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Vögele J, Duchardt-Ferner E, Bains JK, Knezic B, Wacker A, Sich C, Weigand JE, Šponer J, Schwalbe H, Krepl M, Wöhnert J. Structure of an internal loop motif with three consecutive U•U mismatches from stem-loop 1 in the 3'-UTR of the SARS-CoV-2 genomic RNA. Nucleic Acids Res 2024:gkae349. [PMID: 38783391 DOI: 10.1093/nar/gkae349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 03/27/2024] [Accepted: 04/22/2024] [Indexed: 05/25/2024] Open
Abstract
The single-stranded RNA genome of SARS-CoV-2 is highly structured. Numerous helical stem-loop structures interrupted by mismatch motifs are present in the functionally important 5'- and 3'-UTRs. These mismatches modulate local helical geometries and feature unusual arrays of hydrogen bonding donor and acceptor groups. However, their conformational and dynamical properties cannot be directly inferred from chemical probing and are difficult to predict theoretically. A mismatch motif (SL1-motif) consisting of three consecutive U•U base pairs is located in stem-loop 1 of the 3'-UTR. We combined NMR-spectroscopy and MD-simulations to investigate its structure and dynamics. All three U•U base pairs feature two direct hydrogen bonds and are as stable as Watson-Crick A:U base pairs. Plasmodium falciparum 25S rRNA contains a triple U•U mismatch motif (Pf-motif) differing from SL1-motif only with respect to the orientation of the two closing base pairs. Interestingly, while the geometry of the outer two U•U mismatches was identical in both motifs the preferred orientation of the central U•U mismatch was different. MD simulations and potassium ion titrations revealed that the potassium ion-binding mode to the major groove is connected to the different preferred geometries of the central base pair in the two motifs.
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Affiliation(s)
- Jennifer Vögele
- Institute of Molecular Biosciences, Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Elke Duchardt-Ferner
- Institute of Molecular Biosciences, Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Jasleen Kaur Bains
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- Institute of Organic Chemistry and Chemical Biology, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
| | - Bozana Knezic
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- Institute of Organic Chemistry and Chemical Biology, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
| | - Anna Wacker
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- Institute of Organic Chemistry and Chemical Biology, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
| | - Christian Sich
- Volkswagen AG, Brieffach 1617/0, 38436 Wolfsburg, Germany
| | - Julia E Weigand
- Institute of Pharmaceutical Chemistry, University of Marburg, Marbacher Weg 6, 35037 Marburg, Germany
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska 135, 612 00 Brno, Czech Republic
| | - Harald Schwalbe
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- Institute of Organic Chemistry and Chemical Biology, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
| | - Miroslav Krepl
- Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska 135, 612 00 Brno, Czech Republic
| | - Jens Wöhnert
- Institute of Molecular Biosciences, Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
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2
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Srivastava Y, Blau ME, Jenkins JL, Wedekind JE. Full-Length NAD +-I Riboswitches Bind a Single Cofactor but Cannot Discriminate against Adenosine Triphosphate. Biochemistry 2023; 62:3396-3410. [PMID: 37947391 PMCID: PMC10702441 DOI: 10.1021/acs.biochem.3c00391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 10/19/2023] [Accepted: 10/19/2023] [Indexed: 11/12/2023]
Abstract
Bacterial riboswitches are structured RNAs that bind small metabolites to control downstream gene expression. Two riboswitch classes have been reported to sense nicotinamide adenine dinucleotide (NAD+), which plays a key redox role in cellular metabolism. The NAD+-I (class I) riboswitch stands out because it comprises two homologous, tandemly arranged domains. However, previous studies examined the isolated domains rather than the full-length riboswitch. Crystallography and ligand binding analyses led to the hypothesis that each domain senses NAD+ but with disparate equilibrium binding constants (KD) of 127 μM (domain I) and 3.4 mM (domain II). Here, we analyzed individual domains and the full-length riboswitch by isothermal titration calorimetry to quantify the cofactor affinity and specificity. Domain I senses NAD+ with a KD of 24.6 ± 8.4 μM but with a reduced ligand-to-receptor stoichiometry, consistent with nonproductive domain self-association observed by gel-filtration chromatography; domain II revealed no detectable binding. By contrast, the full-length riboswitch binds a single NAD+ with a KD of 31.5 ± 1.5 μM; dinucleotides NADH and AP2-ribavirin also bind with one-to-one stoichiometry. Unexpectedly, the full-length riboswitch also binds a single ATP equivalent (KD = 11.0 ± 3.5 μM). The affinity trend of the full-length riboswitch is ADP = ATP > NAD+ = AP2-ribavirin > NADH. Although our results support riboswitch sensing of a single NAD+ at concentrations significantly below the intracellular levels of this cofactor, our findings do not support the level of specificity expected for a riboswitch that exclusively senses NAD+. Gene regulatory implications and future challenges are discussed.
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Affiliation(s)
- Yoshita Srivastava
- Department
of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, New York 14642, United States
| | - Maya E. Blau
- Department
of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, New York 14642, United States
| | - Jermaine L. Jenkins
- Department
of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, New York 14642, United States
| | - Joseph E. Wedekind
- Department
of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, New York 14642, United States
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3
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Gibaut QR, Bush JA, Tong Y, Baisden JT, Taghavi A, Olafson H, Yao X, Childs-Disney JL, Wang ET, Disney MD. Transcriptome-Wide Studies of RNA-Targeted Small Molecules Provide a Simple and Selective r(CUG) exp Degrader in Myotonic Dystrophy. ACS CENTRAL SCIENCE 2023; 9:1342-1353. [PMID: 37521782 PMCID: PMC10375898 DOI: 10.1021/acscentsci.2c01223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Indexed: 08/01/2023]
Abstract
Myotonic dystrophy type 1 (DM1) is caused by a highly structured RNA repeat expansion, r(CUG)exp, harbored in the 3' untranslated region (3' UTR) of dystrophia myotonica protein kinase (DMPK) mRNA and drives disease through a gain-of-function mechanism. A panel of low-molecular-weight fragments capable of reacting with RNA upon UV irradiation was studied for cross-linking to r(CUG)expin vitro, affording perimidin-2-amine diazirine (1) that bound to r(CUG)exp. The interactions between the small molecule and RNA were further studied by nuclear magnetic resonance (NMR) spectroscopy and molecular modeling. Binding of 1 in DM1 myotubes was profiled transcriptome-wide, identifying 12 transcripts including DMPK that were bound by 1. Augmenting the functionality of 1 with cleaving capability created a chimeric degrader that specifically targets r(CUG)exp for elimination. The degrader broadly improved DM1-associated defects as assessed by RNA-seq, while having limited effects on healthy myotubes. This study (i) provides a platform to investigate molecular recognition of ligands directly in disease-affected cells; (ii) illustrates that RNA degraders can be more specific than the binders from which they are derived; and (iii) suggests that repeating transcripts can be selectively degraded due to the presence of multiple ligand binding sites.
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Affiliation(s)
- Quentin
M. R. Gibaut
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jessica A. Bush
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Yuquan Tong
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jared T. Baisden
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Amirhossein Taghavi
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Hailey Olafson
- Center
for NeuroGenetics, University of Florida, Gainesville, Florida 32610, United States
- Department
of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville, Florida 32610, United States
| | - Xiyuan Yao
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jessica L. Childs-Disney
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Eric T. Wang
- Center
for NeuroGenetics, University of Florida, Gainesville, Florida 32610, United States
- Department
of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville, Florida 32610, United States
| | - Matthew D. Disney
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
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4
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Wang SC, Chen YT, Satange R, Chu JW, Hou MH. Structural basis for water modulating RNA duplex formation in the CUG repeats of myotonic dystrophy type 1. J Biol Chem 2023:104864. [PMID: 37245780 PMCID: PMC10316006 DOI: 10.1016/j.jbc.2023.104864] [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: 03/31/2023] [Revised: 05/19/2023] [Accepted: 05/21/2023] [Indexed: 05/30/2023] Open
Abstract
Secondary structures formed by expanded CUG RNA are involved in the pathobiology of myotonic dystrophy type 1. Understanding the molecular basis of toxic RNA structures can provide insights into the mechanism of disease pathogenesis and accelerate the drug discovery process. Here, we report the crystal structure of CUG repeat RNA containing three U-U mismatches between C-G and G-C base pairs. The CUG RNA crystallizes as an A-form duplex, with the first and third U-U mismatches adopting a water-mediated asymmetric mirror isoform geometry. We found for the first time that a symmetric, water-bridged U-H2O-U mismatch is well tolerated within the CUG RNA duplex, which was previously suspected but not observed. The new water-bridged U-U mismatch resulted in high base-pair opening and single-sided cross-strand stacking interactions, which in turn dominate the CUG RNA structure. Furthermore, we performed molecular dynamics (MD) simulations that complemented the structural findings and proposed that the first and third U-U mismatches are interchangeable conformations, while the central water-bridged U-U mismatch represents an intermediate state that modulates the RNA duplex conformation. Collectively, the new structural features provided in this work are important for understanding the recognition of U-U mismatches in CUG repeats by external ligands such as proteins or small molecules.
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Affiliation(s)
- Shun-Ching Wang
- Institute of Genomics and Bioinformatics; National Chung Hsing University, Taichung 402, Taiwan; Ph.D. Program in Medical Biotechnology, National Chung Hsing University, Taichung 402, Taiwan
| | - Yi-Tsao Chen
- Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu, 30068 Taiwan
| | - Roshan Satange
- Institute of Genomics and Bioinformatics; National Chung Hsing University, Taichung 402, Taiwan
| | - Jhih-Wei Chu
- Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu, 30068 Taiwan; Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, 30068 Taiwan; Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu, 30068 Taiwan.
| | - Ming-Hon Hou
- Institute of Genomics and Bioinformatics; National Chung Hsing University, Taichung 402, Taiwan; Ph.D. Program in Medical Biotechnology, National Chung Hsing University, Taichung 402, Taiwan; Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan.
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5
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Jouravleva K, Golovenko D, Demo G, Dutcher RC, Hall TMT, Zamore PD, Korostelev AA. Structural basis of microRNA biogenesis by Dicer-1 and its partner protein Loqs-PB. Mol Cell 2022; 82:4049-4063.e6. [PMID: 36182693 PMCID: PMC9637774 DOI: 10.1016/j.molcel.2022.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/24/2022] [Accepted: 08/31/2022] [Indexed: 12/22/2022]
Abstract
In animals and plants, Dicer enzymes collaborate with double-stranded RNA-binding domain (dsRBD) proteins to convert precursor-microRNAs (pre-miRNAs) into miRNA duplexes. We report six cryo-EM structures of Drosophila Dicer-1 that show how Dicer-1 and its partner Loqs‑PB cooperate (1) before binding pre-miRNA, (2) after binding and in a catalytically competent state, (3) after nicking one arm of the pre-miRNA, and (4) following complete dicing and initial product release. Our reconstructions suggest that pre-miRNA binds a rare, open conformation of the Dicer‑1⋅Loqs‑PB heterodimer. The Dicer-1 dsRBD and three Loqs‑PB dsRBDs form a tight belt around the pre-miRNA, distorting the RNA helix to place the scissile phosphodiester bonds in the RNase III active sites. Pre-miRNA cleavage shifts the dsRBDs and partially closes Dicer-1, which may promote product release. Our data suggest a model for how the Dicer‑1⋅Loqs‑PB complex affects a complete cycle of pre-miRNA recognition, stepwise endonuclease cleavage, and product release.
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Affiliation(s)
- Karina Jouravleva
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Dmitrij Golovenko
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Gabriel Demo
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, MA 01605, USA; Central European Institute of Technology, Masaryk University, Kamenice 5, Brno 62500, Czech Republic
| | - Robert C Dutcher
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Traci M Tanaka Hall
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA.
| | - Phillip D Zamore
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, MA 01605, USA; Howard Hughes Medical Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, MA 01605, USA.
| | - Andrei A Korostelev
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, MA 01605, USA.
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6
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Liang Y, Miao S, Mao J, Devari S, Gonzalez M, Bong D. Screening of Minimalist Noncanonical Sites in Duplex DNA and RNA Reveals Context and Motif-Selective Binding by Fluorogenic Base Probes. Chemistry 2022; 28:e202103616. [PMID: 34693570 PMCID: PMC8758549 DOI: 10.1002/chem.202103616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Indexed: 01/12/2023]
Abstract
We hypothesize that programmable hybridization to noncanonical nucleic acid motifs may be achieved by macromolecular display of binders to individual noncanonical pairs (NCPs). As each recognition element may individually have weak binding to an NCP, we developed a semi-rational approach to detect low affinity interactions between selected nitrogenous bases and noncanonical sites in duplex DNA and RNA. A set of fluorogenic probes was synthesized by coupling abiotic (triazines, pyrimidines) and native RNA bases to thiazole orange (TO) dye. This probe library was screened against duplex nucleic acid substrates bearing single abasic, single NCP, and tandem NCP sites. Probe engagement with NCP sites was reported by 100-1000× fluorescence enhancement over background. Binding is strongly context-dependent, reflective of both molecular recognition and stability: less stable motifs are more likely to bind a synthetic probe. Further, DNA and RNA substrates exhibit entirely different abasic and single NCP binding profiles. While probe binding in the abasic and single NCP screens was monotonous, much richer binding profiles were observed with the screen of tandem NCP sites in RNA, in part due to increased steric accessibility. In addition to known binding interactions between the triazine melamine (M) and T/U sites, the NCP screens identified new targeting elements for pyrimidine-rich motifs in single NCPs and 2×2 internal bulges. We anticipate that semi-rational approaches of this type will lead to programmable noncanonical hybridization strategies at the macromolecular level.
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Affiliation(s)
- Yufeng Liang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210
| | - Shiqin Miao
- Department of Chemistry & Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210
| | - Jie Mao
- Department of Chemistry & Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210
| | - Shekaraiah Devari
- Department of Chemistry & Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210
| | - Maricarmen Gonzalez
- Department of Chemistry & Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210
| | - Dennis Bong
- Department of Chemistry & Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210
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7
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Kolenko P, Svoboda J, Černý J, Charnavets T, Schneider B. Structural variability of CG-rich DNA 18-mers accommodating double T-T mismatches. Acta Crystallogr D Struct Biol 2020; 76:1233-1243. [PMID: 33263329 PMCID: PMC7709200 DOI: 10.1107/s2059798320014151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 10/23/2020] [Indexed: 11/26/2022] Open
Abstract
Solution and crystal data are reported for DNA 18-mers with sequences related to those of bacterial noncoding single-stranded DNA segments called repetitive extragenic palindromes (REPs). Solution CD and melting data showed that the CG-rich, near-palindromic REPs from various bacterial species exhibit dynamic temperature-dependent and concentration-dependent equilibria, including architectures compatible with not only hairpins, which are expected to be biologically relevant, but also antiparallel duplexes and bimolecular tetraplexes. Three 18-mer oligonucleotides named Hpar-18 (PDB entry 6rou), Chom-18 (PDB entry 6ros) and its brominated variant Chom-18Br (PDB entry 6ror) crystallized as isomorphic right-handed A-like duplexes. The low-resolution crystal structures were solved with the help of experimental phases for Chom-18Br. The center of the duplexes is formed by two successive T-T noncanonical base pairs (mismatches). They do not deform the double-helical geometry. The presence of T-T mismatches prompted an analysis of the geometries of these and other noncanonical pairs in other DNA crystals in terms of their fit to the experimental electron densities (RSCC) and their geometric fit to the NtC (dinucleotide conformational) classes (https://dnatco.datmos.org/). Throughout this work, knowledge of the NtC classes was used to refine and validate the crystal structures, and to analyze the mismatches.
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Affiliation(s)
- Petr Kolenko
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 11519 Prague 1, Czech Republic
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Jakub Svoboda
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Jiří Černý
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Tatsiana Charnavets
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Bohdan Schneider
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
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8
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Divalent cations can control a switch-like behavior in heterotypic and homotypic RNA coacervates. Sci Rep 2019; 9:12161. [PMID: 31434954 PMCID: PMC6704260 DOI: 10.1038/s41598-019-48457-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 08/06/2019] [Indexed: 01/30/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) of RNA-protein complexes plays a major role in the cellular function of membraneless organelles (MLOs). MLOs are sensitive to changes in cellular conditions, such as fluctuations in cytoplasmic ion concentrations. To investigate the effect of these changes on MLOs, we studied the influence of divalent cations on the physical and chemical properties of RNA coacervates. Using a model system comprised of an arginine-rich peptide and RNA, we predicted and observed that variations in signaling cations exert interaction-dependent effects on RNA LLPS. Changing the ionic environment has opposing effects on the propensity for heterotypic peptide-RNA and homotypic RNA LLPS, which results in a switch between coacervate types. Furthermore, divalent ion variations continuously tune the microenvironments and fluid properties of heterotypic and homotypic droplets. Our results may provide a general mechanism for modulating the biochemical environment of RNA coacervates in a cellular context.
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9
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Yonkunas MJ, Baird NJ. A highly ordered, nonprotective MALAT1 ENE structure is adopted prior to triplex formation. RNA (NEW YORK, N.Y.) 2019; 25:975-984. [PMID: 31113838 PMCID: PMC6633196 DOI: 10.1261/rna.069906.118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 05/13/2019] [Indexed: 05/06/2023]
Abstract
The 3' end of the ∼7 kb lncRNA MALAT1 contains an evolutionarily and structurally conserved element for nuclear expression (ENE) which confers protection from cellular degradation pathways. Formation of an ENE triple helix is required to support transcript accumulation, leading to persistent oncogenic activity of MALAT1 in multiple cancer types. Though the specific mechanism of triplex-mediated protection remains unknown, the MALAT1 ENE triplex has been identified as a promising target for therapeutic intervention. Interestingly, a maturation step of the nascent lncRNA 3' end is required prior to triplex formation. We hypothesize that disruption of the maturation or folding process may be a viable mechanism of inhibition. To assess putative cotranscriptional ENE conformations prior to triplex formation, we perform microsecond MD simulations of a partially folded ENE conformation and the ENE triplex. We identify a highly ordered ENE structure prior to triplex formation. Extensive formation of U•U base pairs within the large U-rich internal loops produces a global rod-like architecture. We present a three-dimensional structure of the isolated ENE motif, the global features of which are consistent with small angle X-ray scattering (SAXS) experiments. Our structural model represents a nonprotective conformation of the MALAT1 ENE, providing a molecular description useful for future mechanistic and inhibition studies. We anticipate that targeting stretches of U•U pairs within the ENE motif will prove advantageous for the design of therapeutics targeting this oncogenic lncRNA.
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Affiliation(s)
- Michael J Yonkunas
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, Pennsylvania 19104, USA
| | - Nathan J Baird
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, Pennsylvania 19104, USA
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10
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Zhu L, Kandasamy SK, Fukunaga R. Dicer partner protein tunes the length of miRNAs using base-mismatch in the pre-miRNA stem. Nucleic Acids Res 2019; 46:3726-3741. [PMID: 29373753 PMCID: PMC5909426 DOI: 10.1093/nar/gky043] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 01/17/2018] [Indexed: 12/19/2022] Open
Abstract
Dicer partner proteins Drosophila Loquacious-PB (Loqs-PB) and human TRBP tune the length of miRNAs produced by Dicer from a subset of pre-miRNAs and thereby alter their target repertoire, by an unknown mechanism. Here, we developed a novel high-throughput method that we named Dram-seq (Dice randomized pre-miRNA pool and seq) to study length distributions of miRNAs produced from thousands of different pre-miRNA variants. Using Dram-seq, we found that a base-mismatch in the pre-miRNA stem can alter the length of miRNAs compared with a base-pair at the same position in both Drosophila and human, and is important for the miRNA length tuning by Loqs-PB. Loqs-PB directly bound base-mismatched nucleotides in the pre-miRNA stem. We speculate that Loqs-PB tunes miRNA length by changing the conformation of base-mismatched nucleotides in the pre-miRNA stem to that of base-paired ones and thereby altering the distance of the pre-miRNA stem.
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Affiliation(s)
- Li Zhu
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, 521A Physiology Building, Baltimore, MD 21205, USA
| | - Suresh K Kandasamy
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, 521A Physiology Building, Baltimore, MD 21205, USA
| | - Ryuya Fukunaga
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, 521A Physiology Building, Baltimore, MD 21205, USA
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11
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Humphreys SC, Thayer MB, Lade JM, Wu B, Sham K, Basiri B, Hao Y, Huang X, Smith R, Rock BM. Plasma and Liver Protein Binding of N-Acetylgalactosamine–Conjugated Small Interfering RNA. Drug Metab Dispos 2019; 47:1174-1182. [DOI: 10.1124/dmd.119.086967] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/06/2019] [Indexed: 12/20/2022] Open
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12
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Royuela S, García-Garrido E, Martín Arroyo M, Mancheño MJ, Ramos MM, González-Rodríguez D, Somoza Á, Zamora F, Segura JL. Uracil grafted imine-based covalent organic framework for nucleobase recognition. Chem Commun (Camb) 2018; 54:8729-8732. [DOI: 10.1039/c8cc04346a] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An imine-based covalent organic framework (COF) decorated in its cavities with uracil groups has shown selective recognition towards adenine in water.
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Affiliation(s)
- Sergio Royuela
- Departamento de Química Orgánica I
- Facultad de CC. Químicas
- Universidad Complutense de Madrid
- Madrid 28040
- Spain
| | - Eduardo García-Garrido
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia)
- Cantoblanco
- Madrid E-28049
- Spain
| | - Miguel Martín Arroyo
- Departamento de Orgánica
- Facultad de Ciencias
- Universidad Autónoma de Madrid
- Madrid 28049
- Spain
| | - María J. Mancheño
- Departamento de Química Orgánica I
- Facultad de CC. Químicas
- Universidad Complutense de Madrid
- Madrid 28040
- Spain
| | - María M. Ramos
- Departamento de Tecnología Química y Ambiental
- Universidad Rey Juan Carlos
- Madrid 28933
- Spain
| | | | - Álvaro Somoza
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia)
- Cantoblanco
- Madrid E-28049
- Spain
| | - Félix Zamora
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia)
- Cantoblanco
- Madrid E-28049
- Spain
- Departamento de Inorgánica
| | - José L. Segura
- Departamento de Química Orgánica I
- Facultad de CC. Químicas
- Universidad Complutense de Madrid
- Madrid 28040
- Spain
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13
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Matsuura MF, Kim HJ, Takahashi D, Abboud KA, Benner SA. Crystal structures of deprotonated nucleobases from an expanded DNA alphabet. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2016; 72:952-959. [PMID: 27918296 DOI: 10.1107/s2053229616017071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 10/24/2016] [Indexed: 11/10/2022]
Abstract
Reported here is the crystal structure of a heterocycle that implements a donor-donor-acceptor hydrogen-bonding pattern, as found in the Z component [6-amino-5-nitropyridin-2(1H)-one] of an artificially expanded genetic information system (AEGIS). AEGIS is a new form of DNA from synthetic biology that has six replicable nucleotides, rather than the four found in natural DNA. Remarkably, Z crystallizes from water as a 1:1 complex of its neutral and deprotonated forms, and forms a `skinny' pyrimidine-pyrimidine pair in this structure. The pair resembles the known intercalated cytosine pair. The formation of the same pair in two different salts, namely poly[[aqua(μ6-2-amino-6-oxo-3-nitro-1,6-dihydropyridin-1-ido)sodium]-6-amino-5-nitropyridin-2(1H)-one-water (1/1/1)], denoted Z-Sod, {[Na(C5H4N3O3)(H2O)]·C5H5N3O3·H2O}n, and ammonium 2-amino-6-oxo-3-nitro-1,6-dihydropyridin-1-ide-6-amino-5-nitropyridin-2(1H)-one-water (1/1/1), denoted Z-Am, NH4+·C5H4N3O3-·C5H5N3O3·H2O, under two different crystallization conditions suggests that the pair is especially stable. Implications of this structure for the use of this heterocycle in artificial DNA are discussed.
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Affiliation(s)
- Mariko F Matsuura
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Hyo Joong Kim
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Blvd, Box 17, Alachua, FL 32615, USA
| | - Daisuke Takahashi
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Khalil A Abboud
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Steven A Benner
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Blvd, Box 17, Alachua, FL 32615, USA
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14
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Phosphoribosylphosphate and phosphoribosylnicotinate pairing with phosphoribosylamine at the origin of the RNA world. J Theor Biol 2015; 379:94-7. [PMID: 25997795 DOI: 10.1016/j.jtbi.2015.05.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/14/2015] [Accepted: 03/19/2015] [Indexed: 11/23/2022]
Abstract
The gap between prebiotic chemistry and the RNA origin of life lies in the nature of the pre-ribonucleotides that initiated replication-like activity. The present paper illustrates how the constraints for self-catalytic synthesis of the building blocks point to ionic pairing of the first pre-ribonucleotides and point to a central role for nicotinate.
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15
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Zhong Z, Soh LH, Lim MH, Chen G. A U⋅U Pair-to-U⋅C Pair Mutation-Induced RNA Native Structure Destabilisation and Stretching-Force-Induced RNA Misfolding. Chempluschem 2015; 80:1267-1278. [PMID: 31973291 DOI: 10.1002/cplu.201500144] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 04/21/2015] [Indexed: 12/21/2022]
Abstract
Little is known about how a non-Watson-Crick pair affects the RNA folding dynamics. We studied the effects of a U⋅U-to-U⋅C pair mutation on the folding of a hairpin in human telomerase RNA. The ensemble thermal melting of the hairpins shows an on-pathway intermediate with the disruption of the internal loop structure containing the U⋅U/U⋅C pairs. By using optical tweezers, we applied a stretching force on the terminal ends of the hairpins to probe directly the non-nearest-neighbour effects upon the mutations. The single U⋅U to U⋅C mutations are observed to 1) lower the mechanical unfolding force by approximately 1 picoNewton (pN) per mutation without affecting the unfolding reaction transition-state position (thus suggesting that removing a single hydrogen bond affects the structural dynamics at least two base pairs away), 2) result in more frequent misfolding into a small hairpin at approximately 10 pN and 3) shift the folding reaction transition-state position towards the native hairpin structure and slightly increase the mechanical folding kinetics (thus suggesting that untrapping from the misfolded state is not the rate-limiting step).
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Affiliation(s)
- Zhensheng Zhong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore), Fax: (+65) 6791-1961
| | - Lai Huat Soh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore), Fax: (+65) 6791-1961
| | - Ming Hui Lim
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore), Fax: (+65) 6791-1961
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore), Fax: (+65) 6791-1961
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16
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Weber M, Weber F. Segmented negative-strand RNA viruses and RIG-I: divide (your genome) and rule. Curr Opin Microbiol 2014; 20:96-102. [PMID: 24930021 DOI: 10.1016/j.mib.2014.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 05/02/2014] [Accepted: 05/11/2014] [Indexed: 11/18/2022]
Abstract
The group of negative-stranded RNA viruses (NSVs) with a segmented genome comprises pathogens like influenza virus (eight segments), Rift Valley fever virus and Hantavirus (three segments), or Lassa virus (two segments). Partitioning the genome allows rapid evolution of new strains by reassortment. Each segment carries a short double-stranded (ds) 'panhandle' structure which serves as promoter. Similar dsRNA structures, however, represent the optimal ligand for RIG-I, a cytoplasmic pathogen sensor of the antiviral interferon response. Thus, segmenting a virus genome can entail an increased RIG-I sensitivity. Here, we outline the astonishingly diverse and efficient strategies by which segmented NSVs are compensating for the elevated number of RIG-I ligands in their genome.
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Affiliation(s)
- Michaela Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany.
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17
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Halder S, Bhattacharyya D. RNA structure and dynamics: a base pairing perspective. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2013; 113:264-83. [PMID: 23891726 DOI: 10.1016/j.pbiomolbio.2013.07.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 06/25/2013] [Accepted: 07/16/2013] [Indexed: 12/12/2022]
Abstract
RNA is now known to possess various structural, regulatory and enzymatic functions for survival of cellular organisms. Functional RNA structures are generally created by three-dimensional organization of small structural motifs, formed by base pairing between self-complementary sequences from different parts of the RNA chain. In addition to the canonical Watson-Crick or wobble base pairs, several non-canonical base pairs are found to be crucial to the structural organization of RNA molecules. They appear within different structural motifs and are found to stabilize the molecule through long-range intra-molecular interactions between basic structural motifs like double helices and loops. These base pairs also impart functional variation to the minor groove of A-form RNA helices, thus forming anchoring site for metabolites and ligands. Non-canonical base pairs are formed by edge-to-edge hydrogen bonding interactions between the bases. A large number of theoretical studies have been done to detect and analyze these non-canonical base pairs within crystal or NMR derived structures of different functional RNA. Theoretical studies of these isolated base pairs using ab initio quantum chemical methods as well as molecular dynamics simulations of larger fragments have also established that many of these non-canonical base pairs are as stable as the canonical Watson-Crick base pairs. This review focuses on the various structural aspects of non-canonical base pairs in the organization of RNA molecules and the possible applications of these base pairs in predicting RNA structures with more accuracy.
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Affiliation(s)
- Sukanya Halder
- Biophysics division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700 064, India
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18
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Kondo J, Dock-Bregeon AC, Willkomm DK, Hartmann RK, Westhof E. Structure of an A-form RNA duplex obtained by degradation of 6S RNA in a crystallization droplet. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:634-9. [PMID: 23722840 PMCID: PMC3668581 DOI: 10.1107/s1744309113013018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 05/13/2013] [Indexed: 12/29/2022]
Abstract
In the course of a crystallographic study of a 132 nt variant of Aquifex aeolicus 6S RNA, a crystal structure of an A-form RNA duplex containing 12 base pairs was solved at a resolution of 2.6 Å. In fact, the RNA duplex is part of the 6S RNA and was obtained by accidental but precise degradation of the 6S RNA in a crystallization droplet. 6S RNA degradation was confirmed by microscopic observation of crystals and gel electrophoresis of crystallization droplets. The RNA oligomers obtained form regular A-form duplexes containing three GoU wobble-type base pairs, one of which engages in intermolecular contacts through a ribose-zipper motif at the crystal-packing interface.
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Affiliation(s)
- Jiro Kondo
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan.
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19
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DNA self-assembly: from chirality to evolution. Int J Mol Sci 2013; 14:8252-70. [PMID: 23591841 PMCID: PMC3645741 DOI: 10.3390/ijms14048252] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 03/03/2013] [Accepted: 03/21/2013] [Indexed: 01/12/2023] Open
Abstract
Transient or long-term DNA self-assembly participates in essential genetic functions. The present review focuses on tight DNA-DNA interactions that have recently been found to play important roles in both controlling DNA higher-order structures and their topology. Due to their chirality, double helices are tightly packed into stable right-handed crossovers. Simple packing rules that are imposed by DNA geometry and sequence dictate the overall architecture of higher order DNA structures. Close DNA-DNA interactions also provide the missing link between local interactions and DNA topology, thus explaining how type II DNA topoisomerases may sense locally the global topology. Finally this paper proposes that through its influence on DNA self-assembled structures, DNA chirality played a critical role during the early steps of evolution.
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20
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Timsit Y. DNA-directed base pair opening. Molecules 2012; 17:11947-64. [PMID: 23060287 PMCID: PMC6268293 DOI: 10.3390/molecules171011947] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 09/28/2012] [Accepted: 10/09/2012] [Indexed: 11/16/2022] Open
Abstract
Strand separation is a fundamental molecular process essential for the reading of the genetic information during DNA replication, transcription and recombination. However, DNA melting in physiological conditions in which the double helix is expected to be stable represents a challenging problem. Current models propose that negative supercoiling destabilizes the double helix and promotes the spontaneous, sequence-dependent DNA melting. The present review examines an alternative view and reveals how DNA compaction may trigger the sequence dependent opening of the base pairs. This analysis shows that in DNA crystals, tight DNA-DNA interactions destabilize the double helices at various degrees, from the alteration of the base-stacking to the opening of the base-pairs. The electrostatic repulsion generated by the DNA close approach of the negatively charged sugar phosphate backbones may therefore provide a potential source of the energy required for DNA melting. These observations suggest a new molecular mechanism for the initial steps of strand separation in which the coupling of the DNA tertiary and secondary interactions both actively triggers the base pair opening and stabilizes the intermediate states during the melting pathway.
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Affiliation(s)
- Youri Timsit
- CNRS, Aix-Marseille Université, IGS UMR7256, FR-13288 Marseille, France.
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21
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Tamjar J, Katorcha E, Popov A, Malinina L. Structural dynamics of double-helical RNAs composed of CUG/CUG- and CUG/CGG-repeats. J Biomol Struct Dyn 2012; 30:505-23. [PMID: 22731704 DOI: 10.1080/07391102.2012.687517] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Human genetic trinucleotide repeat expansion diseases (TREDs) are characterized by triplet repeat expansions, most frequently found as CNG-tracts in genome. At RNA level, such expansions suggestively result in formation of double-helical hairpins that become a potential source for small RNAs involved in RNA interference (RNAi). Here, we present three crystal structures of RNA fragments composed of triplet repeats CUG and CGG/CUG, as well as two crystal structures of same triplets in a protein-bound state. We show that both 20mer pG(CUG)(6)C and 19mer pGG(CGG)(3)(CUG)(2)CC form A-RNA duplexes, in which U·U or G·U mismatches are flanked/stabilized by two consecutive Watson-Crick G·C base pairs resulting in high-stacking GpC steps in every third position of the duplex. Despite interruption of this regularity in another 19mer, p(CGG)(3)C(CUG)(3), the oligonucleotide still forms regular double-helical structure, characterized, however, by 12 bp (rather than 11 bp) per turn. Analysis of newly determined molecular structures reveals the dynamic aspects of U·U and G·U mismatching within CNG-repetitive A-RNA and in a protein-bound state, as well as identifies an additional mode of U·U pairing essential for its dynamics and sheds the light on possible role of regularity of trinucleotide repeats for double-helical RNA structure. Findings are important for understanding the structural behavior of CNG-repetitive RNA double helices implicated in TREDs.
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Affiliation(s)
- Jevgenia Tamjar
- Structural Biology Unit, CIC bioGUNE, Technology Park of Bizkaia, Derio-Bilbao 48160, Spain
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22
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Timsit Y. Local sensing of global DNA topology: from crossover geometry to type II topoisomerase processivity. Nucleic Acids Res 2011; 39:8665-76. [PMID: 21764774 PMCID: PMC3203592 DOI: 10.1093/nar/gkr556] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Type II topoisomerases are ubiquitous enzymes that control the topology and higher order structures of DNA. Type IIA enzymes have the remarkable property to sense locally the global DNA topology. Although many theoretical models have been proposed, the molecular mechanism of chiral discrimination is still unclear. While experimental studies have established that topoisomerases IIA discriminate topology on the basis of crossover geometry, a recent single-molecule experiment has shown that the enzyme has a different processivity on supercoiled DNA of opposite sign. Understanding how cross-over geometry influences enzyme processivity is, therefore, the key to elucidate the mechanism of chiral discrimination. Analysing this question from the DNA side reveals first, that the different stability of chiral DNA cross-overs provides a way to locally sense the global DNA topology. Second, it shows that these enzymes have evolved to recognize the G- and T-segments stably assembled into a right-handed cross-over. Third, it demonstrates how binding right-handed cross-overs across their large angle imposes a different topological link between the topoIIA rings and the plectonemes of opposite sign thus directly affecting the enzyme freedom of motion and processivity. In bridging geometry and kinetic data, this study brings a simple solution for type IIA topoisomerase chiral discrimination.
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Affiliation(s)
- Youri Timsit
- Information Génomique et Structurale, CNRS - UPR2589, Institut de Microbiologie de la Méditerranée, Aix-Marseille University, Parc Scientifique de Luminy, Marseille, France
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23
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Halder S, Bhattacharyya D. Structural Stability of Tandemly Occurring Noncanonical Basepairs within Double Helical Fragments: Molecular Dynamics Studies of Functional RNA. J Phys Chem B 2010; 114:14028-40. [DOI: 10.1021/jp102835t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Sukanya Halder
- Biophysics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata—700 064, India
| | - Dhananjay Bhattacharyya
- Biophysics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata—700 064, India
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24
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25
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Bilbille Y, Vendeix FAP, Guenther R, Malkiewicz A, Ariza X, Vilarrasa J, Agris PF. The structure of the human tRNALys3 anticodon bound to the HIV genome is stabilized by modified nucleosides and adjacent mismatch base pairs. Nucleic Acids Res 2009; 37:3342-53. [PMID: 19324888 PMCID: PMC2691828 DOI: 10.1093/nar/gkp187] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Replication of human immunodeficiency virus (HIV) requires base pairing of the reverse transcriptase primer, human tRNALys3, to the viral RNA. Although the major complementary base pairing occurs between the HIV primer binding sequence (PBS) and the tRNA's 3′-terminus, an important discriminatory, secondary contact occurs between the viral A-rich Loop I, 5′-adjacent to the PBS, and the modified, U-rich anticodon domain of tRNALys3. The importance of individual and combined anticodon modifications to the tRNA/HIV-1 Loop I RNA's interaction was determined. The thermal stabilities of variously modified tRNA anticodon region sequences bound to the Loop I of viral sub(sero)types G and B were analyzed and the structure of one duplex containing two modified nucleosides was determined using NMR spectroscopy and restrained molecular dynamics. The modifications 2-thiouridine, s2U34, and pseudouridine, Ψ39, appreciably stabilized the interaction of the anticodon region with the viral subtype G and B RNAs. The structure of the duplex results in two coaxially stacked A-form RNA stems separated by two mismatched base pairs, U162•Ψ39 and G163•A38, that maintained a reasonable A-form helix diameter. The tRNA's s2U34 stabilized the interaction between the A-rich HIV Loop I sequence and the U-rich anticodon, whereas the tRNA's Ψ39 stabilized the adjacent mismatched pairs.
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Affiliation(s)
- Yann Bilbille
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695-7622, USA
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26
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Li N, Wang Y, Pothukuchy A, Syrett A, Husain N, Gopalakrisha S, Kosaraju P, Ellington AD. Aptamers that recognize drug-resistant HIV-1 reverse transcriptase. Nucleic Acids Res 2008; 36:6739-51. [PMID: 18948292 PMCID: PMC2588506 DOI: 10.1093/nar/gkn775] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Drug-resistant variants of HIV-1 reverse transcriptase (RT) are also known to be resistant to anti-RT RNA aptamers. In order to be able to develop diagnostics and therapies that can focus on otherwise drug-resistant viruses, we have isolated two aptamers against a well-known, drug-resistant HIV-1 RT, Mutant 3 (M3) from the multidrug-resistant HIV-1 RT panel. One aptamer, M302, bound M3 but showed no significant affinity for wild-type (WT) HIV-1 RT, while another aptamer, 12.01, bound to both M3 and WT HIV-1 RTs. In contrast to all previously selected anti-RT aptamers, neither of these aptamers showed observable inhibition of either polymerase or RNase H activities. Aptamers M302 and 12.01 competed with one another for binding to M3, but they did not compete with a pseudoknot aptamer for binding to the template/primer cleft of WT HIV-1 RT. These results represent the surprising identification of an additional RNA-binding epitope on the surface of HIV-1 RT. M3 and WT HIV-1 RTs could be distinguished using an aptamer-based microarray. By probing protein conformation as a correlate to drug resistance we introduce an additional and useful measure for determining HIV-1 drug resistance.
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Affiliation(s)
- Na Li
- Department of Chemistry and Biochemistry, Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
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27
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Jones CN, Jones CI, Graham WD, Agris PF, Spremulli LL. A disease-causing point mutation in human mitochondrial tRNAMet rsults in tRNA misfolding leading to defects in translational initiation and elongation. J Biol Chem 2008; 283:34445-56. [PMID: 18835817 DOI: 10.1074/jbc.m806992200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mitochondrial tRNA genes are hot spots for mutations that lead to human disease. A single point mutation (T4409C) in the gene for human mitochondrial tRNA(Met) (hmtRNA(Met)) has been found to cause mitochondrial myopathy. This mutation results in the replacement of U8 in hmtRNA(Met) with a C8. The hmtRNA(Met) serves both in translational initiation and elongation in human mitochondria making this tRNA of particular interest in mitochondrial protein synthesis. Here we show that the single 8U-->C mutation leads to a failure of the tRNA to respond conformationally to Mg(2+). This mutation results in a drastic disruption of the structure of the hmtRNA(Met), which significantly reduces its aminoacylation. The small fraction of hmtRNA(Met) that can be aminoacylated is not formylated by the mitochondrial Met-tRNA transformylase preventing its function in initiation, and it is unable to form a stable ternary complex with elongation factor EF-Tu preventing any participation in chain elongation. We have used structural probing and molecular reconstitution experiments to examine the structures formed by the normal and mutated tRNAs. In the presence of Mg(2+), the normal tRNA displays the structural features expected of a tRNA. However, even in the presence of Mg(2+), the mutated tRNA does not form the cloverleaf structure typical of tRNAs. Thus, we believe that this mutation has disrupted a critical Mg(2+)-binding site on the tRNA required for formation of the biologically active structure. This work establishes a foundation for understanding the physiological consequences of the numerous mitochondrial tRNA mutations that result in disease in humans.
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Affiliation(s)
- Christie N Jones
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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28
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Abstract
Preparation of suitably large and well-ordered single crystals is usually the rate-limiting step in the determination of the three-dimensional structure of RNAs and their complexes with proteins by X-ray crystallography. This unit discusses a variety of experimental considerations for obtaining crystals of RNAs and RNA-protein complexes. Topics include design of crystallizable constructs, screening, and optimization of crystallization conditions.
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29
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Smirnov A, Tarassov I, Mager-Heckel AM, Letzelter M, Martin RP, Krasheninnikov IA, Entelis N. Two distinct structural elements of 5S rRNA are needed for its import into human mitochondria. RNA (NEW YORK, N.Y.) 2008; 14:749-59. [PMID: 18314502 PMCID: PMC2271358 DOI: 10.1261/rna.952208] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
RNA import into mitochondria is a widespread phenomenon. Studied in details for yeast, protists, and plants, it still awaits thorough investigation for human cells, in which the nuclear DNA-encoded 5S rRNA is imported. Only the general requirements for this pathway have been described, whereas specific protein factors needed for 5S rRNA delivery into mitochondria and its structural determinants of import remain unknown. In this study, a systematic analysis of the possible role of human 5S rRNA structural elements in import was performed. Our experiments in vitro and in vivo show that two distinct regions of the human 5S rRNA molecule are needed for its mitochondrial targeting. One of them is located in the proximal part of the helix I and contains a conserved uncompensated G:U pair. The second and most important one is associated with the loop E-helix IV region with several noncanonical structural features. Destruction or even destabilization of these sites leads to a significant decrease of the 5S rRNA import efficiency. On the contrary, the beta-domain of the 5S rRNA was proven to be dispensable for import, and thus it can be deleted or substituted without affecting the 5S rRNA importability. This finding was used to demonstrate that the 5S rRNA can function as a vector for delivering heterologous RNA sequences into human mitochondria. 5S rRNA-based vectors containing a substitution of a part of the beta-domain by a foreign RNA sequence were shown to be much more efficiently imported in vivo than the wild-type 5S rRNA.
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Affiliation(s)
- Alexandre Smirnov
- Department of Molecular and Cellular Genetics, UMR 7156, Centre National de Recherche Scientifique-Université Louis Pasteur,Strasbourg 67084, France
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30
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Shankar N, Xia T, Kennedy SD, Krugh TR, Mathews DH, Turner DH. NMR reveals the absence of hydrogen bonding in adjacent UU and AG mismatches in an isolated internal loop from ribosomal RNA. Biochemistry 2007; 46:12665-78. [PMID: 17929882 DOI: 10.1021/bi700802s] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
NMR studies provide insights into structural features of internal loops. These insights can be combined with thermodynamic studies to generate models for predicting structure and energetics. The tandem mismatch internal loop, 5'GUGG3'(3'CUAC5'), has been studied by NMR. The NMR structure reveals an internal loop with no hydrogen bonding between the loop bases and with the G in the AG mismatch flipped out of the helix. The sequence of this internal loop is highly conserved in rRNA. The loop is located in the large ribosomal subunit and is part of a conserved 58-nt fragment that is the binding domain of ribosomal protein L11. Structural comparisons between variants of this internal loop in crystal structures of the 58-nt domain complexed with L11 protein and of the large ribosomal subunit (LSU) suggest that this thermodynamically destabilizing internal loop is partially preorganized for tertiary interactions and for binding L11. A model for predicting the base pairing and free energy of 2 x 2 nucleotide internal loops with a purine-purine mismatch next to a pyrimidine-pyrimidine mismatch is proposed on the basis of the present NMR structure and previously reported thermodynamics.
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Affiliation(s)
- Neelaabh Shankar
- Department of Biochemistry and Biophysics, University of Rochester, Rochester, New York 14642, USA
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Chen HC, Hsu YH, Lin NS. Downregulation of Bamboo mosaic virus replication requires the 5' apical hairpin stem loop structure and sequence of satellite RNA. Virology 2007; 365:271-84. [PMID: 17482233 DOI: 10.1016/j.virol.2007.03.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Revised: 12/13/2006] [Accepted: 03/28/2007] [Indexed: 10/23/2022]
Abstract
Satellite RNAs associated with Bamboo mosaic virus (satBaMV) exhibit different phenotypes. Some isolates could reduce the accumulation of BaMV RNA and attenuate the BaMV-induced symptoms in co-inoculated plants. The determinants of the downregulation of BaMV replication were mapped in the 5' hypervariable region of satBaMV, which folds into a conserved apical hairpin stem loop (AHSL) structure comprising an apical loop and two internal loops, as evidenced by enzymatic probing. We also demonstrated that the integrity of the AHSL structure of interfering satBaMV was essential for the interference of BaMV accumulation. Concurrent analyses of natural satBaMV isolates revealed that all of the interfering isolates contained the same structures and sequences in the internal loops. Further, refined analyses indicated that, besides the AHSL structure, specific nucleotides in the internal loops play a crucial role in the downregulation, which implies that they may be required for the interaction of viral/cellular factors in this process.
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Affiliation(s)
- Hsin-Chuan Chen
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan, ROC
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32
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Karbstein K, Lee J, Herschlag D. Probing the role of a secondary structure element at the 5'- and 3'-splice sites in group I intron self-splicing: the tetrahymena L-16 ScaI ribozyme reveals a new role of the G.U pair in self-splicing. Biochemistry 2007; 46:4861-75. [PMID: 17385892 PMCID: PMC2597287 DOI: 10.1021/bi062169g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several ribozyme constructs have been used to dissect aspects of the group I self-splicing reaction. The Tetrahymena L-21 ScaI ribozyme, the best studied of these intron analogues, catalyzes a reaction analogous to the first step of self-splicing, in which a 5'-splice site analogue (S) and guanosine (G) are converted into a 5'-exon analogue (P) and GA. This ribozyme preserves the active site but lacks a short 5'-terminal segment (called the IGS extension herein) that forms dynamic helices, called the P1 extension and P10 helix. The P1 extension forms at the 5'-splice site in the first step of self-splicing, and P10 forms at the 3'-splice site in the second step of self-splicing. To dissect the contributions from the IGS extension and the helices it forms, we have investigated the effects of each of these elements at each reaction step. These experiments were performed with the L-16 ScaI ribozyme, which retains the IGS extension, and with 5'- and 3'-splice site analogues that differ in their ability to form the helices. The presence of the IGS extension strengthens binding of P by 40-fold, even when no new base pairs are formed. This large effect was especially surprising, as binding of S is essentially unaffected for S analogues that do not form additional base pairs with the IGS extension. Analysis of a U.U pair immediately 3' to the cleavage site suggests that a previously identified deleterious effect from a dangling U residue on the L-21 ScaI ribozyme arises from a fortuitous active site interaction and has implications for RNA tertiary structure specificity. Comparisons of the affinities of 5'-splice site analogues that form only a subset of base pairs reveal that inclusion of the conserved G.U base pair at the cleavage site of group I introns destabilizes the P1 extension >100-fold relative to the stability of a helix with all Watson-Crick base pairs. Previous structural data with model duplexes and the recent intron structures suggest that this effect can be attributed to partial unstacking of the P1 extension at the G.U step. These results suggest a previously unrecognized role of the G.U wobble pair in self-splicing: breaking cooperativity in base pair formation between P1 and the P1 extensions. This effect may facilitate replacement of the P1 extension with P10 after the first chemical step of self-splicing and release of the ligated exons after the second step of self-splicing.
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Affiliation(s)
| | - Jihee Lee
- Department of Chemistry, Stanford University
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University
- Department of Chemistry, Stanford University
- Correspondence should be addressed to: Daniel Herschlag, Department of Biochemistry, Stanford University, Stanford, CA 94305-5307, , Phone: (650) 723 9442, Fax: (650) 723 6783
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33
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Schumacher MA, Karamooz E, Zíková A, Trantírek L, Lukes J. Crystal structures of T. brucei MRP1/MRP2 guide-RNA binding complex reveal RNA matchmaking mechanism. Cell 2006; 126:701-11. [PMID: 16923390 DOI: 10.1016/j.cell.2006.06.047] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 05/19/2006] [Accepted: 06/23/2006] [Indexed: 11/19/2022]
Abstract
The mitochondrial RNA binding proteins MRP1 and MRP2 form a heteromeric complex that functions in kinetoplastid RNA editing. In this process, MRP1/MRP2 serves as a matchmaker by binding to guide RNAs and facilitating their hybridization with cognate preedited mRNAs. To understand the mechanism by which this complex performs RNA matchmaking, we determined structures of Trypanosoma brucei apoMRP1/MRP2 and an MRP1/MRP2-gRNA complex. The structures show that MRP1/MRP2 is a heterotetramer and, despite little sequence homology, each MRP subunit exhibits the same "Whirly" transcription-factor fold. The gRNA molecule binds to the highly basic beta sheet surface of the MRP complex via nonspecific, electrostatic contacts. Strikingly, while the gRNA stem/loop II base is anchored to the basic surface, stem/loop I (the anchor sequence) is unfolded and its bases exposed to solvent. Thus, MRP1/MRP2 acts as an RNA matchmaker by stabilizing the RNA molecule in an unfolded conformation suitable for RNA-RNA hybridization.
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MESH Headings
- Amino Acid Sequence
- Animals
- Crystallography, X-Ray
- Mitochondrial Proteins/chemistry
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Protein Binding
- Protein Folding
- Protein Structure, Quaternary
- Protein Structure, Secondary
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- RNA, Guide, Kinetoplastida/chemistry
- RNA, Guide, Kinetoplastida/genetics
- RNA, Guide, Kinetoplastida/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Sequence Alignment
- Trypanosoma brucei brucei/chemistry
- Trypanosoma brucei brucei/metabolism
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Affiliation(s)
- Maria A Schumacher
- Department of Biochemistry and Molecular Biology, University of Texas, M.D. Anderson Cancer Center, Unit 1000, Houston, 77030, USA.
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Jang SB, Hung LW, Jeong MS, Holbrook EL, Chen X, Turner DH, Holbrook SR. The crystal structure at 1.5 angstroms resolution of an RNA octamer duplex containing tandem G.U basepairs. Biophys J 2006; 90:4530-7. [PMID: 16581850 PMCID: PMC1471874 DOI: 10.1529/biophysj.106.081018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The crystal structure of the RNA octamer, 5'-GGCGUGCC-3' has been determined from x-ray diffraction data to 1.5 angstroms resolution. In the crystal, this oligonucleotide forms five self-complementary double-helices in the asymmetric unit. Tandem 5'GU/3'UG basepairs comprise an internal loop in the middle of each duplex. The NMR structure of this octameric RNA sequence is also known, allowing comparison of the variation among the five crystallographic duplexes and the solution structure. The G.U pairs in the five duplexes of the crystal form two direct hydrogen bonds and are stabilized by water molecules that bridge between the base of guanine (N2) and the sugar (O2') of uracil. This contrasts with the NMR structure in which only one direct hydrogen bond is observed for the G.U pairs. The reduced stability of the r(CGUG)2 motif relative to the r(GGUC)2 motif may be explained by the lack of stacking of the uracil bases between the Watson-Crick and G.U pairs as observed in the crystal structure.
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Affiliation(s)
- Se Bok Jang
- Korea Nanobiotechnology Center, Pusan National University, Jangjeon-dong, Keumjeong-gu, Busan, Korea.
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35
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Mooers BHM, Logue JS, Berglund JA. The structural basis of myotonic dystrophy from the crystal structure of CUG repeats. Proc Natl Acad Sci U S A 2005; 102:16626-31. [PMID: 16269545 PMCID: PMC1283809 DOI: 10.1073/pnas.0505873102] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Myotonic dystrophy (DM) type 1 is associated with an expansion of (>50) CTG repeats within the 3' untranslated region (UTR) of the dystrophin myotonin protein kinase gene (dmpk). In the corresponding mRNA transcript, the CUG repeats form an extended stem-loop structure. The double-stranded RNA of the stem sequesters RNA binding proteins away from their normal cellular targets resulting in aberrant transcription, alternative splicing patterns, or both, thereby leading to DM. To better understand the structural basis of DM type 1, we determined to 1.58-A resolution the x-ray crystal structure of an 18-bp RNA containing six CUG repeats. The CUG repeats form antiparallel double-stranded helices that stack end-on-end in the crystal to form infinite, pseudocontinuous helices similar to the long CUG stem loops formed by the expanded CUG repeats in DM type 1. The CUG helix is very similar in structure to A-form RNA with the exception of the unique U-U mismatches. This structure provides a high-resolution view of a toxic, trinucleotide repeat RNA.
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Affiliation(s)
- Blaine H M Mooers
- Department of Chemistry, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403-1229, USA
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36
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Sobczak K, Krzyzosiak WJ. Imperfect CAG repeats form diverse structures in SCA1 transcripts. J Biol Chem 2004; 279:41563-72. [PMID: 15292212 DOI: 10.1074/jbc.m405130200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The expanded CAG repeat in the coding sequence of the spinocerebellar ataxia type 1 (SCA1) gene is responsible for SCA1, one of the hereditary human neurodegenerative diseases. In the normal SCA1 alleles usually 1-3 CAT triplets break the continuity of the CAG repeat tracts. Here we show what is the structural role of the CAU interruptions in the SCA1 transcripts. Depending on their number and localization within the repeat tract the interruptions either enlarge the terminal loop of the hairpin formed by the repeats, nucleate the internal loops in its stem structure, or force the repeats to fold into two smaller hairpins. Thus, the interruptions destabilize the CAG repeat hairpin, which is likely to decrease its ability to participate in the putative RNA pathogenesis mechanism driven by the long CAG repeat hairpins.
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Affiliation(s)
- Krzysztof Sobczak
- Laboratory of Cancer Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
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37
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Chandrasekhar K, Malathhi R. Non-Watson Crick base pairs might stabilize RNA structural motifs in ribozymes -- a comparative study of group-I intron structures. J Biosci 2004; 28:547-55. [PMID: 14517358 DOI: 10.1007/bf02703330] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In recent decades studies on RNA structure and function have gained significance due to discoveries on diversified functions of RNA. A common element for RNA secondary structure formed by series of non- Watson/Watson Crick base pairs, internal loops and pseudoknots have been the highlighting feature of recent structural determination of RNAs. The recent crystal structure of group-I introns has demonstrated that these might constitute RNA structural motifs in ribozymes, playing a crucial role in their enzymatic activity. To understand the functional significance of these non-canonical base pairs in catalytic RNA, we analysed the sequences of group-I introns from nuclear genes. The results suggest that they might form the building blocks of folded RNA motifs which are crucial to the catalytic activity of the ribozyme. The conservation of these, as observed from divergent organisms, argues for the presence of non-canonical base pairs as an important requisite for the structure and enzymatic property of ribozymes by enabling them to carry out functions such as replication, polymerase activity etc. in primordial conditions in the absence of proteins.
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Affiliation(s)
- K Chandrasekhar
- Department of Genetics, Dr ALM PG Institute of Basic Medical Sciences, University of Madras,Taramani Campus, Chennai 600 113, India
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38
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Johnson SJ, Beese LS. Structures of mismatch replication errors observed in a DNA polymerase. Cell 2004; 116:803-16. [PMID: 15035983 DOI: 10.1016/s0092-8674(04)00252-1] [Citation(s) in RCA: 241] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2003] [Revised: 01/07/2004] [Accepted: 01/23/2004] [Indexed: 11/21/2022]
Abstract
Accurate DNA replication is essential for genomic stability. One mechanism by which high-fidelity DNA polymerases maintain replication accuracy involves stalling of the polymerase in response to covalent incorporation of mismatched base pairs, thereby favoring subsequent mismatch excision. Some polymerases retain a "short-term memory" of replication errors, responding to mismatches up to four base pairs in from the primer terminus. Here we a present a structural characterization of all 12 possible mismatches captured at the growing primer terminus in the active site of a polymerase. Our observations suggest four mechanisms that lead to mismatch-induced stalling of the polymerase. Furthermore, we have observed the effects of extending a mismatch up to six base pairs from the primer terminus and find that long-range distortions in the DNA transmit the presence of the mismatch back to the enzyme active site, suggesting the structural basis for the short-term memory of replication errors.
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Affiliation(s)
- Sean J Johnson
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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39
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Girard G, Roussis A, Gultyaev AP, Pleij CWA, Spaink HP. Structural motifs in the RNA encoded by the early nodulation gene enod40 of soybean. Nucleic Acids Res 2003; 31:5003-15. [PMID: 12930950 PMCID: PMC212817 DOI: 10.1093/nar/gkg721] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2003] [Revised: 06/30/2003] [Accepted: 07/17/2003] [Indexed: 11/13/2022] Open
Abstract
The plant gene enod40 is highly conserved among legumes and also present in various non-legume species. It is presumed to play a central regulatory role in the Rhizobium-legume interaction, being expressed well before the initiation of cortical cell divisions resulting in nodule formation. Two small peptides encoded by enod40 mRNA as well as its secondary structure have been shown to be key elements in the signalling processes underlying nodule organogenesis. Here results concerning the secondary structure of mRNA of enod40 in soybean are presented. This study combined a theoretical approach, involving structure prediction and comparison, as well as structure probing. Our study indicates five conserved domains in enod40 mRNA among numerous leguminous species. Structure comparison suggests that some domains are also conserved in non-leguminous species and that an additional domain exists that was found only in leguminous species developing indeterminate nodules. Enzymatic and chemical probing data support the structure for three of the domains, and partially for the remaining two. The rest of the molecule appears to be less structured. Some of the domains include motifs, such as U-containing internal loops and bulges, which seem to be conserved. Therefore, they might be involved in the regulatory role of enod40 RNA.
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Affiliation(s)
- Geneviève Girard
- Institute of Biology, Leiden University, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands
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40
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Walberer BJ, Cheng AC, Frankel AD. Structural diversity and isomorphism of hydrogen-bonded base interactions in nucleic acids. J Mol Biol 2003; 327:767-80. [PMID: 12654262 DOI: 10.1016/s0022-2836(03)00090-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The wide structural diversity of RNA results in part from the diversity of non-Watson-Crick interactions between bases. To examine the repertoire of possible hydrogen bond interactions among bases, we computed databases of base-pairs and base-triples by systematically matching all possible hydrogen-bond donors and acceptors between bases and evaluating the geometries of each planar configuration. For base-pairs, we find 53 arrangements having at least two hydrogen bonds, including 23 pairs with protonated bases that have not previously been modeled. A comparison with experimentally observed base-pairs reveals an unexpected G:U pair recently observed in the ribosome. For base-triples, we find 840 arrangements in which the three bases are constrained by a total of at least three hydrogen bonds. Base-triples in particular exhibit a wide range of structural diversity, suggesting how compact or elongated nucleic acid structures may be constructed using different hydrogen-bonding patterns. Base-pair and base-triple conformations were systematically compared to identify structurally isomorphic combinations, and the experimentally observed arrangements within double and triple helices are among the most isomorphic. Unexpectedly, however, other combinations in the database are even more isomorphic, including several in which all-purine arrangements overlap with all-pyrimidine arrangements. These studies highlight some of the combinatoric and geometric versatility of base interactions and help provide a framework for analyzing and modeling isomorphic interactions and potentially for designing novel nucleic acid structures.
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Affiliation(s)
- Bernhard J Walberer
- Department of Biochemistry and Biophysics, University of California, 513 Parnassus Avenue, San Francisco, CA 94143-0448, USA
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41
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Vicens Q, Westhof E. Crystal structure of geneticin bound to a bacterial 16S ribosomal RNA A site oligonucleotide. J Mol Biol 2003; 326:1175-88. [PMID: 12589761 DOI: 10.1016/s0022-2836(02)01435-3] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Aminoglycosides are antibacterial molecules that decrease translation accuracy by binding to the decoding aminoacyl-tRNA site (A site) on 16S ribosomal RNA. We have solved the crystal structure of an RNA fragment containing the A site bound to geneticin at 2.40A resolution. Geneticin, also known as G418, is a gentamicin-related aminoglycoside: it contains three rings that are functionalized by hydroxyl, ammonium and methyl groups. The detailed comparison of the distinctive behaviour of geneticin (binding to pro- and eukaryotic A sites) with the crystallographic, biochemical and microbiological results obtained so far for aminoglycoside-A site complexes offers new insights on the system. The two sugar rings constituting the neamine part common to most of the aminoglycosides bind to the A site, as already observed in the crystal structures solved previously with paromomycin and tobramycin. The essential hydrogen bonds involving ring I (to A1408) and ring II (to the phosphate oxygen atoms of the bulged adenine bases 1492 and 1493 and to G1494) are conserved and additional contacts are observed from ring III (to phosphate oxygen atoms of G1405 and U1406). The present work illustrates a molecular basis of the range in sensitiveness exhibited by geneticin towards common point A site mutations associated to resistance phenotypes. In addition, analysis and comparisons of the structures cast light on the role played by the conserved U1406.U1495 pair in the recognition of the A site by aminoglycosides.
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Affiliation(s)
- Quentin Vicens
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Modélisation et simulations des Acides Nucléiques, UPR 9002, Université Louis Pasteur, 15 rue René Descartes, 67084 Cedex, Strasbourg, France
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42
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Theimer CA, Finger LD, Trantirek L, Feigon J. Mutations linked to dyskeratosis congenita cause changes in the structural equilibrium in telomerase RNA. Proc Natl Acad Sci U S A 2003; 100:449-54. [PMID: 12525685 PMCID: PMC141015 DOI: 10.1073/pnas.242720799] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Autosomal dominant dyskeratosis congenita (DKC), as well as aplastic anemia, has been linked to mutations in the RNA component of telomerase, the ribonucleoprotein responsible for telomere maintenance. Here we examine the effect of the DKC mutations on the structure and stability of human telomerase RNA pseudoknot and CR7 domains by using NMR and thermal melting. The CR7 domain point mutation decreases stability and alters a conserved secondary structure thought to be involved in human telomerase RNA accumulation in vivo. We find that pseudoknot constructs containing the conserved elements of the pseudoknot domain are in equilibrium with a hairpin conformation. The solution structure of the wild-type hairpin reveals that it forms a continuous helix containing a novel run of three consecutive U.U and a U.C base pairs closed by a pentaloop. The six base pairs unique to the hairpin conformation are phylogenetically conserved in mammals, suggesting that this conformation is also functionally important. The DKC mutation in the pseudoknot domain results in a shift in the equilibrium toward the hairpin form, primarily due to destabilization of the pseudoknot. Our results provide insight into the effect of these mutations on telomerase structure and suggest that the catalytic cycle of telomerase involves a delicate interplay between RNA conformational states, alteration of which leads to the disease state.
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Affiliation(s)
- Carla A Theimer
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095-1569, USA
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43
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John DM, Weeks KM. Chemical interrogation of mismatches in DNA-DNA and DNA-RNA duplexes under nonstringent conditions by selective 2'-amine acylation. Biochemistry 2002; 41:6866-74. [PMID: 12022892 DOI: 10.1021/bi025611d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2'-Amine-substituted nucleotides in hybridized duplexes can be chemically tagged in an acylation reaction that is faster for mismatched or flexible nucleotides than for residues constrained by base pairing. Here we explore mismatch and hybridization detection using probe oligodeoxynucleotides containing single 2'-aminocytidine or -uridine nucleotides annealed to DNA or RNA targets under nonstringent conditions, below T(m). Consistent with a mechanism in which 2'-amine acylation is gated by local nucleotide flexibility, we find that efficient acylation is correlated with formation of weaker or fewer hydrogen bonds in base pair mismatches. Using 2'-aminocytidine-containing probes annealed to both DNA and RNA targets, mismatches are reliably detected as rapid selective acylation of the 2'-amine group in two sequence contexts. For probe oligonucleotides containing 2'-aminouridine residues, good discrimination between U-A base pairs and U-G mismatches could be obtained for DNA-DNA but not for DNA-RNA duplexes upon the introduction of a single 2'-O-Me group 5' to the 2'-amino nucleotide. The 2'-O-Me group introduces a structural perturbation, presumably to a more A-form-like structure, that exaggerates local flexibility at mismatches in DNA strands. Thus, 2'-amine acylation can be used to interrogate all possible mismatches in DNA-DNA duplexes and mismatches involving 2'-amine-substituted cytidine nucleotides in DNA-RNA heteroduplexes. Applications of this chemistry include detecting and chemically proofreading single nucleotide polymorphisms in both DNA and RNA targets and quantifying absolute amounts of RNA.
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Affiliation(s)
- Deborah M John
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, USA
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44
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Abstract
In this paper, hydrogen bonding interaction and hydration in crystal structures of both DNA and RNA oligonucleotides are discussed. Their roles in the formation and stabilization of oligonucleotides have been covered. Details of the Watson-Crick base pairs G.C and A.U in DNA and RNA are illustrated. The geometry of the wobble (mismatched) G.U base pairs and the cis and almost trans conformations of the mismatched U.U base pairs in RNA is described. The difference in hydration of the Watson-Crick base pairs G.C, A.U and the wobble G.U in different sequences of codon-anticodon interaction in double helical molecules are indicative of the effect of hydration. The hydration patterns of the phosphate, the 2'-hydroxyl groups, the water bridges linking the phosphate group, N7 (purine) and N4 of Cs or O4 of Us in the major groove, the water bridges between the 2'-hydroxyl group and N3 (purine) and O2 (pyrimidine) in the minor groove are discussed.
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Affiliation(s)
- Muttaiya Sundaralingam
- Biological Macromolecular Structure Center, Department of Chemistry, and The Ohio State Biochemistry Program, The Ohio State University, 1060 Carmack Road, Columbus, OH 43210-1002, USA.
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45
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Abstract
The energetics of small internal loops are important for prediction of RNA secondary and tertiary structure, selection of drug target sites, and understanding RNA structure-function relationships. Hydrogen bonding, base stacking, electrostatic interactions, backbone distortion, and base-pair size compatibility all contribute to the energetics of small internal loops. Thus, the sequence dependence of these energetics are idiosyncratic. Current approximations for predicting the free energies of internal loops consider size, asymmetry, closing base pairs, and the potential to form GA, GG, or UU pairs. The database of known three-dimensional structures allows for comparison with the models used for predicting stability from sequence.
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Affiliation(s)
- S J Schroeder
- Department of Chemistry, University of Rochester, RC Box 270216, Rochester, NY 14627-0216, USA
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46
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Wu B, Vanti WB, White KA. An RNA domain within the 5' untranslated region of the tomato bushy stunt virus genome modulates viral RNA replication. J Mol Biol 2001; 305:741-56. [PMID: 11162089 DOI: 10.1006/jmbi.2000.4298] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The terminal half of the 5' untranslated region (UTR) in the (+)-strand RNA genome of tomato bushy stunt virus was analyzed for possible roles in viral RNA replication. Computer-aided thermodynamic analysis of secondary structure, phylogenetic comparisons for base-pair covariation, and chemical and enzymatic solution structure probing were used to analyze the 78 nucleotide long 5'-terminal sequence. The results indicate that this sequence adopts a branched secondary structure containing a three-helix junction core. The T-shaped domain (TSD) formed by this terminal sequence is closed by a prominent ten base-pair long helix, termed stem 1 (S1). Deletion of either the 5' or 3' segment forming S1 (coordinates 1-10 or 69-78, respectively) in a model subviral RNA replicon, i.e. a prototypical defective interfering (DI) RNA, reduced in vivo accumulation levels of this molecule approximately 20-fold. Compensatory-type mutational analysis of S1 within this replicon revealed a strong correlation between formation of the predicted S1 structure and efficient DI RNA accumulation. RNA decay studies in vivo did not reveal any notable changes in the physical stabilities of DI RNAs containing disrupted S1s, thus implicating RNA replication as the affected process. Further investigation revealed that destabilization of S1 in the (+)-strand was significantly more detrimental to DI RNA accumulation than (-)-strand destabilization, therefore S1-mediated activity likely functions primarily via the (+)-strand. The essential role of S1 in DI RNA accumulation prompted us to examine the 5'-proximal secondary structure of a previously identified mutant DI RNA, RNA B, that lacks the 5' UTR but is still capable of low levels of replication. Mutational analysis of a predicted S1-like element present within a cryptic 5'-terminal TSD confirmed the importance of the former in RNA B accumulation. Collectively, these data support a fundamental role for the TSD, and in particular its S1 subelement, in tombusvirus RNA replication.
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Affiliation(s)
- B Wu
- Department of Biology, York University, Toronto, Ontario, M3J 1P3, Canada
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47
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Chen JY, Stands L, Staley JP, Jackups RR, Latus LJ, Chang TH. Specific alterations of U1-C protein or U1 small nuclear RNA can eliminate the requirement of Prp28p, an essential DEAD box splicing factor. Mol Cell 2001; 7:227-32. [PMID: 11172727 DOI: 10.1016/s1097-2765(01)00170-8] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
While some members of the ubiquitous DExD/H box family of proteins have RNA helicase activity in vitro, their roles in vivo remain virtually unknown. Here, we show that the function of an otherwise essential DEAD box protein, Prp28p, can be bypassed by mutations that alter either the protein U1-C or the U1 small nuclear RNA. Further analysis suggests that the conserved L13 residue in the U1-C protein makes specific contact to stabilize the U1 snRNA/5' splice site duplex in the prespliceosome, and that Prp28p functions to counteract the stabilizing effect of the U1-C protein, thereby promoting the dissociation of the U1 small nuclear ribonucleoprotein particle from the 5' splice site. Thus, in addition to unwinding RNA, the DExD/H box proteins may affect RNA-RNA rearrangements by antagonizing specific RNA-stabilizing proteins.
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Affiliation(s)
- J Y Chen
- Department of Molecular Genetics, Ohio State University, Columbus, OH 43210, USA
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48
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Brandl M, Meyer M, Sühnel J. Water-Mediated Base Pairs in RNA: A Quantum-Chemical Study. J Phys Chem A 2000. [DOI: 10.1021/jp002022d] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- M. Brandl
- Biocomputing Group, Institute of Molecular Biotechnology, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - M. Meyer
- Biocomputing Group, Institute of Molecular Biotechnology, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - J. Sühnel
- Biocomputing Group, Institute of Molecular Biotechnology, Beutenbergstrasse 11, D-07745 Jena, Germany
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49
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Szymański M, Barciszewska MZ, Erdmann VA, Barciszewski J. An analysis of G-U base pair occurrence in eukaryotic 5S rRNAs. Mol Biol Evol 2000; 17:1194-8. [PMID: 10908639 DOI: 10.1093/oxfordjournals.molbev.a026402] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The structure-function relationship in RNA molecules is a key to understanding of the expression of genetic information. Various types of RNA play crucial roles at almost every step of protein biosynthesis. In recent years, it has been shown that one of the most important structural elements in RNA is a wobble pair G-U. In this paper, we present for the first time an analysis of the distribution of G-U pairs in eukaryotic 5S ribosomal RNAs. Interestingly, the G-U pair in 5S rRNA species is predominantly found in two intrahelical regions of the stems I and V and at the junction of helix IV and loop A. The distribution of G-U pairs and the nature of adjacent bases suggests their possible role as a recognition site in interactions with other components of protein biosynthesis machinery.
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Affiliation(s)
- M Szymański
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poland
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50
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Abstract
The current state of three-dimensional structure analysis of RNA by x-ray crystallography is summarized. The methods of sample preparation, crystallization, data collection, and structure solution are discussed, followed by a review of the RNA structures that have been determined and of common structural features, and finally, an appraisal of future prospects for x-ray crystal structure analysis of RNA.
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Affiliation(s)
- S R Holbrook
- Structural Biology Division, Lawrence Berkeley National Laboratory, University of California at Berkeley 94720, USA
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