One of several host factors that binds to TAR RNA is the La autoantigen, an RNA-binding protein which functions in RNA polymerase III transcription termination and has also been implicated in cap-independent internal translation initiation on poliovirus RNA. Here we show that La autoantigen alleviates translational repression by the HIV-1 leader RNA. In rabbit reticulocyte lysate, La relieves the cis-inhibitory effect of the TAR RNA on translation of bacterial chloramphenicol acetyltransferase (CAT) mRNA but not inhibition that is mediated by an artificial secondary structure element. Canonical translation factors exhibited slight (eIF-2 and GEF) or no (eIF-4A, eIF-4B, eIF-4E, eIF-4F, eIF-3, and eEF-1 alpha) stimulatory activity on translation of TAR-containing CAT mRNA. In addition, we show that poliovirus RNA, in spite of being an inefficient template in rabbit reticulocyte lysate, is a strong competitive inhibitor of translation of TAR-containing CAT mRNA but not CAT mRNA. This inhibition can be relieved by La but not by any other translation factor. The results suggest a possible involvement of the La autoantigen in HIV-1 gene expression.
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Affiliation(s)
- Y V Svitkin
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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25
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Coward P, Nagai K, Chen D, Thomas HD, Nagamine CM, Lau YF. Polymorphism of a CAG trinucleotide repeat within Sry correlates with B6.YDom sex reversal. Nat Genet 1994; 6:245-50. [PMID: 8012385 DOI: 10.1038/ng0394-245] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Breeding the Y chromosome from certain Mus musculus domesticus strains onto the inbred laboratory mouse strain, C57BL/6J (B6), results in hermaphroditic progeny. This strain-dependent sex reversal suggests that there may be significant allelic variation in the murine sex determining gene, Sry. We have analysed the Sry genes from several domesticus-type Y chromosomes and show that they encode smaller proteins than the molossinus-type alleles SryB6 and Sry129. We have also identified a polymorphic stretch of trinucleotide repeats that is unique to strains causing sex reversal and show that specific changes in the predicted polyglutamine amino acid sequence at this site are associated with different degrees of sex reversal.
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Affiliation(s)
- P Coward
- Department of Medicine, VA Medical Center, University of California, San Francisco 94121
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Altmann M, Trachsel H. The yeast Saccharomyces cerevisiae system: a powerful tool to study the mechanism of protein synthesis initiation in eukaryotes. Biochimie 1994; 76:853-61. [PMID: 7880902 DOI: 10.1016/0300-9084(94)90187-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
This review summarizes recent progress in the study of initiation of protein synthesis in the yeast Saccharomyces cerevisiae. Biochemical and genetic approaches provide new insight into the recognition of the 5'-end of mRNA by initiation factors and 40S ribosomes, unwinding of mRNA secondary structures in the untranslated region and proper recognition of the AUG start codon. Experiments with initiation factor-dependent cell-free systems have facilitated studies of factor functions and factor requirements for translation of different mRNAs. The analysis of mutations which suppress the inhibitory effect on translation of RNA secondary structure in the 5'-untranslated region of yeast mRNAs has led to the identification of gene products which may be involved in both transcription and translation.
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Affiliation(s)
- M Altmann
- Institut für Biochemie und Molekularbiologie, Universität Bern, Switzerland
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27
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Evstafieva AG, Beletsky AV, Borovjagin AV, Bogdanov AA. Internal ribosome entry site of encephalomyocarditis virus RNA is unable to direct translation in Saccharomyces cerevisiae. FEBS Lett 1993; 335:273-6. [PMID: 8253211 DOI: 10.1016/0014-5793(93)80745-g] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To evaluate the potential of the encephalomyocarditis virus (EMCV) internal ribosome entry site (IRES) to promote efficient expression of foreign genes in the yeast, S. cerevisiae, we have constructed E. coli-yeast shuttle vectors in which the EMCV 5' non-coding region was fused to the reporter gene, human prothymosin alpha. Efficiency of translation of corresponding RNA transcripts in mammalian cell-free systems was highly dependent on the sequence context and/or position of the initiation codon. No translation of these IRES-dependent mRNAs occurred in S. cerevisiae.
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Affiliation(s)
- A G Evstafieva
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russian Federation
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