1
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A comprehensive review of methods to study lncRNA-protein interactions in solution. Biochem Soc Trans 2022; 50:1415-1426. [PMID: 36250427 DOI: 10.1042/bst20220604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/10/2022] [Accepted: 09/27/2022] [Indexed: 11/17/2022]
Abstract
The long non-coding RNAs (lncRNAs) other than rRNA and tRNA were earlier assumed to be 'junk genomic material'. However, recent advancements in genomics methods have highlighted their roles not only in housekeeping but also in the progression of diseases like cancer as well as viral infections. lncRNAs owing to their length, have both short-range and long-range interactions resulting in complex folded structures that recruit various biomolecules enabling lncRNAs to undertake their various biological functions. Using cell lysate pull-down assays increasing number of lnRNAs-interacting proteins are being identified. These interactions can be further exploited to develop targeted novel therapeutic strategies to inhibit lncRNA-protein interactions. This review attempts to succinctly techniques that can identify and characterize the lnRNAs-protein interactions (i.e. affinity, stoichiometry, and thermodynamics). Furthermore, using other sophisticated biophysical techniques, one can also perform size estimations, and determine low-resolution structures. Since these methods study the biomolecules in solution, large-scale structural observations can be performed in real-time. This review attempts to briefly introduce the readers to biochemical and biophysical techniques, such that they can utilize these methods to obtain a holistic characterization of the biomolecules of interest. Additionally, it should be noted that the use of these methods is not limited to the characterization of the interacting molecules but can also be used to determine the efficacy of the therapeutic molecules to disrupt these interactions.
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2
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Largy E, König A, Ghosh A, Ghosh D, Benabou S, Rosu F, Gabelica V. Mass Spectrometry of Nucleic Acid Noncovalent Complexes. Chem Rev 2021; 122:7720-7839. [PMID: 34587741 DOI: 10.1021/acs.chemrev.1c00386] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Nucleic acids have been among the first targets for antitumor drugs and antibiotics. With the unveiling of new biological roles in regulation of gene expression, specific DNA and RNA structures have become very attractive targets, especially when the corresponding proteins are undruggable. Biophysical assays to assess target structure as well as ligand binding stoichiometry, affinity, specificity, and binding modes are part of the drug development process. Mass spectrometry offers unique advantages as a biophysical method owing to its ability to distinguish each stoichiometry present in a mixture. In addition, advanced mass spectrometry approaches (reactive probing, fragmentation techniques, ion mobility spectrometry, ion spectroscopy) provide more detailed information on the complexes. Here, we review the fundamentals of mass spectrometry and all its particularities when studying noncovalent nucleic acid structures, and then review what has been learned thanks to mass spectrometry on nucleic acid structures, self-assemblies (e.g., duplexes or G-quadruplexes), and their complexes with ligands.
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Affiliation(s)
- Eric Largy
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Alexander König
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Anirban Ghosh
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Debasmita Ghosh
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Sanae Benabou
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Frédéric Rosu
- Univ. Bordeaux, CNRS, INSERM, IECB, UMS 3033, F-33600 Pessac, France
| | - Valérie Gabelica
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
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3
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Zhao L, Huang Y, Dong Y, Han X, Wang S, Liang X. Aptamers and Aptasensors for Highly Specific Recognition and Sensitive Detection of Marine Biotoxins: Recent Advances and Perspectives. Toxins (Basel) 2018; 10:E427. [PMID: 30366456 PMCID: PMC6265707 DOI: 10.3390/toxins10110427] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 10/13/2018] [Accepted: 10/22/2018] [Indexed: 02/07/2023] Open
Abstract
Marine biotoxins distribute widely, have high toxicity, and can be easily accumulated in water or seafood, exposing a serious threat to consumer health. Achieving specific and sensitive detection is the most effective way to prevent emergent issues caused by marine biotoxins; however, the previous detection methods cannot meet the requirements because of ethical or technical drawbacks. Aptamers, a kind of novel recognition element with high affinity and specificity, can be used to fabricate various aptasensors (aptamer-based biosensors) for sensitive and rapid detection. In recent years, an increasing number of aptamers and aptasensors have greatly promoted the development of marine biotoxins detection. In this review, we summarized the recent aptamer-related advances for marine biotoxins detection and discussed their perspectives. Firstly, we summarized the sequences, selection methods, affinity, secondary structures, and the ion conditions of all aptamers to provide a database-like information; secondly, we summarized the reported aptasensors for marine biotoxins, including principles, detection sensitivity, linear detection range, etc.; thirdly, on the basis of the existing reports and our own research experience, we forecast the development prospects of aptamers and aptasensors for marine biotoxins detection. We hope this review not only provides a comprehensive summary of aptamer selection and aptasensor development for marine biotoxins, but also arouses a broad readership amongst academic researchers and industrial chemists.
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Affiliation(s)
- Lianhui Zhao
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
| | - Yunfei Huang
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
| | - Yiyang Dong
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Xutiange Han
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
| | - Sai Wang
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
| | - Xingguo Liang
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
- Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266000, China.
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4
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Gülbakan B, Barylyuk K, Schneider P, Pillong M, Schneider G, Zenobi R. Native Electrospray Ionization Mass Spectrometry Reveals Multiple Facets of Aptamer–Ligand Interactions: From Mechanism to Binding Constants. J Am Chem Soc 2018; 140:7486-7497. [DOI: 10.1021/jacs.7b13044] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Basri Gülbakan
- Department of Chemistry and Applied Bioscience, ETH Zürich, CH-8093 Zürich, Switzerland
- Hacettepe University Institute of Child Health, Ihsan Dogramaci Children’s Hospital, Sıhhiye Square, 06100 Ankara, Turkey
| | - Konstantin Barylyuk
- Department of Chemistry and Applied Bioscience, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Petra Schneider
- Department of Chemistry and Applied Bioscience, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Max Pillong
- Department of Chemistry and Applied Bioscience, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Gisbert Schneider
- Department of Chemistry and Applied Bioscience, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Renato Zenobi
- Department of Chemistry and Applied Bioscience, ETH Zürich, CH-8093 Zürich, Switzerland
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5
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Mondragón E, Maher LJ. Anti-Transcription Factor RNA Aptamers as Potential Therapeutics. Nucleic Acid Ther 2015; 26:29-43. [PMID: 26509637 PMCID: PMC4753637 DOI: 10.1089/nat.2015.0566] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Transcription factors (TFs) are DNA-binding proteins that play critical roles in regulating gene expression. These proteins control all major cellular processes, including growth, development, and homeostasis. Because of their pivotal role, cells depend on proper TF function. It is, therefore, not surprising that TF deregulation is linked to disease. The therapeutic drug targeting of TFs has been proposed as a frontier in medicine. RNA aptamers make interesting candidates for TF modulation because of their unique characteristics. The products of in vitro selection, aptamers are short nucleic acids (DNA or RNA) that bind their targets with high affinity and specificity. Aptamers can be expressed on demand from transgenes and are intrinsically amenable to recognition by nucleic acid-binding proteins such as TFs. In this study, we review several natural prokaryotic and eukaryotic examples of RNAs that modulate the activity of TFs. These examples include 5S RNA, 6S RNA, 7SK, hepatitis delta virus-RNA (HDV-RNA), neuron restrictive silencer element (NRSE)-RNA, growth arrest-specific 5 (Gas5), steroid receptor RNA activator (SRA), trophoblast STAT utron (TSU), the 3' untranslated region of caudal mRNA, and heat shock RNA-1 (HSR1). We then review examples of unnatural RNA aptamers selected to inhibit TFs nuclear factor-kappaB (NF-κB), TATA-binding protein (TBP), heat shock factor 1 (HSF1), and runt-related transcription factor 1 (RUNX1). The field of RNA aptamers for DNA-binding proteins continues to show promise.
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Affiliation(s)
- Estefanía Mondragón
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine , Rochester, Minnesota
| | - Louis James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine , Rochester, Minnesota
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6
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Deng QP, Tie C, Zhou YL, Zhang XX. Cocaine detection by structure-switch aptamer-based capillary zone electrophoresis. Electrophoresis 2012; 33:1465-70. [PMID: 22648816 DOI: 10.1002/elps.201100680] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Aptamers, which are nucleic acid oligonucleotides that can bind targets with high affinity and specificity, have been widely applied as affinity probes in capillary electrophoresis (CE). Due to relative weak interaction between aptamers and small molecules, the application of aptamer-based CE is still limited in certain compounds. A new strategy that is based on the aptamer structure-switch concept was designed for small molecule detection by a novel CE method. A carboxyfluorescein (fluorescein amidite, FAM) label DNA aptamer was first incubated with partial complementary strand (CS), and then the free aptamer and the aptamer-CS duplex were well separated and determined by metal cation mediated CE/laser-induced fluorescence. When the target was introduced into the incubated sample, the hybridized form was destabilized, resulting in the changes of the fluorescence intensities of the free aptamer and the aptamer-CS duplex. The length of CS was investigated and 12 mer CS showed the best sensitivity for the detection of cocaine. The presented CE-LIF method, which combines the separation power of CE with the specificity of interactions occurring between target, aptamer, and CS, could be a universal detection strategy for other aptamer-specified small molecules.
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Affiliation(s)
- Qin-Pei Deng
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Institute of Analytical Chemistry, College of Chemistry, Peking University, Beijing, China
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7
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Bida JP, Maher LJ. Improved prediction of RNA tertiary structure with insights into native state dynamics. RNA (NEW YORK, N.Y.) 2012; 18:385-393. [PMID: 22279150 PMCID: PMC3285927 DOI: 10.1261/rna.027201.111] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 11/28/2011] [Indexed: 05/31/2023]
Abstract
The importance of RNA tertiary structure is evident from the growing number of published high resolution NMR and X-ray crystallographic structures of RNA molecules. These structures provide insights into function and create a knowledge base that is leveraged by programs such as Assemble, ModeRNA, RNABuilder, NAST, FARNA, Mc-Sym, RNA2D3D, and iFoldRNA for tertiary structure prediction and design. While these methods sample native-like RNA structures during simulations, all struggle to capture the native RNA conformation after scoring. We propose RSIM, an improved RNA fragment assembly method that preserves RNA global secondary structure while sampling conformations. This approach enhances the quality of predicted RNA tertiary structure, provides insights into the native state dynamics, and generates a powerful visualization of the RNA conformational space. RSIM is available for download from http://www.github.com/jpbida/rsim.
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Affiliation(s)
- John Paul Bida
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
| | - L. James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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8
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Barbazuk WB. A conserved alternative splicing event in plants reveals an ancient exonization of 5S rRNA that regulates TFIIIA. RNA Biol 2010; 7:397-402. [PMID: 20699638 DOI: 10.4161/rna.7.4.12684] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Uncovering conserved alternative splicing (AS) events can identify AS events that perform important functions. This is especially useful for identifying premature stop codon containing (PTC) AS isoforms that may regulate protein expression by being targets for nonsense mediated decay. This report discusses the identification of a PTC containing splice isoform of the TFIIIA gene that is highly conserved in land plants. TFIIIA is essential for RNA Polymerase III-based transcription of 5S rRNA in eukaryotes. Two independent groups have determined that the PTC containing alternative exon is ultraconserved and is coupled with nonsense-mediated mRNA decay. The alternative exon appears to have been derived by the exonization of 5S ribosomal RNA (5S rRNA) within the gene of its own transcription regulator, TFIIIA. This provides the first evidence of ancient exaptation of 5S rRNA in plants, suggesting a novel gene regulation model mediated by the AS of an anciently exonized non-coding element.
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Affiliation(s)
- W Brad Barbazuk
- Department of Biology and the Florida Genetics Institute, University of Florida, Gainesville, FL USA.
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9
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Barton JL, Bunka DHJ, Knowling SE, Lefevre P, Warren AJ, Bonifer C, Stockley PG. Characterization of RNA aptamers that disrupt the RUNX1-CBFbeta/DNA complex. Nucleic Acids Res 2009; 37:6818-30. [PMID: 19740763 PMCID: PMC2777437 DOI: 10.1093/nar/gkp728] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The transcription factor RUNX1 (AML1) is an important regulator of haematopoiesis, and an important fusion partner in leukaemic translocations. High-affinity DNA binding by RUNX1 requires the interaction of the RUNX1 Runt-Homology-Domain (RHD) with the core-binding factor β protein (CBFβ). To generate novel reagents for in vitro and in vivo studies of RUNX1 function, we have selected high-affinity RNA aptamers against a recombinant RHD–CBFβ complex. Selection yielded two sequence families, each dominated by a single consensus sequence. Aptamers from each family disrupt DNA binding by the RUNX1 protein in vitro and compete with sequence-specific dsDNA binding. Minimal, high-affinity (∼100–160 nM) active aptamer fragments 28 and 30 nts in length, consisting of simple short stem-loop structures, were then identified. These bind to the RHD subunit and disrupt its interaction with CBFβ, which is consistent with reduced DNA affinity in the presence of aptamer. These aptamers represent new reagents that target a novel surface on the RHD required to stabilize the recombinant RHD–CBFβ complex and thus will further aid exploring the functions of this key transcription factor.
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Affiliation(s)
- Jenny L Barton
- Section of Experimental Haematology, Leeds Institute of Molecular Medicine, St James's University Hospital, Leeds LS9 7TF, UK
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10
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Wurster SE, Bida JP, Her YF, Maher LJ. Characterization of anti-NF-kappaB RNA aptamer-binding specificity in vitro and in the yeast three-hybrid system. Nucleic Acids Res 2009; 37:6214-24. [PMID: 19696077 PMCID: PMC2764441 DOI: 10.1093/nar/gkp670] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
RNA aptamers offer a potential therapeutic approach to the competitive inhibition of DNA-binding transcription factors. In previous reports we described in vitro selection and characterization of anti-NF-κB p50 and p65 RNA aptamers. We now describe the further characterization of these aptamers in vitro and in vivo. We show that sub-saturating concentrations of certain anti-p50 RNA aptamers promote complex formation with NF-κB p50 tetramers, whereas anti-p65 R1 RNA aptamers bind NF-κB dimers under all conditions tested. Yeast three-hybrid RNA aptamer specificity studies corroborate previous in vitro results, verifying that anti-p50 and anti-p65 R1 RNA aptamers are highly specific for NF-κB p502 and p652, respectively. These studies introduce a novel T-cassette RNA transcript that improves RNA display from a four-way RNA junction. Mutagenesis of the anti-p65 R1 aptamer reveals tolerated substitutions, suggesting a complex tertiary structure. We describe in vivo selections from a yeast three-hybrid RNA library containing sequences present early in the R1 SELEX process to identify novel anti-p65 RNA aptamers, termed Y1 and Y3. These aptamers appear to be compact bulged hairpins, reminiscent of anti-p50. Y1 competitively inhibits the DNA-binding domain of NF-κB p652in vitro.
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Affiliation(s)
- Susan E Wurster
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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11
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Affiliation(s)
- Juewen Liu
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
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12
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Wurster SE, Maher LJ. Selection and characterization of anti-NF-kappaB p65 RNA aptamers. RNA (NEW YORK, N.Y.) 2008; 14:1037-47. [PMID: 18426920 PMCID: PMC2390809 DOI: 10.1261/rna.878908] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Accepted: 02/18/2008] [Indexed: 05/20/2023]
Abstract
NF-kappaB transcription factors include a group of five mammalian proteins that form hetero- or homodimers and regulate hundreds of target genes involved in acute inflammation, HIV-1 transcription activation, and resistance to cancer therapy. We previously used in vitro selection to develop a small RNA aptamer (anti-p50) that binds the DNA-binding domain of NF-kappaB p50(2) with low nanomolar affinity but does not bind NF-kappaB p65(2). Here, we report the in vitro selection of anti-NF-kappaB p65 RNA aptamers using parallel in vitro selections with either a fully randomized RNA library or a degenerate RNA library based on the primary sequence of the 31-nucleotide anti-p50 RNA aptamer. We report the characterization of these aptamers with respect to NF-kappaB target specificity, affinity, minimal sequence requirements, secondary structure, and competition with DNA kappaB sites. These results expand opportunities for artificial inhibition of NF-kappaB transcription factor dimers containing p65 subunits.
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Affiliation(s)
- Susan E Wurster
- Department of Biochemistry and Molecular Biology, College of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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13
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Crystal structure of Thermus thermophilus tRNA m1A58 methyltransferase and biophysical characterization of its interaction with tRNA. J Mol Biol 2008; 377:535-50. [PMID: 18262540 DOI: 10.1016/j.jmb.2008.01.041] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 01/11/2008] [Accepted: 01/16/2008] [Indexed: 11/22/2022]
Abstract
Methyltransferases from the m(1)A(58) tRNA methyltransferase (TrmI) family catalyze the S-adenosyl-l-methionine-dependent N(1)-methylation of tRNA adenosine 58. The crystal structure of Thermus thermophilus TrmI, in complex with S-adenosyl-l-homocysteine, was determined at 1.7 A resolution. This structure is closely related to that of Mycobacterium tuberculosis TrmI, and their comparison enabled us to enlighten two grooves in the TrmI structure that are large enough and electrostatically compatible to accommodate one tRNA per face of TrmI tetramer. We have then conducted a biophysical study based on electrospray ionization mass spectrometry, site-directed mutagenesis, and molecular docking. First, we confirmed the tetrameric oligomerization state of TrmI, and we showed that this protein remains tetrameric upon tRNA binding, with formation of complexes involving one to two molecules of tRNA per TrmI tetramer. Second, three key residues for the methylation reaction were identified: the universally conserved D170 and two conserved aromatic residues Y78 and Y194. We then used molecular docking to position a N(9)-methyladenine in the active site of TrmI. The N(9)-methyladenine snugly fits into the catalytic cleft, where the side chain of D170 acts as a bidentate ligand binding the amino moiety of S-adenosyl-l-methionine and the exocyclic amino group of the adenosine. Y194 interacts with the N(9)-methyladenine ring, whereas Y78 can stabilize the sugar ring. From our results, we propose that the conserved residues that form the catalytic cavity (D170, Y78, and Y194) are essential for fashioning an optimized shape of the catalytic pocket.
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14
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Fu H, Guthrie JW, Le XC. Study of binding stoichiometries of the human immunodeficiency virus type 1 reverse transcriptase by capillary electrophoresis and laser-induced fluorescence polarization using aptamers as probes. Electrophoresis 2006; 27:433-41. [PMID: 16331583 DOI: 10.1002/elps.200500460] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Binding stoichiometries between four DNA aptamers (RT12, RT26, RTlt49, and ODN93) and the reverse transcriptase (RT) of the type 1 human immunodeficiency virus (HIV-1) were studied using affinity CE (ACE) coupled with LIF polarization and fluorescence polarization (FP). The ACE/LIF study showed evidence of two binding stoichiometries between the HIV-1 RT protein and aptamers RT12, RT26, and ODN93, suggesting that these aptamers can bind to both the p66 and p51 subunits of the HIV-1 RT. Only one binding stoichiometry for aptamer RTlt49 was found. The affinity complexes were easily separated from the unbound aptamers; however, the different stoichiometries were not well resolved. A complementary technique, FP, was able to provide additional information about the binding and supporting evidence for the ACE/LIF results. The ACE/LIFP study also revealed that the FP values of the 1:1 complexes of the HIV-1 RT protein with aptamers RT12, RT26, and ODN93 were always much greater than those of the 1:2 complexes. This was initially surprising because the larger molecular size of the 1:2 complexes was expected to result in higher FP values than the corresponding 1:1 complexes. This phenomenon was probably a result of fluorescence resonance energy transfer between the two fluorescent molecules bound to the HIV-1 RT protein.
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Affiliation(s)
- Hao Fu
- Environmental Health Sciences, Department of Public Health Sciences, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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15
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Keller KM, Breeden MM, Zhang J, Ellington AD, Brodbelt JS. Electrospray ionization of nucleic acid aptamer/small molecule complexes for screening aptamer selectivity. JOURNAL OF MASS SPECTROMETRY : JMS 2005; 40:1327-37. [PMID: 16217837 DOI: 10.1002/jms.915] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Molecular recognition of small molecule ligands by the nucleic acid aptamers for tobramycin, ATP, and FMN has been examined using electrospray ionization mass spectrometry (ESI-MS). Mass spectrometric data for binding stoichiometry and relative binding affinity correlated well with solution data for tobramycin aptamer complexes, in which aptamer/ligand interactions are mediated by hydrogen bonds. For the ATP and FMN aptamers, where ligand interactions involve both hydrogen bonding and significant pi-stacking, the relative binding affinities determined by MS did not fully correlate with results obtained from solution experiments. Some high-affinity aptamer/ligand complexes appeared to be destabilized in the gas phase by internal Coulombic repulsion. In CAD experiments, complexes with a greater number of intermolecular hydrogen bonds exhibited greater gas-phase stability even in cases when solution binding affinities were equivalent. These results indicate that in at least some cases, mass spectrometric data on aptamer/ligand binding affinities should be used in conjunction with complementary techniques to fully assess aptamer molecular recognition properties.
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Affiliation(s)
- Karin M Keller
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin TX 78712, USA
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16
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Ashcroft AE. Recent developments in electrospray ionisation mass spectrometry: noncovalently bound protein complexes. Nat Prod Rep 2005; 22:452-64. [PMID: 16047045 DOI: 10.1039/b417724j] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Alison E Ashcroft
- Astbury Centre for Structural Molecular Biology, School of Biochemistry & Microbiology, The University of Leeds, UK
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17
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Cavanagh J, Benson LM, Thompson R, Naylor S. In line desalting mass spectrometry for the study of noncovalent biological complexes. Anal Chem 2004; 75:3281-6. [PMID: 14570174 DOI: 10.1021/ac030182q] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electrospray ionization-mass spectrometry is becoming widely used as a high-throughput method for the study of biomolecular interactions. It allows for the analysis of complexes from heterogeneous mixtures with high sensitivity and selectivity. In many cases, biomolecules and their complexes must be stored in nonvolatile salt buffers and other solubilizing agents, such as organics or detergents, to maintain stability and integrity. To ensure an efficient electrospray process, desalting and exchanging the biomolecular solutions into a volatile buffer is imperative. Current off-line or on-line methods to accomplish this are time-consuming, frequently disrupt noncovalent interactions, and can result in considerable sample loss. Here we describe a simple, general, and highly efficient, rapid in-line desalting approach using a small gel cartridge to assist in the mass spectrometric analysis of biomolecules and their complexes. Though the method has broad applicability, we focus our analysis on proteins and demonstrate its usefulness by examining protein-metal, protein-protein, protein-DNA, and protein-RNA interactions. The method is shown to provide rapid direct analysis of analyte solutions containing salts, glycerol, organics, and involatile buffers without deleterious effects.
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Affiliation(s)
- John Cavanagh
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, USA.
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18
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Ghosh G, Huang DB, Huxford T. Molecular mimicry of the NF-κB DNA target site by a selected RNA aptamer. Curr Opin Struct Biol 2004; 14:21-7. [PMID: 15102445 DOI: 10.1016/j.sbi.2004.01.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
During the past two decades, structural and biophysical studies of DNA-protein and RNA-protein complexes have enhanced our understanding of the physico-chemical basis of nucleic acid recognition by proteins. However, it remains unclear what protein surface features are most important for nucleic acid binding and whether the same protein surface could bind specifically to both DNA and RNA. The recently described X-ray crystal structure of the transcription factor NF-kappaB p50 homodimer bound to a high-affinity RNA aptamer allows the direct comparison of NF-kappaB-RNA and NF-kappaB-DNA binding modes. The RNA aptamer, which bears no sequence homology to natural NF-kappaB DNA targets, adopts a structure with similar physico-chemical properties to kappaB DNA and contacts a common nucleic-acid-binding 'consensus surface' on the p50 homodimer.
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Affiliation(s)
- Gourisankar Ghosh
- Department of Chemistry & Biochemistry, University of California San Diego, Mail Code 0359, Urey Hall 5230, 9500 Gilman Drive, La Jolla, CA 92093-0359, USA.
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Cassiday LA, Maher LJ. Yeast genetic selections to optimize RNA decoys for transcription factor NF-kappa B. Proc Natl Acad Sci U S A 2003; 100:3930-5. [PMID: 12637683 PMCID: PMC153025 DOI: 10.1073/pnas.0736013100] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In vitro-selected RNA aptamers are potential inhibitors of disease-related proteins. Our laboratory previously isolated an RNA aptamer that binds with high affinity to human transcription factor NF-kappaB. This RNA aptamer competitively inhibits DNA binding by NF-kappaB in vitro and is recognized by its target protein in vivo in a yeast three-hybrid system. In the present study, yeast genetic selections were used to optimize the RNA aptamer for binding to NF-kappaB in the eukaryotic nucleus. Selection for improved binding to NF-kappaB from RNA libraries encoding (i) degenerate aptamer variants and (ii) sequences present at round 8 of 14 total rounds of in vitro selection yielded RNA aptamers with dramatically improved in vivo activity. Furthermore, we show that an in vivo-optimized RNA aptamer exhibits specific "decoy" activity, inhibiting transcriptional activation by its NF-kappaB target protein in a yeast one-hybrid assay. This decoy activity is enhanced by the expression of a bivalent aptamer. The combination of in vitro and in vivo genetic selections was crucial for obtaining RNA aptamers with in vivo decoy activity.
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Affiliation(s)
- Laura A Cassiday
- Department of Biochemistry and Molecular Biology, Mayo Foundation, Rochester, MN 55905, USA
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Cassiday LA, Maher LJ. Having it both ways: transcription factors that bind DNA and RNA. Nucleic Acids Res 2002; 30:4118-26. [PMID: 12364590 PMCID: PMC140532 DOI: 10.1093/nar/gkf512] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Multifunctional proteins challenge the conventional 'one protein-one function' paradigm. Here we note apparent multifunctional proteins with nucleic acid partners, tabulating eight examples. We then focus on eight additional cases of transcription factors that bind double-stranded DNA with sequence specificity, but that also appear to lead alternative lives as RNA-binding proteins. Exemplified by the prototypic Xenopus TFIIIA protein, and more recently by mammalian p53, this list of transcription factors includes WT-1, TRA-1, bicoid, the bacterial sigma(70) subunit, STAT1 and TLS/FUS. The existence of transcription factors that bind both DNA and RNA provides an interesting puzzle. Little is known concerning the biological roles of these alternative protein-nucleic acid interactions, and even less is known concerning the structural basis for dual nucleic acid specificity. We discuss how these natural examples have motivated us to identify artificial RNA sequences that competitively inhibit a DNA-binding transcription factor not known to have a natural RNA partner. The identification of such RNAs raises the possibility that RNA binding by DNA-binding proteins is more common than currently appreciated.
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Affiliation(s)
- Laura A Cassiday
- Department of Biochemistry and Molecular Biology, Mayo Foundation, 200 First Street SW, Rochester, MN 55905, USA
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