1
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Amson R, Senff-Ribeiro A, Karafin T, Lespagnol A, Honoré J, Baylot V, Banroques J, Tanner NK, Chamond N, Dimitrov JD, Hoebeke J, Droin NM, Job B, Piard J, Bommer UA, Choi KW, Abdelfatah S, Efferth T, Telerman SB, Geyer FC, Reis-Filho J, Telerman A. TCTP regulates genotoxic stress and tumorigenicity via intercellular vesicular signaling. EMBO Rep 2024; 25:1962-1986. [PMID: 38548973 PMCID: PMC11014985 DOI: 10.1038/s44319-024-00108-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 02/04/2024] [Accepted: 02/21/2024] [Indexed: 04/14/2024] Open
Abstract
Oncogenic intercellular signaling is regulated by extracellular vesicles (EVs), but the underlying mechanisms remain mostly unclear. Since TCTP (translationally controlled tumor protein) is an EV component, we investigated whether it has a role in genotoxic stress signaling and malignant transformation. By generating a Tctp-inducible knockout mouse model (Tctp-/f-), we report that Tctp is required for genotoxic stress-induced apoptosis signaling via small EVs (sEVs). Human breast cancer cells knocked-down for TCTP show impaired spontaneous EV secretion, thereby reducing sEV-dependent malignant growth. Since Trp53-/- mice are prone to tumor formation, we derived tumor cells from Trp53-/-;Tctp-/f- double mutant mice and describe a drastic decrease in tumori-genicity with concomitant decrease in sEV secretion and content. Remarkably, Trp53-/-;Tctp-/f- mice show highly prolonged survival. Treatment of Trp53-/- mice with sertraline, which inhibits TCTP function, increases their survival. Mechanistically, TCTP binds DDX3, recruiting RNAs, including miRNAs, to sEVs. Our findings establish TCTP as an essential protagonist in the regulation of sEV-signaling in the context of apoptosis and tumorigenicity.
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Affiliation(s)
- Robert Amson
- Institut Gustave Roussy (IGR), Unité Inserm U981, Bâtiment B2M, 114 rue Édouard-Vaillant, 94805, Villejuif, France
| | - Andrea Senff-Ribeiro
- Institut Gustave Roussy (IGR), Unité Inserm U981, Bâtiment B2M, 114 rue Édouard-Vaillant, 94805, Villejuif, France
| | - Teele Karafin
- Institut Gustave Roussy (IGR), Unité Inserm U981, Bâtiment B2M, 114 rue Édouard-Vaillant, 94805, Villejuif, France
| | - Alexandra Lespagnol
- Institut Gustave Roussy (IGR), Unité Inserm U981, Bâtiment B2M, 114 rue Édouard-Vaillant, 94805, Villejuif, France
| | - Joane Honoré
- Institut Gustave Roussy (IGR), Unité Inserm U981, Bâtiment B2M, 114 rue Édouard-Vaillant, 94805, Villejuif, France
| | - Virginie Baylot
- Institut Gustave Roussy (IGR), Unité Inserm U981, Bâtiment B2M, 114 rue Édouard-Vaillant, 94805, Villejuif, France
| | - Josette Banroques
- Université de Paris Cité & CNRS, Expression Génétique Microbienne, IBPC, 13 rue Pierre et Marie Curie and Institut de Biologie Physico-Chimique, Paris Sciences et Lettres University, CNRS UMR8261, EGM, 75005, Paris, France
| | - N Kyle Tanner
- Université de Paris Cité & CNRS, Expression Génétique Microbienne, IBPC, 13 rue Pierre et Marie Curie and Institut de Biologie Physico-Chimique, Paris Sciences et Lettres University, CNRS UMR8261, EGM, 75005, Paris, France
| | - Nathalie Chamond
- Faculté de Pharmacie de Paris, Laboratoire CiTCom - UMR CNRS 8038 Université Paris Descartes 4 Avenue de l'Observatoire, 75270, Paris, France
| | - Jordan D Dimitrov
- Centre de Recherche des Cordeliers, INSERM, CNRS, Sorbonne Université, Université de Paris, 75006, Paris, France
| | - Johan Hoebeke
- Institut de Biologie Moléculaire et Cellulaire, UPR CNRS 9021, 15, rue René Descartes, 67084, Strasbourg, France
| | - Nathalie M Droin
- Institut Gustave Roussy (IGR), Unité Inserm U1287, 114 rue Édouard-Vaillant, 94805, Villejuif, France
| | - Bastien Job
- Institut Gustave Roussy (IGR), Bioinformatics Core Facility, 114 rue Édouard-Vaillant, 94805, Villejuif, France
| | - Jonathan Piard
- Département de Chimie, Ecole Normale Supérieure Paris-Saclay, 4 avenue Des Sciences, 91110, Gif-sur-Yvette, France
| | - Ulrich-Axel Bommer
- Graduate School of Medicine, Faculty of Science, Medicine & Health, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Kwang-Wook Choi
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Korea
| | - Sara Abdelfatah
- Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Science, Johannes Gutenberg University, Staudinger Weg 5, 55128, Mainz, Germany
| | - Thomas Efferth
- Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Science, Johannes Gutenberg University, Staudinger Weg 5, 55128, Mainz, Germany
| | | | - Felipe Correa Geyer
- Department of Pathology, Memorial Sloan Kettering Cancer Center (MSKCC), 1275 York Ave, New York, NY, 10065, USA
| | - Jorge Reis-Filho
- Department of Pathology, Memorial Sloan Kettering Cancer Center (MSKCC), 1275 York Ave, New York, NY, 10065, USA
| | - Adam Telerman
- Institut Gustave Roussy (IGR), Unité Inserm U981, Bâtiment B2M, 114 rue Édouard-Vaillant, 94805, Villejuif, France.
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2
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Yeter-Alat H, Belgareh-Touzé N, Huvelle E, Banroques J, Tanner NK. The DEAD-Box RNA Helicase Ded1 Is Associated with Translating Ribosomes. Genes (Basel) 2023; 14:1566. [PMID: 37628617 PMCID: PMC10454743 DOI: 10.3390/genes14081566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 07/21/2023] [Accepted: 07/26/2023] [Indexed: 08/27/2023] Open
Abstract
DEAD-box RNA helicases are ATP-dependent RNA binding proteins and RNA-dependent ATPases that possess weak, nonprocessive unwinding activity in vitro, but they can form long-lived complexes on RNAs when the ATPase activity is inhibited. Ded1 is a yeast DEAD-box protein, the functional ortholog of mammalian DDX3, that is considered important for the scanning efficiency of the 48S pre-initiation complex ribosomes to the AUG start codon. We used a modified PAR-CLIP technique, which we call quicktime PAR-CLIP (qtPAR-CLIP), to crosslink Ded1 to 4-thiouridine-incorporated RNAs in vivo using UV light centered at 365 nm. The irradiation conditions are largely benign to the yeast cells and to Ded1, and we are able to obtain a high efficiency of crosslinking under physiological conditions. We find that Ded1 forms crosslinks on the open reading frames of many different mRNAs, but it forms the most extensive interactions on relatively few mRNAs, and particularly on mRNAs encoding certain ribosomal proteins and translation factors. Under glucose-depletion conditions, the crosslinking pattern shifts to mRNAs encoding metabolic and stress-related proteins, which reflects the altered translation. These data are consistent with Ded1 functioning in the regulation of translation elongation, perhaps by pausing or stabilizing the ribosomes through its ATP-dependent binding.
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Affiliation(s)
- Hilal Yeter-Alat
- Expression Génétique Microbienne, Université de Paris Cité & CNRS, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France; (H.Y.-A.); (E.H.); (J.B.)
- Institut de Biologie Physico-Chimique, Paris Sciences et Lettres University, CNRS UMR8261, EGM, 75005 Paris, France
| | - Naïma Belgareh-Touzé
- Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, UMR8226 CNRS, Institut de Biologie Physico-Chimique, Sorbonne Université, 13 Rue Pierre et Marie Curie, 75005 Paris, France;
| | - Emmeline Huvelle
- Expression Génétique Microbienne, Université de Paris Cité & CNRS, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France; (H.Y.-A.); (E.H.); (J.B.)
- Institut de Biologie Physico-Chimique, Paris Sciences et Lettres University, CNRS UMR8261, EGM, 75005 Paris, France
| | - Josette Banroques
- Expression Génétique Microbienne, Université de Paris Cité & CNRS, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France; (H.Y.-A.); (E.H.); (J.B.)
- Institut de Biologie Physico-Chimique, Paris Sciences et Lettres University, CNRS UMR8261, EGM, 75005 Paris, France
| | - N. Kyle Tanner
- Expression Génétique Microbienne, Université de Paris Cité & CNRS, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France; (H.Y.-A.); (E.H.); (J.B.)
- Institut de Biologie Physico-Chimique, Paris Sciences et Lettres University, CNRS UMR8261, EGM, 75005 Paris, France
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3
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Abdelkrim YZ, Harigua-Souiai E, Bassoumi-Jamoussi I, Barhoumi M, Banroques J, Essafi-Benkhadir K, Nilges M, Blondel A, Tanner NK, Guizani I. Enzymatic and Molecular Characterization of Anti- Leishmania Molecules That Differently Target Leishmania and Mammalian eIF4A Proteins, LieIF4A and eIF4A Mus. Molecules 2022; 27:molecules27185890. [PMID: 36144626 PMCID: PMC9502374 DOI: 10.3390/molecules27185890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 08/22/2022] [Accepted: 09/02/2022] [Indexed: 02/05/2023]
Abstract
Previous investigations of the Leishmania infantum eIF4A-like protein (LieIF4A) as a potential drug target delivered cholestanol derivatives inhibitors. Here, we investigated the mode of action of cholesterol derivatives as a novel scaffold structure of LieIF4A inhibitors on the RNA-dependent ATPase activity of LieIF4A and its mammalian ortholog (eIF4AI). We compared their biochemical effects on RNA-dependent ATPase activities of both proteins and investigated if rocaglamide, a known inhibitor of eIF4A, could affect LieIF4A as well. Kinetic measurements were conducted at different concentrations of ATP, of the compound and in the presence of saturating whole yeast RNA concentrations. Kinetic analyses showed different ATP binding affinities for the two enzymes as well as different sensitivities to 7-α-aminocholesterol and rocaglamide. The 7-α-aminocholesterol inhibited LieIF4A with a higher binding affinity relative to cholestanol analogs. Cholesterol, another tested sterol, had no effect on the ATPase activity of LieIF4A or eIF4AI. The 7-α-aminocholesterol demonstrated an anti-Leishmania activity on L. infantum promastigotes. Additionally, docking simulations explained the importance of the double bond between C5 and C6 in 7-α-aminocholesterol and the amino group in the C7 position. In conclusion, Leishmania and mammalian eIF4A proteins appeared to interact differently with effectors, thus making LieIF4A a potential drug against leishmaniases.
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Affiliation(s)
- Yosser Zina Abdelkrim
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR11IPT04/LR16IPT04)/Laboratory of Epidemiology and Ecology of Parasites, Institut Pasteur de Tunis—University Tunis El Manar, Tunis 1002, Tunisia
- Université de Paris Cité & CNRS, Expression Génétique Microbienne, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, F-75005 Paris, France
- Correspondence: (Y.Z.A.); (I.G.)
| | - Emna Harigua-Souiai
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR11IPT04/LR16IPT04)/Laboratory of Epidemiology and Ecology of Parasites, Institut Pasteur de Tunis—University Tunis El Manar, Tunis 1002, Tunisia
| | - Imen Bassoumi-Jamoussi
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR11IPT04/LR16IPT04)/Laboratory of Epidemiology and Ecology of Parasites, Institut Pasteur de Tunis—University Tunis El Manar, Tunis 1002, Tunisia
| | - Mourad Barhoumi
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR11IPT04/LR16IPT04)/Laboratory of Epidemiology and Ecology of Parasites, Institut Pasteur de Tunis—University Tunis El Manar, Tunis 1002, Tunisia
| | - Josette Banroques
- Université de Paris Cité & CNRS, Expression Génétique Microbienne, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, F-75005 Paris, France
- Paris Sciences and Lettres Research University, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, F-75005 Paris, France
| | - Khadija Essafi-Benkhadir
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR11IPT04/LR16IPT04)/Laboratory of Epidemiology and Ecology of Parasites, Institut Pasteur de Tunis—University Tunis El Manar, Tunis 1002, Tunisia
| | - Michael Nilges
- Structural Bioinformatics Unit, Institut Pasteur, F-75015 Paris, France
| | - Arnaud Blondel
- Structural Bioinformatics Unit, Institut Pasteur, F-75015 Paris, France
| | - N. Kyle Tanner
- Université de Paris Cité & CNRS, Expression Génétique Microbienne, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, F-75005 Paris, France
- Paris Sciences and Lettres Research University, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, F-75005 Paris, France
| | - Ikram Guizani
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR11IPT04/LR16IPT04)/Laboratory of Epidemiology and Ecology of Parasites, Institut Pasteur de Tunis—University Tunis El Manar, Tunis 1002, Tunisia
- Correspondence: (Y.Z.A.); (I.G.)
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4
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Mokdadi M, Abdelkrim YZ, Banroques J, Huvelle E, Oualha R, Yeter-Alat H, Guizani I, Barhoumi M, Tanner NK. The In Silico Identification of Potential Members of the Ded1/DDX3 Subfamily of DEAD-Box RNA Helicases from the Protozoan Parasite Leishmania infantum and Their Analyses in Yeast. Genes (Basel) 2021; 12:genes12020212. [PMID: 33535521 PMCID: PMC7912733 DOI: 10.3390/genes12020212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 01/27/2021] [Accepted: 01/29/2021] [Indexed: 12/14/2022] Open
Abstract
DEAD-box RNA helicases are ubiquitous proteins found in all kingdoms of life and that are associated with all processes involving RNA. Their central roles in biology make these proteins potential targets for therapeutic or prophylactic drugs. The Ded1/DDX3 subfamily of DEAD-box proteins is of particular interest because of their important role(s) in translation. In this paper, we identified and aligned the protein sequences of 28 different DEAD-box proteins from the kinetoplast-protozoan parasite Leishmania infantum, which is the cause of the visceral form of leishmaniasis that is often lethal if left untreated, and compared them with the consensus sequence derived from DEAD-box proteins in general, and from the Ded1/DDX3 subfamily in particular, from a wide variety of other organisms. We identified three potential homologs of the Ded1/DDX3 subfamily and the equivalent proteins from the related protozoan parasite Trypanosoma brucei, which is the causative agent of sleeping sickness. We subsequently tested these proteins for their ability to complement a yeast strain deleted for the essential DED1 gene. We found that the DEAD-box proteins from Trypanosomatids are highly divergent from other eukaryotes, and consequently they are suitable targets for protein-specific drugs.
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Affiliation(s)
- Molka Mokdadi
- Expression Génétique Microbienne, UMR8261 CNRS, Université de Paris, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France; (M.M.); (Y.Z.A.); (J.B.); (E.H.); (H.Y.-A.)
- PSL Research University, 75005 Paris, France
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis, Université de Tunis El Manar, 13 Place Pasteur, BP74 Tunis-Belvédère 1002, Tunisia; (R.O.); (I.G.)
- Institut National des Sciences Appliquées et Technologies, Université de Carthage, CEDEX, Tunis 1080, Tunisia
| | - Yosser Zina Abdelkrim
- Expression Génétique Microbienne, UMR8261 CNRS, Université de Paris, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France; (M.M.); (Y.Z.A.); (J.B.); (E.H.); (H.Y.-A.)
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis, Université de Tunis El Manar, 13 Place Pasteur, BP74 Tunis-Belvédère 1002, Tunisia; (R.O.); (I.G.)
| | - Josette Banroques
- Expression Génétique Microbienne, UMR8261 CNRS, Université de Paris, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France; (M.M.); (Y.Z.A.); (J.B.); (E.H.); (H.Y.-A.)
- PSL Research University, 75005 Paris, France
| | - Emmeline Huvelle
- Expression Génétique Microbienne, UMR8261 CNRS, Université de Paris, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France; (M.M.); (Y.Z.A.); (J.B.); (E.H.); (H.Y.-A.)
- PSL Research University, 75005 Paris, France
| | - Rafeh Oualha
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis, Université de Tunis El Manar, 13 Place Pasteur, BP74 Tunis-Belvédère 1002, Tunisia; (R.O.); (I.G.)
| | - Hilal Yeter-Alat
- Expression Génétique Microbienne, UMR8261 CNRS, Université de Paris, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France; (M.M.); (Y.Z.A.); (J.B.); (E.H.); (H.Y.-A.)
- PSL Research University, 75005 Paris, France
| | - Ikram Guizani
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis, Université de Tunis El Manar, 13 Place Pasteur, BP74 Tunis-Belvédère 1002, Tunisia; (R.O.); (I.G.)
| | - Mourad Barhoumi
- Laboratory of Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis, Université de Tunis El Manar, 13 Place Pasteur, BP74 Tunis-Belvédère 1002, Tunisia; (R.O.); (I.G.)
- Correspondence: (M.B.); (N.K.T.); Tel.: +216-71 843 755 (ext. 544) (M.B.); +33-1-58-41-52-37 (N.K.T.); Fax: +216-71-791-833 (M.B.); +33-1-58-41-50-25 (N.K.T.)
| | - N. Kyle Tanner
- Expression Génétique Microbienne, UMR8261 CNRS, Université de Paris, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France; (M.M.); (Y.Z.A.); (J.B.); (E.H.); (H.Y.-A.)
- PSL Research University, 75005 Paris, France
- Correspondence: (M.B.); (N.K.T.); Tel.: +216-71 843 755 (ext. 544) (M.B.); +33-1-58-41-52-37 (N.K.T.); Fax: +216-71-791-833 (M.B.); +33-1-58-41-50-25 (N.K.T.)
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5
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Abstract
RNA helicases are proteins found in all kingdoms of life, and they are associated with all processes involving RNA from transcription to decay. They use NTP binding and hydrolysis to unwind duplexes, to remodel RNA structures and protein-RNA complexes, and to facilitate the unidirectional metabolism of biological processes. Viral, bacterial, and eukaryotic parasites have an intimate need for RNA helicases in their reproduction. Moreover, various disorders, like cancers, are often associated with a perturbation of the host's helicase activity. Thus, RNA helicases provide a rich source of targets for the development of therapeutic or prophylactic drugs. In this review, we provide an overview of the different targeting strategies against helicases, the different types of compounds explored, the proposed inhibitory mechanisms of the compounds on the proteins, and the therapeutic potential of these compounds in the treatment of various disorders.
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Affiliation(s)
- Yosser Zina Abdelkrim
- Expression Génétique Microbienne, UMR8261 CNRS, Institut de Biologie Physico-Chimique, Université de Paris, Paris, France.,Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis/Université de Tunis el Manar, Tunis-Belvédère, Tunisia
| | - Josette Banroques
- Expression Génétique Microbienne, UMR8261 CNRS, Institut de Biologie Physico-Chimique, Université de Paris, Paris, France.,PSL Research University, Paris, France
| | - N Kyle Tanner
- Expression Génétique Microbienne, UMR8261 CNRS, Institut de Biologie Physico-Chimique, Université de Paris, Paris, France.
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6
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Raj S, Bagchi D, Orero JV, Banroques J, Tanner NK, Croquette V. Mechanistic characterization of the DEAD-box RNA helicase Ded1 from yeast as revealed by a novel technique using single-molecule magnetic tweezers. Nucleic Acids Res 2019; 47:3699-3710. [PMID: 30993346 PMCID: PMC6468243 DOI: 10.1093/nar/gkz057] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/21/2019] [Accepted: 02/01/2019] [Indexed: 12/11/2022] Open
Abstract
DEAD-box helicases are involved in all steps of RNA metabolism. They are ATP-dependent RNA binding proteins and RNA-dependent ATPases. They can displace short duplexes, but they lack processivity. Their mechanism and functioning are not clearly understood; classical or bulk biochemical assays are not sufficient to answer these questions. Single-molecule techniques provide useful tools, but they are limited in cases where the proteins are nonprocessive and give weak signals. We present here a new, magnetic-tweezers-based, single-molecule assay that is simple and that can sensitively measure the displacement time of a small, hybridized, RNA oligonucleotide. Tens of molecules can be analyzed at the same time. Comparing the displacement times with and without a helicase gives insights into the enzymatic activity of the protein. We used this assay to study yeast Ded1, which is orthologous to human DDX3. Although Ded1 acts on a variety of substrates, we find that Ded1 requires an RNA substrate for its ATP-dependent unwinding activity and that ATP hydrolysis is needed to see this activity. Further, we find that only intramolecular single-stranded RNA extensions enhance this activity. We propose a model where ATP-bound Ded1 stabilizes partially unwound duplexes and where multiple binding events may be needed to see displacement.
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Affiliation(s)
- Saurabh Raj
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Debjani Bagchi
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Jessica Valle Orero
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Josette Banroques
- Laboratoire d'Expression Génétique Microbienne, CNRS UMR8261/Université Paris 7-Diderot, Sorbonne Paris Cité Universités, 13 rue Pierre et Marie Curie, Paris, France.,Institut de Biologie Physico-Chimique, PSL Research University, 75005 Paris, France
| | - N Kyle Tanner
- Laboratoire d'Expression Génétique Microbienne, CNRS UMR8261/Université Paris 7-Diderot, Sorbonne Paris Cité Universités, 13 rue Pierre et Marie Curie, Paris, France.,Institut de Biologie Physico-Chimique, PSL Research University, 75005 Paris, France
| | - Vincent Croquette
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France.,ESPCI Paris, PSL University, 10 rue Vauquelin, 75005 Paris, France
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7
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Abdelkrim YZ, Harigua-Souiai E, Barhoumi M, Banroques J, Blondel A, Guizani I, Tanner NK. The steroid derivative 6-aminocholestanol inhibits the DEAD-box helicase eIF4A (LieIF4A) from the Trypanosomatid parasite Leishmania by perturbing the RNA and ATP binding sites. Mol Biochem Parasitol 2018; 226:9-19. [PMID: 30365976 DOI: 10.1016/j.molbiopara.2018.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/01/2018] [Accepted: 10/19/2018] [Indexed: 11/20/2022]
Abstract
The antifungal agent 6-aminocholestanol targets the production of ergosterol, which is the principle sterol in many fungi and protozoans; ergosterol serves many of the same roles as cholesterol in animals. We found that it also is an effective inhibitor of the translation-initiation factor eIF4AI from mouse (eIF4AIMus) and the Trypanosomatid parasite Leishmania (LieIF4A). The eIF4A proteins belong to the DEAD-box family of RNA helicases, which are ATP-dependent RNA-binding proteins and RNA-dependent ATPases. DEAD-box proteins contain a commonly-shared core structure consisting of two linked domains with structural homology to that of recombinant protein A (RecA) and that contain conserved motifs that are involved in RNA and ATP binding, and in the enzymatic activity. The compound inhibits both the ATPase and helicase activities by perturbing ATP and RNA binding, and it is capable of binding other proteins containing nucleic acid-binding sites as well. We undertook kinetic analyses and found that the Leishmania LieIF4A protein binds 6-aminocholestanol with a higher apparent affinity than for ATP, although multiple binding sites were probably involved. Competition experiments with the individual RecA-like domains indicate that the primary binding sites are on RecA-like domain 1, and they include a cavity that we previously identified by molecular modeling of LieIF4A that involve conserved RNA-binding motifs. The compound affects the mammalian and Leishmania proteins differently, which indicates the binding sites and affinities are not the same. Thus, it is possible to develop drugs that target DEAD-box proteins from different organisms even when they are implicated in the same biological process.
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Affiliation(s)
- Yosser Zina Abdelkrim
- Expression Génétique Microbienne, CNRS UMR8261/Université Paris Diderot-Paris 7 & Paris Sciences et Lettres Research University, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France; Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis/Université de Tunis el Manar, 13 Place Pasteur, BP74 Tunis-Belvédère, 1002 Tunisia; Faculté des Sciences de Bizerte, Université de Carthage, 7021 Zarzouna-Bizerte, Tunisia
| | - Emna Harigua-Souiai
- Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis/Université de Tunis el Manar, 13 Place Pasteur, BP74 Tunis-Belvédère, 1002 Tunisia
| | - Mourad Barhoumi
- Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis/Université de Tunis el Manar, 13 Place Pasteur, BP74 Tunis-Belvédère, 1002 Tunisia
| | - Josette Banroques
- Expression Génétique Microbienne, CNRS UMR8261/Université Paris Diderot-Paris 7 & Paris Sciences et Lettres Research University, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Arnaud Blondel
- Unité de Bioinformatique Structurale, CNRS UMR 3528, Département de Biologie Structurale et Chimie, Institut Pasteur, 25-28 rue du Dr Roux, 75015 Paris, France
| | - Ikram Guizani
- Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis/Université de Tunis el Manar, 13 Place Pasteur, BP74 Tunis-Belvédère, 1002 Tunisia.
| | - N Kyle Tanner
- Expression Génétique Microbienne, CNRS UMR8261/Université Paris Diderot-Paris 7 & Paris Sciences et Lettres Research University, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France.
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8
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Harigua-Souiai E, Abdelkrim YZ, Bassoumi-Jamoussi I, Zakraoui O, Bouvier G, Essafi-Benkhadir K, Banroques J, Desdouits N, Munier-Lehmann H, Barhoumi M, Tanner NK, Nilges M, Blondel A, Guizani I. Identification of novel leishmanicidal molecules by virtual and biochemical screenings targeting Leishmania eukaryotic translation initiation factor 4A. PLoS Negl Trop Dis 2018; 12:e0006160. [PMID: 29346371 PMCID: PMC5790279 DOI: 10.1371/journal.pntd.0006160] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 01/30/2018] [Accepted: 12/11/2017] [Indexed: 01/25/2023] Open
Abstract
Leishmaniases are neglected parasitic diseases in spite of the major burden they inflict on public health. The identification of novel drugs and targets constitutes a research priority. For that purpose we used Leishmania infantum initiation factor 4A (LieIF), an essential translation initiation factor that belongs to the DEAD-box proteins family, as a potential drug target. We modeled its structure and identified two potential binding sites. A virtual screening of a diverse chemical library was performed for both sites. The results were analyzed with an in-house version of the Self-Organizing Maps algorithm combined with multiple filters, which led to the selection of 305 molecules. Effects of these molecules on the ATPase activity of LieIF permitted the identification of a promising hit (208) having a half maximal inhibitory concentration (IC50) of 150 ± 15 μM for 1 μM of protein. Ten chemical analogues of compound 208 were identified and two additional inhibitors were selected (20 and 48). These compounds inhibited the mammalian eIF4I with IC50 values within the same range. All three hits affected the viability of the extra-cellular form of L. infantum parasites with IC50 values at low micromolar concentrations. These molecules showed non-significant toxicity toward THP-1 macrophages. Furthermore, their anti-leishmanial activity was validated with experimental assays on L. infantum intramacrophage amastigotes showing IC50 values lower than 4.2 μM. Selected compounds exhibited selectivity indexes between 19 to 38, which reflects their potential as promising anti-Leishmania molecules.
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Affiliation(s)
- Emna Harigua-Souiai
- Laboratory of Molecular Epidemiology and Experimental Pathology – LR11IPT04, Institut Pasteur de Tunis, Université de Tunis el Manar, Tunis, Tunisia
- Institut Pasteur, Unité de Bioinformatique Structurale, CNRS UMR 3528, Département de Biologie Structurale et Chimie, Paris, France
| | - Yosser Zina Abdelkrim
- Laboratory of Molecular Epidemiology and Experimental Pathology – LR11IPT04, Institut Pasteur de Tunis, Université de Tunis el Manar, Tunis, Tunisia
- Laboratory of Microbial Gene Expression (EGM), CNRS UMR8261/Université Paris Diderot P7, Sorbonne Paris Cité & PSL, Institut de Biologie Physico-Chimique, Paris, France
- Faculté des Sciences de Bizerte, Université de Carthage, Tunis, Tunisia
| | - Imen Bassoumi-Jamoussi
- Laboratory of Molecular Epidemiology and Experimental Pathology – LR11IPT04, Institut Pasteur de Tunis, Université de Tunis el Manar, Tunis, Tunisia
| | - Ons Zakraoui
- Laboratory of Molecular Epidemiology and Experimental Pathology – LR11IPT04, Institut Pasteur de Tunis, Université de Tunis el Manar, Tunis, Tunisia
| | - Guillaume Bouvier
- Institut Pasteur, Unité de Bioinformatique Structurale, CNRS UMR 3528, Département de Biologie Structurale et Chimie, Paris, France
| | - Khadija Essafi-Benkhadir
- Laboratory of Molecular Epidemiology and Experimental Pathology – LR11IPT04, Institut Pasteur de Tunis, Université de Tunis el Manar, Tunis, Tunisia
| | - Josette Banroques
- Laboratory of Microbial Gene Expression (EGM), CNRS UMR8261/Université Paris Diderot P7, Sorbonne Paris Cité & PSL, Institut de Biologie Physico-Chimique, Paris, France
| | - Nathan Desdouits
- Institut Pasteur, Unité de Bioinformatique Structurale, CNRS UMR 3528, Département de Biologie Structurale et Chimie, Paris, France
| | - Hélène Munier-Lehmann
- Institut Pasteur, Unité de Chimie et Biocatalyse, Département de Biologie Structurale et Chimie, Paris, France
- Unité Mixte de Recherche 3523, Centre National de la Recherche Scientifique, Paris, France
| | - Mourad Barhoumi
- Laboratory of Molecular Epidemiology and Experimental Pathology – LR11IPT04, Institut Pasteur de Tunis, Université de Tunis el Manar, Tunis, Tunisia
| | - N. Kyle Tanner
- Laboratory of Microbial Gene Expression (EGM), CNRS UMR8261/Université Paris Diderot P7, Sorbonne Paris Cité & PSL, Institut de Biologie Physico-Chimique, Paris, France
| | - Michael Nilges
- Institut Pasteur, Unité de Bioinformatique Structurale, CNRS UMR 3528, Département de Biologie Structurale et Chimie, Paris, France
| | - Arnaud Blondel
- Institut Pasteur, Unité de Bioinformatique Structurale, CNRS UMR 3528, Département de Biologie Structurale et Chimie, Paris, France
| | - Ikram Guizani
- Laboratory of Molecular Epidemiology and Experimental Pathology – LR11IPT04, Institut Pasteur de Tunis, Université de Tunis el Manar, Tunis, Tunisia
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9
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Abstract
DEAD-box RNA helicases have core structures consisting of two, tandemly linked, RecA-like domains that contain all of the conserved motifs involved in binding ATP and RNA, and that are needed for the enzymatic activities. The conserved sequence motifs and structural homology indicate that these proteins share common origins and underlining functionality. Indeed, the purified proteins generally act as ATP-dependent RNA-binding proteins and RNA-dependent ATPases in vitro, but for the most part without the substrate specificity or enzymatic regulation that exists in the cell. We are interested in understanding the relationships between the conserved motifs and structures that confer the commonly shared features, and we are interested in understanding how modifications of the core structure alter the enzymatic properties. We use sequence alignments and structural modeling to reveal regions of interest, which we modify by classical molecular biological techniques (mutations and deletions). We then use various biochemical techniques to characterize the purified proteins and their variants for their ATPase, RNA binding, and RNA unwinding activities to determine the functional roles of the different elements. In this chapter, we describe the methods we use to design our constructs and to determine their enzymatic activities in vitro.
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Affiliation(s)
- Josette Banroques
- Institut de Biologie Physico-chimique, CNRS FRE3630, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, Paris, 75005, France
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10
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Senissar M, Le Saux A, Belgareh-Touzé N, Adam C, Banroques J, Tanner NK. The DEAD-box helicase Ded1 from yeast is an mRNP cap-associated protein that shuttles between the cytoplasm and nucleus. Nucleic Acids Res 2014; 42:10005-22. [PMID: 25013175 PMCID: PMC4150762 DOI: 10.1093/nar/gku584] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 06/02/2014] [Accepted: 06/17/2014] [Indexed: 01/13/2023] Open
Abstract
The DEAD-box helicase Ded1 is an essential yeast protein that is closely related to mammalian DDX3 and to other DEAD-box proteins involved in developmental and cell cycle regulation. Ded1 is considered to be a translation-initiation factor that helps the 40S ribosome scan the mRNA from the 5' 7-methylguanosine cap to the AUG start codon. We used IgG pull-down experiments, mass spectrometry analyses, genetic experiments, sucrose gradients, in situ localizations and enzymatic assays to show that Ded1 is a cap-associated protein that actively shuttles between the cytoplasm and the nucleus. NanoLC-MS/MS analyses of purified complexes show that Ded1 is present in both nuclear and cytoplasmic mRNPs. Ded1 physically interacts with purified components of the nuclear CBC and the cytoplasmic eIF4F complexes, and its enzymatic activity is stimulated by these factors. In addition, we show that Ded1 is genetically linked to these factors. Ded1 comigrates with these proteins on sucrose gradients, but treatment with rapamycin does not appreciably alter the distribution of Ded1; thus, most of the Ded1 is in stable mRNP complexes. We conclude that Ded1 is an mRNP cofactor of the cap complex that may function to remodel the different mRNPs and thereby regulate the expression of the mRNAs.
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Affiliation(s)
- Meriem Senissar
- Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France Université Paris-Sud, Ecole Doctorale 426 GGC, Orsay, France
| | - Agnès Le Saux
- Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France
| | - Naïma Belgareh-Touzé
- Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, CNRS UMR8226 (FRE3354), UPMC, Paris 75005, France
| | - Céline Adam
- Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France
| | - Josette Banroques
- Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France
| | - N Kyle Tanner
- Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France
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11
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Barhoumi M, Tanner NK, Garnaoui A, Banroques J, Kaabi B, Linder P, Guizani I. Leishmania infantum LeIF protein is an eIF4A-like RNA helicase that modulates interleukin IL-12p70, IL-10 and TNF-α production in human monocytes. BMC Proc 2011. [DOI: 10.1186/1753-6561-5-s1-p36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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12
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Banroques J, Cordin O, Doère M, Linder P, Tanner NK. Analyses of the functional regions of DEAD-box RNA "helicases" with deletion and chimera constructs tested in vivo and in vitro. J Mol Biol 2011; 413:451-72. [PMID: 21884706 DOI: 10.1016/j.jmb.2011.08.032] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/11/2011] [Accepted: 08/16/2011] [Indexed: 01/11/2023]
Abstract
The DEAD-box family of putative RNA helicases is composed of ubiquitous proteins that are found in nearly all organisms and that are involved in virtually all processes involving RNA. They are characterized by two tandemly linked, RecA-like domains that contain 11 conserved motifs and highly variable amino- and carboxy-terminal flanking sequences. For this reason, they are often considered to be modular multi-domain proteins. We tested this by making extensive BLASTs and sequence alignments to elucidate the minimal functional unit in nature. We then used this information to construct chimeras and deletions of six essential yeast proteins that were assayed in vivo. We purified many of the different constructs and characterized their biochemical properties in vitro. We found that sequence elements can only be switched between closely related proteins and that the carboxy-terminal sequences are important for high ATPase and strand displacement activities and for high RNA binding affinity. The amino-terminal elements were often toxic when overexpressed in vivo, and they may play regulatory roles. Both the amino and the carboxyl regions have a high frequency of sequences that are predicted to be intrinsically disordered, indicating that the flanking regions do not form distinct modular domains but probably assume an ordered structure with ligand binding. Finally, the minimal functional unit of the DEAD-box core starts two amino acids before the isolated phenylalanine of the Q motif and extends to about 35 residues beyond motif VI. These experiments provide evidence for how a highly conserved structural domain can be adapted to different cellular needs.
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Affiliation(s)
- Josette Banroques
- Institut de Biologie Physico-chimique, CNRS UPR9073, Paris 75005, France
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13
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Barhoumi M, Tanner NK, Garnaoui A, Banroques J, Kaabi B, Linder P, Guizani I. Leishmania infantum LeIF protein is an eIF4A-like RNA helicase that modulates interleukin IL-12p70, IL-10 and TNF-α production in human monocytes. BMC Proc 2011. [PMCID: PMC3019461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Mourad Barhoumi
- Laboratoire d’Epidémiologie et d’Ecologie Parasitaire, Institut Pasteur de Tunis, 1002 Tunis-Belvedère, Tunisia
| | - N Kyle Tanner
- Département de Microbiologie et Médicine Moléculaire, Centre Médical Universitaire, Genève, Switzerland
| | - Amel Garnaoui
- Laboratoire d’Immunologie, Vaccinologie et Génétique Moléculaire, Institut Pasteur de Tunis, 1002 Tunis-Belvedère, Tunisia
| | - Josette Banroques
- Département de Microbiologie et Médicine Moléculaire, Centre Médical Universitaire, Genève, Switzerland,Centre de Génétique Moléculaire, CNRS, Gif-sur-Yvette, France
| | - Belhassen Kaabi
- Laboratoire d’Epidémiologie et d’Ecologie Parasitaire, Institut Pasteur de Tunis, 1002 Tunis-Belvedère, Tunisia
| | - Patrick Linder
- Département de Microbiologie et Médicine Moléculaire, Centre Médical Universitaire, Genève, Switzerland
| | - Ikram Guizani
- Laboratoire d’Epidémiologie et d’Ecologie Parasitaire, Institut Pasteur de Tunis, 1002 Tunis-Belvedère, Tunisia
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14
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Banroques J, Doère M, Dreyfus M, Linder P, Tanner NK. Motif III in superfamily 2 "helicases" helps convert the binding energy of ATP into a high-affinity RNA binding site in the yeast DEAD-box protein Ded1. J Mol Biol 2009; 396:949-66. [PMID: 20026132 DOI: 10.1016/j.jmb.2009.12.025] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 12/08/2009] [Accepted: 12/14/2009] [Indexed: 01/09/2023]
Abstract
Motif III in the putative helicases of superfamily 2 is highly conserved in both its sequence and its structural context. It typically consists of the sequence alcohol-alanine-alcohol (S/T-A-S/T). Historically, it was thought to link ATPase activity with a "helicase" strand displacement activity that disrupts RNA or DNA duplexes. DEAD-box proteins constitute the largest family of superfamily 2; they are RNA-dependent ATPases and ATP-dependent RNA binding proteins that, in some cases, are able to disrupt short RNA duplexes. We made mutations of motif III (S-A-T) in the yeast DEAD-box protein Ded1 and analyzed in vivo phenotypes and in vitro properties. Moreover, we made a tertiary model of Ded1 based on the solved structure of Vasa. We used Ded1 because it has relatively high ATPase and RNA binding activities; it is able to displace moderately stable duplexes at a large excess of substrate. We find that the alanine and the threonine in the second and third positions of motif III are more important than the serine, but that mutations of all three residues have strong phenotypes. We purified the wild-type and various mutants expressed in Escherichia coli. We found that motif III mutations affect the RNA-dependent hydrolysis of ATP (k(cat)), but not the affinity for ATP (K(m)). Moreover, mutations alter and reduce the affinity for single-stranded RNA and subsequently reduce the ability to disrupt duplexes. We obtained intragenic suppressors of the S-A-C mutant that compensate for the mutation by enhancing the affinity for ATP and RNA. We conclude that motif III and the binding energy of gamma-PO(4) of ATP are used to coordinate motifs I, II, and VI and the two RecA-like domains to create a high-affinity single-stranded RNA binding site. It also may help activate the beta,gamma-phosphoanhydride bond of ATP.
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Affiliation(s)
- Josette Banroques
- Institut de Biologie Physico-chimique, CNRS UPR 9073 in association with the Université Paris VII, Paris 75005, France
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15
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Barhoumi M, Tanner NK, Banroques J, Linder P, Guizani I. Leishmania infantum LeIF protein is an ATP-dependent RNA helicase and an eIF4A-like factor that inhibits translation in yeast. FEBS J 2006; 273:5086-100. [PMID: 17087726 DOI: 10.1111/j.1742-4658.2006.05506.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
LeIF, a Leishmania protein similar to the eukaryotic initiation factor eIF4A, which is a prototype of the DEAD box protein family, was originally described as a Th1-type natural adjuvant and as an antigen that induces an IL12-mediated Th1 response in the peripheral blood mononuclear cells of leishmaniasis patients. This study aims to characterize this protein by comparative biochemical and genetic analysis with eIF4A in order to assess its potential as a target for drug development. We show that a His-tagged, recombinant, LeIF protein of Leishmania infantum, which was purified from Escherichia coli, is both an RNA-dependent ATPase and an ATP-dependent RNA helicase in vitro, as described previously for other members of the DEAD box helicase protein family. In vivo experiments show that the LeIF gene cannot complement the deletion of the essential TIF1 and TIF2 genes in the yeast Saccharomyces cerevisiae that encode eIF4A. In contrast, expression of LeIF inhibits yeast growth when endogenous eIF4A is expressed off only one of its two encoding genes. Furthermore, in vitro binding assays show that LeIF interacts with yeast eIF4G. These results show an unproductive interaction of LeIF with translation initiation factors in yeast. Furthermore, the 25 amino terminal residues were shown to enhance the ability of LeIF to interfere with the translation machinery in yeast.
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Affiliation(s)
- Mourad Barhoumi
- Laboratoire d'Epidémiologie et d'Ecologie Parasitaire, Institut Pasteur de Tunis, Tunisia
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16
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Cordin O, Banroques J, Tanner NK, Linder P. The DEAD-box protein family of RNA helicases. Gene 2005; 367:17-37. [PMID: 16337753 DOI: 10.1016/j.gene.2005.10.019] [Citation(s) in RCA: 712] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 10/11/2005] [Accepted: 10/15/2005] [Indexed: 11/24/2022]
Abstract
RNA helicases of the DEAD-box protein family have been shown to participate in every aspect of RNA metabolism. They are present in most organisms where they work as RNA helicases or RNPases. The properties of these enzymes in vivo remains poorly described, however some were extensively characterized in vitro, and the solved crystal structures of a few are now available. Taken together, this information gives insight into the regulation of ATP and RNA binding as well as in the ATPase and helicase activities. This review will focus on the description of the molecular characteristics of members of the DEAD-box protein family and on the enzymatic activities they possess.
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Affiliation(s)
- Olivier Cordin
- Département de Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, 1 rue Michel Servet, 1211, Genève 4, Switzerland
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17
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Rocak S, Emery B, Tanner NK, Linder P. Characterization of the ATPase and unwinding activities of the yeast DEAD-box protein Has1p and the analysis of the roles of the conserved motifs. Nucleic Acids Res 2005; 33:999-1009. [PMID: 15718299 PMCID: PMC549409 DOI: 10.1093/nar/gki244] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The yeast DEAD-box protein Has1p is required for the maturation of 18S rRNA, the biogenesis of 40S r-subunits and for the processing of 27S pre-rRNAs during 60S r-subunit biogenesis. We purified recombinant Has1p and characterized its biochemical activities. We show that Has1p is an RNA-dependent ATPase in vitro and that it is able to unwind RNA/DNA duplexes in an ATP-dependent manner. We also report a mutational analysis of the conserved residues in motif I (86AKTGSGKT93), motif III (228SAT230) and motif VI (375HRVGRTARG383). The in vivo lethal K92A substitution in motif I abolishes ATPase activity in vitro. The mutations S228A and T230A partially dissociate ATPase and helicase activities, and they have cold-sensitive and lethal growth phenotypes, respectively. The H375E substitution in motif VI significantly decreased helicase but not ATPase activity and was lethal in vivo. These results suggest that both ATPase and unwinding activities are required in vivo. Has1p possesses a Walker A-like motif downstream of motif VI (383GTKGKGKS390). K389A substitution in this motif significantly increases the Has1p activity in vitro, which indicates it potentially plays a role as a negative regulator. Finally, rRNAs and poly(A) RNA serve as the best stimulators of the ATPase activity of Has1p among the tested RNAs.
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Affiliation(s)
| | | | | | - Patrick Linder
- To whom correspondence should be addressed. Tel: +41 22 379 54 84; Fax: +41 22 379 55 02;
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18
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Cordin O, Tanner NK, Doère M, Linder P, Banroques J. The newly discovered Q motif of DEAD-box RNA helicases regulates RNA-binding and helicase activity. EMBO J 2004; 23:2478-87. [PMID: 15201868 PMCID: PMC449782 DOI: 10.1038/sj.emboj.7600272] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2004] [Accepted: 05/19/2004] [Indexed: 11/08/2022] Open
Abstract
DEAD-box proteins are the most common RNA helicases, and they are associated with virtually all processes involving RNA. They have nine conserved motifs that are required for ATP and RNA binding, and for linking phosphoanhydride cleavage of ATP with helicase activity. The Q motif is the most recently identified conserved element, and it occurs approximately 17 amino acids upstream of motif I. There is a highly conserved, but isolated, aromatic group approximately 17 amino acids upstream of the Q motif. These two elements are involved in adenine recognition and in ATPase activity of DEAD-box proteins. We made extensive analyses of the Q motif and upstream aromatic residue in the yeast translation-initiation factor Ded1. We made site-specific mutations and tested them for viability in yeast. Moreover, we purified various mutant proteins and obtained the Michaelis-Menten parameters for the ATPase activities. We also measured RNA affinities and strand-displacement activities. We find that the Q motif not only regulates ATP binding and hydrolysis but also regulates the affinity of the protein for RNA substrates and ultimately the helicase activity.
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Affiliation(s)
- Olivier Cordin
- Département Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, Geneva, Switzerland
- Centre de Génétique Moléculaire, CNRS, Gif-sur-Yvette, France
| | - N Kyle Tanner
- Département Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, Geneva, Switzerland
| | - Monique Doère
- Département Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, Geneva, Switzerland
| | - Patrick Linder
- Département Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, Geneva, Switzerland
- Département Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, 1 rue Michel Servet, 1211 Geneva 4, Switzerland. Tel.: +41 22 379 5906; Fax: +41 22 379 5502; E-mail:
| | - Josette Banroques
- Département Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, Geneva, Switzerland
- Centre de Génétique Moléculaire, CNRS, Gif-sur-Yvette, France
- Centre de Génétique Moléculaire, CNRS, Avenue de la Terrasse, Gif-sur-Yvette 91198, France. Tel.: +33 1 69 82 38 00; Fax: +33 1 69 82 38 77; E-mail:
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19
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Affiliation(s)
- N Kyle Tanner
- Département de Biochimie Médicale, Centre Médical Universitaire, 1 rue Michel Servet, 1211 Geneva 4, Switzerland.
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20
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Abstract
SF1 and SF2 helicases have structurally conserved cores containing seven to eight distinctive motifs and variable amino- and carboxyl-terminal flanking sequences. We have discovered a motif upstream of motif I that is unique to and characteristic of the DEAD box family of RNA helicases. It consists of a 9 amino acid sequence containing an invariant glutamine. A conserved phenylalanine occurs 17 aa further upstream. Sequence alignments, site-specific mutagenesis, and ATPase assays show that this motif and the upstream phenylalanine are highly conserved, that they are essential for viability in the yeast Saccharomyces cerevisiae, and that they control ATP binding and hydrolysis in the yeast translation-initiation factor eIF4A. These results are consistent with computer studies of the solved crystal structures.
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Affiliation(s)
- N Kyle Tanner
- Département de Biochimie Médicale, Centre Médical Universitaire, 1, rue Michel Servet, 1211 Geneva 4, Switzerland.
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21
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Abstract
RNA helicases of the DEAD box and related DExD/H proteins form a very large superfamily of proteins conserved from bacteria and viruses to humans. They have seven to eight conserved motifs, the characteristics of which are used to subgroup members into individual families. They are associated with all processes involving RNA molecules, including transcription, editing, splicing, ribosome biogenesis, RNA export, translation, RNA turnover, and organelle gene expression. Analysis of the three-dimensional structures obtained through the crystallization of viral and cellular RNA helicases reveals a strong structural homology to DNA helicases. In this review, we discuss our current understanding of RNA helicases and their biological function.
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Affiliation(s)
- N K Tanner
- Department de Biochimie médicale, Centre Médical Universitaire, 1, rue Michel Servet, CH-1211 4, Genève, Switzerland
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22
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Abstract
In eukaryotic cells, all aspects of cellular RNA metabolism require putative RNA helicases of the DEAD and DExH protein families (collectively known as DExD/H families). Based on data from biochemical studies of a few of these RNA helicases, they are generally considered to be involved in the unwinding of duplex RNA molecules. However, recent reports provide evidence indicating that these proteins might also be involved in the active disruption of RNA-protein interactions.
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Affiliation(s)
- P Linder
- Dept de Biochimie Médicale, Centre Médical Universitaire, 1 rue Michel-Servet, CH1211 Genève, Switzerland.
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23
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Abstract
Ribozymes, or catalytic RNAs, were discovered a little more than 15 years ago. They are found in the organelles of plants and lower eukaryotes, in amphibians, in prokaryotes, in bacteriophages, and in viroids and satellite viruses that infect plants. An example is also known of a ribozyme in hepatitis delta virus, a serious human pathogen. Additional ribozymes are bound to be found in the future, and it is tempting to regard the RNA component(s) of various ribonucleoprotein complexes as the catalytic engine, while the proteins serve as mere scaffolding--an unheard-of notion 15 years ago! In nature, ribozymes are involved in the processing of RNA precursors. However, all the characterized ribozymes have been converted, with some clever engineering, into RNA enzymes that can cleave or modify targeted RNAs (or even DNAs) without becoming altered themselves. While their success in vitro is unquestioned, ribozymes are increasingly used in vivo as valuable tools for studying and regulating gene expression. This review is intended as a brief introduction to the characteristics of the different identified ribozymes and their properties.
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Affiliation(s)
- N K Tanner
- Département de Biochimie Médicale, Centre Médical Universitaire, Geneva, Switzerland.
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24
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Tanner NK, Sargueil B. Dissecting and analyzing the secondary structure domains of group I introns through the use of chimeric intron constructs. J Mol Biol 1995; 252:583-95. [PMID: 7563076 DOI: 10.1006/jmbi.1995.0522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The mitochondrial genes of the yeast Saccharomyces cerevisiae are often interrupted by introns defined as either group I or group II. Some of the introns contained within the precursor RNAs of these genes will self splice in vitro. The fourth introns of apocytochrome b (bi4) and cytochrome oxidase (ai4) are group I introns that do not self splice in vitro, even though they can fold into the same RNA secondary structures that are characteristic of the self-splicing introns. They require an intron-encoded maturase protein and a nuclear-encoded protein (a tRNALeu synthetase) for splicing in vivo. We have divided these introns into several sequence or structural elements and assayed them individually for their ability to support self-splicing activity. This was done by replacing the equivalent elements from the self-splicing intron from Tetrahymena thermophila with the mitochondrial elements. These intron chimeras show that peripheral sequences and the elements that define the splice sites are adequate for self-splicing activity but that the central portions containing the catalytic cores of ai4 and bi4 are deficient; these cores are the likely targets of the splicing proteins. In addition, the catalytic activity of the Tetrahymena intron is remarkably resistant to the structural alterations that we have introduced; this suggests that this technique will be of general utility for studying the structural and functional relationships of elements contained within different RNAs.
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Affiliation(s)
- N K Tanner
- Laboratoire du Génétique Moléculaire, Ecole Normale Supérieure, Paris, France
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25
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Tanner NK, Schaff S, Thill G, Petit-Koskas E, Crain-Denoyelle AM, Westhof E. A three-dimensional model of hepatitis delta virus ribozyme based on biochemical and mutational analyses. Curr Biol 1994; 4:488-98. [PMID: 7922369 DOI: 10.1016/s0960-9822(00)00109-3] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Hepatitis delta virus (HDV), which has a single-stranded RNA genome about 1700 nucleotides long, is a satellite virus of hepatitis B, and is associated with a high incidence of fulminant hepatitis and death in infected humans. Like certain pathogenic subviral RNAs that infect plants, HDV RNA features a closed-circular conformation, a rolling-circle mechanism of replication and RNA-catalyzed self-cleaving reactions of both genomic and anti-genomic strands in vitro. The catalytic domains cannot be folded into either the hammerhead or hairpin secondary-structure motifs that have been found in other self-cleaving RNAs. RESULTS A pseudoknot secondary-structure model has been suggested for the catalytic domain (ribozyme) of HDV RNA. We conducted extensive mutational analyses of regions of the HDV ribozyme predicted in this model to be single stranded, and found that several of them are important for catalytic activity. We used these data, sequence comparisons between different isolates and previously published structural analyses to produce a computer graphic model of the three-dimensional architecture of the HDV ribozyme. CONCLUSIONS Our model supports the pseudoknotted structure and rationalizes several observations relating to the lengths of the various stems and the sequence requirements of the single-stranded regions. It also provides insight into the catalytic mechanism of the HDV ribozyme. We specifically propose that residues C75, U20 and C21 form the basis of the catalytic region and are close to the cleavable phosphate.
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MESH Headings
- Base Sequence
- DNA, Viral/genetics
- Hepatitis Delta Virus/enzymology
- Hepatitis Delta Virus/genetics
- Humans
- Kinetics
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Nucleic Acid Conformation
- RNA, Catalytic/chemistry
- RNA, Catalytic/genetics
- RNA, Catalytic/metabolism
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Sequence Homology, Nucleic Acid
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26
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Abstract
The group I intron from Tetrahymena thermophila is able to catalyze its own excision from a precursor RNA. The intron recognizes the splice sites through an intron-encoded sequence called the internal guide sequence, or IGS. The 5' and 3' exons are thought to align on the IGS and form a pseudoknot structure consisting of two stems (P1 and P10). We created a shortened form of the intron that lacks the exon sequences and the entire IGS. This RNA is unable to react upon itself. It can catalyze a sequential two-step transesterification reaction on a P1P10 substrate added in trans that completely mimics splicing. The reaction works for different substrates that contain a U.G base-pair preceding the 5' cleavage site and a guanosine base preceding the 3' cleavage site, but that are otherwise unrelated in sequence. The ribozyme uses primarily the correct 5' and 3' splice sites even in the presence of potential cryptic splice sites, and therefore it must rely on the structure of the substrate (formation of the P1 and P10 helices) for correct splice site recognition. A C-G base-pair after the 5' splice site in P1 decreases activity while a U.G or G.U base-pair enhances activity. The relative position in P1 of the U.G base-pair preceding the 5' splice site is an important determinant. The ability of the intron to recognize primarily a specific structure, rather than a sequence, has ramifications for splice-site selection, for molecular modeling of the group I intron, and for ribozyme-based gene targeting.
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Affiliation(s)
- B Sargueil
- Laboratoire du Génétique Moléculaire, Ecole Normale Supérieure, Paris, France
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27
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Thill G, Vasseur M, Tanner NK. Structural and sequence elements required for the self-cleaving activity of the hepatitis delta virus ribozyme. Biochemistry 1993; 32:4254-62. [PMID: 8476853 DOI: 10.1021/bi00067a013] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The hepatitis delta virus (HDV) is a subviral RNA that contains a self-cleaving activity that is similar to the ribozyme activity found in certain plant pathogens. However, the sequences surrounding the cleavage site are unrelated to the hammerhead or hairpin ribozyme motifs, and it is considered to be a distinct ribozyme type. We made site-specific changes within two regions of the smallest contiguous HDV sequence that has optimal activity and kinetically analyzed the data at different temperatures to determine the potential roles of the residues. We distinguish between those changes that affect the rate of catalysis and those that promote the formation of inactive structures. We find that nucleotides +45 to +72 downstream from the cleavage site, which can form a hairpin structure, are dispensable for catalytic activity but that they enhance the cleavage efficiency. Nucleotides +17 to +19 and +28 to +30 form Watson and Crick base pairs that are important for activity, but the actual sequence is not critical. In contrast, the nucleotides between +21 and +26 are important for activity, and they may be involved in significant tertiary interactions.
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Tanner NK, Hanna MM, Abelson J. Binding interactions between yeast tRNA ligase and a precursor transfer ribonucleic acid containing two photoreactive uridine analogues. Biochemistry 1988; 27:8852-61. [PMID: 2853971 DOI: 10.1021/bi00424a025] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Yeast tRNA ligase, from Saccharomyces cerevisiae, is one of the protein components that is involved in the splicing reaction of intron-containing yeast precursor tRNAs. It is an unusual protein because it has three distinct catalytic activities. It functions as a polynucleotide kinase, as a cyclic phosphodiesterase, and as an RNA ligase. We have studied the binding interactions between ligase and precursor tRNAs containing two photoreactive uridine analogues, 4-thiouridine and 5-bromouridine. When irradiated with long ultraviolet light, RNA containing these analogues can form specific covalent bonds with associated proteins. In this paper, we show that 4-thiouridine triphosphate and 5-bromouridine triphosphate were readily incorporated into a precursor tRNA(Phe) that was synthesized, in vitro, with bacteriophage T7 RNA polymerase. The analogue-containing precursor tRNAs were authentic substrates for the two splicing enzymes that were tested (endonuclease and ligase), and they formed specific covalent bonds with ligase when they were irradiated with long-wavelength ultraviolet light. We have determined the position of three major cross-links and one minor cross-link on precursor tRNA(Phe) that were located within the intron and near the 3' splice site. On the basis of these data, we present a model for the in vivo splicing reaction of yeast precursor tRNAs.
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Affiliation(s)
- N K Tanner
- Department of Biology, California Institute of Technology, Pasadena 91125
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Tanner NK, Cech TR. Guanosine binding required for cyclization of the self-splicing intervening sequence ribonucleic acid from Tetrahymena thermophila. Biochemistry 1987; 26:3330-40. [PMID: 2443161 DOI: 10.1021/bi00386a013] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We have converted the intramolecular cyclization reaction of the self-splicing intervening sequence (IVS) ribonucleic acid (RNA) from Tetrahymena thermophila into an intermolecular guanosine addition reaction. This was accomplished by selectively removing the 3'-terminal nucleotide by oxidation and beta-elimination; the beta-eliminated IVS thereby is no longer capable of reacting with itself. However, under cyclization conditions, a free guanosine molecule can make a nucleophilic attack at the normal cyclization site. We have used this guanosine addition reaction as a model system for a Michaelis-Menten kinetic analysis of the guanosine binding site involved in cyclization. The results indicate that functional groups on the guanine that are used in a G-C Watson-Crick base pair are important for the cyclization reaction. This is the same result that was obtained for the guanosine binding site involved in splicing [Bass, B. L., & Cech, T. R. (1984) Nature (London) 308, 820-826]. Unlike splicing, however, certain additional nucleotides 5' to the guanosine moiety make significant binding contributions. We conclude that the guanosine binding site in cyclization is similar to, but not identical with, the guanosine binding site in splicing. The same binding interactions used in cyclization could help align the 3' splice site of the rRNA precursor for exon ligation. We also report that the phosphodiester bond at the cyclization site is susceptible to a pH-dependent hydrolysis reaction; the phosphodiester bond is somehow activated toward attack by the 3'hydroxyl of a guanosine molecule or by a hydroxyl ion.
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Affiliation(s)
- N K Tanner
- Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215
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31
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Been MD, Barfod ET, Burke JM, Price JV, Tanner NK, Zaug AJ, Cech TR. Structures involved in Tetrahymena rRNA self-splicing and RNA enzyme activity. Cold Spring Harb Symp Quant Biol 1987; 52:147-57. [PMID: 3454258 DOI: 10.1101/sqb.1987.052.01.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- M D Been
- Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309
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Tanner NK, Cech TR. Self-catalyzed cyclization of the intervening sequence RNA of Tetrahymena: inhibition by intercalating dyes. Nucleic Acids Res 1985; 13:7741-58. [PMID: 2415923 PMCID: PMC322084 DOI: 10.1093/nar/13.21.7741] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The intervening sequence (IVS) excised from the pre-rRNA of Tetrahymena undergoes a self-catalyzed cleavage-ligation reaction to form a covalently closed circular RNA. This cyclization reaction is kinetically inhibited by ethidium bromide (50% inhibition at 22 +/- 14 microM, greater than 99% inhibition at 53 +/- 16 microM for a 20 minute reaction). The dye does not alter the sites of the cyclization reaction, but it does increase the relative amount of reaction at a minor site 19 nucleotides from the 5' end of the IVS. The reversibility of the inhibition and the relative inhibitory strength of acridine orange, ethidium and proflavine suggest that inhibition is due to intercalation of the dye in functionally important secondary or tertiary structures of the IVS. The concentration of dye required to inhibit cyclization is much higher than expected from the known binding constants of such dyes to tRNA. At high Mg2+ to Na+ ratios, conditions which should stabilize RNA structure, a subpopulation of the IVS RNA molecules is resistant to ethidium inhibition, even at 200 microM ethidium. These data are interpreted as reflecting two conformational isomers of the IVS that differ in their reactivity and in their sensitivity to dye binding.
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Tanner NK, Cech TR. Self-catalyzed cyclization of the intervening sequence RNA of Tetrahymena: inhibition by methidiumpropyl.EDTA and localization of the major dye binding sites. Nucleic Acids Res 1985; 13:7759-79. [PMID: 2415924 PMCID: PMC322085 DOI: 10.1093/nar/13.21.7759] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The intervening sequence (IVS) excised from the rRNA precursor of Tetrahymena thermophila is converted to a covalently closed circular RNA in the absence of proteins in vitro. This self-catalyzed cyclization reaction is inhibited by the intercalating dye methidiumpropyl.EDTA (MPE; R.P. Hertzberg and P.B. Dervan (1982) J. Am. Chem. Soc. 104, 313-315). The MPE binding sites have been localized by mapping the sites of MPE.Fe(II) cleavage of the IVS RNA. There are three major binding sites within the 414 nucleotide IVS RNA. Two of these sites coincide with the A.B and 9L.2 pairings. These are structural elements that are conserved in all group I introns and are implicated as being functionally important for splicing. We propose that interaction of MPE with these sites is responsible for dye inhibition of cyclization. The reactions of MPE.Fe(II) with an RNA of known structure, tRNAPhe, and with the IVS RNA were studied as a function of temperature, ionic strength and ethidium concentration. Based on the comparison of the reaction with these two RNAs, we conclude that the dye is a very useful probe for structural regions of large RNAs, while it provides more limited structural information about the small, compact tRNA molecule.
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34
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Cech TR, Tanner NK, Tinoco I, Weir BR, Zuker M, Perlman PS. Secondary structure of the Tetrahymena ribosomal RNA intervening sequence: structural homology with fungal mitochondrial intervening sequences. Proc Natl Acad Sci U S A 1983; 80:3903-7. [PMID: 6306649 PMCID: PMC394167 DOI: 10.1073/pnas.80.13.3903] [Citation(s) in RCA: 186] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Splicing of the ribosomal RNA precursor of Tetrahymena is an autocatalytic reaction, requiring no enzyme or other protein in vitro. The structure of the intervening sequence (IVS) appears to direct the cleavage/ligation reactions involved in pre-rRNA splicing and IVS cyclization. We have probed this structure by treating the linear excised IVS RNA under nondenaturing conditions with various single- and double-strand-specific nucleases and then mapping the cleavage sites by using sequencing gel electrophoresis. A computer program was then used to predict the lowest-free-energy secondary structure consistent with the nuclease cleavage data. The resulting structure is appealing in that the ends of the IVS are in proximity; thus, the IVS can help align the adjacent coding regions (exons) for ligation, and IVS cyclization can occur. The Tetrahymena IVS has several sequences in common with those of fungal mitochondrial mRNA and rRNA IVSs, sequences that by genetic analysis are known to be important cis-acting elements for splicing of the mitochondrial RNAs. In the predicted structure of the Tetrahymena IVS, these sequences interact in a pairwise manner similar to that postulated for the mitochondrial IVSs. These findings suggest a common origin of some nuclear and mitochondrial introns and common elements in the mechanism of their splicing.
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