1
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Zhuang J, Shang Q, Rastinejad F, Wu D. Decoding Allosteric Control in Hypoxia-Inducible Factors. J Mol Biol 2024; 436:168352. [PMID: 37935255 DOI: 10.1016/j.jmb.2023.168352] [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: 08/15/2023] [Revised: 10/10/2023] [Accepted: 11/01/2023] [Indexed: 11/09/2023]
Abstract
The mammalian family of basic helix-loop-helix-PER-ARNT-SIM (bHLH-PAS) transcription factors possess the ability to sense and respond to diverse environmental and physiological cues. These proteins all share a common structural framework, comprising a bHLH domain, two PAS domains, and transcriptional activation or repression domain. To function effectively as transcription factors, members of the family must form dimers, bringing together bHLH segments to create a functional unit that allows for DNA response element binding. The significance of bHLH-PAS family is underscored by their involvement in many major human diseases, offering potential avenues for therapeutic intervention. Notably, the clear identification of ligand-binding cavities within their PAS domains enables the development of targeted small molecules. Two examples are Belzutifan, targeting hypoxia-inducible factor (HIF)-2α, and Tapinarof, targeting the aryl hydrocarbon receptor (AHR), both of which have gained regulatory approval recently. Here, we focus on the HIF subfamily. The crystal structures of all three HIF-α proteins have been elucidated, revealing their bHLH and tandem PAS domains are used to engage their dimerization partner aryl hydrocarbon receptor nuclear translocator (ARNT, also called HIF-1β). A broad range of recent findings point to a shared allosteric modulation mechanism among these proteins, whereby small-molecules at the PAS-B domains exert direct influence over the HIF-α transcriptional functions. As our understanding of the architectural and allosteric mechanisms of bHLH-PAS proteins continues to advance, the possibility of discovering new therapeutic drugs becomes increasingly promising.
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Affiliation(s)
- Jingjing Zhuang
- Marine College, Shandong University, Weihai 264209, China; Helmholtz International Lab, State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Qinghong Shang
- Helmholtz International Lab, State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Fraydoon Rastinejad
- Target Discovery Institute, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Oxford OX3 7FZ, UK.
| | - Dalei Wu
- Helmholtz International Lab, State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China.
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2
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Rastinejad F. The protein architecture and allosteric landscape of HNF4α. Front Endocrinol (Lausanne) 2023; 14:1219092. [PMID: 37732120 PMCID: PMC10507258 DOI: 10.3389/fendo.2023.1219092] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 08/01/2023] [Indexed: 09/22/2023] Open
Abstract
Hepatocyte nuclear factor 4 alpha (HNF4α) is a multi-faceted nuclear receptor responsible for governing the development and proper functioning of liver and pancreatic islet cells. Its transcriptional functions encompass the regulation of vital metabolic processes including cholesterol and fatty acid metabolism, and glucose sensing and control. Various genetic mutations and alterations in HNF4α are associated with diabetes, metabolic disorders, and cancers. From a structural perspective, HNF4α is one of the most comprehensively understood nuclear receptors due to its crystallographically observed architecture revealing interconnected DNA binding domains (DBDs) and ligand binding domains (LBDs). This review discusses key properties of HNF4α, including its mode of homodimerization, its binding to fatty acid ligands, the importance of post-translational modifications, and the mechanistic basis for allosteric functions. The surfaces linking HNF4α's DBDs and LBDs create a convergence zone that allows signals originating from any one domain to influence distant domains. The HNF4α-DNA complex serves as a prime illustration of how nuclear receptors utilize individual domains for specific functions, while also integrating these domains to create cohesive higher-order architectures that allow signal responsive functions.
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Affiliation(s)
- Fraydoon Rastinejad
- Nuffield Department of Medicine, Target Discovery Institute (NDMRB), University of Oxford, Oxford, United Kingdom
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3
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Rastinejad F. Retinoic acid receptor structures: the journey from single domains to full-length complex. J Mol Endocrinol 2022; 69:T25-T36. [PMID: 36069789 PMCID: PMC11376212 DOI: 10.1530/jme-22-0113] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 09/07/2022] [Indexed: 11/08/2022]
Abstract
The retinoic acid receptors (RARα, β, and γ) are multi-domain polypeptides that heterodimerize with retinoid X receptors (RXRα, β, and γ) to form functional transcription factors. Understanding the three-dimensional molecular organization of these nuclear receptors (NRs) began with RAR and RXR DNA-binding domains (DBDs), and were followed with studies on isolated ligand-binding domains (LBDs). The more complete picture emerged in 2017 with the multi-domain crystal structure of RXRα-RARβ on its response element with retinoic acid molecules and coactivator segments on both proteins. The analysis of that structure and its complementary studies have clarified the direct communication pathways within RXR-RAR polypeptides, through which DNA binding, protein-ligand, and protein-protein interactions are integrated for overall functional responses. Understanding the molecular connections in the RXR-RAR complex has benefited from direct observations of the multi-domain structures of RXRα-PPARγ, RXRα-LXRβ, HNF-4α homodimer, and androgen receptor homodimer, each bound to its response element. These comprehensive NR structures show unique quaternary architectures, yet all have DBD-DBD, LBD-LBD, and DBD-LBD domain-domain contacts within them. These convergence zones allow signals from discrete domains of their polypeptides to be propagated and integrated across their entire complex, shaping their overall responses in an allosteric fashion.
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Affiliation(s)
- Fraydoon Rastinejad
- Nuffield Department of Medicine, University of Oxford, Target Discovery Institute (NDM RB), Oxford, UK
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4
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Dayie TK, Olenginski LT, Taiwo KM. Isotope Labels Combined with Solution NMR Spectroscopy Make Visible the Invisible Conformations of Small-to-Large RNAs. Chem Rev 2022; 122:9357-9394. [PMID: 35442658 PMCID: PMC9136934 DOI: 10.1021/acs.chemrev.1c00845] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Indexed: 02/07/2023]
Abstract
RNA is central to the proper function of cellular processes important for life on earth and implicated in various medical dysfunctions. Yet, RNA structural biology lags significantly behind that of proteins, limiting mechanistic understanding of RNA chemical biology. Fortunately, solution NMR spectroscopy can probe the structural dynamics of RNA in solution at atomic resolution, opening the door to their functional understanding. However, NMR analysis of RNA, with only four unique ribonucleotide building blocks, suffers from spectral crowding and broad linewidths, especially as RNAs grow in size. One effective strategy to overcome these challenges is to introduce NMR-active stable isotopes into RNA. However, traditional uniform labeling methods introduce scalar and dipolar couplings that complicate the implementation and analysis of NMR measurements. This challenge can be circumvented with selective isotope labeling. In this review, we outline the development of labeling technologies and their application to study biologically relevant RNAs and their complexes ranging in size from 5 to 300 kDa by NMR spectroscopy.
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Affiliation(s)
- Theodore K. Dayie
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Lukasz T. Olenginski
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Kehinde M. Taiwo
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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5
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Sinnaeve D, Ben Bouzayene A, Ottoy E, Hofman GJ, Erdmann E, Linclau B, Kuprov I, Martins J, Torbeev V, Kieffer B. Fluorine NMR study of proline-rich sequences using fluoroprolines. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2021; 2:795-813. [PMID: 37905223 PMCID: PMC10539733 DOI: 10.5194/mr-2-795-2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/28/2021] [Indexed: 11/01/2023]
Abstract
Proline homopolymer motifs are found in many proteins; their peculiar conformational and dynamic properties are often directly involved in those proteins' functions. However, the dynamics of proline homopolymers is hard to study by NMR due to a lack of amide protons and small chemical shift dispersion. Exploiting the spectroscopic properties of fluorinated prolines opens interesting perspectives to address these issues. Fluorinated prolines are already widely used in protein structure engineering - they introduce conformational and dynamical biases - but their use as 19 F NMR reporters of proline conformation has not yet been explored. In this work, we look at model peptides where Cγ -fluorinated prolines with opposite configurations of the chiral Cγ centre have been introduced at two positions in distinct polyproline segments. By looking at the effects of swapping these (4R )-fluoroproline and (4S )-fluoroproline within the polyproline segments, we were able to separate the intrinsic conformational properties of the polyproline sequence from the conformational alterations instilled by fluorination. We assess the fluoroproline 19 F relaxation properties, and we exploit the latter in elucidating binding kinetics to the SH3 (Src homology 3) domain.
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Affiliation(s)
- Davy Sinnaeve
- Univ. Lille, Inserm, Institut Pasteur de Lille, CHU Lille, U1167 – Risk Factors and Molecular Determinants of
Aging-Related Diseases (RID-AGE), 59000 Lille, France
- CNRS, ERL9002 – Integrative Structural Biology, 59000 Lille, France
| | - Abir Ben Bouzayene
- Department of Integrative Structural Biology, IGBMC, University of Strasbourg, Inserm U1258, CNRS UMR 7104, 1 rue Laurent Fries, 67404
Illkirch, France
| | - Emile Ottoy
- Department of Organic and Macromolecular Chemistry, Ghent University,
Campus Sterre, S4, Krijgslaan 281, 9000 Ghent, Belgium
| | - Gert-Jan Hofman
- Department of Organic and Macromolecular Chemistry, Ghent University,
Campus Sterre, S4, Krijgslaan 281, 9000 Ghent, Belgium
- School of Chemistry, University of Southampton, Southampton SO17 1BJ,
United Kingdom
| | - Eva Erdmann
- Department of Integrative Structural Biology, IGBMC, University of Strasbourg, Inserm U1258, CNRS UMR 7104, 1 rue Laurent Fries, 67404
Illkirch, France
| | - Bruno Linclau
- School of Chemistry, University of Southampton, Southampton SO17 1BJ,
United Kingdom
| | - Ilya Kuprov
- School of Chemistry, University of Southampton, Southampton SO17 1BJ,
United Kingdom
| | - José C. Martins
- Department of Organic and Macromolecular Chemistry, Ghent University,
Campus Sterre, S4, Krijgslaan 281, 9000 Ghent, Belgium
| | - Vladimir Torbeev
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS),
International Center for Frontier Research in Chemistry (icFRC), University of Strasbourg,
CNRS UMR 7006, 67000 Strasbourg, France
| | - Bruno Kieffer
- Department of Integrative Structural Biology, IGBMC, University of Strasbourg, Inserm U1258, CNRS UMR 7104, 1 rue Laurent Fries, 67404
Illkirch, France
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6
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Chemo-enzymatic synthesis of 13C- and 19F-labeled uridine-5′-triphosphate for RNA NMR probing. MONATSHEFTE FUR CHEMIE 2021. [DOI: 10.1007/s00706-021-02757-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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7
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Becette OB, Zong G, Chen B, Taiwo KM, Case DA, Dayie TK. Solution NMR readily reveals distinct structural folds and interactions in doubly 13C- and 19F-labeled RNAs. SCIENCE ADVANCES 2020; 6:6/41/eabc6572. [PMID: 33028531 PMCID: PMC7541061 DOI: 10.1126/sciadv.abc6572] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 08/18/2020] [Indexed: 06/10/2023]
Abstract
RNAs form critical components of biological processes implicated in human diseases, making them attractive for small-molecule therapeutics. Expanding the sites accessible to nuclear magnetic resonance (NMR) spectroscopy will provide atomic-level insights into RNA interactions. Here, we present an efficient strategy to introduce 19F-13C spin pairs into RNA by using a 5-fluorouridine-5'-triphosphate and T7 RNA polymerase-based in vitro transcription. Incorporating the 19F-13C label in two model RNAs produces linewidths that are twice as sharp as the commonly used 1H-13C spin pair. Furthermore, the high sensitivity of the 19F nucleus allows for clear delineation of helical and nonhelical regions as well as GU wobble and Watson-Crick base pairs. Last, the 19F-13C label enables rapid identification of a small-molecule binding pocket within human hepatitis B virus encapsidation signal epsilon (hHBV ε) RNA. We anticipate that the methods described herein will expand the size limitations of RNA NMR and aid with RNA-drug discovery efforts.
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Affiliation(s)
- Owen B Becette
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20782, USA
| | - Guanghui Zong
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20782, USA
| | - Bin Chen
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20782, USA
| | - Kehinde M Taiwo
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20782, USA
| | - David A Case
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - T Kwaku Dayie
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20782, USA.
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8
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Metelev VG, Bogdanov AA. Synthesis and applications of theranostic oligonucleotides carrying multiple fluorine atoms. Theranostics 2020; 10:1391-1414. [PMID: 31938071 PMCID: PMC6956824 DOI: 10.7150/thno.37936] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 10/17/2019] [Indexed: 12/17/2022] Open
Abstract
The use of various oligonucleotide (ON) syntheses and post-synthetic strategies for targeted chemical modification enables improving their efficacy as potent modulators of gene expression levels in eukaryotic cells. However, the search still continues for new approaches designed for increasing internalization, lysosomal escape, and tissue specific delivery of ON. In this review we emphasized all aspects related to the synthesis and properties of ON derivatives carrying multifluorinated (MF) groups. These MF groups have unique physico-chemical properties because of their simultaneous hydrophobicity and lipophobicity. Such unusual combination of properties results in the overall modification of ON mode of interaction with the cells and making multi-fluorination highly relevant to the goal of improving potency of ON as components of new therapies. The accumulated evidence so far is pointing to high potential of ON probes, RNAi components and ON imaging beacons carrying single or multiple MF groups for improving the stability, specificity of interaction with biological targets and delivery of ONs in vitro and potentially in vivo.
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Affiliation(s)
- Valeriy G. Metelev
- Laboratory of Molecular Imaging Probes, Department of Radiology, University of Massachusetts Medical School, Worcester MA, USA
- Department of Chemistry, Moscow State University, Moscow, Russian Federation
| | - Alexei A. Bogdanov
- Laboratory of Molecular Imaging Probes, Department of Radiology, University of Massachusetts Medical School, Worcester MA, USA
- Laboratory of Molecular Imaging, A.N. Bakh Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow
- Department of Bioengineering and Bioinformatics, Moscow State University, Moscow
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9
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Silva-Nigenda E, Martínez-Gómez A, Cruz-de la Cruz J, Barroso-Flores J, González-Romero C, Fuentes-Benites A, Jankowski CK, Cuevas-Yáñez E, Díaz-Torres E, Corona-Becerril D. Long range 1H19F coupling through multiple bond in thienopyridines, isoquinolines and 2-aza-carbazoles derivatives. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2018.08.084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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Granqvist L, Virta P. 2'-O-[(4-CF3-triazol-1-yl)methyl] Uridine - A Sensitive (19)F NMR Sensor for the Detection of RNA Secondary Structures. J Org Chem 2015. [PMID: 26214588 DOI: 10.1021/acs.joc.5b00973] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A sensitive uridine-derived sensor (viz., 2'-O-[(4-CF3-triazol-1-yl)methyl]uridine, 1) for (19)F NMR spectroscopic monitoring of RNA secondary structures is described. The applicability of 1 is demonstrated by monitoring the thermal denaturation of the following double and triple helical RNA models: (1) a miR 215 hairpin, (2) a poly U-A*U triple helix RNA (bearing two C-G*C(H+) interrupts), and (3) a polyadenylated nuclear-nuclear retention element complex. In these RNA models, the (19)F NMR shift of the 2'-O-(CF3-triazolylmethyl) group shows high sensitivity to secondary structural arrangements. Moreover, 1 favors the desired N-conformation, and its effect on both RNA duplex and triplex stabilities is marginal.
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Affiliation(s)
- Lotta Granqvist
- Department of Chemistry, University of Turku, Turku 20014, Finland
| | - Pasi Virta
- Department of Chemistry, University of Turku, Turku 20014, Finland
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11
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Applying Thymine Isostere 2,4-Difluoro-5-Methylbenzene as a NMR Assignment Tool and Probe of Homopyrimidine/Homopurine Tract Structural Dynamics. Methods Enzymol 2015; 566:89-110. [PMID: 26791977 DOI: 10.1016/bs.mie.2015.05.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Proton assignment of nuclear magnetic resonance (NMR) spectra of homopyrimidine/homopurine tract oligonucleotides becomes extremely challenging with increasing helical length due to severe cross-peak overlap. As an alternative to the more standard practice of (15)N and (13)C labeling of oligonucleotides, here, we describe a method for assignment of highly redundant DNA sequences that uses single-site substitution of the thymine isostere 2,4-difluoro-5-methylbenzene (dF). The impact of this approach in facilitating the assignment of intractable spectra and analyzing oligonucleotide structure and dynamics is demonstrated using A-tract and TATA box DNA and two polypurine tract-containing RNA:DNA hybrids derived from HIV-1 and the Saccharomyces cerevisiae long-terminal repeat-containing retrotransposon Ty3. Only resonances proximal to the site of dF substitution exhibit sizable chemical shift changes, providing spectral dispersion while still allowing chemical shift mapping of resonances from unaffected residues distal to the site of modification directly back to the unmodified sequence. It is further illustrated that dF incorporation can subtly alter the conformation and dynamics of homopyrimidine/homopurine tract oligonucleotides, and how these NMR observations can be correlated, in the cases of the TATA box DNA, with modulation in the TATA box-binding protein interaction using an orthogonal gel assay.
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12
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Scott LG, Hennig M. ¹⁹F-Site-Specific-Labeled Nucleotides for Nucleic Acid Structural Analysis by NMR. Methods Enzymol 2015; 566:59-87. [PMID: 26791976 DOI: 10.1016/bs.mie.2015.05.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Naturally occurring RNA lacks fluorine-19 ((19)F), thus, their specifically fluorinated counterparts are particularly well suited to noninvasively monitoring the dynamic conformational properties and ligand-binding interactions of the RNA. For nuclear magnetic resonance (NMR) spectroscopy, (19)F-NMR of fluorine-substituted RNA provides an attractive, site-specific probe for structure determination in solution. Advantages of (19)F include high NMR sensitivity (83% of (1)H), high natural abundance (100%), and the extreme sensitivity of (19)F to the chemical environment leading to a large range of chemical shifts. The preparation of base-substituted 2-fluoropurine and 5-fluoropyrimidine 5'-triphosphates (2F-ATP/5F-CTP/5F-UTP) can be carried out using efficient enzymatic synthesis methods. Both pyrimidine analogs, 5-fluorouridine and 5-fluorocytidine, as well as, 2-fluoroadenosine are readily incorporated into RNA transcribed in vitro using T7 RNA polymerase.
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Affiliation(s)
| | - Mirko Hennig
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, USA.
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13
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Granqvist L, Virta P. 4'-C-[(4-trifluoromethyl-1H-1,2,3-triazol-1-yl)methyl]thymidine as a sensitive (19)F NMR sensor for the detection of oligonucleotide secondary structures. J Org Chem 2014; 79:3529-36. [PMID: 24678774 DOI: 10.1021/jo500326j] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
4'-C-[(4-Trifluoromethyl-1H-1,2,3-triazol-1-yl)methyl]thymidine was synthesized and incorporated as a phosphoramidite into oligonucleotide sequences. Its applicability as a sensor for the (19)F NMR spectroscopic detection of DNA and RNA secondary structures was demonstrated. On DNA, the (19)F NMR measurements were focused on monitoring of duplex-triplex conversion, for which this fluorine-labeled 2'-deoxynucleoside proved to be a powerful sensor. This sensor seemingly favors DNA, but its behavior in the RNA environment also turned out to be informative. As a demonstration, invasion of a 2'-O-methyl oligoribonucleotide into an RNA hairpin model (HIV-1 TAR) was monitored by (19)F NMR spectroscopy. According to the thermal denaturation studies by UV spectroscopy, the effect of the 4'-C-(4-trifluoromethyl-1H-1,2,3-triazol-1-yl)methyl moiety on the stability of these DNA and RNA models was marginal.
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Affiliation(s)
- Lotta Granqvist
- Department of Chemistry, University of Turku , 20014 Turku, Finland
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14
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Tanabe K, Tsuda T, Ito T, Nishimoto SI. Probing DNA mismatched and bulged structures by using 19F NMR spectroscopy and oligodeoxynucleotides with an 19F-labeled nucleobase. Chemistry 2013; 19:15133-40. [PMID: 24115235 DOI: 10.1002/chem.201302770] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Indexed: 12/19/2022]
Abstract
In this study, DNA local structures with bulged bases and mismatched base pairs as well as ordinary full-matched base pairs by using (19)F NMR spectroscopy with (19)F-labeled oligodeoxynucleotides (ODNs) were monitored. The chemical shift change in the (19) F NMR spectra allowed discrimination of the DNA structures. Two types of ODNs possessing the bis(trifluoromethyl)benzene unit (F-unit) at specified uridines were prepared and hybridized with their complementary or noncomplementary strands to form matched, mismatched, or bulged duplexes. By using ODN F1, in which an F-unit was connected directly to a propargyl amine-substituted uridine, three local structures, that is, full-matched, G-U mismatch, and A-bulge could be analyzed, whereas other structures could not be discriminated. A molecular modeling study revealed that the F-unit in ODN F1 interacted little with the nucleobases and sugar backbone of the opposite strand because the linker length between the F-unit and the uridine base was too short. Therefore, the capacity of ODN F1 to discriminate the DNA local structures was limited. Thus, ODN F2 was designed to improve this system; aminobenzoic acid was inserted between the F-unit and uridine base so the F-unit could interact more closely with the opposite strand. Eventually, the G-bulge and T-U mismatch and the three aforementioned local structures could be discriminated by using ODN F2. In addition, the dissociation processes of these duplexes could be monitored concurrently by (19)F NMR spectroscopy.
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Affiliation(s)
- Kazuhito Tanabe
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-8510 (Japan).
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15
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Di Pietro ME, Aroulanda C, Merlet D. GET-SERF, a new gradient encoded SERF experiment for the trivial edition of 1H-19F couplings. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 234:101-105. [PMID: 23860340 DOI: 10.1016/j.jmr.2013.06.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/14/2013] [Accepted: 06/18/2013] [Indexed: 06/02/2023]
Abstract
A new spatially encoded heteronuclear (1)H-(19)F selective refocusing NMR experiment (GET-SERF) is proposed. This sequence allows editing in one single 2D experiment all couplings between a selected fluorine site and all the proton nuclei of the molecule. Its efficiency is illustrated in the case of diflunisal, a difluorinated anti-inflammatory drug, in isotropic and anisotropic media.
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Affiliation(s)
- Maria Enrica Di Pietro
- Equipe de RMN en milieu orienté, ICMMO, UMR 8182, Université Paris-Sud. 15, Georges Clemenceau, Orsay, France
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16
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Kiviniemi A, Murtola M, Ingman P, Virta P. Synthesis of fluorine-labeled peptide nucleic acid building blocks as sensors for the 19F NMR spectroscopic detection of different hybridization modes. J Org Chem 2013; 78:5153-9. [PMID: 23638811 DOI: 10.1021/jo400014y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Peptide nucleic acid (PNA) building blocks, bearing a fluorine sensor at C-5 of the uracil base [viz. trifluoromethyl and 3,3-bis(trifluoromethyl)-4,4,4-trifluorobut-1-ynyl], were synthesized and incorporated to a PNA strand, and their applicability for the monitoring of different hybridization modes by (19)F NMR spectroscopy was studied. Both sensors gave unique (19)F resonance shifts in NMR when the PNA was targeted to a complementary antiparallel DNA, antiparallel RNA, parallel DNA, and parallel RNA. The 5-trifluoromethyl-derived sensor was additionally applied for the monitoring of interconversions from a parallel DNA/PNA complex to an antiparallel RNA/PNA complex and from a PNA/PNA complex to two DNA/PNA complexes (i.e., double-duplex invasion).
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Affiliation(s)
- Anu Kiviniemi
- Department of Chemistry, University of Turku, 20014 Turku, Finland
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17
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Nucleic Acid Based Fluorinated Derivatives: New Tools for Biomedical Applications. APPLIED SCIENCES-BASEL 2012. [DOI: 10.3390/app2020245] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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18
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Kiviniemi A, Virta P. Characterization of RNA invasion by (19)F NMR spectroscopy. J Am Chem Soc 2010; 132:8560-2. [PMID: 20521791 DOI: 10.1021/ja1014629] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
(19)F NMR spectroscopy offers an efficient tool for monitoring RNA invasion. The invasion of 2'-O-methyl oligoribonucleotides into a (19)F-labeled HIV-1 TAR RNA model and the temperature-dependent behavior of the complexes obtained have been examined.
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Affiliation(s)
- Anu Kiviniemi
- Department of Chemistry, University of Turku, FIN-20014 Turku, Finland
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19
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Monitoring of duplex and triplex formation by 19F NMR using oligodeoxynucleotides possessing 5-fluorodeoxyuridine unit as 19F signal transmitter. Bioorg Med Chem 2010; 18:6690-4. [PMID: 20729092 DOI: 10.1016/j.bmc.2010.07.066] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 07/27/2010] [Accepted: 07/28/2010] [Indexed: 11/22/2022]
Abstract
We prepared oligodeoxynucleotides (ODNs) possessing a 5-fluorodeoxyuridine (5-FU) unit as a 19F-signal transmitter, and characterized their structures including single strand, duplex, and triplex using 19F NMR. The change in chemical shift induced by incorporation of 5-FU into the ODNs and the formation of higher order structures allowed monitoring of structural changes. Data from UV melting experiments and CD spectra were consistent with the spectral changes in the NMR studies. These 19F-labeled ODNs may be promising molecular probes for the identification of DNA structures in complicated biological conditions.
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20
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Role of nuclear receptors in the modulation of insulin secretion in lipid-induced insulin resistance. Biochem Soc Trans 2008; 36:891-900. [PMID: 18793157 DOI: 10.1042/bst0360891] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In healthy individuals, a hyperbolic relationship exists between whole-body insulin-sensitivity and insulin secretion. Thus, for any difference in insulin-sensitivity, a reciprocal proportionate change occurs in insulin secretion. Such a feedback loop is evident in healthy individuals ingesting diets high in saturated fat and in late pregnancy where, despite lipid-induced insulin resistance, glucose tolerance is maintained through augmented GSIS (glucose-stimulated insulin secretion). NRs (nuclear receptors) are members of a superfamily of ligand-regulated and orphan transcription factors. On activation by a cognate ligand, many ligand-activated NRs recruit the RXR (retinoid X receptor) for heterodimer formation. Such NRs include the PPARs (peroxisome-proliferator-activated receptors), which are involved in lipid sensing and liporegulation. PPARs exert important lipid-lowering effects in vivo, thereby opposing the development of lipid-induced insulin resistance by relieving the inhibition of insulin-stimulated glucose disposal by muscle and lowering the necessity for augmented GSIS to counter lipid-induced insulin resistance. Long-chain fatty acids are proposed as natural PPAR ligands and some specific endogenous pathways of lipid metabolism are believed to generate PPAR agonists. Other NRs, e.g. the LXR (liver X receptor), which senses expansion of the metabolically active pool of cholesterol, and the FXR (farnesoid X receptor; NR1H4), which, like the LXR, is involved in sterol metabolism, also modulate systemic lipid levels and insulin-sensitivity. In this review, we discuss how these NRs impact insulin secretion via effects on the insulin-sensitivity-insulin secretion feedback loop and, in some cases, via direct effects on the islet itself. In addition, we discuss interactions between these nutrient/metabolite-responsive NRs and NRs that are central to the action of metabolically important hormones, including (i) the glucocorticoid receptor, critical for maintaining glucose homoeostasis in stress, inflammation and during fasting, and (ii) the thyroid hormone receptors, vital for maintenance of oxidative functions. We present data indicating that the RXR occupies a key role in directly modulating islet function and that its heterodimerization with at least two of its partners modulates GSIS.
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21
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Hennig M, Munzarova ML, Bermel W, Scott LG, Sklenar V, Williamson JR. Measurement of long-range 1H-19F scalar coupling constants and their glycosidic torsion dependence in 5-fluoropyrimidine-substituted RNA. J Am Chem Soc 2007; 128:5851-8. [PMID: 16637654 PMCID: PMC2556634 DOI: 10.1021/ja060165t] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Long-range scalar 5J(H1',F) couplings were observed in 5-fluoropyrimidine-substituted RNA. We developed a novel S3E-19F-alpha,beta-edited NOESY experiment for quantitation of these long-range scalar 5J(H1',F) couplings, where the J-couplings can be extracted from inspection of intraresidual (H1',H6) NOE cross-peaks. Quantum chemical calculations were exploited to investigate the relation between scalar couplings and conformations around the glycosidic bond in oligonucleotides. The theoretical dependence of the observed 5J(H1',F) couplings on the torsion angle chi can be described by a generalized Karplus relationship. The corresponding density functional theory (DFT) analysis is outlined. Additional NMR experiments facilitating the resonance assignments of 5-fluoropyrimidine-substituted RNAs are described, and chemical shift changes due to altered shielding in the presence of fluorine-19 (19F) are presented.
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Affiliation(s)
- Mirko Hennig
- Department of Molecular Biology and The Skaggs Institute of Chemical Biology, The Scripps Research Institute, MB 33, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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22
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Ennifar E, Bernacchi S, Wolff P, Dumas P. Influence of C-5 halogenation of uridines on hairpin versus duplex RNA folding. RNA (NEW YORK, N.Y.) 2007; 13:1445-52. [PMID: 17630326 PMCID: PMC1950758 DOI: 10.1261/rna.408507] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Halogenation of bases is a widespread method used for solving crystal structures of nucleic acids. However, this modification may have important consequences on RNA folding and thus on the success of crystallization. We have used a combination of UV thermal melting, steady-state fluorescence, X-ray crystallography, and gel electrophoresis techniques to study the influence of uridine halogenation (bromination or iodination) on the RNA folding. The HIV-1 Dimerization Initiation Site is an RNA hairpin that can adopt an alternative duplex conformation and was used as a model. We have shown that, unexpectedly, the RNA hairpin/duplex ratio is strongly dependent not only on the presence but also on the position of halogenation.
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Affiliation(s)
- Eric Ennifar
- Architecture et Réactivité de l'ARN, Université Louis Pasteur, CNRS UPR 9002, Strasbourg, France.
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23
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Kreutz C, Kählig H, Konrat R, Micura R. A General Approach for the Identification of Site-Specific RNA Binders by19F NMR Spectroscopy: Proof of Concept. Angew Chem Int Ed Engl 2006; 45:3450-3. [PMID: 16622887 DOI: 10.1002/anie.200504174] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Christoph Kreutz
- Leopold Franzens University, Institute of Organic Chemistry, Center for Molecular Biosciences, Innrain 52a, 6020 Innsbruck, Austria
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24
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Kreutz C, Kählig H, Konrat R, Micura R. Ein allgemeiner Ansatz zur Identifizierung ortsspezifisch bindender RNA-Liganden mittels19F-NMR-Spektroskopie – Bestätigung des Konzepts. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200504174] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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25
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Yu L, Hajduk PJ, Mack J, Olejniczak ET. Structural studies of Bcl-xL/ligand complexes using 19F NMR. JOURNAL OF BIOMOLECULAR NMR 2006; 34:221-7. [PMID: 16645812 DOI: 10.1007/s10858-006-0005-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Accepted: 01/11/2006] [Indexed: 05/08/2023]
Abstract
Fluorine atoms are often incorporated into drug molecules as part of the lead optimization process in order to improve affinity or modify undesirable metabolic and pharmacokinetic profiles. From an NMR perspective, the abundance of fluorinated drug leads provides an exploitable niche for structural studies using 19F NMR in the drug discovery process. As 19F has no interfering background signal from biological sources, 19F NMR studies of fluorinated drugs bound to their protein receptors can yield easily interpretable and unambiguous structural constraints. 19F can also be selectively incorporated into proteins to obtain additional constraints for structural studies. Despite these advantages, 19F NMR has rarely been exploited for structural studies due to its broad lines in macromolecules and their ligand complexes, leading to weak signals in 1H/19F heteronuclear NOE experiments. Here we demonstrate several different experimental strategies that use 19F NMR to obtain ligand-protein structural constraints for ligands bound to the anti-apoptotic protein Bcl-xL, a drug target for anti-cancer therapy. These examples indicate the applicability of these methods to typical structural problems encountered in the drug development process.
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Affiliation(s)
- Liping Yu
- Pharmaceutical Discovery Division, GPRD, Abbott Laboratories, Abbott Park, IL 60064-6098, USA
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26
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Abstract
The vitamin D receptor (VDR) is a member of the steroid and nuclear hormone receptor superfamily of eukaryotic transcription factors and binds target DNA, or response elements, as a homodimer or heterodimer with the 9-cis retinoid X receptor (RXR). In this chapter, we survey the current understanding of VDR-DNA interactions, emphasizing recent structural insights. We highlight the stereochemical interactions that dictate DNA binding and hexameric half-site sequence affinity as well as the protein-protein interactions that account for preferential binding to a direct repeat of half-sites with three base pairs of spacer DNA (DR3). In addition, we review alternative response element arrangements other than those with DR3. Finally, the chapter discusses the VDR DNA binding domain (DBD) and suggests that it violates classical canons because it does not heterodimerize with the RXR DBD. This unique behavior of VDR is considered in light of recent results demonstrating the formation of VDR DBD-DNA and DR3 DBD-DNA complexes with RXR using a mutant VDR protomer.
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Affiliation(s)
- Paul L Shaffer
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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27
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Kwon K, Jiang YL, Song F, Stivers JT. 19F NMR studies of vaccinia type IB topoisomerase. Conformational dynamics of the bound DNA substrate. J Biol Chem 2002; 277:353-8. [PMID: 11689573 DOI: 10.1074/jbc.m109450200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The site-specific DNA cleavage and religation activities of the vaccinia virus type IB topoisomerase at (C/T)CCTT(+1)X(-1) sites in duplex DNA have allowed detailed investigations of the chemical and conformational steps on the reaction pathway of this enzyme (see accompanying article (Kwon, K., and Stivers, J. T. (2002) J. Biol. Chem. 277, 345-352)). To extend these studies to the DNA substrate, we have performed 19F NMR experiments using substrates in which the +1 T has been replaced with the NMR-sensitive thymidine base analogue 5-fluoro-2'-deoxyuridine (5-F-dUrd). Substitution of 5-F-dUrd has little effect on the binding affinity of topoisomerase I for DNA, results in small changes in the cleavage and religation rate constants, and produces a net 3-fold decrease in the cleavage equilibrium constant as compared with the CCCTT consensus DNA. One-dimensional 19F NMR experiments show that the +1 5-F-dUrd is in a dynamic equilibrium between a stacked and unstacked state in both the noncovalent complex and the covalent phosphotyrosine complex. These NMR observations are supported by the selective sensitivity of the +1 T and +1 5-F-dUrd to KMnO4 oxidation. A role for localized DNA distortion in the topoisomerase I mechanism is suggested.
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Affiliation(s)
- Keehwan Kwon
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185, USA
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28
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Véliz EA, Stephens OM, Beal PA. Synthesis and analysis of RNA containing 6-trifluoromethylpurine ribonucleoside. Org Lett 2001; 3:2969-72. [PMID: 11554820 DOI: 10.1021/ol016295i] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the synthesis of a 5'-DMT-2'-TBDMS-protected phosphoramidite of 6-trifluoromethylpurine ribonucleoside ((TFM)P) and its use in the site-specific incorporation of 6-trifluoromethylpurine into RNA. Properties of (TFM)P-substituted RNA suggest it will be valuable in the study of RNA structure and the binding of RNA-modifying enzymes, particularly the RNA-editing adenosine deaminases. Reaction: see text.
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Affiliation(s)
- E A Véliz
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
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29
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Guckian KM, Krugh TR, Kool ET. Solution Structure of a Nonpolar, Non-Hydrogen-Bonded Base Pair Surrogate in DNA. J Am Chem Soc 2000; 122:6841-6847. [PMID: 20882115 PMCID: PMC2946154 DOI: 10.1021/ja994164v] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We describe the structure in aqueous solution of a DNA duplex containing a base pair that is structurally analogous to A-T but which lacks hydrogen bonds. Base analogues F (a nonpolar isostere of thymine) and Z (a nonpolar isostere of adenine) are paired opposite one another in a 12 base pair duplex. The sequence context is the binding site of recently studied transcription factor hSRY. The Z-F pair has been shown to be replicated surprisingly well and selectively by DNA polymerase enzymes, considering that it is destabilizing and lacks Watson-Crick hydrogen bonds. The enzymatic studies led to the suggestion that part of the functional activity arises because the pair resembles a natural one in geometry. The present results show that, despite the absence of Watson-Crick hydrogen bonds, the Z-F pair structurally resembles an A-T pair in the same context. This lends support to the proposal that shape matching is an important component in replication, and suggests the general utility of using Z-F as a nonpolar replacement for A-T in probing protein-DNA interactions.
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Affiliation(s)
- Kevin M. Guckian
- Contribution from the Department of Chemistry, University of Rochester, Rochester, New York 14627
| | - Thomas R. Krugh
- Contribution from the Department of Chemistry, University of Rochester, Rochester, New York 14627
| | - Eric T. Kool
- To whom correspondence should be addressed. T. R. Krugh, . E. T. Kool,
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30
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Synthesis of indole-ring fluorine-labeled analogs of LY333531, an isoform-selective inhibitor of protein kinase C. J Fluor Chem 1999. [DOI: 10.1016/s0022-1139(99)00095-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Zhang QS, Shen L, Wang ED, Wang YL. Biosynthesis and characterization of 4-fluorotryptophan-labeled Escherichia coli arginyl-tRNA synthetase. JOURNAL OF PROTEIN CHEMISTRY 1999; 18:187-92. [PMID: 10333292 DOI: 10.1023/a:1020675922382] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Escherichia coli 4-fluorotryptophan-substituted arginyl-tRNA synthetase was biosynthetically prepared and purified from a tryptophan auxotroph which could overproduce this enzyme. A method was developed to separate 4-fluorotryptophan from tryptophan and to determine accurately their contents in the 4-fluorotryptophan-containing proteins. It was confirmed that more than 95% of the tryptophan residues in the purified 4-fluorotryptophan-substituted arginyl-tRNA synthetase were replaced by 4-fluorotryptophan. Studies on the effect of the 4-fluorotryptophan replacement on properties of the enzyme showed that, when compared with the native enzyme, both the specific activity and the first-order rate constant of the fluorinated enzyme decreased by approximately 20% with just slightly higher Km values. CD studies, however, did not reveal any difference between the secondary structure of the native and fluorinated enzymes. In addition, thermal unfolding studies showed that the 4-fluorotryptophan replacement did not significantly affect the thermal stability of the enzyme. We may conclude that the substitution of 4-fluorotryptophan in arginyl-tRNA synthetase had no substantial effect on the structure and function of the enzyme. Finally, a preliminary study of 19F nuclear magnetic resonance spectroscopy of the fluorinated enzyme has shown promising prospect for further investigation of its structure and function with NMR.
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Affiliation(s)
- Q S Zhang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry, Academia Sinica, PR China
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32
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Guckian KM, Krugh TR, Kool ET. Solution structure of a DNA duplex containing a replicable difluorotoluene-adenine pair. NATURE STRUCTURAL BIOLOGY 1998; 5:954-9. [PMID: 9808039 DOI: 10.1038/2930] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A nonpolar aromatic nucleoside derivative based on 2,4-difluorotoluene (F), a non-hydrogen bonding shape analog of thymidine, was recently shown to be replicated against adenine with high efficiency and fidelity. This led to the suggestion that geometric matching, potentially even in the absence of hydrogen bonding between bases in a pair, may be sufficient to direct nucleotide selection during replication. We have examined the solution structure of the F-A pair in the context of a 12 base pair DNA duplex. We find that, despite the destabilization caused by this analog, the F-A pair very closely resembles that of a T x A pair in the same context. This lends support to the importance of shape matching in replication.
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Affiliation(s)
- K M Guckian
- Department of Chemistry, University of Rochester, New York 14627, USA
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33
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Klimasauskas S, Szyperski T, Serva S, Wüthrich K. Dynamic modes of the flipped-out cytosine during HhaI methyltransferase-DNA interactions in solution. EMBO J 1998; 17:317-24. [PMID: 9427765 PMCID: PMC1170382 DOI: 10.1093/emboj/17.1.317] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Flipping of a nucleotide out of a B-DNA helix into the active site of an enzyme has been observed for the HhaI and HaeIII cytosine-5 methyltransferases (M.HhaI and M.HaeIII) and for numerous DNA repair enzymes. Here we studied the base flipping motions in the binary M. HhaI-DNA and the ternary M.HhaI-DNA-cofactor systems in solution. Two 5-fluorocytosines were introduced into the DNA in the places of the target cytosine and, as an internal control, a cytosine positioned two nucleotides upstream of the recognition sequence 5'-GCGC-3'. The 19F NMR spectra combined with gel mobility data show that interaction with the enzyme induces partition of the target base among three states, i.e. stacked in the B-DNA, an ensemble of flipped-out forms and the flipped-out form locked in the enzyme active site. Addition of the cofactor analogue S-adenosyl-L-homocysteine greatly enhances the trapping of the target cytosine in the catalytic site. Distinct dynamic modes of the target cytosine have thus been identified along the reaction pathway, which includes novel base-flipping intermediates that were not observed in previous X-ray structures. The new data indicate that flipping of the target base out of the DNA helix is not dependent on binding of the cytosine in the catalytic pocket of M.HhaI, and suggest an active role of the enzyme in the opening of the DNA duplex.
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34
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Danielson MA, Falke JJ. Use of 19F NMR to probe protein structure and conformational changes. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 1996; 25:163-95. [PMID: 8800468 PMCID: PMC2899692 DOI: 10.1146/annurev.bb.25.060196.001115] [Citation(s) in RCA: 248] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
19F NMR has proven to be a powerful technique in the study of protein structure and dynamics because the 19F nucleus is easily incorporated at specific labeling sites, where it provides a relatively nonperturbing yet sensitive probe with no background signals. Recent applications of 19F NMR in mapping out structural and functional features of proteins, including the galactose-binding protein, the transmembrane aspartate receptor, the CheY protein, dihydrofolate reductase, elongation factor-Tu, and D-lactose dehydrogenase, illustrate the utility of 19F NMR in the analysis of protein conformational states even in molecules too large or unstable for full NMR structure determination. These studies rely on the fact that the chemical shift of 19F is extremely sensitive to changes in the local conformational environment, including van der Waals packing interactions and local electrostatic fields. Additional information is provided by solvent-induced isotope shifts or line broadening of the 19F resonance by aqueous and membrane-bound paramagnetic probes, which may reveal the proximity of a 19F label to bulk solvent or a biological membrane. Finally, the effect of exchanging conformations on the 19F resonance can directly determine the kinetic parameters of the conformational transition.
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Affiliation(s)
- M A Danielson
- Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215, USA
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