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Robinson J, Stenspil SG, Maleckaite K, Bartlett M, Di Antonio M, Vilar R, Kuimova MK. Cellular Visualization of G-Quadruplex RNA via Fluorescence- Lifetime Imaging Microscopy. J Am Chem Soc 2024; 146:1009-1018. [PMID: 38151240 PMCID: PMC10786036 DOI: 10.1021/jacs.3c11908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/06/2023] [Accepted: 12/07/2023] [Indexed: 12/29/2023]
Abstract
Over the past decade, appreciation of the roles of G-quadruplex (G4) structures in cellular regulation and maintenance has rapidly grown, making the establishment of robust methods to visualize G4s increasingly important. Fluorescent probes are commonly used for G4 detection in vitro; however, achieving sufficient selectivity to detect G4s in a dense and structurally diverse cellular environment is challenging. The use of fluorescent probes for G4 detection is further complicated by variations of probe uptake into cells, which may affect fluorescence intensity independently of G4 abundance. In this work, we report an alternative small-molecule approach to visualize G4s that does not rely on fluorescence intensity switch-on and, thus, does not require the use of molecules with exclusive G4 binding selectivity. Specifically, we have developed a novel thiazole orange derivative, TOR-G4, that exhibits a unique fluorescence lifetime when bound to G4s compared to other structures, allowing G4 binding to be sensitively distinguished from non-G4 binding, independent of the local probe concentration. Furthermore, TOR-G4 primarily colocalizes with RNA in the cytoplasm and nucleoli of cells, making it the first lifetime-based probe validated for exploring the emerging roles of RNA G4s in cellulo.
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Affiliation(s)
- Jenna Robinson
- Department
of Chemistry, Molecular Science Research Hub, Imperial College London, 82 Wood Lane, London W12
0BZ, U.K.
- Molecular
Science Research Hub, Institute of Chemical
Biology, 82 Wood Lane, London W12 0BZ, U.K.
- The
Francis Crick Institute, 1 Midland Road, London NW1 1AT, U.K.
| | - Stine G. Stenspil
- Department
of Chemistry, Molecular Science Research Hub, Imperial College London, 82 Wood Lane, London W12
0BZ, U.K.
| | - Karolina Maleckaite
- Department
of Chemistry, Molecular Science Research Hub, Imperial College London, 82 Wood Lane, London W12
0BZ, U.K.
| | - Molly Bartlett
- Department
of Chemistry, Molecular Science Research Hub, Imperial College London, 82 Wood Lane, London W12
0BZ, U.K.
| | - Marco Di Antonio
- Department
of Chemistry, Molecular Science Research Hub, Imperial College London, 82 Wood Lane, London W12
0BZ, U.K.
- Molecular
Science Research Hub, Institute of Chemical
Biology, 82 Wood Lane, London W12 0BZ, U.K.
- The
Francis Crick Institute, 1 Midland Road, London NW1 1AT, U.K.
| | - Ramon Vilar
- Department
of Chemistry, Molecular Science Research Hub, Imperial College London, 82 Wood Lane, London W12
0BZ, U.K.
- Molecular
Science Research Hub, Institute of Chemical
Biology, 82 Wood Lane, London W12 0BZ, U.K.
| | - Marina K. Kuimova
- Department
of Chemistry, Molecular Science Research Hub, Imperial College London, 82 Wood Lane, London W12
0BZ, U.K.
- Molecular
Science Research Hub, Institute of Chemical
Biology, 82 Wood Lane, London W12 0BZ, U.K.
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2
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Sato Y, Aiba Y, Yajima S, Tanabe T, Higuchi K, Nishizawa S. Strong Binding and Off–On Signaling Functions of Deep‐Red Fluorescent TO‐PRO‐3 for Influenza A Virus RNA Promoter Region. Chembiochem 2019; 20:2752-2756. [DOI: 10.1002/cbic.201900331] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Yusuke Sato
- Department of ChemistryGraduate School of ScienceTohoku University Sendai 980-8578 Japan
| | - Yuri Aiba
- Department of ChemistryGraduate School of ScienceTohoku University Sendai 980-8578 Japan
| | - Sayaka Yajima
- Department of ChemistryGraduate School of ScienceTohoku University Sendai 980-8578 Japan
| | - Takaaki Tanabe
- Department of ChemistryGraduate School of ScienceTohoku University Sendai 980-8578 Japan
| | - Kei Higuchi
- Department of ChemistryGraduate School of ScienceTohoku University Sendai 980-8578 Japan
| | - Seiichi Nishizawa
- Department of ChemistryGraduate School of ScienceTohoku University Sendai 980-8578 Japan
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3
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Sato Y, Yajima S, Taguchi A, Baba K, Nakagomi M, Aiba Y, Nishizawa S. Trimethine cyanine dyes as deep-red fluorescent indicators with high selectivity to the internal loop of the bacterial A-site RNA. Chem Commun (Camb) 2019; 55:3183-3186. [DOI: 10.1039/c9cc00414a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We report that TO-PRO-3 functions as a deep-red fluorescent indicator for the internal loop structure of the bacterial (Escherichia coli) A-site, which enables the assessment of A-site binding capability of various test compounds including blue and even-green-emitting compounds.
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Affiliation(s)
- Yusuke Sato
- Department of Chemistry
- Graduate School of Science
- Tohoku University
- Sendai 980-8578
- Japan
| | - Sayaka Yajima
- Department of Chemistry
- Graduate School of Science
- Tohoku University
- Sendai 980-8578
- Japan
| | - Akifumi Taguchi
- Department of Chemistry
- Graduate School of Science
- Tohoku University
- Sendai 980-8578
- Japan
| | - Kyosuke Baba
- Department of Chemistry
- Graduate School of Science
- Tohoku University
- Sendai 980-8578
- Japan
| | - Mayu Nakagomi
- Department of Chemistry
- Graduate School of Science
- Tohoku University
- Sendai 980-8578
- Japan
| | - Yuri Aiba
- Department of Chemistry
- Graduate School of Science
- Tohoku University
- Sendai 980-8578
- Japan
| | - Seiichi Nishizawa
- Department of Chemistry
- Graduate School of Science
- Tohoku University
- Sendai 980-8578
- Japan
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4
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Schulte LN, Heinrich B, Janga H, Schmeck BT, Vázquez O. A Far‐Red Fluorescent DNA Binder for Interaction Studies of Live Multidrug‐Resistant Pathogens and Host Cells. Angew Chem Int Ed Engl 2018; 57:11564-11568. [DOI: 10.1002/anie.201804090] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Leon N. Schulte
- Institute for Lung ResearchPhilipps-Universität Marburg Hans-Meerwein-Strasse 2 35043 Marburg Germany
| | - Benedikt Heinrich
- Fachbereich ChemiePhilipps-Universität Marburg Hans-Meerwein-Strasse 4 35043 Marburg Germany
| | - Harshavardhan Janga
- Institute for Lung ResearchPhilipps-Universität Marburg Hans-Meerwein-Strasse 2 35043 Marburg Germany
| | - Bernd T. Schmeck
- Institute for Lung ResearchPhilipps-Universität Marburg Hans-Meerwein-Strasse 2 35043 Marburg Germany
- Member of the German Center for Lung Research (DZL) Germany
| | - Olalla Vázquez
- Fachbereich ChemiePhilipps-Universität Marburg Hans-Meerwein-Strasse 4 35043 Marburg Germany
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5
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Schulte LN, Heinrich B, Janga H, Schmeck BT, Vázquez O. A Far-Red Fluorescent DNA Binder for Interaction Studies of Live Multidrug-Resistant Pathogens and Host Cells. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201804090] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Leon N. Schulte
- Institute for Lung Research; Philipps-Universität Marburg; Hans-Meerwein-Strasse 2 35043 Marburg Germany
| | - Benedikt Heinrich
- Fachbereich Chemie; Philipps-Universität Marburg; Hans-Meerwein-Strasse 4 35043 Marburg Germany
| | - Harshavardhan Janga
- Institute for Lung Research; Philipps-Universität Marburg; Hans-Meerwein-Strasse 2 35043 Marburg Germany
| | - Bernd T. Schmeck
- Institute for Lung Research; Philipps-Universität Marburg; Hans-Meerwein-Strasse 2 35043 Marburg Germany
- Member of the German Center for Lung Research (DZL); Germany
| | - Olalla Vázquez
- Fachbereich Chemie; Philipps-Universität Marburg; Hans-Meerwein-Strasse 4 35043 Marburg Germany
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6
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Novel Naphthalimide Derivatives as Selective G-Quadruplex DNA Binders. Appl Biochem Biotechnol 2018; 186:547-562. [PMID: 29671192 DOI: 10.1007/s12010-018-2749-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/25/2018] [Indexed: 01/08/2023]
Abstract
A new derivate of 4-bromo-1,8-naphthalic anhydride and its quaternized analogue have been prepared and characterized. The interactions of both derivatives with human telomere quadruplex-DNA and ds-DNA have been comparatively studied by UV-visible (UV-Vis), fluorescent intercalator displacement assays, competition dialysis, circular dichroism (CD), agarose gel electrophoresis, and polyacrylamide gel electrophoresis. The results show that both derivatives can stabilize G-quadruplexes DNA, and they show different binding affinities for G-quadruplexes-DNA and ds-DNA. All spectroscopic studies have shown that the derivatives have a modest selectivity for G-quadruplex versus ds-DNA.
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7
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Górecki M, Zinna F, Biver T, Di Bari L. Induced circularly polarized luminescence for revealing DNA binding with fluorescent dyes. J Pharm Biomed Anal 2017; 144:6-11. [DOI: 10.1016/j.jpba.2017.02.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 01/13/2017] [Accepted: 02/04/2017] [Indexed: 11/28/2022]
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8
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Pei X, Huang H, Chen Y, Li C, Liu F, Li N. Modulating fluorescence anisotropy of dye-labeled DNA without involving mass amplification. Talanta 2016; 154:567-73. [DOI: 10.1016/j.talanta.2016.01.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 01/05/2016] [Accepted: 01/08/2016] [Indexed: 11/25/2022]
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9
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Okamoto A. Thiazole Orange-Tethered Nucleic Acids and ECHO Probes for Fluorometric Detection of Nucleic Acids. MODIFIED NUCLEIC ACIDS 2016. [DOI: 10.1007/978-3-319-27111-8_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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10
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Wang L, Tao M, Zhang G, Li S, Gong D. Partial intercalative binding of the food colorant erythrosine to herring sperm DNA. RSC Adv 2015. [DOI: 10.1039/c5ra19626d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Erythrosine partially inserts into the G–C rich region of hsDNA and induces moderate conformational perturbation of the DNA.
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Affiliation(s)
- Langhong Wang
- State Key Laboratory of Food Science and Technology
- Nanchang University
- Nanchang 330047
- China
| | - Mo Tao
- State Key Laboratory of Food Science and Technology
- Nanchang University
- Nanchang 330047
- China
| | - Guowen Zhang
- State Key Laboratory of Food Science and Technology
- Nanchang University
- Nanchang 330047
- China
| | - Song Li
- State Key Laboratory of Food Science and Technology
- Nanchang University
- Nanchang 330047
- China
| | - Deming Gong
- School of Biological Sciences
- The University of Auckland
- Auckland 1142
- New Zealand
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11
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Spectroscopic and Chemometrics Analysis of the Hydrolytic Process of Folpet and Its Interaction with DNA. J SOLUTION CHEM 2014. [DOI: 10.1007/s10953-014-0211-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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12
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Cheng Z, Liu R, Jiang X. Spectroscopic studies on the interaction between tetrandrine and two serum albumins by chemometrics methods. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 115:92-105. [PMID: 23831983 DOI: 10.1016/j.saa.2013.06.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Revised: 05/31/2013] [Accepted: 06/04/2013] [Indexed: 06/02/2023]
Abstract
The binding interactions of tetrandrine (TETD) with bovine serum albumin (BSA) and human serum albumin (HSA) have been investigated by spectroscopic methods. These experimental data were further analyzed using multivariate curve resolution-alternating least squares (MCR-ALS) method, and the concentration profiles and pure spectra for three species (BSA/HSA, TETD and TETD-BSA/HSA) existed in the interaction procedure, as well as, the apparent equilibrium constants Kapp were evaluated. The binding sites number n and the binding constants K were obtained at various temperatures. The binding distance between TETD and BSA/HSA was 1.455/1.451nm. The site markers competitive experiments indicated that TETD primarily bound to the tryptophan residue of BSA/HSA within site I. The thermodynamic parameters (ΔG, ΔH and ΔS) calculated on the basis of different temperatures revealed that the binding of TETD-BSA was mainly depended on the hydrophobic interaction strongly and electrostatic interaction, and yet the binding of TETD-HSA was strongly relied on the hydrophobic interaction. The results of synchronous fluorescence, 3D fluorescence and FT-IR spectra show that the conformation of proteins has altered in the presence of TETD. In addition, the effect of some common ions on the binding constants between TETD and proteins were also discussed.
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Affiliation(s)
- Zhengjun Cheng
- Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637002, China.
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13
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Alves GMS, Magalhães JMCS, Tauler R, Soares HMVM. Simultaneous Anodic Stripping Voltammetric Determination of Pb and Cd, Using a Vibrating Gold Microwire Electrode, Assisted by Chemometric Techniques. ELECTROANAL 2013. [DOI: 10.1002/elan.201300198] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Hayashi G, Okamoto A. Probe design for the effective fluorescence imaging of intracellular RNA. CHEM REC 2013; 13:209-17. [PMID: 23495145 DOI: 10.1002/tcr.201200026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Indexed: 01/18/2023]
Abstract
Over the past two decades, the spatiotemporal analysis of fluorescently labeled single RNA species has provided a broad insight into the synthesis, localization, degradation, and transport of RNA. To elucidate the dynamic behavior of functional RNAs in living cells, researchers throughout the world have proposed numerous fluorometric strategies for intracellular RNA imaging. Because, like most other biological molecules, RNA is intrinsically nonfluorescent, the development of methods for the labeling of RNAs of interest with fluorescent molecules is essential. Several artificial tag sequences have been attached onto the 3' end of target RNAs and used as scaffolds for interacting with their fluorescent counterparts. In this Personal Account, we focus on the methods that have been developed to show how RNAs expressed in cells can be labeled and visualized by fluorescent proteins, small molecules, or nucleic acids. Each of these methods is designed to increase the sensitivity and specificity for imaging or to decrease the background fluorescence.
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Affiliation(s)
- Gosuke Hayashi
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Tokyo 153-8904, Japan
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15
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Ahmadi S, Deligeorgiev TG, Vasilev A, Kubista M. The dimerization study of some cationic monomethine cyanine dyes by chemometrics method. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2012. [DOI: 10.1134/s0036024412130201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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16
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Okamoto A. ECHO probes: a concept of fluorescence control for practical nucleic acid sensing. Chem Soc Rev 2011; 40:5815-28. [PMID: 21660343 DOI: 10.1039/c1cs15025a] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
An excitonic interaction caused by the H-aggregation of fluorescent dyes is a new type of useful photophysical process for fluorescence-controlled nucleic acid sensing. This critical review points out the recent advances in exciton-controlled hybridization-sensitive fluorescent oligonucleotide (ECHO) probes, which have a fluorescence-labeled nucleotide in which two molecules of thiazole orange or its derivatives are linked covalently. ECHO probes show absorption shift and emission switching depending on hybridization with the target nucleic acid. The hybridization-sensitive fluorescence emission of ECHO probes and the further modification of probes have made possible a variety of practical applications, such as multicolor RNA imaging in living cells and facile detection of gene polymorphism (144 references).
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Affiliation(s)
- Akimitsu Okamoto
- RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan.
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Nakayama S, Kelsey I, Wang J, Roelofs K, Stefane B, Luo Y, Lee VT, Sintim HO. Thiazole orange-induced c-di-GMP quadruplex formation facilitates a simple fluorescent detection of this ubiquitous biofilm regulating molecule. J Am Chem Soc 2011; 133:4856-64. [PMID: 21384923 DOI: 10.1021/ja1091062] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Recently, there has been an explosion of research activities in the cyclic dinucleotides field. Cyclic dinucleotides, such as c-di-GMP and c-di-AMP, have been shown to regulate bacterial virulence and biofilm formation. c-di-GMP can exist in different aggregate forms, and it has been demonstrated that the polymorphism of c-di-GMP is influenced by the nature of cation that is present in solution. In previous work, polymorphism of c-di-GMP could only be demonstrated at hundreds of micromolar concentrations of the dinucleotide, and it has been a matter of debate if polymorphism of c-di-GMP exists under in vivo conditions. In this Article, we demonstrate that c-di-GMP can form G-quadruplexes at low micromolar concentrations when aromatic molecules such as thiazole orange template the quadruplex formation. We then use this property of aromatic molecule-induced G-quadruplex formation of c-di-GMP to design a thiazole orange-based fluorescent detection of this important signaling molecule. We determine, using this thiazole orange assay on a crude bacterial cell lysate, that WspR D70E (a constitutively activated diguanylate cyclase) is functional in vivo when overexpressed in E. Coli . The intracellular concentration of c-di-GMP in an E. Coli cell that is overexpressed with WspR D70E is very high and can reach 2.92 mM.
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Affiliation(s)
- Shizuka Nakayama
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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18
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Interference with spectrophotometric analysis of nucleic acids and proteins by leaching of chemicals from plastic tubes. Biotechniques 2010; 48:297-302. [PMID: 20569206 DOI: 10.2144/000113387] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Absorbance spectroscopy is routinely used to monitor the concentrations of nucleic acids and proteins within solutions and to assess changes in their structure caused by interaction with chemicals or other biomolecules. Biological samples used for such analyses are manipulated and stored in small microcentrifuge tubes (microtubes) composed of polypropylene plus several plastic additives. Here we demonstrate that normal handling of laboratory microtubes causes leaching of light-absorbing chemicals into biological samples that interfere with spectrophotometric measurements. The leached chromophores absorbed UV light strongly at 220 and 260 nm, which are the wavelengths normally used to detect and quantitate proteins and DNA. Some common laboratory techniques, including sonication and PCR, were particularly effective inducers of leaching. The magnitude of the increase in absorbance was dependent upon both exposure time and heat history, with greatest induction after tubes were warmed to temperatures at or above 37 degrees C. Mass spectrometry revealed that aqueous solutions stored in plastic microtubes accumulate a complex mixture of leached chemicals with molecular masses of 200-1400 Da. Leaching was ubiquitous among commercially available brands of microtubes, indicating a persistent source of error in biomolecule detection and concentration measurements.
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19
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Towards a fluorescent molecular switch for nucleic acid biosensing. Anal Bioanal Chem 2010; 398:1605-14. [DOI: 10.1007/s00216-010-3794-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 04/26/2010] [Indexed: 10/19/2022]
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20
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Passeri R, Aloisi GG, Elisei F, Latterini L, Caronna T, Fontana F, Sora IN. Photophysical properties of N-alkylated azahelicene derivatives as DNA intercalators: counterion effects. Photochem Photobiol Sci 2009; 8:1574-82. [PMID: 19862416 DOI: 10.1039/b9pp00015a] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, three compounds having the same organic moiety (N-methyl-5-azahelicenium salts) but different counterions (I-, NO3- and COOCF3-) have been investigated in buffered aqueous solutions and in the presence of DNA to give information on the counterion effects on the binding. In particular, the absorption spectra, fluorescence quantum yields and fluorescence lifetimes in aqueous solution for free organic molecules have been determined by steady-state and time-resolved spectrofluorimetric measurements. The obtained values are compared with those of the chromophores in the presence of increasing concentrations of DNA. The results allow determination of the association constants (K(a)) and the number of base couples per chromophore molecule (n) by means of the McGhee Von Hippel model. The binding parameters are strongly affected by the nature of counterions since the highest K(a) value was determined for the compound having COOCF3-; on the other hand the NO3- derivative is able to interact with the highest number of binding sites. The morphology and structural properties of the DNA-chromophore complexes were investigated by circular dichroism (CD) and atomic force microscopy (AFM). The data revealed that I- and COOCF3- derivatives preferentially form intercalation complexes, while the NO3- salt is able to form intercalation and grove binding complexes at the same time.
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Affiliation(s)
- Rosita Passeri
- Dipartimento di Chimica and Centro di Eccellenza Materiali Innovativi Nanostrutturati (CEMIN), Università di Perugia, Via Elce di Sotto, 8, 06123, Perugia, Italy
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