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James W. Towards Gene-Inhibition Therapy: A Review of Progress and Prospects in the Field of Antiviral Antisense Nucleic Acids and Ribozymes. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/095632029100200401] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Antisense RNA and its derivatives may provide the basis for highly selective gene inhibition therapies of virus infections. In this review, I concentrate on advances made in the study of antisense RNA and ribozymes during the last five years and their implications for the development of such therapies. It appears that antisense RNAs synthesized at realistic levels within the cell can be much more effective inhibitors than originally supposed. Looking at those experiments that enable comparisons to be made, it seems that inhibitory antisense RNAs are not those that are complementary to particular sites within mRNAs but those that are able to make stable duplexes with their targets, perhaps by virtue of their secondary structure and length. The inclusion of ribozyme sequences within antisense RNAs confers RNA-cleaving activity upon them in vitro and possibly in cells, thereby offering the possibility of markedly increasing their therapeutic potential. The varieties of natural ribozyme and their adaptation as artificial catalysts are reviewed. The implications of these developments for antiviral therapy are discussed.
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Affiliation(s)
- W. James
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, U.K
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2
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Zaman U, Richter FM, Hofele R, Kramer K, Sachsenberg T, Kohlbacher O, Lenz C, Urlaub H. Dithiothreitol (DTT) Acts as a Specific, UV-inducible Cross-linker in Elucidation of Protein-RNA Interactions. Mol Cell Proteomics 2015; 14:3196-210. [PMID: 26450613 DOI: 10.1074/mcp.m115.052795] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Indexed: 11/06/2022] Open
Abstract
Protein-RNA cross-linking by UV irradiation at 254 nm wavelength has been established as an unbiased method to identify proteins in direct contact with RNA, and has been successfully applied to investigate the spatial arrangement of protein and RNA in large macromolecular assemblies, e.g. ribonucleoprotein-complex particles (RNPs). The mass spectrometric analysis of such peptide-RNA cross-links provides high resolution structural data to the point of mapping protein-RNA interactions to specific peptides or even amino acids. However, the approach suffers from the low yield of cross-linking products, which can be addressed by improving enrichment and analysis methods. In the present article, we introduce dithiothreitol (DTT) as a potent protein-RNA cross-linker. In order to evaluate the efficiency and specificity of DTT, we used two systems, a small synthetic peptide from smB protein incubated with U1 snRNA oligonucleotide and native ribonucleoprotein complexes from S. cerevisiae. Our results unambiguously show that DTT covalently participates in cysteine-uracil crosslinks, which is observable as a mass increment of 151.9966 Da (C(4)H(8)S(2)O(2)) upon mass spectrometric analysis. DTT presents advantages for cross-linking of cysteine containing regions of proteins. This is evidenced by comparison to experiments where (tris(2-carboxyethyl)phosphine) is used as reducing agent, and significantly less cross-links encompassing cysteine residues are found. We further propose insertion of DTT between the cysteine and uracil reactive sites as the most probable structure of the cross-linking products.
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Affiliation(s)
- Uzma Zaman
- From the ‡Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany; §Bioanalytics, Institute for Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Strasse 40, D-37075 Göttingen, Germany
| | - Florian M Richter
- From the ‡Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Romina Hofele
- From the ‡Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany; §Bioanalytics, Institute for Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Strasse 40, D-37075 Göttingen, Germany
| | - Katharina Kramer
- From the ‡Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany; §Bioanalytics, Institute for Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Strasse 40, D-37075 Göttingen, Germany
| | - Timo Sachsenberg
- ¶Center for Bioinformatics, ‖Department of Computer Science, University of Tübingen, Sand 14, D-72076 Tübingen, Germany
| | - Oliver Kohlbacher
- ¶Center for Bioinformatics, ‖Department of Computer Science, University of Tübingen, Sand 14, D-72076 Tübingen, Germany; ¶¶Biomolecular Interactions, Max Planck Institute for Developmental Biology, Spemannstraße 35, D-72076 Tübingen, Germany
| | - Christof Lenz
- From the ‡Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany; §Bioanalytics, Institute for Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Strasse 40, D-37075 Göttingen, Germany
| | - Henning Urlaub
- From the ‡Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany; §Bioanalytics, Institute for Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Strasse 40, D-37075 Göttingen, Germany;
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3
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Mitchell D, Jarmoskaite I, Seval N, Seifert S, Russell R. The long-range P3 helix of the Tetrahymena ribozyme is disrupted during folding between the native and misfolded conformations. J Mol Biol 2013; 425:2670-86. [PMID: 23702292 DOI: 10.1016/j.jmb.2013.05.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/07/2013] [Accepted: 05/09/2013] [Indexed: 02/07/2023]
Abstract
RNAs are prone to misfolding, but how misfolded structures are formed and resolved remains incompletely understood. The Tetrahymena group I intron ribozyme folds in vitro to a long-lived misfolded conformation (M) that includes extensive native structure but is proposed to differ in topology from the native state (N). A leading model predicts that exchange of the topologies requires unwinding of the long-range, core helix P3, despite the presence of P3 in both conformations. To test this model, we constructed 16 mutations to strengthen or weaken P3. Catalytic activity and in-line probing showed that nearly all of the mutants form the M state before folding to N. The P3-weakening mutations accelerated refolding from M (3- to 30-fold) and the P3-strengthening mutations slowed refolding (6- to 1400-fold), suggesting that P3 indeed unwinds transiently. Upon depletion of Mg(2+), the mutations had analogous effects on unfolding from N to intermediates that subsequently fold to M. The magnitudes for the P3-weakening mutations were larger than in refolding from M, and small-angle X-ray scattering showed that the ribozyme expands rapidly to intermediates from which P3 is disrupted subsequently. These results are consistent with previous results indicating unfolding of native peripheral structure during refolding from M, which probably permits rearrangement of the core. Together, our results demonstrate that exchange of the native and misfolded conformations requires loss of a core helix in addition to peripheral structure. Further, the results strongly suggest that misfolding arises from a topological error within the ribozyme core, and a specific topology is proposed.
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Affiliation(s)
- David Mitchell
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
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4
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Grabow WW, Zhuang Z, Swank ZN, Shea JE, Jaeger L. The right angle (RA) motif: a prevalent ribosomal RNA structural pattern found in group I introns. J Mol Biol 2012; 424:54-67. [PMID: 22999957 DOI: 10.1016/j.jmb.2012.09.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 09/11/2012] [Accepted: 09/12/2012] [Indexed: 12/16/2022]
Abstract
The right angle (RA) motif, previously identified in the ribosome and used as a structural module for nano-construction, is a recurrent structural motif of 13 nucleotides that establishes a 90° bend between two adjacent helices. Comparative sequence analysis was used to explore the sequence space of the RA motif within ribosomal RNAs in order to define its canonical sequence space signature. We investigated the sequence constraints associated with the RA signature using several artificial self-assembly systems. Thermodynamic and topological investigations of sequence variants associated with the RA motif in both minimal and expanded structural contexts reveal that the presence of a helix at the 3' end of the RA motif increases the thermodynamic stability and rigidity of the resulting three-helix junction domain. A search for the RA in naturally occurring RNAs as well as its experimental characterization led to the identification of the RA in groups IC1 and ID intron ribozymes, where it is suggested to play an integral role in stabilizing peripheral structural domains. The present study exemplifies the need of empirical analysis of RNA structural motifs for facilitating the rational design and structure prediction of RNAs.
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Affiliation(s)
- Wade W Grabow
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA
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5
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Ariza-Mateos A, Prieto-Vega S, Díaz-Toledano R, Birk A, Szeto H, Mena I, Berzal-Herranz A, Gómez J. RNA self-cleavage activated by ultraviolet light-induced oxidation. Nucleic Acids Res 2011; 40:1748-66. [PMID: 21989404 PMCID: PMC3287179 DOI: 10.1093/nar/gkr822] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A novel UV-C-light-induced ribozyme activity was discovered within the highly structured 5'-genomic regions of both Hepatitis C Virus (HCV) and the related Classic Swine Fever Virus (CSFV). Cleavage is mediated by exposure to UV-C light but not by exogenous oxygen radicals. It is also very selective, occurring at base positions HCV C(79) and CSFV A(45) in some molecules and at the immediately adjacent 5'-positions HCV U(78) and CSFV U(44) in others. Among other reaction products, the majority of biochemically active products detected contained 3'-phosphate and 5'-phosphate-end groups at the newly generated termini, along with a much lower amount of 3'-hydroxyl end group. While preservation of an E-loop RNA structure in the vicinity of the cleavage site was a requisite for HCV RNA self-cleavage, this was not the case for CSFV RNA. The short size of the reactive domains (~33 nt), which are compatible with primitive RNA motifs, and the lack of sequence homology, indicate that as-yet unidentified UV-activated ribozymes are likely to be found throughout structured RNAs, thereby providing clues to whether early RNA self-cleavage events were mediated by photosensitive RNA structures.
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Affiliation(s)
- Ascensión Ariza-Mateos
- Laboratory of RNA Archeology, Instituto de Parasitología y Biomedicina 'López-Neyra', CSIC, Armilla, 18100 Granada, Spain
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6
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Lönnberg T. Understanding Catalysis of Phosphate‐Transfer Reactions by the Large Ribozymes. Chemistry 2011; 17:7140-53. [DOI: 10.1002/chem.201100009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Tuomas Lönnberg
- Department of Chemistry, University of Turku, Vatselankatu 2, 20140 Turku (Finland), Fax: (+358) 2‐333‐6700
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7
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Tamkovich NV, Zenkov AN, Vlasov VV, Zenkova MA. [An RNA sequence determines the speed of its splitting by artificial ribonucleases]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2010; 36:223-35. [PMID: 20531481 DOI: 10.1134/s106816201002010x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Phosphodiester bonds in RNA situated between similar nucleotides but in different sequences (context) were split under the action of artificial and natural ribonucleases with different speeds, and the reason for this phenomenon has not yet been fully revealed. In this study, the influence of one-nucleotide substitution on the sensitivity to splitting of the phosphodiester bonds in linear and structured RNA with homologous sequences is studied for the first time. It is indicated that the introduction of one-nucleotide substitution in the RNA sequence significantly (up to 10 times) changes the speed of the splitting of the bonds that are separated from the substitution point not only by 1-3, but also 6-8 nucleotides, by artificial ribonucleases. The observed regularities may be explained by the fact that the introduction of a one-nucleotide substitution significantly changes the stacking interactions and the net of hydrogen bonds in the RNA molecule. The applied value of this study consists of the ability of using low-molecular artificial ribonucleases with the aim of choosing the region of the binding of the oligonucleotide in the construction of a conjugate for the site-directed cutting of RNA, because the choice of a phosphodiester bond (motif) easily subjected to splitting significantly determines the effectiveness of artificial ribonucleases of directed action.
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Affiliation(s)
- N V Tamkovich
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent'eva 8, Novosibirsk, 630090 Russia
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8
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Abstract
RNA-RNA crosslinking provides a rapid means of obtaining evidence for the proximity of functional groups in structurally complex RNAs and ribonucleoproteins. Such evidence can be used to provide a physical context for interpreting structural information from other biochemical and biophysical methods and for the design of further experiments. The identification of crosslinks that accurately reflect the native conformation of the RNA of interest is strongly dependent on the position of the crosslinking agent, the conditions of the crosslinking reaction, and the method for mapping the crosslink position. Here, we provide an overview of protocols and experimental considerations for RNA-RNA crosslinking with the most commonly used long- and short-range photoaffinity reagents. Specifically, we describe the merits and strategies for random and site-specific incorporation of these reagents into RNA, the crosslinking reaction and isolation of crosslinked products, the mapping crosslinked sites, and assessment of the crosslinking data.
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Affiliation(s)
- Michael E Harris
- Center for RNA Molecular Biology, Department of Biochemistry, Case Western Reserve University Schoolof Medicine, Cleveland, Ohio, USA
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9
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Cech TR. Self-splicing and enzymatic activity of an intervening sequence RNA from Tetrahymena. Biosci Rep 2005; 24:362-85. [PMID: 16134019 DOI: 10.1007/s10540-005-2738-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Affiliation(s)
- Thomas R Cech
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA
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10
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Zhirnov OV, Wollenzien P. Action spectra for UV-light induced RNA-RNA crosslinking in 16S ribosomal RNA in the ribosome. Photochem Photobiol Sci 2003; 2:688-93. [PMID: 12859155 DOI: 10.1039/b208677h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
UV irradiation induces intramolecular crosslinks in ribosomal RNA in the ribosome. These crosslinks occur between nucleotides distant in primary sequence and they are specific, limited in number and have crosslinking efficiencies sufficient to allow their use in monitoring conformational changes. In this work, the frequency of crosslinking for eight 16S rRNA crosslinks was determined as a function of wavelength of irradiation. For six of the crosslinks, the action spectra correspond to the absorption spectra of at least one of the participating nucleotides. For a crosslink between nucleotides C967 and C1400 the maximum frequency of crosslinking occurs at wavelengths blue-shifted from the absorbance maximum of cytidine and for a crosslink between C1402 and C1501 the maximum frequency of crosslinking is red-shifted. Photoreversal of the crosslinks was also studied by deproteinizing crosslinked RNA under mild conditions and then re-irradiating it with specific wavelengths under conditions in which the crosslinks were reversed but not formed. The different crosslinks exhibit significantly different extents of photoreversal versus wavelength profiles. The differences in the crosslinking action spectra can be accounted for in the absorbance spectra of the nucleotides that are involved in the crosslink as well as by the photoreversal action spectra.
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MESH Headings
- Base Sequence
- DNA/chemistry
- DNA/radiation effects
- Electrophoresis, Polyacrylamide Gel
- Escherichia coli/chemistry
- Molecular Sequence Data
- Nucleic Acid Conformation
- Photochemistry
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Bacterial/radiation effects
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/metabolism
- RNA, Ribosomal, 16S/radiation effects
- Ribosomes/radiation effects
- Spectrophotometry, Ultraviolet
- Ultraviolet Rays
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Affiliation(s)
- Oksana V Zhirnov
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
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11
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Circle DA, Lyons AJ, Neel OD, Robertson HD. Recurring features of local tertiary structural elements in RNA molecules exemplified by hepatitis D virus RNA. RNA (NEW YORK, N.Y.) 2003; 9:280-286. [PMID: 12592001 PMCID: PMC1370394 DOI: 10.1261/rna.2173903] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2002] [Accepted: 11/11/2002] [Indexed: 05/24/2023]
Abstract
Elements of local tertiary structure in RNA molecules are important in understanding structure-function relationships. The loop E motif, first identified in several eukaryotic RNAs at functional sites which share an exceptional propensity for UV crosslinking between specific bases, was subsequently shown to have a characteristic tertiary structure. Common sequences and secondary structures have allowed other examples of the E-loop motif to be recognized in a number of RNAs at sites of protein binding or other biological function. We would like to know if more elements of local tertiary structure, in addition to the E-loop, can be identified by such common features. The highly structured circular RNA genome of the hepatitis D virus (HDV) provides an ideal test molecule because it has extensive internal structure, a UV-crosslinkable tertiary element, and specific sites for functional interactions with proteins including host PKR. We have now found a UV-crosslinkable element of local tertiary structure in antigenomic HDV RNA which, although differing from the E-loop, has a very similar pattern of sequence and secondary structure to the UV-crosslinkable element found in the genomic strand. Despite the fact that the two structures map close to one another, the sequences comprising them are not the templates for each other. Instead, the template regions for each element are additional sites for potential higher order structure on their respective complementary strands. This wealth of recurring sequences interspersed with base-paired stems provides a context to examine other RNA species for such features and their correlations with biological function.
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Affiliation(s)
- David A Circle
- Department of Biochemistry, Cornell University Medical College, New York, New York 10021, USA
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12
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Juzumiene D, Shapkina T, Kirillov S, Wollenzien P. Short-range RNA-RNA crosslinking methods to determine rRNA structure and interactions. Methods 2001; 25:333-43. [PMID: 11860287 DOI: 10.1006/meth.2001.1245] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We describe details of procedures to analyze RNA-RNA crosslinks made by far-UV irradiation (< 300 nm) or made by irradiation with near-UV light (320-365 nm) on RNA containing photosensitive nucleotides, in the present case containing 4-thiouridine. Zero-length crosslinks of these types must occur because of the close proximity of the participants through either specific interactions or transient contacts in the folded RNA structure, so they are valuable monitors of the conformation of the RNA. Procedures to produce crosslinks in the 16S ribosomal RNA and between the 16S rRNA and mRNA or tRNA are described. Gel electrophoresis conditions are described that separate the products according to their structure to allow the determination of the number and frequency of the crosslinking products. Gel electrophoresis together with an ultracentrifugation procedure for the efficient recovery of RNA from the polyacrylamide gels allows the purification of molecules containing different crosslinks. These separation techniques allow the analysis of the sites of crosslinking by primer extension and RNA sequencing techniques. The procedures are applicable to other types of RNA molecules with some differences to control levels of crosslinking and separation conditions.
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Affiliation(s)
- D Juzumiene
- Department of Molecular and Structural Biochemistry, North Carolina State University, 126 Polk Hall, Raleigh, North Carolina 27695, USA
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13
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Noah JW, Shapkina T, Wollenzien P. UV-induced crosslinks in the 16S rRNAs of Escherichia coli, Bacillus subtilis and Thermus aquaticus and their implications for ribosome structure and photochemistry. Nucleic Acids Res 2000; 28:3785-92. [PMID: 11000271 PMCID: PMC110760 DOI: 10.1093/nar/28.19.3785] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2000] [Revised: 07/31/2000] [Accepted: 07/31/2000] [Indexed: 11/13/2022] Open
Abstract
Sixteen long-range crosslinks are induced in Escherichia coli 16S rRNA by far-UV irradiation. Crosslinking patterns in two other organisms, Bacillus subtilis and Thermus aquaticus, were investigated to determine if the number and location of crosslinks in E.coli occur because of unusually photoreactive nucleotides at particular locations in the rRNA sequence. Thirteen long-range crosslinks in B.subtilis and 15 long-range crosslinks in T.aquaticus were detected by gel electrophoresis and 10 crosslinks in each organism were identified completely by reverse transcription analysis. Of the 10 identified crosslinks in B.subtilis, eight correspond exactly to E.coli crosslinks and two crosslinks are formed close to sites of crosslinks in E.coli. Of the 10 identified crosslinks in T.aquaticus, five correspond exactly to E.coli crosslinks, three are formed close to E.coli crosslinking sites, one crosslink corresponds to a UV laser irradiation-induced crosslink in E.coli and the last is not seen in E.coli. The overall similarity of crosslink positions in the three organisms suggests that the crosslinks arise from tertiary interactions that are highly conserved but with differences in detail in some regions.
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MESH Headings
- Bacillus subtilis/cytology
- Bacillus subtilis/genetics
- Bacillus subtilis/radiation effects
- Base Composition
- Base Sequence
- Binding Sites
- Conserved Sequence/genetics
- Conserved Sequence/radiation effects
- Escherichia coli/cytology
- Escherichia coli/genetics
- Escherichia coli/radiation effects
- Hot Temperature
- Lasers
- Molecular Sequence Data
- Nucleic Acid Conformation/radiation effects
- Nucleotides/chemistry
- Nucleotides/genetics
- Nucleotides/metabolism
- Nucleotides/radiation effects
- Photochemistry
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Bacterial/radiation effects
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 16S/metabolism
- RNA, Ribosomal, 16S/radiation effects
- Ribosomes/chemistry
- Ribosomes/genetics
- Ribosomes/radiation effects
- Thermus/cytology
- Thermus/genetics
- Thermus/radiation effects
- Transcription, Genetic
- Ultraviolet Rays
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Affiliation(s)
- J W Noah
- Department of Biochemistry, 128 Polk Hall, North Carolina State University, Raleigh, NC 27695-7622, USA
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14
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Pan J, Woodson SA. The effect of long-range loop-loop interactions on folding of the Tetrahymena self-splicing RNA. J Mol Biol 1999; 294:955-65. [PMID: 10588899 DOI: 10.1006/jmbi.1999.3298] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bas?e-pairing between the terminal loops of helices P2.1 and P9.1a (P13) and P2 and P5c (P14) stabilize the folded structure of the Tetrahymena group I intron. Using native gel electrophoresis to analyze the folding kinetics of a natural pre-RNA containing the Tetrahymena intron, we show that P13 and P14 are the only native loop-loop interactions among six possible combinations. Other base-pairing interactions of the loop sequences stabilize misfolded and inactive pre-RNAs. Mismatches in P13 or P14 raised the midpoints and decreased the cooperativity of the Mg(2+)-dependent eqXuilibrium folding transitions. Although some mutations in P13 resulted in slightly higher folding rates, others led to slower folding compared to the wild-type, suggesting that P13 promotes formation of P3 and P7. In contrast, mismatches in P14 increased the rate of folding, suggesting that base-pairing between P5c and P2 stabilizes intermediates in which the catalytic core is misfolded. Although the peripheral helices stabilize the native structure of the catalytic core, our results show that formation of long-range interactions, and competition between correct and incorrect loop-loop base-pairs, decrease the rate at which the active pre-RNA structure is assembled.
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Affiliation(s)
- J Pan
- College Park, University of Maryland, College Park, MD 20742-2021, USA
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15
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Golden BL, Podell ER, Gooding AR, Cech TR. Crystals by design: a strategy for crystallization of a ribozyme derived from the Tetrahymena group I intron. J Mol Biol 1997; 270:711-23. [PMID: 9245599 DOI: 10.1006/jmbi.1997.1155] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Recently, the 2.8 A crystal structure of one domain of the self-splicing Tetrahymena group I intron was reported. Although it revealed much about RNA tertiary interactions, it contained only half of the active site. We have now designed a series of larger molecules that contain about 70% of the intron and all of the catalytic core. These RNAs were efficient in cleavage of a substrate RNA, consisting of the approximately 100 nucleotides from the 5' end of the intron, at a site corresponding to the 5' splice site. A sparse matrix was designed specifically for large RNAs and used to screen for preliminary crystallization conditions. Of the six RNAs initially tested, five were crystallized in this initial trial. Two of these crystals were further examined. The first diffracted X-rays to only approximately 16 A resolution, even when the crystal were very large. The second diffracted as high as 3.5 A, but the crystals were twinned and therefore unusable for structural studies. Site-specific mutagenesis was performed on the latter RNA to disrupt interactions that might have been responsible for the twinning. One of these mutant RNAs produced large, single, diffraction-quality crystals. The crystals belong to the tetragonal space group P42212 and have large unit cell dimensions, a=b=178 A and c=199 A. Thus, by variation of both sequence elements and crystallization conditions, crystals of a 247 nucleotide catalytic RNA were obtained.
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Affiliation(s)
- B L Golden
- Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309, USA
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16
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Abstract
Structured RNA molecules play essential roles in RNA processing, chromosome maintenance and protein biosynthesis. RNA necessarily uses different strategies than proteins for folding and assembly of complex architectures. The RNA-folding problem is largely an issue of helical packing: how does RNA organize and pack short, double-helical segments to produce active sites and recognition motifs for proteins? Noncanonical base pairs, metal ions and 2'-hydroxyl groups are key elements in RNA higher-order structure formation.
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Affiliation(s)
- S A Strobel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
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17
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Lehnert V, Jaeger L, Michel F, Westhof E. New loop-loop tertiary interactions in self-splicing introns of subgroup IC and ID: a complete 3D model of the Tetrahymena thermophila ribozyme. CHEMISTRY & BIOLOGY 1996; 3:993-1009. [PMID: 9000010 DOI: 10.1016/s1074-5521(96)90166-0] [Citation(s) in RCA: 243] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Group I introns self-splice via two consecutive trans-esterification reactions in the presence of guanosine cofactor and magnesium ions. Comparative sequence analysis has established that a catalytic core of about 120 nucleotides is conserved in all known group I introns. This core is generally not sufficient for activity, however, and most self-splicing group I introns require non-conserved peripheral elements to stabilize the complete three-dimensional (3D) structure. The physico-chemical properties of group I introns make them excellent systems for unraveling the structural basis of the RNA-RNA interactions responsible for promoting the self-assembly of complex RNAs. RESULTS We present phylogenetic and experimental evidence for the existence of three additional tertiary base pairings between hairpin loops within peripheral components of subgroup IC1 and ID introns. Each of these new long range interactions, called P13, P14 and P16, involves a terminal loop located in domain 2. Although domains 2 of IC and ID introns share very strong sequence similarity, their terminal loops interact with domains 5 and 9 (subgroup IC1) and domain 6 (subgroup ID). Based on these tertiary contacts, comparative sequence analysis, and published experimental results such as Fe(II)-EDTA protection patterns, we propose 3D models for two entire group I introns, the subgroup IC1 intron in the large ribosomal precursor RNA of Tetrahymena thermophila and the SdCob.1 subgroup ID intron found in the cytochrome b gene of Saccharomyces douglasii. CONCLUSIONS Three-dimensional models of group I introns belonging to four different subgroups are now available. They all emphasize the modular and hierarchical organization of the architecture of group I introns and the widespread use of base-pairings between terminal hairpin loops for stabilizing the folded and active structures of large and complex RNA molecules.
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Affiliation(s)
- V Lehnert
- Institut de Biologie Moléculaire et Cellulaire du CNRS, UPR9002, 15 rue Descartes, 67084, Strasbourg, France
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18
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Shaw LC, Thomas J, Lewin AS. The Cbp2 protein suppresses splice site mutations in a group I intron. Nucleic Acids Res 1996; 24:3415-23. [PMID: 8811097 PMCID: PMC146108 DOI: 10.1093/nar/24.17.3415] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Cbp2 protein facilitates the folding of a group I intron in the COB pre-mRNA of yeast mitochondria. Based on its ability to suppress mutations affecting the auto-catalytic reaction, the protein appears to play a role in the selection of splice sites. Adding Cbp2 did not overcome the effects of mutations in P1 whose primary effect was on the first step of splicing. In contrast, most mutations affecting the ligation of exons were suppressed in vitro by Cbp2. These included mutations in P1, P9.0 and P10. In fact, a mutant transcript lacking both P9.0 and P10 ligated efficiently in the presence of Cbp2. P9.0 and P10 mutations also reduced the rate of cleavage at the 5' splice junction, and this effect was only partially mitigated by adding Cbp2. A competitive secondary structure near the 3' splice junction blocked Cbp2-stimulated splicing, but this mutation could be suppressed by co-transcriptional splicing in the presence of Cbp2. Our data underscore the importance of the interaction between the 5' and 3' splice junctions in group I introns and suggest that nucleotide-nucleotide interactions that stabilize the structure of group I introns can be superceded by protein-RNA interactions.
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Affiliation(s)
- L C Shaw
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville 32610-0266, USA
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19
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Narlikar GJ, Herschlag D. Isolation of a local tertiary folding transition in the context of a globally folded RNA. NATURE STRUCTURAL BIOLOGY 1996; 3:701-10. [PMID: 8756329 DOI: 10.1038/nsb0896-701] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Binding of the Tetrahymena ribozyme's oligonucleotide substrate represents a local folding event in the context of a globally folded RNA. Substrate binding involves P1 duplex formation with the ribozyme's internal guide sequence to give an "open complex', followed by docking of the P1 duplex into tertiary interactions to give a "closed complex'. We have isolated the open complex as a thermodynamically stable species using a site-specific modification and high Na+ concentrations. This has allowed characterization of P1 docking, which represents a folding transition between local secondary and local tertiary structure. P1 docking is entropically driven, possibly accompanied by a release of bound water molecules. Strategies analogous to those described here can be used more generally to study local folding events in large structured RNAs and to explore the structural and energetic landscape for RNA folding.
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Affiliation(s)
- G J Narlikar
- Department of Chemistry, Stanford University, California 94305-5307, USA
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20
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Goodwin JT, Osborne SE, Scholle EJ, Glick GD. Design, Synthesis, and Analysis of Yeast tRNAPhe Analogs Possessing Intra- and Interhelical Disulfide Cross-Links. J Am Chem Soc 1996. [DOI: 10.1021/ja960091t] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jay T. Goodwin
- Contribution from the Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Scott E. Osborne
- Contribution from the Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Emily J. Scholle
- Contribution from the Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Gary D. Glick
- Contribution from the Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055
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21
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Branch AD, Levine BJ, Polaskova JA. An RNA tertiary structure of the hepatitis delta agent contains UV-sensitive bases U-712 and U-865 and can form in a bimolecular complex. Nucleic Acids Res 1995; 23:491-9. [PMID: 7885846 PMCID: PMC306702 DOI: 10.1093/nar/23.3.491] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Genomic RNA of the hepatitis delta agent has a highly conserved element of local tertiary structure. This element contains two nucleotides which become covalently crosslinked to each other upon irradiation with UV light. Using direct RNA analysis, we now identify the two nucleotides as U-712 and U-865 and show that the UV-induced crosslink can be broken by re-exposure to a 254 nm peak UV light source. In the rod-like secondary structural model of delta RNA, nucleotides U-712 and U-865 are off-set from each other by 5-6 bases, a distance too great to permit crosslinking. This model needs to be modified. Our data indicate that bases U-712 and U-865 closely approximate each other and suggest that the smooth helical contour proposed for delta RNA is interrupted by the UV-sensitive element. The nucleotide sequence shows that the UV-sensitive site does not have a particularly high density of conventional Watson-Crick base pairs compared to the rest of the genome. However, this element may have a number of non-Watson-Crick bonds which confer stability. Following UV-crosslinking and digestion with 1 mg/ml of RNase T1 at 37 degrees C for 45 min in 10 mM Tris-HCl, 1 mM EDTA (conditions expected to give complete digestion), this element can be isolated as part of a 54 nucleotide long partial digestion product containing at least 16 internal G residues. UV-crosslinking analysis shows that this unusual tertiary structural element can form in a bimolecular complex.
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Affiliation(s)
- A D Branch
- Center for Studies of the Addictive Diseases, Rockefeller University, New York, NY 10021
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22
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Caprara MG, Waring RB. Deletion of P9 and stem-loop structures downstream from the catalytic core affects both 5' and 3' splicing activities in a group-I intron. Gene 1994; 143:29-37. [PMID: 8200535 DOI: 10.1016/0378-1119(94)90600-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The P9 stem-loop is one of the conserved structural elements found in all group-I introns. Using two deletion mutants in this region of the Tetrahymena thermophilia large ribosomal subunit intron, we show that removal of the P9 element, either alone, or together with the non-conserved downstream P9.1 and P9.2 elements, results in an intron incapable of the first step of the splicing reaction at a low concentration of Mg2+. The mutant introns also require high concentrations of Mg2+ for the second step in splicing, as well as hydrolysis reactions, suggesting that P9, as well as P9.1 and P9.2, are important structural elements in the final folded form of the intron. In addition, RNase-T1-mediated-structure-probing experiments demonstrated that the loss of P9, P9.1 and P9.2 changes the structural context of the region binding the 5' splice site. The deletions lead to less efficient recognition of the 3' splice site and an accumulation of unligated exons. These observations support the view that the P9, P9.1 and P9.2 stem-loops play an important role in the binding of the 3' splice site.
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Affiliation(s)
- M G Caprara
- Department of Biology, Temple University, Philadelphia, PA 19122
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23
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Downs WD, Cech TR. A tertiary interaction in the Tetrahymena intron contributes to selection of the 5' splice site. Genes Dev 1994; 8:1198-211. [PMID: 7926724 DOI: 10.1101/gad.8.10.1198] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The utilization of cryptic splice sites has been observed in a number of RNA splicing reactions. In the self-splicing group I intron of Tetrahymena thermophila, point mutations of either A57 or A95 promote cleavage at two sites other than the normal 5' splice site, suggesting that these nucleotides are involved in a common tertiary interaction. These results are unusual since A57 and A95 are neither at nor near the 5' splice site in the sequence or secondary structure. Cleavage at the alternative sites appears to occur by intron cyclization, a reaction with well-established structural and mechanistic similarities to the first step of RNA self-splicing. Alternative docking of P1 (the helix containing the 5' splice site paired to the internal guide sequence of the intron) into the catalytic core accounts for cleavage at the cryptic reaction sites. We propose that the A57/A95 interaction, along with an element implicated previously (J1/2), provide structural connectivity from the reaction site in P1 to the catalytic core of the Tetrahymena intron. It seems likely that RNA splicing in general will require such tertiary interactions to position RNA helices.
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Affiliation(s)
- W D Downs
- Department of Molecular, Cellular, and Developmental Biology, Howard Hughes Medical Institute, University of Colorado, Boulder 80309-0215
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24
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Cech TR, Damberger SH, Gutell RR. Representation of the secondary and tertiary structure of group I introns. NATURE STRUCTURAL BIOLOGY 1994; 1:273-80. [PMID: 7545072 DOI: 10.1038/nsb0594-273] [Citation(s) in RCA: 220] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Group I introns, which are widespread in nature, carry out RNA self-splicing. The secondary structure common to these introns was for the most part established a decade ago. Information about their higher order structure has been derived from a range of experimental approaches, comparative sequence analysis, and molecular modelling. This information now provides the basis for a new two-dimensional structural diagram that more accurately represents the domain organization and orientation of helices within the intron, the coaxial stacking of certain helices, and the proximity of key nucleotides in three-dimensional space. It is hoped that this format will facilitate the detailed comparison of group I intron structures.
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Affiliation(s)
- T R Cech
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215, USA
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25
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Strobel SA, Cech TR. Translocation of an RNA duplex on a ribozyme. NATURE STRUCTURAL BIOLOGY 1994; 1:13-7. [PMID: 7544680 DOI: 10.1038/nsb0194-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
RNA cleavage by the Tetrahymena ribozyme requires recognition of the reaction-site helix by the catalytic apparatus. This binding can occur in several registers, each of which results in reaction at a different nucleotide in the helix. We now identify commensurate sets of 2'-hydroxyl interactions on both strands of the reaction-site helix that account for its translocation into alternative binding registers. These results indicate that the ribozyme has a relatively rigid substrate-binding pocket into which the helix can bind in different alignments. A similar mechanism of reaction site recognition is proposed to occur during intron circularization and ribozyme polymerase activity. Translocation of the reaction site duplex provides an example of structural heterogeneity in packing of helices during the tertiary folding of RNA.
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Affiliation(s)
- S A Strobel
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215, USA
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26
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Castanotto D, Rossi JJ, Sarver N. Antisense catalytic RNAs as therapeutic agents. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1994; 25:289-317. [PMID: 8204504 DOI: 10.1016/s1054-3589(08)60435-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- D Castanotto
- Division of Biology, Beckman Research Institute of the City of Hope, Duarte, California 91010
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27
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Wang JF, Downs WD, Cech TR. Movement of the guide sequence during RNA catalysis by a group I ribozyme. Science 1993; 260:504-8. [PMID: 7682726 DOI: 10.1126/science.7682726] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Ribozymes derived from the self-splicing pre-ribosomal RNA of Tetrahymena act as sequence-specific endonucleases. The reaction involves binding an RNA or DNA substrate by base pairing to the internal guide sequence (IGS) to form helix P1. Site-specific photo-crosslinking localized the 5' end of the IGS in helix P1 to the vicinity of conserved bases between helices P4 and P5, supporting a major feature of the Michel-Westhof three-dimensional structure model. The crosslinked ribozyme retained catalytic activity. When not base-paired, the IGS was still specifically crosslinked, but the major site was 37 A distant from the reactive site in the experimentally supported three-dimensional model. The data indicate that a substantial induced-fit conformational change accompanies P1 formation, and they provide a physical basis for understanding the transport of oligonucleotides to the catalytic core of the ribozyme. The ability of RNA to orchestrate large-scale conformational changes may help explain why the ribosome and the spliceosome are RNA-based machines.
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Affiliation(s)
- J F Wang
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309
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28
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Christian EL, Yarus M. Analysis of the role of phosphate oxygens in the group I intron from Tetrahymena. J Mol Biol 1992; 228:743-58. [PMID: 1469712 DOI: 10.1016/0022-2836(92)90861-d] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have developed a quantitative substitution interference technique to examine the role of Pro-Rp oxygens in the phosphodiester backbone of RNA, using phosphorothioates as a structural probe. This approach is generally applicable to any reaction involving RNA in which the precursor and reaction products can be separated. We have applied the technique to identity structural requirements in the group I intron from Tetrahymena thermophila for catalysis of hydrolysis at the 3' splice site; 44 phosphate oxygens are important in 3' splice site hydrolysis. These include four or five oxygens previously observed to be important in exon ligation. Although phosphate oxygens having a functional significance can be found throughout the intron, the strongest phosphorothioate effects are closely associated with positions in the highly conserved intron core, which are likely to be involved in tertiary interactions, substrate recognition and catalysis.
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Affiliation(s)
- E L Christian
- Department of Molecular Cellular and Developmental Biology, University of Colorado, Boulder 80309-0347
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29
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30
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Behlen LS, Sampson JR, Uhlenbeck OC. An ultraviolet light-induced crosslink in yeast tRNA(Phe). Nucleic Acids Res 1992; 20:4055-9. [PMID: 1508690 PMCID: PMC334087 DOI: 10.1093/nar/20.15.4055] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The irradiation of native or unmodified yeast tRNA(Phe) by short wavelength UV light (260 nM) results in an intramolecular crosslink that has been mapped to occur between C48 in the variable loop and U59 in the T loop. Photo-reversibility of the crosslink and the absence of fluorescent photo adducts suggest that the crosslink product is a cytidine-uridine cyclobutane dimer. This is consistent with the relative geometries of C48 and U59 in the crystal structure of yeast tRNA(Phe). Evaluation of the crosslinking efficiency of the mutants of tRNA(Phe) indicates that the reaction depends on the correct tertiary structure of the RNA.
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Affiliation(s)
- L S Behlen
- Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215
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31
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Paul CP, Levine BJ, Robertson HD, Branch AD. Transcripts of the viroid central conserved region contain the local tertiary structural element found in full-length viroid. FEBS Lett 1992; 305:9-14. [PMID: 1633862 DOI: 10.1016/0014-5793(92)80644-v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The viroid central conserved region (CCR) is highly conserved among different viroids and is thought to be involved in viroid replication. A novel tertiary structure occurs in the CCR of native circular potato spindle tuber RNAs. To permit more detailed studies of this structural element, a small RNA oligonucleotide containing the CCR of the viroid genome was synthesized. The tertiary structure of these CCR transcripts was examined by UV-crosslinking of the RNA, followed by mapping of the crosslink using limited alkaline digestion and classical RNA secondary analysis. The CCR transcript was found to undergo UV-crosslinking between the same two bases as in full-length viroid, indicating that the tertiary structure is the same and that the CCR transcript will be useful for the affinity purification of host components.
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Affiliation(s)
- C P Paul
- Department of Biochemistry, Cornell University Medical College, New York, NY 10021
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32
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Piccirilli JA, McConnell TS, Zaug AJ, Noller HF, Cech TR. Aminoacyl esterase activity of the Tetrahymena ribozyme. Science 1992; 256:1420-4. [PMID: 1604316 DOI: 10.1126/science.1604316] [Citation(s) in RCA: 157] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Several classes of ribozymes (catalytic RNA's) catalyze reactions at phosphorus centers, but apparently no reaction at a carbon center has been demonstrated. The active site of the Tetrahymena ribozyme was engineered to bind an oligonucleotide derived from the 3' end of N-formyl-methionyl-tRNA(fMet). This ribozyme catalyzes the hydrolysis of the aminoacyl ester bond to a modest extent, 5 to 15 times greater than the uncatalyzed rate. Catalysis involves binding of the oligonucleotide to the internal guide sequence of the ribozyme and requires Mg2+ and sequence elements of the catalytic core. The ability of RNA to catalyze reactions with aminoacyl esters expands the catalytic versatility of RNA and suggests that the first aminoacyl tRNA synthetase could have been an RNA molecule.
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Affiliation(s)
- J A Piccirilli
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309
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33
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Mohr G, Zhang A, Gianelos JA, Belfort M, Lambowitz AM. The neurospora CYT-18 protein suppresses defects in the phage T4 td intron by stabilizing the catalytically active structure of the intron core. Cell 1992; 69:483-94. [PMID: 1533818 DOI: 10.1016/0092-8674(92)90449-m] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Neurospora CYT-18 protein, a tyrosyl-tRNA synthetase, which functions in splicing group I introns in mitochondria, promotes splicing of mutants of the distantly related bacteriophage T4 td intron. In an in vivo assay, wild-type CYT-18 protein expressed in E. coli suppressed mutations in the td intron's catalytic core. CYT-18-suppressible mutations were also suppressed by high Mg2+ or spermidine in vitro, suggesting they affect intron structure. Both the N- and C-terminal domains of CYT-18 are required for efficient splicing, but CYT-18 with a large C-terminal truncation retains some activity. Our results indicate that CYT-18 interacts with conserved structural features of group I introns, and they provide direct evidence that a protein promotes splicing by stabilizing the catalytically active structure of the intron RNA.
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Affiliation(s)
- G Mohr
- Department of Molecular Genetics, Ohio State University, Columbus 43210
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34
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Herschlag D. Evidence for processivity and two-step binding of the RNA substrate from studies of J1/2 mutants of the Tetrahymena ribozyme. Biochemistry 1992; 31:1386-99. [PMID: 1736996 DOI: 10.1021/bi00120a015] [Citation(s) in RCA: 92] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
J1/2 of the Tetrahymena ribozyme, a sequence of three A residues, connects the RNA-binding site to the catalytic core. Addition or deletion of bases from J1/2 improves turnover and substrate specificity in the site-specific endonuclease reaction catalyzed by this ribozyme: G2CCCUCUA5 (S) + G in-equilibrium G2CCCUCU (P) + GA5. These paradoxical enhancements are caused by decreased affinity of the ribozyme for S and P [Young, B., Herschlag, D., & Cech, T.R. (1991) Cell 67, 1007]. An additional property of these mutant ribozymes, decreased fidelity of RNA cleavage, is now analyzed. (Fidelity is the ability to cleave at the correct phosphodiester bond within a particular RNA substrate.) Introduction of deoxy residues to give "chimeric" ribo/deoxyribooligonucleotides changes the positions of incorrect cleavage. Previous work indicated that S is bound to the ribozyme by both base pairing and teritary interactions involving 2'-hydroxyl groups of S. The data herein strongly suggest that the P1 duplex, which consists of S base-paired with the 5' exon binding site of the ribozyme, can dock into tertiary interactions in different registers; different 2'-hydroxyl groups of S plug into tertiary contacts with the ribozyme in the different registers. It is concluded that the mutations decrease fidelity by increasing the probability of docking out of register relative to docking in the normal register, thereby giving cleavage at different positions along S. These data also show that the contribution of J1/2 to the teritiary interactions is indirect, not direct. Thus, a structural role of the nonconserved J1/2 is indicated: this sequence positions S to optimize tertiary binding interactions and to ensure cleavage at the phosphodiester bond corresponding to the 5' splice site. Substitution of sulfur for the nonbridging pro-RP oxygen atom at the normal cleavage site has no effect on (kcat/Km)S but decreases the fraction of cleavage at the normal site in reactions catalyzed by the -3A mutant ribozyme, which has all three A residues of J1/2 removed. Thus, the ribozyme chooses where to cleave S after rate-limiting binding of S, indicating that docking can change after binding and suggesting that the ribozyme could act processively. Indeed, it is shown that the +2A ribozyme cleaves at one position along an RNA substrate and then, before releasing that RNA product, cleaves it again.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- D Herschlag
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Colorado, Boulder 80309-0215
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35
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Salvo J, Belfort M. The P2 element of the td intron is dispensable despite its normal role in splicing. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50658-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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36
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Clivio P, Favre A, Fontaine C, Fourrey JL, Gasche J, Guittet E, Laugâa P. NMR and molecular modelling studies of two photoproducts of 2′-deoxy-4- thiouridylyl-(3′,5′)- thymidine. Tetrahedron 1992. [DOI: 10.1016/s0040-4020(01)88719-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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37
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Sanders J, Towner P. Circle reopening in the Tetrahymena ribozyme resembles site-specific hydrolysis at the 3' splice site. J Mol Biol 1992; 223:351-60. [PMID: 1731080 DOI: 10.1016/0022-2836(92)90736-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The Tetrahymena intron, after splicing from its flanking exons, can mediate its own circularization. This is followed by site-specific hydrolysis of the phosphodiester bond formed during the circularization reaction. The structural components involved in recognition of this bond for hydrolysis have not been established. We have made base substitutions to the P9.0 pairing and at the 3'-terminal guanosine residue (G414) of the intron to investigate their effects on circle formation and reopening. We have found that disruption of either P9.0 pairing or binding of the terminal nucleotide result in the formation of a large circle, C-413:5E23 from precursor RNA molecules that have undergone hydrolysis at the 3' splice site. This circle is formed at the phosphodiester bond of the 5'-terminal guanosine residue of the upstream exon via nucleophilic attack by the 3'-terminal nucleotide of the intron. The large circle is novel since it can reopen eight bases downstream from the original circularization junction at a site resembling the normal 3' splice site, restoring a guanosine to the 3' terminus and re-establishing P9.0 pairing. The new 3' terminus of the intron is capable of recircularization at any of the three normal wild-type sites. We conclude that both P9.0 and the 3'-terminal guanosine residue are required for the selection of the phosphodiester bond hydrolysed during circle reopening.
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Affiliation(s)
- J Sanders
- Department of Biochemistry, University of Bath, Avon, U.K
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38
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Young B, Herschlag D, Cech TR. Mutations in a nonconserved sequence of the Tetrahymena ribozyme increase activity and specificity. Cell 1991; 67:1007-19. [PMID: 1959129 DOI: 10.1016/0092-8674(91)90373-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The RNA substrate-binding site of the Tetrahymena ribozyme is connected to the catalytic core by the joining region J1/2. Although J1/2 is not conserved among group I introns, small insertions or deletions in this sequence have dramatic effects, enhancing the turnover number and sequence specificity of ribozyme-catalyzed RNA cleavage. Measurements of rate constants for individual steps in the reaction have revealed the basis of these improvements. Ironically, the higher turnover and specificity both result from decreased affinity for RNA, rather than better cleavage. These results provide evidence that the nonconserved J1/2 sequence positions the RNA substrate to optimize tertiary interactions and ensure cleavage at the position corresponding to the 5' splice site. The wild-type RNA is well adapted to its biological function, and its limitations in multiple turnover can be corrected by mutation.
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Affiliation(s)
- B Young
- Department of Molecular, Cellular and Developmental Biology, Howard Hughes Medical Institute, University of Colorado, Boulder 80309-0215
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Bevilacqua PC, Turner DH. Comparison of binding of mixed ribose-deoxyribose analogues of CUCU to a ribozyme and to GGAGAA by equilibrium dialysis: evidence for ribozyme specific interactions with 2' OH groups. Biochemistry 1991; 30:10632-40. [PMID: 1931984 DOI: 10.1021/bi00108a005] [Citation(s) in RCA: 92] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Dissociation constants at 15 degrees C were measured by equilibrium dialysis for the binding of rCrUrCrU, dCrUrCrU, rCdUrCrU, rCrUdCrU, and rCrUrCdU to the L-21 ScaI form of the self-splicing group I LSU intron from Tetrahymena thermophila. Substitution of deoxyribose for ribose in each of the middle two positions makes the free energy change for binding 1-2 kcal/mol less favorable, compared to about 0.3 kcal/mol less favorable for each of the terminal positions. Dissociation constants for binding of the same oligomers to rGGAGAA were measured by optical melting methods. Substitution of a single deoxyribose for ribose makes the free energy change for binding less favorable by 0.4-0.9 kcal/mol for this simple duplex formation. Comparison of the effects for binding to ribozyme and to rGGAGAA indicate that ribozyme-specific tertiary interactions dependent on the middle two 2' OH groups of rCrUrCrU add about 2 kcal/mol of favorable free energy for binding to L-21 ScaI. Comparisons are made with results from gel retardation studies [Pyle, A. M., McSwiggen, J. A., & Cech, T. R. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 8187-8191; Pyle, A. M., & Cech, T. R. (1991) Nature (London) 350, 628-631].
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Affiliation(s)
- P C Bevilacqua
- Department of Chemistry, University of Rochester, New York 14627-0216
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40
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Watkins KP, Agabian N. In vivo UV cross-linking of U snRNAs that participate in trypanosome trans-splicing. Genes Dev 1991; 5:1859-69. [PMID: 1655571 DOI: 10.1101/gad.5.10.1859] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The maturation of mRNAs in Trypanosoma brucei involves a trans-splicing reaction whereby the 5' 39 nucleotides of a small RNA, called the spliced leader (SL) RNA, are joined with a pre-mRNA transcript. The trans-splicing reaction appears mechanistically similar to cis-splicing of nuclear pre-mRNAs, and homologs of the U2, U4, and U6 snRNAs are required for the process. In the work presented here, potential RNA-RNA interactions between the SL RNA and the U snRNAs of trypanosomes were examined by UV light induction of RNA-RNA cross-links in vivo. We detected cross-linkage between U2 and U6 RNAs and, as might be expected, between the trypanosome U4 and U6 RNAs. The latter contain extensive sequence complementarity and are thought to exist predominantly in a single RNP. We also detected an SL RNA species following in vivo UV treatment, which may represent either an intramolecular cross-link in the SL RNA or a cross-link formed between the SL RNA and an as yet unidentified small RNA. Mapping of the cross-link position between U2 and U6 RNAs is consistent with base-pairing between the 5' domain of U2 and the 3' end of U6 RNA. These results reveal the existence, in vivo, of cognate RNA-RNA interactions in the RNA homologs that participate in trans-splicing in trypanosomes and cis-splicing in other eukaryotes.
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Kumar S, Joshi PC, Sharma ND, Bose SN, Jeremy R, Davies H, Takeda N, McCloskey JA. Adenine photodimerization in deoxyadenylate sequences: elucidation of the mechanism through structural studies of a major d(ApA) photoproduct. Nucleic Acids Res 1991; 19:2841-7. [PMID: 2057348 PMCID: PMC328241 DOI: 10.1093/nar/19.11.2841] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The mechanism of the photodimerization of adjacent adenine bases on the same strand of DNA has been elucidated by determining the structure of one of the two major photoproducts that are formed by UV irradiation of the deoxydinucleoside monophosphate d(ApA). The photoproduct, denoted d(ApA)*, corresponds to a species of adenine photodimer first described by Pörschke (Pörschke, D. (1973) J.Am.Chem.Soc. 95, 8440-8446). From a detailed examination of its chemical and spectroscopic properties, including comparisons with the model compound N-cyano-N1-(1-methylimidazol-5-yl)formamidine, it is deduced that d(ApA)* contains a deoxyadenosine unit covalently linked through its C(8) position to C(4) of an imidazole N(1) deoxyribonucleoside moiety bearing an N-cyanoformamidino substituent at C(5). On treatment with acid, d(ApA)* is degraded with high specificity to 8-(5-amino-imidazol-4-yl)adenine whose identity has been confirmed by independent chemical synthesis. It is concluded that the primary event in adenine photodimerization entails photoaddition of the N(7)-C(8) double bond of the 5'-adenine across the C(6) and C(5) positions of the 3'-adenine. The azetidine species thus generated acts as a common precursor to both types of d(ApA) photoproduct which are formed from it by competing modes of azetidine ring fission.
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Affiliation(s)
- S Kumar
- Biochemistry Division, School of Biology and Biochemistry, Queen's University, Belfast, UK
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42
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Abstract
The higher order folding process of the catalytic RNA derived from the self-splicing intron of Tetrahymena thermophila was monitored with the use of Fe(II)-EDTA-induced free radical chemistry. The overall tertiary structure of the RNA molecule forms cooperatively with the uptake of at least three magnesium ions. Local folding transitions display different metal ion dependencies, suggesting that the RNA tertiary structure assembles through a specific folding intermediate before the catalytic core is formed. Enzymatic activity, assayed with an RNA substrate that is complementary to the catalytic RNA active site, coincides with the cooperative structural transition. The higher order RNA foldings produced by Mg(II), Ca(II), and Sr(II) are similar; however, only the Mg(II)-stabilized RNA is catalytically active. Thus, these results directly demonstrate that divalent metal ions participate in general folding of the ribozyme tertiary structure, and further indicate a more specific involvement of Mg(II) in catalysis.
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Affiliation(s)
- D W Celander
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215
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Pyle AM, McSwiggen JA, Cech TR. Direct measurement of oligonucleotide substrate binding to wild-type and mutant ribozymes from Tetrahymena. Proc Natl Acad Sci U S A 1990; 87:8187-91. [PMID: 2236030 PMCID: PMC54920 DOI: 10.1073/pnas.87.21.8187] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Like protein enzymes, RNA enzymes (ribozymes) provide specific binding sites for their substrates. We now show that equilibrium dissociation constants for complexes between the Tetrahymena ribozyme and its RNA substrates and products can be directly measured by electrophoresis in polyacrylamide gels containing divalent cations. Binding is 10(3)- to 10(4)-fold tighter (4-5 kcal/mol at 42 degrees C) than expected from base-pairing interactions alone, implying that tertiary interactions also contribute to energetic stabilization. Binding decreases with single base changes in the substrate, substitution of deoxyribose sugars, and lower Mg2+ concentration. Ca2+, which enables the ribozyme to fold but is unable to mediate efficient RNA cleavage, promotes weaker substrate binding than Mg2+. This indicates that Mg2+ has special roles in both substrate binding and catalysis. Mutagenesis of a region near the internal guide sequence disrupts substrate binding, whereas binding is not significantly affected by a mutation of the guanosine-binding site. This approach should be generally useful for analysis of ribozyme variants independent of their catalytic activities.
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Affiliation(s)
- A M Pyle
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215
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Cech TR. Selbstspleißen und enzymatische Aktivität einer intervenierenden Sequenz der RNA vonTetrahymena (Nobel-Vortrag). Angew Chem Int Ed Engl 1990. [DOI: 10.1002/ange.19901020705] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Cech TR. Nobel lecture. Self-splicing and enzymatic activity of an intervening sequence RNA from Tetrahymena. Biosci Rep 1990; 10:239-61. [PMID: 1699616 DOI: 10.1007/bf01117241] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A living cell requires thousands of different chemical reactions to utilize energy, move, grow, respond to external stimuli and reproduce itself. While these reactions take place spontaneously, they rarely proceed at a rate fast enough for life. Enzymes, biological catalysts found in all cells, greatly accelerate the rates of these chemical reactions and impart on them extraordinary specificity. In 1926, James B. Summer crystallized the enzyme urease and found that it was a protein. Skeptics argued that the enzymatic activity might reside in a trace component of the preparation rather than in the protein (Haldane, 1930), and it took another decade for the generality of Summer's finding to be established. As more and more examples of protein enzymes were found, it began to appear that biological catalysis would be exclusively the realm of proteins. In 1981 and 1982, my research group and I found a case in which RNA, a form of genetic material, was able to cleave and rejoin its own nucleotide linkages. This self-splicing RNA provided the first example of a catalytic active site formed of ribonucleic acid. This lecture gives a personal view of the events that led to our realization of RNA self-splicing and the catalytic potential of RNA. It provides yet another illustration of the circuitous path by which scientific inquiry often proceeds. The decision to expand so many words describing the early experiments means that much of our current knowledge about the system will not be mentioned. For a more comprehensive view of the mechanism and structure of the Tetrahymena self-splicing RNA and RNA catalysis in general, the reader is directed to a number of recent reviews (Cech & Bass, 1986: Cech, 1987, 1988a, 1990; Burke, 1988; Altman, 1989). Possible medical and pharmaceutical implications of RNA catalysis have also been described recently (Cech, 1988b).
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Affiliation(s)
- T R Cech
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215
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