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Ueda T, Nishimura KI, Nishiyama Y, Tominaga Y, Miyazaki K, Furuta H, Matsumura S, Ikawa Y. Pairwise Engineering of Tandemly Aligned Self-Splicing Group I Introns for Analysis and Control of Their Alternative Splicing. Biomolecules 2023; 13:biom13040654. [PMID: 37189401 DOI: 10.3390/biom13040654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 04/03/2023] [Accepted: 04/03/2023] [Indexed: 04/08/2023] Open
Abstract
Alternative splicing is an important mechanism in the process of eukaryotic nuclear mRNA precursors producing multiple protein products from a single gene. Although group I self-splicing introns usually perform regular splicing, limited examples of alternative splicing have also been reported. The exon-skipping type of splicing has been observed in genes containing two group I introns. To characterize splicing patterns (exon-skipping/exon-inclusion) of tandemly aligned group I introns, we constructed a reporter gene containing two Tetrahymena introns flanking a short exon. To control splicing patterns, we engineered the two introns in a pairwise manner to design pairs of introns that selectively perform either exon-skipping or exon-inclusion splicing. Through pairwise engineering and biochemical characterization, the structural elements important for the induction of exon-skipping splicing were elucidated.
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Affiliation(s)
- Tomoki Ueda
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
| | - Kei-ichiro Nishimura
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Moto-oka 744, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yuka Nishiyama
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
| | - Yuto Tominaga
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Moto-oka 744, Nishi-ku, Fukuoka 819-0395, Japan
| | - Katsushi Miyazaki
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
| | - Hiroyuki Furuta
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Moto-oka 744, Nishi-ku, Fukuoka 819-0395, Japan
| | - Shigeyoshi Matsumura
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
- Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
| | - Yoshiya Ikawa
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
- Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
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Luo B, Zhang C, Ling X, Mukherjee S, Jia G, Xie J, Jia X, Liu L, Baulin EF, Luo Y, Jiang L, Dong H, Wei X, Bujnicki JM, Su Z. Cryo-EM reveals dynamics of Tetrahymena group I intron self-splicing. Nat Catal 2023. [DOI: 10.1038/s41929-023-00934-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
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3
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Dobirul Islam M, Motiar Rahman M, Matsumura S, Ikawa Y. Effects of chain length of polyethylene glycol molecular crowders on a mutant Tetrahymena group I ribozyme lacking large peripheral module. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2021; 40:867-883. [PMID: 34402751 DOI: 10.1080/15257770.2021.1956531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
While current group I ribozymes use several distinct strategies to function under conditions of low Mg2+ concentration (≤ 3 mM), a deletion mutant of the Tetrahymena ribozyme (ΔP5 ribozyme) is virtually inactive with 3 mM Mg2+ due to removal of the large peripheral module, P5abc, supporting the active conformation of the core module. We investigated the molecular crowding effects of synthetic polyethylene glycols (PEGs) on the activity of the ΔP5 ribozyme. Among PEG molecules with different chain lengths, PEG600 improved the activity of the ΔP5 ribozyme most effectively in the presence of 3 mM Mg2+.
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Affiliation(s)
- Md Dobirul Islam
- Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan
| | - Md Motiar Rahman
- Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan
| | - Shigeyoshi Matsumura
- Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan.,Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
| | - Yoshiya Ikawa
- Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan.,Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
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4
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Cryo-EM structures of full-length Tetrahymena ribozyme at 3.1 Å resolution. Nature 2021; 596:603-607. [PMID: 34381213 PMCID: PMC8405103 DOI: 10.1038/s41586-021-03803-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 07/06/2021] [Indexed: 02/07/2023]
Abstract
Single-particle cryogenic electron microscopy (cryo-EM) has become a standard technique for determining protein structures at atomic resolution1-3. However, cryo-EM studies of protein-free RNA are in their early days. The Tetrahymena thermophila group I self-splicing intron was the first ribozyme to be discovered and has been a prominent model system for the study of RNA catalysis and structure-function relationships4, but its full structure remains unknown. Here we report cryo-EM structures of the full-length Tetrahymena ribozyme in substrate-free and bound states at a resolution of 3.1 Å. Newly resolved peripheral regions form two coaxially stacked helices; these are interconnected by two kissing loop pseudoknots that wrap around the catalytic core and include two previously unforeseen (to our knowledge) tertiary interactions. The global architecture is nearly identical in both states; only the internal guide sequence and guanosine binding site undergo a large conformational change and a localized shift, respectively, upon binding of RNA substrates. These results provide a long-sought structural view of a paradigmatic RNA enzyme and signal a new era for the cryo-EM-based study of structure-function relationships in ribozymes.
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B2 and ALU retrotransposons are self-cleaving ribozymes whose activity is enhanced by EZH2. Proc Natl Acad Sci U S A 2019; 117:415-425. [PMID: 31871160 DOI: 10.1073/pnas.1917190117] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Transposable elements make up half of the mammalian genome. One of the most abundant is the short interspersed nuclear element (SINE). Among their million copies, B2 accounts for ∼350,000 in the mouse genome and has garnered special interest because of emerging roles in epigenetic regulation. Our recent work demonstrated that B2 RNA binds stress genes to retard transcription elongation. Although epigenetically silenced, B2s become massively up-regulated during thermal and other types of stress. Specifically, an interaction between B2 RNA and the Polycomb protein, EZH2, results in cleavage of B2 RNA, release of B2 RNA from chromatin, and activation of thermal stress genes. Although an established RNA-binding protein and histone methyltransferase, EZH2 is not known to be a nuclease. Here, we provide evidence for the surprising conclusion that B2 is a self-cleaving ribozyme. Ribozyme activity depends on Mg+2 and monovalent cations but is resistant to protease treatment. However, contact with EZH2 accelerates cleavage rate by >100-fold, suggesting that EZH2 promotes a cleavage-competent RNA conformation. B2 modification-interference analysis demonstrates that phosphorothioate changes at A and C nucleotides can substitute for EZH2. B2 nucleotides 45 to 55 and 100 to 101 are essential for activity. Finally, another family of SINEs, the human ALU element, also produces a self-cleaving RNA and is cleaved during T-cell activation as well as thermal and endoplasmic reticulum (ER) stress. Thus, B2/ALU SINEs may be classified as "epigenetic ribozymes" that function as transcriptional switches during stress. Given their high copy numbers, B2 and ALU may represent the predominant ribozyme activity in mammalian cells.
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Gulshan MA, Tsuji K, Matsumura S, Higuchi T, Umezawa N, Ikawa Y. Distinct modulation of group I ribozyme activity among stereoisomers of a synthetic pentamine with structural constraints. Biochem Biophys Res Commun 2018; 504:698-703. [PMID: 30213632 DOI: 10.1016/j.bbrc.2018.09.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 09/03/2018] [Indexed: 11/25/2022]
Abstract
Among cationic molecules that can modulate ribozyme activities, polyamines act as both activator and inhibitor of ribozyme reactions partly due to their structural flexibility. Restriction of structural flexibility of polyamines may allow them to emphasize particular modulation effects. We examined eight stereoisomers of a synthetic pentamine bearing three cyclopentane rings. In the reaction of a structurally unstable group I ribozyme, three stereoisomers exhibited distinct effects as inhibitor, an additive with a neutral effect, and also as an activator.
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Affiliation(s)
- Mst Ara Gulshan
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, 930-8555, Japan; Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, 930-8555, Japan
| | - Kasumi Tsuji
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan
| | - Shigeyoshi Matsumura
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, 930-8555, Japan; Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, 930-8555, Japan
| | - Tsunehiko Higuchi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan
| | - Naoki Umezawa
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan
| | - Yoshiya Ikawa
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, 930-8555, Japan; Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, 930-8555, Japan.
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Lee CH, Han SR, Lee SW. Group I Intron-Based Therapeutics Through Trans-Splicing Reaction. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 159:79-100. [PMID: 30340790 DOI: 10.1016/bs.pmbts.2018.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In 1982, the Cech group discovered that an intron structure in an rRNA precursor of Tetrahymena thermophila is sufficient to complete splicing without assistance from proteins. This was the first moment that scientists recognized RNAs can have catalytic activities derived from their own unique three-dimensional structures and thus play more various roles in biological processes than thought before. Several additional catalytic RNAs, called ribozymes, were subsequently identified in nature followed by intense studies to reveal their mechanisms of action and to engineer them for use in fields such as molecular cell biology, therapeutics, imaging, etc. Naturally occurring RNA-targeting ribozymes can be broadly classified into two categories by their abilities: Self-cleavage and self-splicing. Since ribozymes use base-pairing to recognize cleavage sites, identification of the catalytic center of naturally occurring ribozymes enables to engineer from "self" to "trans" acting ones which has accelerated to design and use ribozyme as valuable tools in gene therapy fields. Especially, group I intron-based trans-splicing ribozyme has unique property to use as a gene therapeutic agent. It can destroy and simultaneously repair (and/or reprogram) target RNAs to yield the desired therapeutic RNAs, maintaining endogenous spatial and temporal gene regulation of target RNAs. There have been progressive improvements in trans-splicing ribozymes and successful applications of these elements in gene therapy and molecular imaging approaches for various pathogenic conditions. In this chapter, current status of trans-splicing ribozyme therapeutics, focusing on Tetrahymena group I intron-based ribozymes, and their future prospects will be discussed.
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Affiliation(s)
- Chang Ho Lee
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea
| | | | - Seong-Wook Lee
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea; Rznomics Inc., Gwangju, Republic of Korea.
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8
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Gulshan MA, Matsumura S, Higuchi T, Umezawa N, Ikawa Y. Comparative study of polyethylene polyamines as activator molecules for a structurally unstable group I ribozyme. Biosci Biotechnol Biochem 2018; 82:1404-1407. [PMID: 29699448 DOI: 10.1080/09168451.2018.1465811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Polyamines are a promising class of molecules that can modulate RNA enzyme activities. To analyze the effects of the number of amine moieties systematically, we employed four polyamines sharing dimethylene units to connect amine moieties. As a model RNA enzyme, we used a structurally unstable group I ribozyme, which was activated most and least efficiently by tetraethylenepentamine and diethylenetriamine respectively.
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Affiliation(s)
- Mst Ara Gulshan
- a Department of Chemistry, Graduate School of Science and Engineering , University of Toyama , Toyama , Japan.,b Graduate School of Innovative Life Science , University of Toyama , Toyama , Japan
| | - Shigeyoshi Matsumura
- a Department of Chemistry, Graduate School of Science and Engineering , University of Toyama , Toyama , Japan
| | - Tsunehiko Higuchi
- c Graduate School of Pharmaceutical Sciences , Nagoya City University , Nagoya , Japan
| | - Naoki Umezawa
- c Graduate School of Pharmaceutical Sciences , Nagoya City University , Nagoya , Japan
| | - Yoshiya Ikawa
- a Department of Chemistry, Graduate School of Science and Engineering , University of Toyama , Toyama , Japan
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9
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Gulshan MA, Rahman MM, Matsumura S, Higuchi T, Umezawa N, Ikawa Y. Biogenic triamine and tetraamine activate core catalytic ability of Tetrahymena group I ribozyme in the absence of its large activator module. Biochem Biophys Res Commun 2018; 496:594-600. [DOI: 10.1016/j.bbrc.2018.01.085] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 01/11/2018] [Indexed: 10/18/2022]
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10
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Lee CH, Han SR, Lee SW. Therapeutic applications of group I intron-based trans-splicing ribozymes. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1466. [PMID: 29383855 DOI: 10.1002/wrna.1466] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 12/10/2017] [Accepted: 12/14/2017] [Indexed: 12/21/2022]
Abstract
Since the breakthrough discovery of catalytic RNAs (ribozymes) in the early 1980s, valuable ribozyme-based gene therapies have been developed for incurable diseases ranging from genetic disorders to viral infections and cancers. Ribozymes can be engineered and used to downregulate or repair pathogenic genes via RNA cleavage mediated by trans-cleaving ribozymes or repair and reprograming mediated by trans-splicing ribozymes, respectively. Uniquely, trans-splicing ribozymes can edit target RNAs via simultaneous destruction and repair (and/or reprograming) to yield the desired therapeutic RNAs, thus selectively inducing therapeutic gene activity in cells expressing the target RNAs. In contrast to traditional gene therapy approaches, such as simple addition of therapeutic transgenes or inhibition of disease-causing genes, the selective repair and/or reprograming abilities of trans-splicing ribozymes in target RNA-expressing cells facilitates the maintenance of endogenous spatial and temporal gene regulation and reduction of disease-associated transcript expression. In molecular imaging technologies, trans-splicing ribozymes can be used to reprogram specific RNAs in living cells and organisms by the 3'-tagging of reporter RNAs. The past two decades have seen progressive improvements in trans-splicing ribozymes and the successful application of these elements in gene therapy and molecular imaging approaches for various pathogenic conditions, such as genetic, infectious, and malignant disease. This review provides an overview of the current status of trans-splicing ribozyme therapeutics, focusing on Tetrahymena group I intron-based ribozymes, and their future prospects. This article is categorized under: RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Chang Ho Lee
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea
| | - Seung Ryul Han
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea
| | - Seong-Wook Lee
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea
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11
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Use of a Fluorescent Aptamer RNA as an Exonic Sequence to Analyze Self-Splicing Ability of aGroup I Intron from Structured RNAs. BIOLOGY 2016; 5:biology5040043. [PMID: 27869660 PMCID: PMC5192423 DOI: 10.3390/biology5040043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 11/14/2016] [Accepted: 11/15/2016] [Indexed: 11/17/2022]
Abstract
Group I self-splicing intron constitutes an important class of functional RNA molecules that can promote chemical transformation. Although the fundamental mechanism of the auto-excision from its precursor RNA has been established, convenient assay systems for its splicing activity are still useful for a further understanding of its detailed mechanism and of its application. Because some host RNA sequences, to which group I introns inserted form stable three-dimensional (3D) structures, the effects of the 3D structures of exonic elements on the splicing efficiency of group I introns are important but not a fully investigated issue. We developed an assay system for group I intron self-splicing by employing a fluorescent aptamer RNA (spinach RNA) as a model exonic sequence inserted by the Tetrahymena group I intron. We investigated self-splicing of the intron from spinach RNA, serving as a model exonic sequence with a 3D structure.
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12
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Tanaka T, Matsumura S, Furuta H, Ikawa Y. Tecto-GIRz: Engineered Group I Ribozyme the Catalytic Ability of Which Can Be Controlled by Self-Dimerization. Chembiochem 2016; 17:1448-55. [DOI: 10.1002/cbic.201600190] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Indexed: 01/17/2023]
Affiliation(s)
- Takahiro Tanaka
- Department of Chemistry and Biochemistry; Graduate School of Engineering; Kyushu University; Moto-oka 744 Nishi-ku Fukuoka 819-0395 Japan
| | - Shigeyoshi Matsumura
- Department of Chemistry; Graduate School of Science and Engineering; University of Toyama; Gofuku 3190 Toyama 930-8555 Japan
| | - Hiroyuki Furuta
- Department of Chemistry and Biochemistry; Graduate School of Engineering; Kyushu University; Moto-oka 744 Nishi-ku Fukuoka 819-0395 Japan
| | - Yoshiya Ikawa
- Department of Chemistry; Graduate School of Science and Engineering; University of Toyama; Gofuku 3190 Toyama 930-8555 Japan
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13
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Abstract
Recent progress with techniques for monitoring RNA structure in cells such as ‘DMS-Seq’ and ‘Structure-Seq’ suggests that a new era of RNA structure-function exploration is on the horizon. This will also include systematic investigation of the factors required for the structural integrity of RNA. In this context, much evidence accumulated over 50 years suggests that polyamines play important roles as modulators of RNA structure. Here, we summarize and discuss recent literature relating to the roles of these small endogenous molecules in RNA function. We have included studies directed at understanding the binding interactions of polyamines with polynucleotides, tRNA, rRNA, mRNA and ribozymes using chemical, biochemical and spectroscopic tools. In brief, polyamines bind RNA in a sequence-selective fashion and induce changes in RNA structure in context-dependent manners. In some cases the functional consequences of these interactions have been observed in cells. Most notably, polyamine-mediated effects on RNA are frequently distinct from those of divalent cations (i.e. Mg2+) confirming their roles as independent molecular entities which help drive RNA-mediated processes.
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Affiliation(s)
- Helen L Lightfoot
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zürich, CH-8093, Zürich, Switzerland
| | - Jonathan Hall
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zürich, CH-8093, Zürich, Switzerland
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Tanaka T, Furuta H, Ikawa Y. Installation of orthogonality to the interface that assembles two modular domains in the Tetrahymena group I ribozyme. J Biosci Bioeng 2014; 117:407-12. [DOI: 10.1016/j.jbiosc.2013.10.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 01/08/2023]
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15
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A two-piece derivative of a group I intron RNA as a platform for designing self-assembling RNA templates to promote Peptide ligation. J Nucleic Acids 2012; 2012:305867. [PMID: 22966423 PMCID: PMC3432377 DOI: 10.1155/2012/305867] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 07/17/2012] [Indexed: 12/16/2022] Open
Abstract
Multicomponent RNA-peptide complexes are attractive from the viewpoint of artificial design of functional biomacromolecular systems. We have developed self-folding and self-assembling RNAs that serve as templates to assist chemical ligation between two reactive peptides with RNA-binding capabilities. The design principle of previous templates, however, can be applied only to limited classes of RNA-binding peptides. In this study, we employed a two-piece derivative of a group I intron RNA from the Tetrahymena large subunit ribosomal RNA (LSU rRNA) as a platform for new template RNAs. In this group I intron-based self-assembling platform, modules for the recognition of substrate peptides can be installed independently from modules holding the platform structure. The new self-assembling platform allows us to expand the repertoire of substrate peptides in template RNA design.
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Benz-Moy TL, Herschlag D. Structure-function analysis from the outside in: long-range tertiary contacts in RNA exhibit distinct catalytic roles. Biochemistry 2011; 50:8733-55. [PMID: 21815635 PMCID: PMC3186870 DOI: 10.1021/bi2008245] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The conserved catalytic core of the Tetrahymena group I ribozyme is encircled by peripheral elements. We have conducted a detailed structure-function study of the five long-range tertiary contacts that fasten these distal elements together. Mutational ablation of each of the tertiary contacts destabilizes the folded ribozyme, indicating a role of the peripheral elements in overall stability. Once folded, three of the five tertiary contact mutants exhibit defects in overall catalysis that range from 20- to 100-fold. These and the subsequent results indicate that the structural ring of peripheral elements does not act as a unitary element; rather, individual connections have distinct roles as further revealed by kinetic and thermodynamic dissection of the individual reaction steps. Ablation of P14 or the metal ion core/metal ion core receptor (MC/MCR) destabilizes docking of the substrate-containing P1 helix into tertiary interactions with the ribozyme's conserved core. In contrast, ablation of the L9/P5 contact weakens binding of the guanosine nucleophile by slowing its association, without affecting P1 docking. The P13 and tetraloop/tetraloop receptor (TL/TLR) mutations had little functional effect and small, local structural changes, as revealed by hydroxyl radical footprinting, whereas the P14, MC/MCR, and L9/P5 mutants show structural changes distal from the mutation site. These changes extended into regions of the catalytic core involved in docking or guanosine binding. Thus, distinct allosteric pathways couple the long-range tertiary contacts to functional sites within the conserved core. This modular functional specialization may represent a fundamental strategy in RNA structure-function interrelationships.
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Affiliation(s)
- Tara L. Benz-Moy
- Department of Chemistry, Stanford University, Stanford, California 94305
| | - Daniel Herschlag
- Department of Chemistry, Stanford University, Stanford, California 94305
- Department of Biochemistry, Stanford University, Stanford, California 94305
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17
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Fujita Y, Ishikawa J, Furuta H, Ikawa Y. Generation and development of RNA ligase ribozymes with modular architecture through "design and selection". Molecules 2010; 15:5850-65. [PMID: 22273983 PMCID: PMC6257700 DOI: 10.3390/molecules15095850] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 08/12/2010] [Accepted: 08/18/2010] [Indexed: 12/27/2022] Open
Abstract
In vitro selection with long random RNA libraries has been used as a powerful method to generate novel functional RNAs, although it often requires laborious structural analysis of isolated RNA molecules. Rational RNA design is an attractive alternative to avoid this laborious step, but rational design of catalytic modules is still a challenging task. A hybrid strategy of in vitro selection and rational design has been proposed. With this strategy termed “design and selection,” new ribozymes can be generated through installation of catalytic modules onto RNA scaffolds with defined 3D structures. This approach, the concept of which was inspired by the modular architecture of naturally occurring ribozymes, allows prediction of the overall architectures of the resulting ribozymes, and the structural modularity of the resulting ribozymes allows modification of their structures and functions. In this review, we summarize the design, generation, properties, and engineering of four classes of ligase ribozyme generated by design and selection.
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Affiliation(s)
- Yuki Fujita
- Graduate School of Engineering, Kyushu University, 819-0395, Fukuoka, Japan
| | - Junya Ishikawa
- Graduate School of Engineering, Kyushu University, 819-0395, Fukuoka, Japan
| | - Hiroyuki Furuta
- Graduate School of Engineering, Kyushu University, 819-0395, Fukuoka, Japan
- International Research Center for Molecular Systems, Kyushu University, 819-0395, Fukuoka, Japan
| | - Yoshiya Ikawa
- Graduate School of Engineering, Kyushu University, 819-0395, Fukuoka, Japan
- International Research Center for Molecular Systems, Kyushu University, 819-0395, Fukuoka, Japan
- PRESTO, Japan Science and Technology Agency, Tokyo 102-0075, Japan
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +81-92-802-2866; Fax: +81-92-802-2865
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18
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Fiskaa T, Birgisdottir AB. RNA reprogramming and repair based on trans-splicing group I ribozymes. N Biotechnol 2010; 27:194-203. [PMID: 20219714 DOI: 10.1016/j.nbt.2010.02.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
While many traditional gene therapy strategies attempt to deliver new copies of wild-type genes back to cells harboring the defective genes, RNA-directed strategies offer a range of novel therapeutic applications. Revision or reprogramming of mRNA is a form of gene therapy that modifies mRNA without directly changing the transcriptional regulation or the genomic gene sequence. Group I ribozymes can be engineered to act in trans by recognizing a separate RNA molecule in a sequence-specific manner, and to covalently link a new RNA sequence to this separate RNA molecule. Group I ribozymes have been shown to repair defective transcripts that cause human genetic or malignant diseases, as well as to replace transcript sequences by foreign RNA resulting in new cellular functions. This review provides an overview of current strategies using trans-splicing group I ribozymes in RNA repair and reprogramming.
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Affiliation(s)
- Tonje Fiskaa
- RNA and Transcriptomics Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway.
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19
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Vicens Q, Paukstelis PJ, Westhof E, Lambowitz AM, Cech TR. Toward predicting self-splicing and protein-facilitated splicing of group I introns. RNA (NEW YORK, N.Y.) 2008; 14:2013-2029. [PMID: 18768647 PMCID: PMC2553746 DOI: 10.1261/rna.1027208] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2008] [Accepted: 07/08/2008] [Indexed: 05/26/2023]
Abstract
In the current era of massive discoveries of noncoding RNAs within genomes, being able to infer a function from a nucleotide sequence is of paramount interest. Although studies of individual group I introns have identified self-splicing and nonself-splicing examples, there is no overall understanding of the prevalence of self-splicing or the factors that determine it among the >2300 group I introns sequenced to date. Here, the self-splicing activities of 12 group I introns from various organisms were assayed under six reaction conditions that had been shown previously to promote RNA catalysis for different RNAs. Besides revealing that assessing self-splicing under only one condition can be misleading, this survey emphasizes that in vitro self-splicing efficiency is correlated with the GC content of the intron (>35% GC was generally conductive to self-splicing), and with the ability of the introns to form particular tertiary interactions. Addition of the Neurospora crassa CYT-18 protein activated splicing of two nonself-splicing introns, but inhibited the second step of self-splicing for two others. Together, correlations between sequence, predicted structure and splicing begin to establish rules that should facilitate our ability to predict the self-splicing activity of any group I intron from its sequence.
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Affiliation(s)
- Quentin Vicens
- Howard Hughes Medical Institute, University of Colorado, Department of Chemistry and Biochemistry, Boulder, Colorado 80309-0215, USA.
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20
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Bhaskaran H, Russell R. Kinetic redistribution of native and misfolded RNAs by a DEAD-box chaperone. Nature 2007; 449:1014-8. [PMID: 17960235 DOI: 10.1038/nature06235] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 09/11/2007] [Indexed: 11/09/2022]
Abstract
DExD/H-box proteins are ubiquitously involved in RNA-mediated processes and use ATP to accelerate conformational changes in RNA. However, their mechanisms of action, and what determines which RNA species are targeted, are not well understood. Here we show that the DExD/H-box protein CYT-19, a general RNA chaperone, mediates ATP-dependent unfolding of both the native conformation and a long-lived misfolded conformation of a group I catalytic RNA with efficiencies that depend on the stabilities of the RNA species but not on specific structural features. CYT-19 then allows the RNA to refold, changing the distribution from equilibrium to kinetic control. Because misfolding is favoured kinetically, conditions that allow unfolding of the native RNA yield large increases in the population of misfolded species. Our results suggest that DExD/H-box proteins act with sufficient breadth and efficiency to allow structured RNAs to populate a wider range of conformations than would be present at equilibrium. Thus, RNAs may face selective pressure to stabilize their active conformations relative to inactive ones to avoid significant redistribution by DExD/H-box proteins. Conversely, RNAs whose functions depend on forming multiple conformations may rely on DExD/H-box proteins to increase the populations of less stable conformations, thereby increasing their overall efficiencies.
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Affiliation(s)
- Hari Bhaskaran
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA
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21
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Saito H, Inoue T. RNA and RNP as new molecular parts in synthetic biology. J Biotechnol 2007; 132:1-7. [PMID: 17875338 DOI: 10.1016/j.jbiotec.2007.07.952] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Accepted: 07/22/2007] [Indexed: 12/29/2022]
Abstract
Synthetic biology has a promising outlook in biotechnology and for understanding the self-organizing principle of biological molecules in life. However, synthetic biologists have been looking for new molecular "parts" that function as modular units required in designing and constructing new "devices" and "systems" for regulating cell function because the number of such parts is strictly limited at present. In this review, we focus on RNA/ribonucleoprotein (RNP) architectures that hold promise as new "parts" for synthetic biology. They are constructed with molecular design and an experimental evolution technique. So far, designed self-folding RNAs, RNA (RNP) enzymes, and nanoscale RNA architectures have been successfully constructed by utilizing Watson-Crick base-pairs together with specific RNA-RNA or RNA-protein binding motifs of known defined 3D structures. Riboregulators for regulating targeted gene expression have also been designed and produced in vitro as well as in vivo. Lately, RNA and ribonucleoprotein complexes have been strongly attracting the attention of molecular biologists because a variety of noncoding RNAs discovered in nature perform spatiotemporal gene expressions. Thus we hope that newly accumulating knowledge on naturally occurring RNAs and RNP complexes will provide a variety of new parts, devices and systems for synthetic biology.
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Affiliation(s)
- Hirohide Saito
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan; ICORP, Japan Science and Technology Corporation (JST), Honcho, Kawaguchi-shi, Saitama 332-0012, Japan.
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22
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Halls C, Mohr S, Del Campo M, Yang Q, Jankowsky E, Lambowitz AM. Involvement of DEAD-box proteins in group I and group II intron splicing. Biochemical characterization of Mss116p, ATP hydrolysis-dependent and -independent mechanisms, and general RNA chaperone activity. J Mol Biol 2006; 365:835-55. [PMID: 17081564 PMCID: PMC1832103 DOI: 10.1016/j.jmb.2006.09.083] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Revised: 09/22/2006] [Accepted: 09/27/2006] [Indexed: 12/14/2022]
Abstract
The RNA-catalyzed splicing of group I and group II introns is facilitated by proteins that stabilize the active RNA structure or act as RNA chaperones to disrupt stable inactive structures that are kinetic traps in RNA folding. In Neurospora crassa and Saccharomyces cerevisiae, the latter function is fulfilled by specific DEAD-box proteins, denoted CYT-19 and Mss116p, respectively. Previous studies showed that purified CYT-19 stimulates the in vitro splicing of structurally diverse group I and group II introns, and uses the energy of ATP binding or hydrolysis to resolve kinetic traps. Here, we purified Mss116p and show that it has RNA-dependent ATPase activity, unwinds RNA duplexes in a non-polar fashion, and promotes ATP-independent strand-annealing. Further, we show that Mss116p binds RNA non-specifically and promotes in vitro splicing of both group I and group II intron RNAs, as well as RNA cleavage by the aI5gamma-derived D135 ribozyme. However, Mss116p also has ATP hydrolysis-independent effects on some of these reactions, which are not shared by CYT-19 and may reflect differences in its RNA-binding properties. We also show that a non-mitochondrial DEAD-box protein, yeast Ded1p, can function almost as efficiently as CYT-19 and Mss116p in splicing the yeast aI5gamma group II intron and less efficiently in splicing the bI1 group II intron. Together, our results show that Mss116p, like CYT-19, can act broadly as an RNA chaperone to stimulate the splicing of diverse group I and group II introns, and that Ded1p also has an RNA chaperone activity that can be assayed by its effect on splicing mitochondrial introns. Nevertheless, these DEAD-box protein RNA chaperones are not completely interchangeable and appear to function in somewhat different ways, using biochemical activities that have likely been tuned by coevolution to function optimally on specific RNA substrates.
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Affiliation(s)
- Coralie Halls
- Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, and Section of Molecular Genetics and Microbiology, School of Biological Sciences, University of Texas at Austin, Austin, Texas 78712
| | - Sabine Mohr
- Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, and Section of Molecular Genetics and Microbiology, School of Biological Sciences, University of Texas at Austin, Austin, Texas 78712
| | - Mark Del Campo
- Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, and Section of Molecular Genetics and Microbiology, School of Biological Sciences, University of Texas at Austin, Austin, Texas 78712
| | - Quansheng Yang
- Department of Biochemistry and Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, OH 44106
| | - Eckhard Jankowsky
- Department of Biochemistry and Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, OH 44106
| | - Alan M. Lambowitz
- Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, and Section of Molecular Genetics and Microbiology, School of Biological Sciences, University of Texas at Austin, Austin, Texas 78712
- *Corresponding author: Phone: 512-232-3418, Fax: 512-232-3420, e-mail:
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23
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Cao S, Chen SJ. Predicting RNA folding thermodynamics with a reduced chain representation model. RNA (NEW YORK, N.Y.) 2005; 11:1884-97. [PMID: 16251382 PMCID: PMC1370876 DOI: 10.1261/rna.2109105] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Based on the virtual bond representation for the nucleotide backbone, we develop a reduced conformational model for RNA. We use the experimentally measured atomic coordinates to model the helices and use the self-avoiding walks in a diamond lattice to model the loop conformations. The atomic coordinates of the helices and the lattice representation for the loops are matched at the loop-helix junction, where steric viability is accounted for. Unlike the previous simplified lattice-based models, the present virtual bond model can account for the atomic details of realistic three-dimensional RNA structures. Based on the model, we develop a statistical mechanical theory for RNA folding energy landscapes and folding thermodynamics. Tests against experiments show that the theory can give much more improved predictions for the native structures, the thermal denaturation curves, and the equilibrium folding/unfolding pathways than the previous models. The application of the model to the P5abc region of Tetrahymena group I ribozyme reveals the misfolded intermediates as well as the native-like intermediates in the equilibrium folding process. Moreover, based on the free energy landscape analysis for each and every loop mutation, the model predicts five lethal mutations that can completely alter the free energy landscape and the folding stability of the molecule.
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Affiliation(s)
- Song Cao
- Department of biochemistry, University of Missouri-Columbia, Columbia, MO 65211, USA
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24
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Kwok LW, Shcherbakova I, Lamb JS, Park HY, Andresen K, Smith H, Brenowitz M, Pollack L. Concordant exploration of the kinetics of RNA folding from global and local perspectives. J Mol Biol 2005; 355:282-93. [PMID: 16303138 DOI: 10.1016/j.jmb.2005.10.070] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 10/21/2005] [Accepted: 10/25/2005] [Indexed: 11/16/2022]
Abstract
Time-resolved small-angle X-ray scattering (SAXS) with millisecond time-resolution reveals two discrete phases of global compaction upon Mg2+-mediated folding of the Tetrahymena thermophila ribozyme. Electrostatic relaxation of the RNA occurs rapidly and dominates the first phase of compaction during which the observed radius of gyration (R(g)) decreases from 75 angstroms to 55 angstroms. A further decrease in R(g) to 45 angstroms occurs in a well-defined second phase. An analysis of mutant ribozymes shows that the latter phase depends upon the formation of long-range tertiary contacts within the P4-P6 domain of the ribozyme; disruption of the three remaining long-range contacts linking the peripheral helices has no effect on the 55-45 angstroms compaction transition. A better understanding of the role of specific tertiary contacts in compaction was obtained by concordant time-resolved hydroxyl radical (OH) analyses that report local changes in the solvent accessibility of the RNA backbone. Comparison of the global and local measures of folding shows that formation of a subset of native tertiary contacts (i.e. those defining the ribozyme core) can occur within a highly compact ensemble whose R(g) is close to that of the fully folded ribozyme. Analyses of additional ribozyme mutants and reaction conditions establish the generality of the rapid formation of a partially collapsed state with little to no detectable tertiary structure. These studies directly link global RNA compaction with formation of tertiary structure as the molecule acquires its biologically active structure, and underscore the strong dependence on salt of both local and global measures of folding kinetics.
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Affiliation(s)
- Lisa W Kwok
- School of Applied & Engineering Physics, Cornell University, Ithaca NY 14853, USA
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25
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Xiao M, Li T, Yuan X, Shang Y, Wang F, Chen S, Zhang Y. A peripheral element assembles the compact core structure essential for group I intron self-splicing. Nucleic Acids Res 2005; 33:4602-11. [PMID: 16100381 PMCID: PMC1185575 DOI: 10.1093/nar/gki770] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The presence of non-conserved peripheral elements in all naturally occurring group I introns underline their importance in ensuring the natural intron function. Recently, we reported that some peripheral elements are conserved in group I introns of IE subgroup. Using self-splicing activity as a readout, our initial screening revealed that one such conserved peripheral elements, P2.1, is mainly required to fold the catalytically active structure of the Candida ribozyme, an IE intron. Unexpectedly, the essential function of P2.1 resides in a sequence-conserved short stem of P2.1 but not in a long-range interaction associated with the loop of P2.1 that stabilizes the ribozyme structure. The P2.1 stem is indispensable in folding the compact ribozyme core, most probably by forming a triple helical interaction with two core helices, P3 and P6. Surprisingly, although the ribozyme lacking the P2.1 stem renders a loosely folded core and the loss of self-splicing activity requires two consecutive transesterifications, the mutant ribozyme efficiently catalyzes the first transesterification reaction. These results suggest that the intron self-splicing demands much more ordered structure than does one independent transesterification, highlighting that the universally present peripheral elements achieve their functional importance by enabling the highly ordered structure through diverse tertiary interactions.
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Affiliation(s)
| | | | | | | | | | | | - Yi Zhang
- To whom correspondence should be addressed. Tel: +86 27 68756207; Fax: +86 27 68754945;
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26
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Johnson TH, Tijerina P, Chadee AB, Herschlag D, Russell R. Structural specificity conferred by a group I RNA peripheral element. Proc Natl Acad Sci U S A 2005; 102:10176-81. [PMID: 16009943 PMCID: PMC1177367 DOI: 10.1073/pnas.0501498102] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Indexed: 11/18/2022] Open
Abstract
Like proteins, structured RNAs must specify a native conformation that is more stable than all other possible conformations. Local structure is much more stable for RNA than for protein, so it is likely that the principal challenge for RNA is to stabilize the native structure relative to misfolded and partially folded intermediates rather than unfolded structures. Many structured RNAs contain peripheral structural elements, which surround the core elements. Although it is clear that peripheral elements stabilize structure within RNAs that contain them, it has not yet been explored whether they specifically stabilize the native states relative to alternative folds. A two-piece version of the group I intron RNA from Tetrahymena is used here to show that the peripheral element P5abc binds to the native conformation of the rest of the RNA 50,000 times more tightly than it binds to a long-lived misfolded conformation. Thus, P5abc stabilizes the native conformation by approximately 6 kcal/mol relative to this misfolded conformation. Further, activity measurements show that for the RNA lacking P5abc, the native conformation is only marginally preferred over the misfolded conformation (<0.5 kcal/mol), indicating that the peripheral structure of this RNA is required to achieve a significant thermodynamic preference for the native state. Such "structural specificity" may be a general function of RNA peripheral domains.
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Affiliation(s)
- Travis H Johnson
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
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27
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Abstract
The gene coding for the small ribosomal subunit RNA of Ploeotia costata contains an actively splicing group I intron (Pco.S516) which is unique among euglenozoans. Secondary structure predictions indicate that paired segments P1-P10 as well as several conserved elements typical of group I introns and of subclass IC1 in particular are present. Phylogenetic analyses of SSU rDNA sequences demonstrate a well-supported placement of Ploeotia costata within the Euglenozoa; whereas, analyses of intron data sets uncover a close phylogenetic relation of Pco.S516 to S-516 introns from Acanthamoeba, Aureoumbra lagunensis (Stramenopila) and red algae of the order Bangiales. Discrepancies between SSU rDNA and intron phylogenies suggest horizontal spread of the group I intron. Monophyly of IC1 516 introns from Ploeotia costata, A. lagunensis and rhodophytes is supported by a unique secondary structure element: helix P5b possesses an insertion of 19 nt length with a highly conserved tetraloop which is supposed to take part in tertiary interactions. Neither functional nor degenerated ORFs coding for homing endonucleases can be identified in Pco.S516. Nevertheless, degenerated ORFs with His-Cys box motifs in closely related intron sequences indicate that homing may have occurred during evolution of the investigated intron group.
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Affiliation(s)
- Ingo Busse
- Fakultät für Biologie, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany
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28
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Ikawa Y, Tsuda K, Matsumura S, Atsumi S, Inoue T. Putative intermediary stages for the molecular evolution from a ribozyme to a catalytic RNP. Nucleic Acids Res 2003; 31:1488-96. [PMID: 12595557 PMCID: PMC149818 DOI: 10.1093/nar/gkg225] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A hypothetical evolutionary pathway from a ribozyme to a catalytic RNA-protein complex (RNP) is proposed and examined. In this hypothesis for an early phase of molecular evolution, one RNA-RNA interaction in the starting ribozyme is replaced with an RNA-protein interaction via two intermediary stages. At each stage, the original RNA-RNA interaction and a newly introduced RNA-protein interaction are designed to coexist. The catalytic RNPs corresponding to the intermediary stages were constructed by employing the Tetrahymena ribozyme together with molecular modeling. Analyses of the RNPs indicate that the protein can fully replace the original role of the RNA-RNA interaction in the starting ribozyme and that the association of a protein with a ribozyme might be beneficial for improving the ribozymatic activity.
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Affiliation(s)
- Yoshiya Ikawa
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
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29
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Ayre BG, Köhler U, Turgeon R, Haseloff J. Optimization of trans-splicing ribozyme efficiency and specificity by in vivo genetic selection. Nucleic Acids Res 2002; 30:e141. [PMID: 12490732 PMCID: PMC140090 DOI: 10.1093/nar/gnf141] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2002] [Revised: 10/09/2002] [Accepted: 10/20/2002] [Indexed: 11/14/2022] Open
Abstract
Trans-splicing ribozymes are RNA-based catalysts capable of splicing RNA sequences from one transcript specifically into a separate target transcript. In doing so, a chimeric mRNA can be produced, and new gene activities triggered in living cells dependent on the presence of the target mRNA. Based on this ability of trans-splicing ribozymes to deliver new gene activities, a simple and versatile plating assay was developed in Saccharomyces cerevisiae for assessing and optimizing constructs in vivo. Trans-splicing ribozymes were used to splice sequences encoding a GAL4-derived transcription activator into a target transcript from a prevalent viral pathogen. The transcription activator translated from this new mRNA in turn triggered the expression of genes under the regulatory control of GAL4 upstream-activating sequences. Two of the activated genes complemented metabolic deficiencies in the host strain, and allowed growth on selective media. A simple genetic assay based on phenotypic conversion from auxotrophy to prototrophy was established to select efficient and specific trans-splicing ribozymes from a ribozyme library. This simple assay may prove valuable for selecting optimal target sites for therapeutic agents such as ribozymes, antisense RNA and antisense oligodeoxyribonucleotides, and for optimizing the design of the therapeutic agents themselves, in higher eukaryotes.
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Affiliation(s)
- Brian G Ayre
- Plant Biology Department, Cornell University, Ithaca, NY 14853, USA and. Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
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30
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Thompson KM, Syrett HA, Knudsen SM, Ellington AD. Group I aptazymes as genetic regulatory switches. BMC Biotechnol 2002; 2:21. [PMID: 12466025 PMCID: PMC139998 DOI: 10.1186/1472-6750-2-21] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2002] [Accepted: 12/04/2002] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Allosteric ribozymes (aptazymes) that have extraordinary activation parameters have been generated in vitro by design and selection. For example, hammerhead and ligase ribozymes that are activated by small organic effectors and protein effectors have been selected from random sequence pools appended to extant ribozymes. Many ribozymes, especially self-splicing introns, are known control gene regulation or viral replication in vivo. We attempted to generate Group I self-splicing introns that were activated by a small organic effector, theophylline, and to show that such Group I aptazymes could mediate theophylline-dependent splicing in vivo. RESULTS By appending aptamers to the Group I self-splicing intron, we have generated a Group I aptazyme whose in vivo splicing is controlled by exogenously added small molecules. Substantial differences in gene regulation could be observed with compounds that differed by as little as a single methyl group. The effector-specificity of the Group I aptazyme could be rationally engineered for new effector molecules. CONCLUSION Group I aptazymes may find applications as genetic regulatory switches for generating conditional knockouts at the level of mRNA or for developing economically viable gene therapies.
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Affiliation(s)
- Kristin M Thompson
- Present address: Archemix Corp., 1 Hampshire St., Cambridge, MA 02139, USA
| | - Heather A Syrett
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Scott M Knudsen
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Andrew D Ellington
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA
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31
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Ikawa Y, Yoshimura T, Hara H, Shiraishi H, Inoue T. Two conserved structural components, A-rich bulge and P4 XJ6/7 base-triples, in activating the group I ribozymes. Genes Cells 2002; 7:1205-15. [PMID: 12485161 DOI: 10.1046/j.1365-2443.2002.00601.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The A-rich bulge of the group I intron ribozyme, a highly conserved structural element in its P5 peripheral region, plays a significant role in activating the ribozyme. The bulge has been known to interact with the P4 stem forming P4 XJ6/7 base-triples in the conserved core. The base-triples by themselves have also been identified as a distinctive element responsible for enhancing the activity of the ribozyme. RESULTS A weakly active variant of the Tetrahymena ribozyme lacking the P5 extension was dramatically activated by the addition of an A-rich bulge at the peripheral region, or by replacement of the original P4 XJ6/7 base-triples in the core structure with more stabilized isosteric ones. Biochemical analyses showed that the two methods of activation affect the ribozyme differently. CONCLUSIONS The long-range interaction between the A-rich bulge and P4 or additionally stabilized P4 XJ6/7 base-triples can contribute dramatically to activation of the Tetrahymena ribozyme. Both improve the kcat value, which represents the rate of the limiting step of the ribozyme reaction when its binding site is saturated with GTP. However, the bulge or the modified base-triples gave a moderate reduction or considerable increase, respectively, to the Km(GTP) value.
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Affiliation(s)
- Yoshiya Ikawa
- Graduate School of Biostudies, Kyoto University, Japan
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32
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Abstract
Ribonucleoproteins (RNPs) consisting of derivatives of a ribozyme and an RNA-binding protein were designed and constructed based upon high-resolution structures of the corresponding prototype molecules, the Tetrahymena group I self-splicing intron RNA and two proteins (bacteriophage lambdaN and HIV Rev proteins) containing RNA-binding motifs. The splicing reaction proceeds efficiently only when the designed RNA associates with the designed protein either in vivo or in vitro. In vivo mutagenic protein selection was effective for improving the capability of the protein. Kinetic analyses indicate that the protein promotes RNA folding to establish an active conformation. The fact that the conversion of a ribozyme to an RNP can be accomplished by simple molecular design supports the RNA world hypothesis and suggests that a natural active RNP might have evolved readily from a ribozyme.
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Affiliation(s)
- Shota Atsumi
- Graduate School of Science, Kyoto University, Kyoto 606-8502 and Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan Corresponding author e-mail:
| | - Yoshiya Ikawa
- Graduate School of Science, Kyoto University, Kyoto 606-8502 and Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan Corresponding author e-mail:
| | - Hideaki Shiraishi
- Graduate School of Science, Kyoto University, Kyoto 606-8502 and Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan Corresponding author e-mail:
| | - Tan Inoue
- Graduate School of Science, Kyoto University, Kyoto 606-8502 and Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan Corresponding author e-mail:
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33
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Doherty EA, Doudna JA. Ribozyme structures and mechanisms. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2001; 30:457-75. [PMID: 11441810 DOI: 10.1146/annurev.biophys.30.1.457] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The past few years have seen exciting advances in understanding the structure and function of catalytic RNA. Crystal structures of several ribozymes have provided detailed insight into the folds of RNA molecules. Models of other biologically important RNAs have been constructed based on structural, phylogenetic, and biochemical data. However, many questions regarding the catalytic mechanisms of ribozymes remain. This review compares the structures and possible catalytic mechanisms of four small self-cleaving RNAs: the hammerhead, hairpin, hepatitis delta virus, and in vitro-selected lead-dependent ribozymes. The organization of these small catalysts is contrasted to that of larger ribozymes, such as the group I intron.
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Affiliation(s)
- E A Doherty
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA.
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34
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Geese WJ, Waring RB. A comprehensive characterization of a group IB intron and its encoded maturase reveals that protein-assisted splicing requires an almost intact intron RNA. J Mol Biol 2001; 308:609-22. [PMID: 11350164 DOI: 10.1006/jmbi.2001.4609] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The group I intron (AnCOB) of the mitochondrial apocytochrome b gene from Aspergillus nidulans encodes a bi-functional maturase protein that is also a DNA endonuclease. Although the AnCOB intron self-splices, the encoded maturase protein greatly facilitates splicing, in part, by stabilizing RNA tertiary structure. To determine their role in self-splicing and in protein-assisted splicing, several peripheral RNA sub-domains in the 313 nucleotide intron were deleted (P2, P9, P9.1) or truncated (P5ab, P6a). The sequence in two helices (P2 and P9) was also inverted. Except for P9, the deleted regions are not highly conserved among group I introns and are often dispensable for catalytic activity. Nevertheless, despite the very tight binding of AnCOB RNA to the maturase and the high activity of the bimolecular complex (the rate of 5' splice-site cleavage was >20 min(-1) with guanosine as the cofactor), the intron was surprisingly sensitive to these modifications. Several mutations inactivated splicing completely and virtually all impaired splicing to varying degrees. Mutants containing comparatively small deletions in various regions of the intron significantly decreased binding affinity (generally >10(4)-fold), indicating that none of the domains that remained constitutes the primary recognition site of the maturase. The data argue that tight binding requires tertiary interactions that can be maintained by only a relatively intact intron RNA, and that the binding mechanism of the maturase differs from those of two other well-characterized group I intron splicing factors, CYT-18 and Cpb2. A model is proposed in which the protein promotes widespread cooperative folding of an RNA lacking extensive initial tertiary structure.
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Affiliation(s)
- W J Geese
- Department of Biology, Temple University, Philadelphia, PA 19122, USA
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35
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Abstract
The past few years have seen exciting advances in understanding the structure and function of catalytic RNA. Crystal structures of several ribozymes have provided detailed insight into the folds of RNA molecules. Models of other biologically important RNAs have been constructed based on structural, phylogenetic, and biochemical data. However, many questions regarding the catalytic mechanisms of ribozymes remain. This review compares the structures and possible catalytic mechanisms of four small self-cleaving RNAs: the hammerhead, hairpin, hepatitis delta virus, and in vitro-selected lead-dependent ribozymes. The organization of these small catalysts is contrasted to that of larger ribozymes, such as the group I intron.
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Affiliation(s)
- E A Doherty
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA.
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36
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Ikawa Y, Naito D, Shiraishi H, Inoue T. Structure-function relationships of two closely related group IC3 intron ribozymes from Azoarcus and Synechococcus pre-tRNA. Nucleic Acids Res 2000; 28:3269-77. [PMID: 10954594 PMCID: PMC110692 DOI: 10.1093/nar/28.17.3269] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The two group IC3 pre-tRNA introns from Azoarcus and Synechococcus share very analogous secondary structures. They are small group I ribozymes that possess only two peripheral domains, P2 and P9. However, the 3'-splice site hydrolysis activity of the Synechococcus ribozyme critically depends on P2 whereas that of Azoarcus does not, indicating that the structure-function relationships of the two ribozymes are strikingly different despite their structural resemblance. To identify the element(s) that determines the catalytic properties of these ribozymes, we undertook analyses of chimeric ribozymes prepared by swapping their structural elements. We found that the difference can be attributed to a small number of nucleotides within the conserved core region. Further analysis by employing in vitro selection revealed that a base triple interaction (P4bp3 x J6/7-2) is a critical element for determining activity and suggests the existence of a novel base quintuple involving the base triple P4bp5 x J8/7-5.
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Affiliation(s)
- Y Ikawa
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
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37
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Engelhardt MA, Doherty EA, Knitt DS, Doudna JA, Herschlag D. The P5abc peripheral element facilitates preorganization of the tetrahymena group I ribozyme for catalysis. Biochemistry 2000; 39:2639-51. [PMID: 10704214 DOI: 10.1021/bi992313g] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phylogenetic comparisons and site-directed mutagenesis indicate that group I introns are composed of a catalytic core that is universally conserved and peripheral elements that are conserved only within intron subclasses. Despite this low overall conservation, peripheral elements are essential for efficient splicing of their parent introns. We have undertaken an in-depth structure-function analysis to investigate the role of one of these elements, P5abc, using the well-characterized ribozyme derived from the Tetrahymena group I intron. Structural comparisons using solution-based free radical cleavage revealed that a ribozyme lacking P5abc (E(DeltaP5abc)) and E(DeltaP5abc) with P5abc added in trans (E(DeltaP5abc).P5abc) adopt a similar global tertiary structure at Mg(2+) concentrations greater than 20 mM [Doherty, E. A., et al. (1999) Biochemistry 38, 2982-90]. However, free E(DeltaP5abc) is greatly compromised in overall oligonucleotide cleavage activity, even at Mg(2+) concentrations as high as 100 mM. Further characterization of E(DeltaP5abc) via DMS modification revealed local structural differences at several positions in the conserved core that cluster around the substrate binding sites. Kinetic and thermodynamic dissection of individual reaction steps identified defects in binding of both substrates to E(DeltaP5abc), with > or =25-fold weaker binding of a guanosine nucleophile and > or =350-fold weaker docking of the oligonucleotide substrate into its tertiary interactions with the ribozyme core. These defects in binding of the substrates account for essentially all of the 10(4)-fold decrease in overall activity of the deletion mutant. Together, the structural and functional observations suggest that the P5abc peripheral element not only provides stability but also positions active site residues through indirect interactions, thereby preferentially stabilizing the active ribozyme structure relative to alternative less active states. This is consistent with the view that peripheral elements engage in a network of mutually reinforcing interactions that together ensure cooperative folding of the ribozyme to its active structure.
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Affiliation(s)
- M A Engelhardt
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
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38
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Pan J, Deras ML, Woodson SA. Fast folding of a ribozyme by stabilizing core interactions: evidence for multiple folding pathways in RNA. J Mol Biol 2000; 296:133-44. [PMID: 10656822 DOI: 10.1006/jmbi.1999.3439] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Folding of the Tetrahymena ribozyme under physiological conditions in vitro is limited by slow conversion of long-lived intermediates to the active structure. These intermediates arise because the most stable domain of the ribozyme folds 10-50 times more rapidly than the core region containing helix P3. Native gel electrophoresis and time-resolved X-ray-dependent hydroxyl radical cleavage revealed that mutations that weaken peripheral interactions between domains accelerated folding fivefold, while a point mutation that stabilizes P3 enabled 80 % of the mutant RNA to reach the native conformation within 30 seconds at 22 degrees C. The P3 mutation increased the folding rate of the catalytic core as much as 50-fold, so that both domains of the ribozyme were formed at approximately the same rate. The results show that the ribozyme folds rapidly without significantly populating metastable intermediates when native interactions in the ribozyme core are stabilized relative to peripheral structural elements.
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Affiliation(s)
- J Pan
- Department of Chemistry and Biochemistry, University of Maryland, MD 20904-2021, USA
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39
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Ikawa Y, Shiraishi H, Inoue T. Characterization of P8 and J8/7 elements in the conserved core of the tetrahymena group I intron ribozyme. Biochem Biophys Res Commun 2000; 267:85-90. [PMID: 10623579 DOI: 10.1006/bbrc.1999.1930] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The universally conserved core region in the group I intron ribozymes is responsible for its catalytic activity. The structural elements in this region have been known to organize the active site of this class of ribozymes. However, it has been unclear whether all elements are requisite or some elements are dispensable for conducting the catalysis. To investigate the necessity of these elements in the catalysis, we prepared and examined a series of mutants having a nick or deletion in these elements. In this report, we show that two elements, P8 and 5' portion of J8/7, are nonessential for activity.
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Affiliation(s)
- Y Ikawa
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan
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40
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Sardesai NY, Stagg SM, VanLoock MS, Harvey SC, Schimmel P. RNA Scaffolds for Minihelix-Based Aminoacyl Transfer: Design of “Transpeptizymes”. J Biomol Struct Dyn 2000; 17 Suppl 1:29-37. [DOI: 10.1080/07391102.2000.10506601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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41
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Abstract
Previous studies have shown that the earliest detectable step in folding of the Tetrahymena ribozyme is tertiary structure formation of the peripheral element P5abc. This, along with other results, has suggested that P5abc may serve as a scaffold upon which additional tertiary structure is built. Herein we use the onset of oligonucleotide cleavage activity as a readout for native state formation and investigate the effect of P5abc on the rate of folding to the native structure. Despite the early folding of P5abc, its removal to give the E delta P5abc variant decreases the rate of attainment of an active structure less than fivefold (20-100 mM Mg2+, 15-50 degrees C). Furthermore, P5abc added in trans is able to bind the folded E delta P5abc ribozyme and promote oligonucleotide cleavage at least tenfold more rapidly than folding of the wild-type ribozyme, indicating that E delta P5abc does not have to first unfold before productively binding P5abc to form the true native state. This suggests that a state with the overall tertiary structure formed but with P5abc unfolded represents a viable on-pathway intermediate for the wild-type ribozyme. These results provide strong evidence for the existence of two pathways to the native state: in one pathway P5abc forms tertiary structure first, and in another it forms late. The pathway in which P5abc forms first is favored because P5abc can fold quickly and because its tertiary structure is stable in the absence of additional structured elements, not because P5abc formation is required for subsequent folding steps. In the course of these experiments, we also found that most of the ribozyme population does not reach the native state directly under standard conditions in vitro, but instead forms an inactive structure that is stable for hours. Finally, the fraction that does fold to the native state folds with a single rate constant of 1 min-1, suggesting that there are no significantly populated "fast-track" pathways that reach the native state directly by avoiding slow folding steps.
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Affiliation(s)
- R Russell
- Department of Biochemistry, Stanford University, CA 94305-5307, USA
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42
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Wank H, SanFilippo J, Singh RN, Matsuura M, Lambowitz AM. A reverse transcriptase/maturase promotes splicing by binding at its own coding segment in a group II intron RNA. Mol Cell 1999; 4:239-50. [PMID: 10488339 DOI: 10.1016/s1097-2765(00)80371-8] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Group II introns encode reverse transcriptases that promote RNA splicing (maturase activity) and then with the excised intron form a DNA endonuclease that mediates intron mobility by target DNA-primed reverse transcription (TPRT). Here, we show that the primary binding site for the maturase (LtrA) encoded by the Lactococcus lactis Ll.LtrB intron is within a region of intron domain IV that includes the start codon of the LtrA ORF. This binding is enhanced by other elements, particularly domain I and the EBS/IBS interactions, and helps position LtrA to initiate cDNA synthesis in the 3' exon as occurs during TPRT. Our results suggest how the maturase functions in RNA splicing and support the hypothesis that the reverse transcriptase coding region was derived from an independent genetic element that was inserted into a preexisting group II intron.
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Affiliation(s)
- H Wank
- Department of Chemistry and Biochemistry, University of Texas at Austin 78712, USA
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43
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Colmenarejo G, Tinoco I. Structure and thermodynamics of metal binding in the P5 helix of a group I intron ribozyme. J Mol Biol 1999; 290:119-35. [PMID: 10388561 DOI: 10.1006/jmbi.1999.2867] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The solution structure of an RNA hairpin modelling the P5 helix of a group I intron, complexed with Co(NH3)63+, has been determined by nuclear magnetic resonance. Co(NH3)63+, which possesses a geometry very close to Mg(H2O)62+, was used to identify and characterize a Mg2+binding site in the RNA. Strong and positive intermolecular nuclear Overhauser effect (NOE) cross-peaks define a specific complex in which the Co(NH3)63+molecule is in the major groove of tandem G.U base-pairs. The structure of the RNA is characterized by a very low twist angle between the two G.U base-pairs, providing a flat and narrowed major groove. The Co(NH3)63+, although highly localized, is free to rotate to hydrogen bond in several ways to the O4 atoms of the uracil bases and to N7 and O6 of the guanine bases. Negative and small NOE cross-peaks to other protons in the sequence reveal a non-specific or delocalized interaction, characterized by a high mobility of the cobalt ion. Mn2+titrations of P5 show specific broadening of protons of the G.U base-pairs that form the metal ion binding site, in agreement with the NOE data from Co(NH3)63+. Binding constants for the interaction of Co(NH3)63+and of Mg2+to P5 were determined by monitoring imino proton chemical shifts during titration of the RNA with the metal ions. Dissociation constants are on the order of 0.1 mM for Co(NH3)63+and 1 mM for Mg2+. Binding studies were done on mutants with sequences corresponding to the three orientations of tandem G.U base-pairs. The affinities of Co(NH3)63+and Mg2+for the tandem G.U base-pairs depend strongly on their sequences; the differences can be understood in terms of the different structures of the corresponding metal ion-RNA complexes. Substitution of G.C or A.U for G.U pairs also affected the binding, as expected. These structural and thermodynamic results provide systematic new information about major groove metal ion binding in RNA.
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Affiliation(s)
- G Colmenarejo
- University of California Berkeley and Structural Biology Department Physical Biosciences Division, Berkeley, CA, 94720-1460, USA
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44
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Ayre BG, Köhler U, Goodman HM, Haseloff J. Design of highly specific cytotoxins by using trans-splicing ribozymes. Proc Natl Acad Sci U S A 1999; 96:3507-12. [PMID: 10097066 PMCID: PMC22323 DOI: 10.1073/pnas.96.7.3507] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have designed ribozymes based on a self-splicing group I intron that can trans-splice exon sequences into a chosen RNA target to create a functional chimeric mRNA and provide a highly specific trigger for gene expression. We have targeted ribozymes against the coat protein mRNA of a widespread plant pathogen, cucumber mosaic virus. The ribozymes were designed to trans-splice the coding sequence of the diphtheria toxin A chain in frame with the viral initiation codon of the target sequence. Diphtheria toxin A chain catalyzes the ADP ribosylation of elongation factor 2 and can cause the cessation of protein translation. In a Saccharomyces cerevisiae model system, ribozyme expression was shown to specifically inhibit the growth of cells expressing the virus mRNA. A point mutation at the target splice site alleviated this ribozyme-mediated toxicity. Increasing the extent of base pairing between the ribozyme and target dramatically increased specific expression of the cytotoxin and reduced illegitimate toxicity in vivo. Trans-splicing ribozymes may provide a new class of agents for engineering virus resistance and therapeutic cytotoxins.
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Affiliation(s)
- B G Ayre
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, England
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45
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Köhler U, Ayre BG, Goodman HM, Haseloff J. Trans-splicing ribozymes for targeted gene delivery. J Mol Biol 1999; 285:1935-50. [PMID: 9925776 DOI: 10.1006/jmbi.1998.2447] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ribozymes are potential tools for genetic manipulation, and various naturally occurring catalytic RNAs have been dissected and used as the basis for the design of new endoribonuclease activities. While such cleaving ribozymes may work well in vitro, they have not proved to be routinely effective in depleting living cells of the chosen target RNA. Recently, trans-splicing ribozymes have been employed to repair mutant mRNAs in vivo. We have designed modified trans-splicing ribozymes with improved biological activity. These allow accurate splicing of a new 3' exon sequence into a chosen site within a target RNA, and in frame fusion of the exon can result in expression of a new gene product. These trans-splicing ribozymes contain catalytic sequences derived from a self-splicing group I intron, which have been adapted to a chosen target mRNA by fusion of a region of extended complementarity to the target RNA and precise alteration of the guide sequences required for substrate recognition. Both modifications are required for improved biological activity of the ribozymes. Whereas cleaving ribozymes must efficiently deplete a chosen mRNA species to be effective in vivo, even inefficient trans-splicing can allow the useful expression of a new gene activity, dependent on the presence of a chosen RNA. We have targeted trans-splicing ribozymes against mRNAs of chloramphenicol acetyltransferase, human immunodeficiency virus, and cucumber mosaic virus, and demonstrated trans-splicing and delivery of a marker gene in Escherichia coli cells. The improved trans-splicing ribozymes may be tailored for virtually any target RNA, and provide a new tool for triggering gene expression in specific cell types.
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Affiliation(s)
- U Köhler
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, England
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46
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Golden BL, Gooding AR, Podell ER, Cech TR. A preorganized active site in the crystal structure of the Tetrahymena ribozyme. Science 1998; 282:259-64. [PMID: 9841391 DOI: 10.1126/science.282.5387.259] [Citation(s) in RCA: 262] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Group I introns possess a single active site that catalyzes the two sequential reactions of self-splicing. An RNA comprising the two domains of the Tetrahymena thermophila group I intron catalytic core retains activity, and the 5.0 angstrom crystal structure of this 247-nucleotide ribozyme is now described. Close packing of the two domains forms a shallow cleft capable of binding the short helix that contains the 5' splice site. The helix that provides the binding site for the guanosine substrate deviates significantly from A-form geometry, providing a tight binding pocket. The binding pockets for both the 5' splice site helix and guanosine are formed and oriented in the absence of these substrates. Thus, this large ribozyme is largely preorganized for catalysis, much like a globular protein enzyme.
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Affiliation(s)
- B L Golden
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA.
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47
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Naito Y, Shiraishi H, Inoue T. P5abc of the Tetrahymena ribozyme consists of three functionally independent elements. RNA (NEW YORK, N.Y.) 1998; 4:837-846. [PMID: 9671056 PMCID: PMC1369663 DOI: 10.1017/s1355838298972016] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
P5abc domain of Tetrahymena LSU intron functions as an activator that is not essential for but enhances the activity of the ribozyme either when present in cis or when added in trans. This domain contains three regions (A-rich bulge, L5b, and L5c) that have been demonstrated to interact with the rest of the intron. Although these regions are presumably important for efficient activation, the role of each element is not understood in the mechanism of activation. We employed circularly permuted introns and examined the roles of each element. The results show that each of the three elements can activate the intron independently. We also found that a correlation between the activation by P5abc and the physical affinity of P5abc to the intron exists.
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Affiliation(s)
- Y Naito
- Department of Chemistry, Faculty of Science, Kyoto University, Japan
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48
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Cate JH, Hanna RL, Doudna JA. A magnesium ion core at the heart of a ribozyme domain. NATURE STRUCTURAL BIOLOGY 1997; 4:553-8. [PMID: 9228948 DOI: 10.1038/nsb0797-553] [Citation(s) in RCA: 254] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Large ribozymes require divalent metal ions to fold. We show here that the tertiary structure of the Tetrahymena group I intron P4-P6 domain nucleates around a magnesium ion core. In the domain crystal structure, five magnesium ions bind in a three-helix junction at the centre of the molecule. Single atom changes in any one of four magnesium sites in this three-helix junction destroy folding of the entire 160-nucleotide P4-P6 domain. The magnesium ion core may be the RNA counterpart to the protein hydrophobic core, burying parts of the RNA molecule in the native structure.
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Affiliation(s)
- J H Cate
- Dept. of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
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49
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Ikawa Y, Ohta H, Shiraishi H, Inoue T. Long-range interaction between the P2.1 and P9.1 peripheral domains of the Tetrahymena ribozyme. Nucleic Acids Res 1997; 25:1761-5. [PMID: 9108158 PMCID: PMC146647 DOI: 10.1093/nar/25.9.1761] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The Tetrahymena ribozyme possesses peripheral domains, termed P9.1 and P9.2. They are nonessential in the mechanism of the catalytic reaction but contribute to enhance the catalytic activity of the ribozyme. It has been postulated that P9.1 is capable of forming Watson-Crick base pairings with another peripheral domain, P2.1. We report here the existence of long-range base pairings between the loop regions of these two domains and show that this interaction apparently plays a role in enhancing the catalytic activity of the ribozyme.
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Affiliation(s)
- Y Ikawa
- Department of Chemistry, Faculty of Science, Kyoto University, Kyoto 606-01, Japan
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50
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Sclavi B, Woodson S, Sullivan M, Chance MR, Brenowitz M. Time-resolved synchrotron X-ray "footprinting", a new approach to the study of nucleic acid structure and function: application to protein-DNA interactions and RNA folding. J Mol Biol 1997; 266:144-59. [PMID: 9054977 DOI: 10.1006/jmbi.1996.0775] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Hydroxyl radicals (.OH) can cleave the phosphodiester backbone of nucleic acids and are valuable reagents in the study of nucleic acid structure and protein-nucleic acid interactions. Irradiation of solutions by high flux "white light" X-ray beams based on bending magnet beamlines at the National Synchrotron Light Source (NSLS) yields sufficient concentrations of .OH so that quantitative nuclease protection ("footprinting") studies of DNA and RNA can be conducted with a duration of exposure in the range of 50 to 100 ms. The sensitivity of DNA and RNA to X-ray mediated .OH cleavage is equivalent. Both nucleic acids are completely protected from synchrotron X-ray induced cleavage by the presence of thiourea in the sample solution, demonstrating that cleavage is suppressed by a free radical scavenger. The utility of this time-dependent approach to footprinting is demonstrated with a synchrotron X-ray footprint of a protein-DNA complex and by a time-resolved footprinting analysis of the Mg(2+)-dependent folding of the Tetrahymena thermophilia L-21 ScaI ribozyme RNA. Equilibrium titrations reveal differences among the ribozyme domains in the cooperativity of Mg(2+)-dependent .OH protection. RNA .OH protection progress curves were obtained for several regions of the ribozyme over timescales of 30 seconds to several minutes. Progress curves ranging from > or = 3.5 to 0.4 min-1 were obtained for the P4-P6 and P5 sub-domains and the P3-P7 domain, respectively. The .OH protection progress curves have been correlated with the available biochemical, structural and modeling data to generate a model of the ribozyme folding pathway. Rate differences observed for specific regions within domains provide evidence for steps in the folding pathway not previously observed. Synchrotron X-ray footprinting is a new approach of general applicability for the study of time-resolved structural changes of nucleic acid conformation and protein-nucleic acid complexes.
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Affiliation(s)
- B Sclavi
- Department of Physiology and Biophysics, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA
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