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Shanmugavel A, Rene ER, Balakrishnan SP, Krishnakumar N, Jose SP. Heavy metal ion sensing strategies using fluorophores for environmental remediation. ENVIRONMENTAL RESEARCH 2024:119544. [PMID: 38969312 DOI: 10.1016/j.envres.2024.119544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 05/27/2024] [Accepted: 07/01/2024] [Indexed: 07/07/2024]
Abstract
The main aim of this review is to provide an extensive summary of the latest advances within the emerging research area focused on detecting heavy metal ion pollution, particularly sensing strategies. The review explores various heavy metal ion detection approaches, encompassing spectrometry, electrochemical methods, and optical techniques. Numerous initiatives have been undertaken in recent times in response to the increasing demand for fast, sensitive, and selective sensors. Notably, fluorescent sensors have acquired prominence owing to the numerous advantages such as outstanding specificity, reversibility, and sensitivity. Further, it also explores the discussion of various nanomaterials employed in sensing heavy metal ions. In this regard, the exclusive emphasis is placed on fluorescent nanomaterials based on organic dyes, quantum dots, and fluorescent aptasensors for metal ion removal from aqueous systems to identify the destiny of dangerous heavy metal ions in clean circumstances.
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Affiliation(s)
- Abinaya Shanmugavel
- School of Physics, Madurai Kamaraj University, Madurai, 625021, Tamil Nadu, India
| | - Eldon R Rene
- Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft Institute for Water Education, Westvest 7, 2601DA, Delft, The Netherlands
| | | | | | - Sujin P Jose
- School of Physics, Madurai Kamaraj University, Madurai, 625021, Tamil Nadu, India.
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2
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K G, Verma A, Mondal P, Mandal SS. Molecular contacts in the Cren7-DNA complex: A quantitative investigation for electrostatic interaction. Biophys J 2023; 122:1701-1719. [PMID: 37016575 PMCID: PMC10183371 DOI: 10.1016/j.bpj.2023.03.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 02/15/2023] [Accepted: 03/29/2023] [Indexed: 04/06/2023] Open
Abstract
The molecular association of proteins with nucleic acids leading to the formation of macromolecular complexes is a crucial step in several biological processes. Stabilization of these complexes involves electrostatic interactions between ion pairs (salt bridges) of nucleic acid phosphates and protein side chains. The crenarchaeal DNA binding protein, Cren7 plays a key role in the regulation of chromosomal structure and gene expression in eukaryotic extremophiles. However, the molecular contacts that occur at the interface of protein-DNA complexes and their contribution to the electrostatic interaction have not been fully elucidated. This work presents a quantitative description of the mechanism of the electrostatic interaction between the protein and DNA. We have identified a few residues located at the Cren7-DNA interface that could potentially be responsible for the interaction. Structural studies using circular dichroism indicate mutation of these surface residues minimally affect their structure and stability. The binding affinity of these mutants for the DNA duplexes was examined from reverse titration, biolayer interferometry, and fluorescence anisotropy measurements with calf thymus DNA, polynucleotides, and small DNA oligonucleotides. The resulting kinetic parameters highlight a difference in electrostatic interactions potentials exhibited by residues positioned at different locations of the protein-DNA interface. Computational studies attribute this difference to their surrounding atmosphere and energetic stabilization parameters. The biophysical approach described here can be extended for other proteins that play a crucial role in DNA bending and compaction, to properly evaluate the role of specific residues on the mechanisms of DNA binding.
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Affiliation(s)
- Geethika K
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati, Andhra Pradesh, India
| | - Arunima Verma
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati, Andhra Pradesh, India
| | - Padmabati Mondal
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati, Andhra Pradesh, India.
| | - Soumit S Mandal
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati, Andhra Pradesh, India.
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3
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A bacteriophage mimic of the bacterial nucleoid-associated protein Fis. Biochem J 2020; 477:1345-1362. [PMID: 32207815 PMCID: PMC7166090 DOI: 10.1042/bcj20200146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/19/2020] [Accepted: 03/24/2020] [Indexed: 11/17/2022]
Abstract
We report the identification and characterization of a bacteriophage λ-encoded protein, NinH. Sequence homology suggests similarity between NinH and Fis, a bacterial nucleoid-associated protein (NAP) involved in numerous DNA topology manipulations, including chromosome condensation, transcriptional regulation and phage site-specific recombination. We find that NinH functions as a homodimer and is able to bind and bend double-stranded DNA in vitro. Furthermore, NinH shows a preference for a 15 bp signature sequence related to the degenerate consensus favored by Fis. Structural studies reinforced the proposed similarity to Fis and supported the identification of residues involved in DNA binding which were demonstrated experimentally. Overexpression of NinH proved toxic and this correlated with its capacity to associate with DNA. NinH is the first example of a phage-encoded Fis-like NAP that likely influences phage excision-integration reactions or bacterial gene expression.
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4
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Burger M, Rein S, Weber S, Gräber P, Kacprzak S. Distance measurements in the F 0F 1-ATP synthase from E. coli using smFRET and PELDOR spectroscopy. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2019; 49:1-10. [PMID: 31705179 DOI: 10.1007/s00249-019-01408-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/09/2019] [Accepted: 10/29/2019] [Indexed: 12/12/2022]
Abstract
Fluorescence resonance energy transfer in single enzyme molecules (smFRET, single-molecule measurement) allows the measurement of multicomponent distance distributions in complex biomolecules similar to pulsed electron-electron double resonance (PELDOR, ensemble measurement). Both methods use reporter groups: FRET exploits the distance dependence of the electric interaction between electronic transition dipole moments of the attached fluorophores, whereas PELDOR spectroscopy uses the distance dependence of the interaction between the magnetic dipole moments of attached spin labels. Such labels can be incorporated easily to cysteine residues in the protein. Comparison of distance distributions obtained with both methods was carried out with the H+-ATPase from Escherichia coli (EF0F1). The crystal structure of this enzyme is known. It contains endogenous cysteines, and as an internal reference two additional cysteines were introduced (EF0F1-γT106C-εH56C). These positions were chosen to allow application of both methods under optimal conditions. Both methods yield very similar multicomponent distance distributions. The dominating distance distribution (> 50%) is due to the two cysteines introduced by site-directed mutagenesis and the distance is in agreement with the crystal structure. Two additional distance distributions are detected with smFRET and with PELDOR. These can be assigned by comparison with the structure to labels at endogenous cysteines. One additional distribution is detected only with PELDOR. The comparison indicates that under optimal conditions smFRET and PELDOR result in the same distance distributions. PELDOR has the advantage that different distributions can be obtained with ensemble measurements, whereas FRET requires single-molecule techniques.
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Affiliation(s)
- Markus Burger
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg, Germany
| | - Stephan Rein
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg, Germany
| | - Stefan Weber
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg, Germany
| | - Peter Gräber
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg, Germany.
| | - Sylwia Kacprzak
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg, Germany
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5
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Sharma S, Zajac M, Krishnan Y. A DNA Aptamer for Cyclic Adenosine Monophosphate that Shows Adaptive Recognition. Chembiochem 2019; 21:157-162. [PMID: 31099939 DOI: 10.1002/cbic.201900259] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Indexed: 12/12/2022]
Abstract
As a ubiquitous second messenger, cyclic adenosine monophosphate (cAMP) mediates diverse biological processes such as cell growth, inflammation, and metabolism. The ability to probe these pathways would be significantly enhanced if we had a DNA-based sensor for cAMP. Herein, we describe a new, 31-base long single-stranded DNA aptamer for cAMP, denoted caDNApt-1, that was isolated by in vitro selection using systemic evolution of ligands after exponential enrichment (SELEX). caDNApt-1 has an approximately threefold higher affinity for cAMP than ATP, ADP, and AMP. Using non-denaturing gel electrophoresis and fluorescence spectroscopy, we characterized the structural changes caDNApt-1 undergoes upon binding to cAMP and revealed its potential as a cAMP sensor.
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Affiliation(s)
- Suruchi Sharma
- Tata Institute of Fundamental Research, GKVK, National Centre for Biological Sciences, Bellary Road, Bengaluru, 560065, India
| | - Matthew Zajac
- Present address: Department of Chemistry, The University of Chicago, GCIS E305A, 929E, 57th Street, ., Chicago, IL, 60637, USA
| | - Yamuna Krishnan
- Tata Institute of Fundamental Research, GKVK, National Centre for Biological Sciences, Bellary Road, Bengaluru, 560065, India.,Present address: Department of Chemistry, The University of Chicago, GCIS E305A, 929E, 57th Street, ., Chicago, IL, 60637, USA.,Grossman Institute of Neuroscience, Quantitative Biology and, Human Behavior, University of Chicago, Chicago, IL, 60637, USA
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6
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Velmurugu Y, Vivas P, Connolly M, Kuznetsov SV, Rice PA, Ansari A. Two-step interrogation then recognition of DNA binding site by Integration Host Factor: an architectural DNA-bending protein. Nucleic Acids Res 2019; 46:1741-1755. [PMID: 29267885 PMCID: PMC5829579 DOI: 10.1093/nar/gkx1215] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/08/2017] [Indexed: 12/23/2022] Open
Abstract
The dynamics and mechanism of how site-specific DNA-bending proteins initially interrogate potential binding sites prior to recognition have remained elusive for most systems. Here we present these dynamics for Integration Host factor (IHF), a nucleoid-associated architectural protein, using a μs-resolved T-jump approach. Our studies show two distinct DNA-bending steps during site recognition by IHF. While the faster (∼100 μs) step is unaffected by changes in DNA or protein sequence that alter affinity by >100-fold, the slower (1–10 ms) step is accelerated ∼5-fold when mismatches are introduced at DNA sites that are sharply kinked in the specific complex. The amplitudes of the fast phase increase when the specific complex is destabilized and decrease with increasing [salt], which increases specificity. Taken together, these results indicate that the fast phase is non-specific DNA bending while the slow phase, which responds only to changes in DNA flexibility at the kink sites, is specific DNA kinking during site recognition. Notably, the timescales for the fast phase overlap with one-dimensional diffusion times measured for several proteins on DNA, suggesting that these dynamics reflect partial DNA bending during interrogation of potential binding sites by IHF as it scans DNA.
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Affiliation(s)
- Yogambigai Velmurugu
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Paula Vivas
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Mitchell Connolly
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Serguei V Kuznetsov
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Phoebe A Rice
- Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Anjum Ansari
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
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7
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Nagy J, Eilert T, Michaelis J. Precision and accuracy in smFRET based structural studies-A benchmark study of the Fast-Nano-Positioning System. J Chem Phys 2018; 148:123308. [PMID: 29604844 DOI: 10.1063/1.5006477] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Modern hybrid structural analysis methods have opened new possibilities to analyze and resolve flexible protein complexes where conventional crystallographic methods have reached their limits. Here, the Fast-Nano-Positioning System (Fast-NPS), a Bayesian parameter estimation-based analysis method and software, is an interesting method since it allows for the localization of unknown fluorescent dye molecules attached to macromolecular complexes based on single-molecule Förster resonance energy transfer (smFRET) measurements. However, the precision, accuracy, and reliability of structural models derived from results based on such complex calculation schemes are oftentimes difficult to evaluate. Therefore, we present two proof-of-principle benchmark studies where we use smFRET data to localize supposedly unknown positions on a DNA as well as on a protein-nucleic acid complex. Since we use complexes where structural information is available, we can compare Fast-NPS localization to the existing structural data. In particular, we compare different dye models and discuss how both accuracy and precision can be optimized.
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Affiliation(s)
- Julia Nagy
- Ulm University, Institute of Biophysics, Albert-Einstein-Allee 11, Ulm 89069, Germany
| | - Tobias Eilert
- Ulm University, Institute of Biophysics, Albert-Einstein-Allee 11, Ulm 89069, Germany
| | - Jens Michaelis
- Ulm University, Institute of Biophysics, Albert-Einstein-Allee 11, Ulm 89069, Germany
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8
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Kinetic Basis of the Bifunctionality of SsoII DNA Methyltransferase. Molecules 2018; 23:molecules23051192. [PMID: 29772716 PMCID: PMC6100179 DOI: 10.3390/molecules23051192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/04/2018] [Accepted: 05/08/2018] [Indexed: 12/04/2022] Open
Abstract
Type II restriction–modification (RM) systems are the most widespread bacterial antiviral defence mechanisms. DNA methyltransferase SsoII (M.SsoII) from a Type II RM system SsoII regulates transcription in its own RM system in addition to the methylation function. DNA with a so-called regulatory site inhibits the M.SsoII methylation activity. Using circular permutation assay, we show that M.SsoII monomer induces DNA bending of 31° at the methylation site and 46° at the regulatory site. In the M.SsoII dimer bound to the regulatory site, both protein subunits make equal contributions to the DNA bending, and both angles are in the same plane. Fluorescence of TAMRA, 2-aminopurine, and Trp was used to monitor conformational dynamics of DNA and M.SsoII under pre-steady-state conditions by stopped-flow technique. Kinetic data indicate that M.SsoII prefers the regulatory site to the methylation site at the step of initial protein–DNA complex formation. Nevertheless, in the presence of S-adenosyl-l-methionine, the induced fit is accelerated in the M.SsoII complex with the methylation site, ensuring efficient formation of the catalytically competent complex. The presence of S-adenosyl-l-methionine and large amount of the methylation sites promote efficient DNA methylation by M.SsoII despite the inhibitory effect of the regulatory site.
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9
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Patowary S, Pisterzi LF, Biener G, Holz JD, Oliver JA, Wells JW, Raicu V. Experimental verification of the kinetic theory of FRET using optical microspectroscopy and obligate oligomers. Biophys J 2016; 108:1613-1622. [PMID: 25863053 DOI: 10.1016/j.bpj.2015.02.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 01/26/2015] [Accepted: 02/02/2015] [Indexed: 11/20/2022] Open
Abstract
Förster resonance energy transfer (FRET) is a nonradiative process for the transfer of energy from an optically excited donor molecule (D) to an acceptor molecule (A) in the ground state. The underlying theory predicting the dependence of the FRET efficiency on the sixth power of the distance between D and A has stood the test of time. In contrast, a comprehensive kinetic-based theory developed recently for FRET efficiencies among multiple donors and acceptors in multimeric arrays has waited for further testing. That theory has been tested in the work described in this article using linked fluorescent proteins located in the cytoplasm and at the plasma membrane of living cells. The cytoplasmic constructs were fused combinations of Cerulean as donor (D), Venus as acceptor (A), and a photo-insensitive molecule (Amber) as a nonfluorescent (N) place holder: namely, NDAN, NDNA, and ADNN duplexes, and the fully fluorescent quadruplex ADAA. The membrane-bound constructs were fused combinations of GFP2 as donor (D) and eYFP as acceptor (A): namely, two fluorescent duplexes (i.e., DA and AD) and a fluorescent triplex (ADA). According to the theory, the FRET efficiency of a multiplex such as ADAA or ADA can be predicted from that of analogs containing a single acceptor (e.g., NDAN, NDNA, and ADNN, or DA and AD, respectively). Relatively small but statistically significant differences were observed between the measured and predicted FRET efficiencies of the two multiplexes. While elucidation of the cause of this mismatch could be a worthy endeavor, the discrepancy does not appear to question the theoretical underpinnings of a large family of FRET-based methods for determining the stoichiometry and quaternary structure of complexes of macromolecules in living cells.
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Affiliation(s)
- Suparna Patowary
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | | | - Gabriel Biener
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Jessica D Holz
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Julie A Oliver
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - James W Wells
- The Leslie L. Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Valerică Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin; Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin.
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10
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Fenyk S, Dixon CH, Gittens WH, Townsend PD, Sharples GJ, Pålsson LO, Takken FLW, Cann MJ. The Tomato Nucleotide-binding Leucine-rich Repeat Immune Receptor I-2 Couples DNA-binding to Nucleotide-binding Domain Nucleotide Exchange. J Biol Chem 2015; 291:1137-47. [PMID: 26601946 PMCID: PMC4714197 DOI: 10.1074/jbc.m115.698589] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Indexed: 12/19/2022] Open
Abstract
Plant nucleotide-binding leucine-rich repeat (NLR) proteins enable plants to recognize and respond to pathogen attack. Previously, we demonstrated that the Rx1 NLR of potato is able to bind and bend DNA in vitro. DNA binding in situ requires its genuine activation following pathogen perception. However, it is unknown whether other NLR proteins are also able to bind DNA. Nor is it known how DNA binding relates to the ATPase activity intrinsic to NLR switch function required to immune activation. Here we investigate these issues using a recombinant protein corresponding to the N-terminal coiled-coil and nucleotide-binding domain regions of the I-2 NLR of tomato. Wild type I-2 protein bound nucleic acids with a preference of ssDNA ≈ dsDNA > ssRNA, which is distinct from Rx1. I-2 induced bending and melting of DNA. Notably, ATP enhanced DNA binding relative to ADP in the wild type protein, the null P-loop mutant K207R, and the autoactive mutant S233F. DNA binding was found to activate the intrinsic ATPase activity of I-2. Because DNA binding by I-2 was decreased in the presence of ADP when compared with ATP, a cyclic mechanism emerges; activated ATP-associated I-2 binds to DNA, which enhances ATP hydrolysis, releasing ADP-bound I-2 from the DNA. Thus DNA binding is a general property of at least a subset of NLR proteins, and NLR activation is directly linked to its activity at DNA.
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Affiliation(s)
- Stepan Fenyk
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - Christopher H Dixon
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - William H Gittens
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - Philip D Townsend
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - Gary J Sharples
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - Lars-Olof Pålsson
- the Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom and
| | - Frank L W Takken
- the Molecular Plant Pathology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - Martin J Cann
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
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11
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Nardo L, Lamperti M, Salerno D, Cassina V, Missana N, Bondani M, Tempestini A, Mantegazza F. Effects of non-CpG site methylation on DNA thermal stability: a fluorescence study. Nucleic Acids Res 2015; 43:10722-33. [PMID: 26354864 PMCID: PMC4678853 DOI: 10.1093/nar/gkv884] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 08/21/2015] [Indexed: 11/14/2022] Open
Abstract
Cytosine methylation is a widespread epigenetic regulation mechanism. In healthy mature cells, methylation occurs at CpG dinucleotides within promoters, where it primarily silences gene expression by modifying the binding affinity of transcription factors to the promoters. Conversely, a recent study showed that in stem cells and cancer cell precursors, methylation also occurs at non-CpG pairs and involves introns and even gene bodies. The epigenetic role of such methylations and the molecular mechanisms by which they induce gene regulation remain elusive. The topology of both physiological and aberrant non-CpG methylation patterns still has to be detailed and could be revealed by using the differential stability of the duplexes formed between site-specific oligonucleotide probes and the corresponding methylated regions of genomic DNA. Here, we present a systematic study of the thermal stability of a DNA oligonucleotide sequence as a function of the number and position of non-CpG methylation sites. The melting temperatures were determined by monitoring the fluorescence of donor-acceptor dual-labelled oligonucleotides at various temperatures. An empirical model that estimates the methylation-induced variations in the standard values of hybridization entropy and enthalpy was developed.
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Affiliation(s)
- Luca Nardo
- Department of Health Sciences, University of Milano Bicocca, Via Cadore 48, Monza, MB 20900, Italy
| | - Marco Lamperti
- Department of Science and High Technology, University of Insubria, Via Valleggio 11, Como, CO 22100, Italy
| | - Domenico Salerno
- Department of Health Sciences, University of Milano Bicocca, Via Cadore 48, Monza, MB 20900, Italy
| | - Valeria Cassina
- Department of Health Sciences, University of Milano Bicocca, Via Cadore 48, Monza, MB 20900, Italy
| | - Natalia Missana
- Department of Health Sciences, University of Milano Bicocca, Via Cadore 48, Monza, MB 20900, Italy
| | - Maria Bondani
- Institute for Photonics and Nanotechnology, National Research Council, Via Valleggio 11, Como, CO 22100, Italy
| | - Alessia Tempestini
- LENS-Department of Physics and Astronomy, University of Firenze, Via Sansone 1, Sesto Fiorentino, FI 50019, Italy
| | - Francesco Mantegazza
- Department of Health Sciences, University of Milano Bicocca, Via Cadore 48, Monza, MB 20900, Italy
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12
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Dougherty CA, Vaidyanathan S, Orr BG, Banaszak Holl MM. Fluorophore:dendrimer ratio impacts cellular uptake and intracellular fluorescence lifetime. Bioconjug Chem 2015; 26:304-15. [PMID: 25625297 DOI: 10.1021/bc5005735] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
G5-NH2-TAMRAn (n = 1-4, 5+, and 1.5(avg)) were prepared with n = 1-4 as a precise dye:dendrimer ratio, 5+ as a mixture of dendrimers with 5 or more dye per dendrimer, and 1.5(avg) as a Poisson distribution of dye:dendrimer ratios with a mean of 1.5 dye per dendrimer. The absorption intensity increased sublinearly with n whereas the fluorescence emission and lifetime decreased with an increasing number of dyes per dendrimer. Flow cytometry was employed to quantify uptake into HEK293A cells. Dendrimers with 2-4 dyes were found to have greater uptake than dendrimer with a single dye. Fluorescence lifetime imaging microscopy (FLIM) showed that the different dye:dendrimer ratio alone was sufficient to change the fluorescence lifetime of the material observed inside cells. We also observed that the lifetime of G5-NH2-TAMRA5+ increased when present in the cell as compared to solution. However, cells treated with G5-NH2-TAMRA1.5(avg) did not exhibit the high lifetime components present in G5-NH2-TAMRA1 and G5-NH2-TAMRA5+. In general, the effects of the dye:dendrimer ratio on fluorescence lifetime were of similar magnitude to environmentally induced lifetime shifts.
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Affiliation(s)
- Casey A Dougherty
- Department of Chemistry, ‡Department of Biomedical Engineering, and §Department of Physics, University of Michigan , Ann Arbor, Michigan 48109, United States
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13
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Nagy J, Grohmann D, Cheung ACM, Schulz S, Smollett K, Werner F, Michaelis J. Complete architecture of the archaeal RNA polymerase open complex from single-molecule FRET and NPS. Nat Commun 2015; 6:6161. [PMID: 25635909 DOI: 10.1038/ncomms7161] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 12/21/2014] [Indexed: 01/23/2023] Open
Abstract
The molecular architecture of RNAP II-like transcription initiation complexes remains opaque due to its conformational flexibility and size. Here we report the three-dimensional architecture of the complete open complex (OC) composed of the promoter DNA, TATA box-binding protein (TBP), transcription factor B (TFB), transcription factor E (TFE) and the 12-subunit RNA polymerase (RNAP) from Methanocaldococcus jannaschii. By combining single-molecule Förster resonance energy transfer and the Bayesian parameter estimation-based Nano-Positioning System analysis, we model the entire archaeal OC, which elucidates the path of the non-template DNA (ntDNA) strand and interaction sites of the transcription factors with the RNAP. Compared with models of the eukaryotic OC, the TATA DNA region with TBP and TFB is positioned closer to the surface of the RNAP, likely providing the mechanism by which DNA melting can occur in a minimal factor configuration, without the dedicated translocase/helicase encoding factor TFIIH.
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Affiliation(s)
- Julia Nagy
- Biophysics Institute, Ulm University, Albert-Einstein-Allee 11, Ulm 89069, Germany
| | - Dina Grohmann
- Institut für Physikalische und Theoretische Chemie-NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Straße 10, 38106 Braunschweig, Germany
| | - Alan C M Cheung
- Division of Biosciences, Institute for Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Sarah Schulz
- Institut für Physikalische und Theoretische Chemie-NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Straße 10, 38106 Braunschweig, Germany
| | - Katherine Smollett
- Division of Biosciences, Institute for Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Finn Werner
- Division of Biosciences, Institute for Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Jens Michaelis
- Biophysics Institute, Ulm University, Albert-Einstein-Allee 11, Ulm 89069, Germany
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14
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Hohlbein J, Craggs TD, Cordes T. Alternating-laser excitation: single-molecule FRET and beyond. Chem Soc Rev 2014; 43:1156-71. [PMID: 24037326 DOI: 10.1039/c3cs60233h] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The alternating-laser excitation (ALEX) scheme continues to expand the possibilities of fluorescence-based assays to study biological entities and interactions. Especially the combination of ALEX and single-molecule Förster Resonance Energy Transfer (smFRET) has been very successful as ALEX enables the sorting of fluorescently labelled species based on the number and type of fluorophores present. ALEX also provides a convenient way of accessing the correction factors necessary for determining accurate molecular distances. Here, we provide a comprehensive overview of the concept and current applications of ALEX and we explicitly discuss how to obtain fully corrected distance information across the entire FRET range. We also present new ideas for applications of ALEX which will push the limits of smFRET-based experiments in terms of temporal and spatial resolution for the study of complex biological systems.
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Affiliation(s)
- Johannes Hohlbein
- Laboratory of Biophysics, Wageningen UR, Wageningen, The Netherlands.
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15
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Savarese M, Raucci U, Adamo C, Netti PA, Ciofini I, Rega N. Non-radiative decay paths in rhodamines: new theoretical insights. Phys Chem Chem Phys 2014; 16:20681-8. [DOI: 10.1039/c4cp02622e] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A photoinduced electron transfer is individuated as a possible non-radiative pathway in rhodamine B photophysics in solvent. The quenching mechanism is studied through an electronic density based index to assess and quantify the nature of the excited states.
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Affiliation(s)
- Marika Savarese
- Dipartimento di Scienze Chimiche
- Università di Napoli ‘Federico II’
- Complesso Universitario di M.S.Angelo
- I-80126 Napoli, Italy
- Italian Institute of Technology
| | - Umberto Raucci
- Dipartimento di Scienze Chimiche
- Università di Napoli ‘Federico II’
- Complesso Universitario di M.S.Angelo
- I-80126 Napoli, Italy
| | - Carlo Adamo
- Laboratoire d'Electrochimie
- Chimie des Interfaces et Modelisation pour l’Energie
- CNRS UMR-7575
- Ecole Nationale Supérieure de Chimie de Paris
- Chimie ParisTech
| | - Paolo A. Netti
- Italian Institute of Technology
- IIT@CRIB Center for Advanced Biomaterials for Healthcare
- Largo Barsanti e Matteucci
- I-80125 Napoli, Italy
| | - Ilaria Ciofini
- Laboratoire d'Electrochimie
- Chimie des Interfaces et Modelisation pour l’Energie
- CNRS UMR-7575
- Ecole Nationale Supérieure de Chimie de Paris
- Chimie ParisTech
| | - Nadia Rega
- Dipartimento di Scienze Chimiche
- Università di Napoli ‘Federico II’
- Complesso Universitario di M.S.Angelo
- I-80126 Napoli, Italy
- Center for Advanced Biomaterials for Health Care@CRIB
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16
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Stennett EMS, Ma N, van der Vaart A, Levitus M. Photophysical and dynamical properties of doubly linked Cy3-DNA constructs. J Phys Chem B 2013; 118:152-63. [PMID: 24328104 DOI: 10.1021/jp410976p] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photophysical measurements are reported for Cy3-DNA constructs in which both Cy3 nitrogen atoms are attached to the DNA backbone by short linkers. While this linking was thought to rigidify the orientation of the dye and hinder cis-isomerization, the relatively low fluorescence quantum yield and the presence of a short component in the time-resolved fluorescence decay of the dye indicated that cis-isomerization remained possible. Fluorescence correlation spectroscopy and transient absorption experiments showed that photoisomerization occurred with high efficiency. Molecular dynamics simulations of the trans dye system indicated the presence of stacked and unstacked states, and free energy simulations showed that the barriers for stacking/unstacking were low. In addition, simulations showed that the ground cis state was feasible without DNA distortions. Based on these observations, a model is put forward in which the doubly linked dye can photoisomerize in the unstacked state.
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Affiliation(s)
- Elana M S Stennett
- Department of Chemistry and Biochemistry and the Biodesign Institute, Arizona State University , PO Box 875601, Tempe, Arizona 85287, United States
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17
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Jahromi AH, Fu Y, Miller KA, Nguyen L, Luu LM, Baranger AM, Zimmerman SC. Developing bivalent ligands to target CUG triplet repeats, the causative agent of myotonic dystrophy type 1. J Med Chem 2013; 56:9471-9481. [PMID: 24188018 DOI: 10.1021/jm400794z] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An expanded CUG repeat transcript (CUG(exp)) is the causative agent of myotonic dystrophy type 1 (DM1) by sequestering muscleblind-like 1 protein (MBNL1), a regulator of alternative splicing. On the basis of a ligand (1) that was previously reported to be active in an in vitro assay, we present the synthesis of a small library containing 10 dimeric ligands (4-13) that differ in length, composition, and attachment point of the linking chain. The oligoamino linkers gave a greater gain in affinity for CUG RNA and were more effective when compared to oligoether linkers. The most potent in vitro ligand (9) was shown to be aqueous-soluble and both cell- and nucleus-permeable, displaying almost complete dispersion of MBNL1 ribonuclear foci in a DM1 cell model. Direct evidence for the bioactivity of 9 was observed in its ability to disperse ribonuclear foci in individual live DM1 model cells using time-lapse confocal fluorescence microscopy.
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Affiliation(s)
- Amin Haghighat Jahromi
- Center for Biophysics and Computational Biology, University of Illinois, Urbana, IL, USA.,Department of Chemistry, University of Illinois, Urbana, IL, USA
| | - Yuan Fu
- Department of Chemistry, University of Illinois, Urbana, IL, USA
| | - Kali A Miller
- Department of Chemistry, University of Illinois, Urbana, IL, USA
| | - Lien Nguyen
- Department of Chemistry, University of Illinois, Urbana, IL, USA
| | - Long M Luu
- Department of Chemistry, University of Illinois, Urbana, IL, USA
| | - Anne M Baranger
- Department of Chemistry, University of Illinois, Urbana, IL, USA
| | - Steven C Zimmerman
- Center for Biophysics and Computational Biology, University of Illinois, Urbana, IL, USA.,Department of Chemistry, University of Illinois, Urbana, IL, USA
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18
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Blythe KL, Titus EJ, Willets KA. Triplet-State-Mediated Super-Resolution Imaging of Fluorophore-Labeled Gold Nanorods. Chemphyschem 2013; 15:784-93. [DOI: 10.1002/cphc.201300767] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Indexed: 01/16/2023]
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19
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Techen A, Czapla S, Möllnitz K, Budach D, Wessig P, Kumke MU. Synthesis and Spectroscopic Characterization of Fluorophore-Labeled Oligospiroketal Rods. Helv Chim Acta 2013. [DOI: 10.1002/hlca.201200616] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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20
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Evaluation of intrinsic spectroscopic properties of chromophore assemblies by shielding with cyclohexyl base pairs within a DNA duplex. Bioorg Med Chem 2013; 21:6191-7. [DOI: 10.1016/j.bmc.2013.04.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 03/28/2013] [Accepted: 04/05/2013] [Indexed: 11/21/2022]
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21
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Haghighat Jahromi A, Honda M, Zimmerman SC, Spies M. Single-molecule study of the CUG repeat-MBNL1 interaction and its inhibition by small molecules. Nucleic Acids Res 2013; 41:6687-97. [PMID: 23661680 PMCID: PMC3711446 DOI: 10.1093/nar/gkt330] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Effective drug discovery and optimization can be accelerated by techniques capable of deconvoluting the complexities often present in targeted biological systems. We report a single-molecule approach to study the binding of an alternative splicing regulator, muscleblind-like 1 protein (MBNL1), to (CUG)n = 4,6 and the effect of small molecules on this interaction. Expanded CUG repeats (CUG(exp)) are the causative agent of myotonic dystrophy type 1 by sequestering MBNL1. MBNL1 is able to bind to the (CUG)n-inhibitor complex, indicating that the inhibition is not a straightforward competitive process. A simple ligand, highly selective for CUG(exp), was used to design a new dimeric ligand that binds to (CUG)n almost 50-fold more tightly and is more effective in destabilizing MBNL1-(CUG)4. The single-molecule method and the analysis framework might be extended to the study of other biomolecular interactions.
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Affiliation(s)
- Amin Haghighat Jahromi
- Center for Biophysics and Computational Biology, University of Illinois, Urbana, IL 61801, USA
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22
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Blythe KL, Mayer KM, Weber ML, Willets KA. Ground state depletion microscopy for imaging interactions between gold nanowires and fluorophore-labeled ligands. Phys Chem Chem Phys 2013; 15:4136-45. [DOI: 10.1039/c2cp43152a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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23
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Chen T, Fu L, Zu L. Steady-state and time-resolved fluorescence of tetramethylrhodamine attached to DNA: correlation with DNA sequences. LUMINESCENCE 2012; 28:860-4. [DOI: 10.1002/bio.2446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 08/30/2012] [Accepted: 09/06/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Tingting Chen
- Department of Chemistry; Beijing Normal University; Beijing 100875 People's Republic of China
| | - Leixiaomeng Fu
- Department of Chemistry; Beijing Normal University; Beijing 100875 People's Republic of China
| | - Lily Zu
- Department of Chemistry; Beijing Normal University; Beijing 100875 People's Republic of China
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24
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Preus S, Wilhelmsson LM. Advances in quantitative FRET-based methods for studying nucleic acids. Chembiochem 2012; 13:1990-2001. [PMID: 22936620 DOI: 10.1002/cbic.201200400] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Indexed: 01/02/2023]
Abstract
Förster resonance energy transfer (FRET) is a powerful tool for monitoring molecular distances and interactions at the nanoscale level. The strong dependence of transfer efficiency on probe separation makes FRET perfectly suited for "on/off" experiments. To use FRET to obtain quantitative distances and three-dimensional structures, however, is more challenging. This review summarises recent studies and technological advances that have improved FRET as a quantitative molecular ruler in nucleic acid systems, both at the ensemble and at the single-molecule levels.
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Affiliation(s)
- Søren Preus
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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25
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Savarese M, Aliberti A, De Santo I, Battista E, Causa F, Netti PA, Rega N. Fluorescence Lifetimes and Quantum Yields of Rhodamine Derivatives: New Insights from Theory and Experiment. J Phys Chem A 2012; 116:7491-7. [DOI: 10.1021/jp3021485] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marika Savarese
- Dipartimento di
Scienze Chimiche, Università di Napoli ‘Federico II’, Complesso Universitario
di M.S.Angelo, via Cintia, I-80126 Napoli, Italy
- Center for Advanced Biomaterials
for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, I-80125 Napoli, Italy
| | - Anna Aliberti
- Center for Advanced Biomaterials
for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, I-80125 Napoli, Italy
| | - Ilaria De Santo
- Center for Advanced Biomaterials
for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, I-80125 Napoli, Italy
| | - Edmondo Battista
- Center for Advanced Biomaterials
for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, I-80125 Napoli, Italy
| | - Filippo Causa
- Center for Advanced Biomaterials
for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, I-80125 Napoli, Italy
| | - Paolo A. Netti
- Center for Advanced Biomaterials
for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, I-80125 Napoli, Italy
| | - Nadia Rega
- Dipartimento di
Scienze Chimiche, Università di Napoli ‘Federico II’, Complesso Universitario
di M.S.Angelo, via Cintia, I-80126 Napoli, Italy
- Center for Advanced Biomaterials
for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, I-80125 Napoli, Italy
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26
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Pakuła S, Orłowski M, Rymarczyk G, Krusiński T, Jakób M, Zoglowek A, Ożyhar A, Dobryszycki P. Conformational changes in the DNA-binding domains of the ecdysteroid receptor during the formation of a complex with the hsp27 response element. J Biomol Struct Dyn 2012; 30:379-93. [PMID: 22694217 DOI: 10.1080/07391102.2012.682215] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The ecdysone receptor (EcR) and the ultraspiracle protein (Usp) form the functional receptor for ecdysteroids that initiates metamorphosis in insects. The Usp and EcR DNA-binding domains (UspDBD and EcRDBD, respectively) form a heterodimer on the natural pseudopalindromic element from the hsp27 gene promoter. The conformational changes in the protein-DNA during the formation of the UspDBD-EcRDBD-hsp27 complex were analyzed. Recombined UspDBD and EcRDBD proteins were purified and fluorescein labeled (FL) using the intein method at the C-ends of both proteins. The changes in the distances from the respective C-ends of EcRDBD and/or UspDBD to the 5'- and/or 3'-end of the response element were measured using fluorescence resonance energy transfer (FRET) methodology. The binding of EcRDBD induced a strong conformational change in UspDBD and caused the C-terminal fragment of the UspDBD molecule to move away from both ends of the regulatory element. UspDBD also induced a significant conformational change in the EcRDBD molecule. The EcRDBD C-terminus moved away from the 5'-end of the regulatory element and moved close to the 3'-end. An analysis was also done on the effect that DHR38DBD, the Drosophila ortholog of the mammalian NGFI-B, had on the interaction of UspDBD and EcRDBD with hsp27. FRET analysis demonstrated that hsp27 bending was induced by DHR38DBD. Fluorescence data revealed that hsp27 had a shorter end-to-end distance both in the presence of EcRDBD as well as in the presence of EcRDBD together with DHR38DBD, with DNA bend angles of about 36.2° and 33.6°, respectively. A model of how DHR38DBD binds to hsp27 in the presence of EcRDBD is presented.
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Affiliation(s)
- Szymon Pakuła
- Faculty of Chemistry, Division of Biochemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland
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27
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Linck L, Kapusta P, Resch-Genger U. Spectroscopic and photophysical properties of dUTP and internally DNA bound fluorophores for optimized signal detection in biological formats. Photochem Photobiol 2012; 88:867-75. [PMID: 22360746 DOI: 10.1111/j.1751-1097.2012.01119.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Efficient signal generation in DNA-based assays requires understanding of the influence of fluorophore's interactions on the spectroscopic properties. The resulting changes in fluorescence intensity, quantum yield, emission anisotropy, and fluorescence lifetime provide straightforward tools for the study of molecular dynamics and interaction between labels and nucleic acids. Searching for bright fluorescent reporters for rolling circle amplification (RCA) as efficient signal enhancement strategy for biological formats, we investigated the spectroscopic properties of seven dyes: cyanines, rhodamines, and BODIPYs. They spectrally resemble Cy3, the most frequently used fluorophore in biodetection formats, and are measured in six samples (free dye, dye-dUTP, internally labeled ssDNA and dsDNA-single- and triple-labeled) using steady-state and time-resolved fluorometry. Special emphasis was dedicated to characterizing the nature of the interaction of these fluorophores differing in dye class, charge, and rigidity. Our results suggest dye charge and structure as main factors governing the dye's interactions, with DY-555 and Cy3B presenting the best candidates for our envisaged signal amplification strategy. This label comparison underlines the importance of a proper understanding of structure-property relations and dye-biomolecule interactions for reporter choice and presents a road map towards the design and interpretation of experiments using these labels on DNA of known sequence.
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Affiliation(s)
- Lena Linck
- BAM Federal Institute for Materials Research and Testing, Berlin, Germany
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28
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Ha T, Tinnefeld P. Photophysics of fluorescent probes for single-molecule biophysics and super-resolution imaging. Annu Rev Phys Chem 2012; 63:595-617. [PMID: 22404588 PMCID: PMC3736144 DOI: 10.1146/annurev-physchem-032210-103340] [Citation(s) in RCA: 451] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Single-molecule fluorescence spectroscopy and super-resolution microscopy are important elements of the ongoing technical revolution to reveal biochemical and cellular processes in unprecedented clarity and precision. Demands placed on the photophysical properties of the fluorophores are stringent and drive the choice of appropriate probes. Such fluorophores are not simple light bulbs of a certain color and brightness but instead have their own "personalities" regarding spectroscopic parameters, redox properties, size, water solubility, photostability, and several other factors. Here, we review the photophysics of fluorescent probes, both organic fluorophores and fluorescent proteins, used in applications such as particle tracking, single-molecule FRET, stoichiometry determination, and super-resolution imaging. Of particular interest is the thiol-induced blinking of Cy5, a curse for single-molecule biophysical studies that was later overcome using Trolox through a reducing/oxidizing system but a boon for super-resolution imaging owing to the controllable photoswitching. Understanding photophysics is critical in the design and interpretation of single-molecule experiments.
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Affiliation(s)
- Taekjip Ha
- Department of Physics, University of Illinois at Urbana-Champaign, 61801, USA.
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29
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Vitoc CI, Mukerji I. HU binding to a DNA four-way junction probed by Förster resonance energy transfer. Biochemistry 2011; 50:1432-41. [PMID: 21230005 PMCID: PMC4724199 DOI: 10.1021/bi1007589] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The Escherichia coli protein HU is a non-sequence-specific DNA-binding protein that interacts with DNA primarily through electrostatic interactions. In addition to nonspecific binding to linear DNA, HU has been shown to bind with nanomolar affinity to discontinuous DNA substrates, such as repair and recombination intermediates. This work specifically examines the HU-four-way junction (4WJ) interaction using fluorescence spectroscopic methods. The conformation of the junction in the presence of different counterions was investigated by Förster resonance energy transfer (FRET) measurements, which revealed an ion-type conformational dependence, where Na(+) yields the most stacked conformation followed by K(+) and Mg(2+). HU binding induces a greater degree of stacking in the Na(+)-stabilized and Mg(2+)-stabilized junctions but not the K(+)-stabilized junction, which is attributed to differences in the size of the ionic radii and potential differences in ion binding sites. Interestingly, junction conformation modulates binding affinity, where HU exhibits the lowest affinity for the Mg(2+)-stabilized form (24 μM(-1)), which is the least stacked conformation. Protein binding to a mixed population of open and stacked forms of the junction leads to nearly complete formation of a protein-stabilized stacked-X junction. These results strongly support a model in which HU binds to and stabilizes the stacked-X conformation.
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Affiliation(s)
- Codruta Iulia Vitoc
- Molecular Biology and Biochemistry Department, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut 06459-0175
| | - Ishita Mukerji
- Molecular Biology and Biochemistry Department, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut 06459-0175
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30
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Sindbert S, Kalinin S, Nguyen H, Kienzler A, Clima L, Bannwarth W, Appel B, Müller S, Seidel CAM. Accurate Distance Determination of Nucleic Acids via Förster Resonance Energy Transfer: Implications of Dye Linker Length and Rigidity. J Am Chem Soc 2011; 133:2463-80. [DOI: 10.1021/ja105725e] [Citation(s) in RCA: 210] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Simon Sindbert
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Universitätsstrasse 1, Geb 26.32, 40225 Düsseldorf, Germany
| | - Stanislav Kalinin
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Universitätsstrasse 1, Geb 26.32, 40225 Düsseldorf, Germany
| | - Hien Nguyen
- Institut für Biochemie, Bioorganische Chemie, Ernst-Moritz-Arndt-Universität Greifswald, Felix-Hausdorff-Strasse 4, 17487, Greifswald, Germany
| | - Andrea Kienzler
- Fakultät für Chemie und Biochemie, Albert-Ludwigs Universität Freiburg, AK Bannwarth, Albertstrasse 21, 79104, Freiburg, Germany
| | - Lilia Clima
- Fakultät für Chemie und Biochemie, Albert-Ludwigs Universität Freiburg, AK Bannwarth, Albertstrasse 21, 79104, Freiburg, Germany
| | - Willi Bannwarth
- Fakultät für Chemie und Biochemie, Albert-Ludwigs Universität Freiburg, AK Bannwarth, Albertstrasse 21, 79104, Freiburg, Germany
| | - Bettina Appel
- Institut für Biochemie, Bioorganische Chemie, Ernst-Moritz-Arndt-Universität Greifswald, Felix-Hausdorff-Strasse 4, 17487, Greifswald, Germany
| | - Sabine Müller
- Institut für Biochemie, Bioorganische Chemie, Ernst-Moritz-Arndt-Universität Greifswald, Felix-Hausdorff-Strasse 4, 17487, Greifswald, Germany
| | - Claus A. M. Seidel
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Universitätsstrasse 1, Geb 26.32, 40225 Düsseldorf, Germany
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31
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Ranasinghe RT, Brown T. Ultrasensitive fluorescence-based methods for nucleic acid detection: towards amplification-free genetic analysis. Chem Commun (Camb) 2011; 47:3717-35. [DOI: 10.1039/c0cc04215c] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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32
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The energetic contribution of induced electrostatic asymmetry to DNA bending by a site-specific protein. J Mol Biol 2010; 406:285-312. [PMID: 21167173 DOI: 10.1016/j.jmb.2010.12.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 11/30/2010] [Accepted: 12/04/2010] [Indexed: 11/21/2022]
Abstract
DNA bending can be promoted by reducing the net negative electrostatic potential around phosphates on one face of the DNA, such that electrostatic repulsion among phosphates on the opposite face drives bending toward the less negative surface. To provide the first assessment of energetic contribution to DNA bending when electrostatic asymmetry is induced by a site-specific DNA binding protein, we manipulated the electrostatics in the EcoRV endonuclease-DNA complex by mutation of cationic side chains that contact DNA phosphates and/or by replacement of a selected phosphate in each strand with uncharged methylphosphonate. Reducing the net negative charge at two symmetrically located phosphates on the concave DNA face contributes -2.3 kcal mol(-1) to -0.9 kcal mol(-1) (depending on position) to complex formation. In contrast, reducing negative charge on the opposing convex face produces a penalty of +1.3 kcal mol(-1). Förster resonance energy transfer experiments show that the extent of axial DNA bending (about 50°) is little affected in modified complexes, implying that modification affects the energetic cost but not the extent of DNA bending. Kinetic studies show that the favorable effects of induced electrostatic asymmetry on equilibrium binding derive primarily from a reduced rate of complex dissociation, suggesting stabilization of the specific complex between protein and markedly bent DNA. A smaller increase in the association rate may suggest that the DNA in the initial encounter complex is mildly bent. The data imply that protein-induced electrostatic asymmetry makes a significant contribution to DNA bending but is not itself sufficient to drive full bending in the specific EcoRV-DNA complex.
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Kalinin S, Valeri A, Antonik M, Felekyan S, Seidel CAM. Detection of structural dynamics by FRET: a photon distribution and fluorescence lifetime analysis of systems with multiple states. J Phys Chem B 2010; 114:7983-95. [PMID: 20486698 DOI: 10.1021/jp102156t] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two complementary methods in confocal single-molecule fluorescence spectroscopy are presented to analyze conformational dynamics by Forster resonance energy transfer (FRET) measurements considering simulated and experimental data. First, an extension of photon distribution analysis (PDA) is applied to characterize conformational exchange between two or more states via global analysis of the shape of FRET peaks for different time bins. PDA accurately predicts the shape of FRET efficiency histograms in the presence of FRET fluctuations, taking into account shot noise and background contributions. Dynamic-PDA quantitatively recovers FRET efficiencies of the interconverting states and relaxation times of dynamics on the time scale of the diffusion time t(d) (typically milliseconds), with a dynamic range of the method of about +/-1 order of magnitude with respect to t(d). Correction procedures are proposed to consider the factors limiting the accuracy of dynamic-PDA, such as brightness variations, shortening of the observation time due to diffusion, and a contribution of multimolecular events. Second, an analysis procedure for multiparameter fluorescence detection is presented, where intensity-derived FRET efficiency is correlated with the fluorescence lifetime of the donor quenched by FRET. If a maximum likelihood estimator is applied to compute a mean fluorescence lifetime of mixed states, one obtains a fluorescence weighted mean lifetime. Thus a mixed state is detected by a characteristic shift of the fluorescence lifetime, which becomes longer than that expected for a single species with the same intensity-derived FRET efficiency. Analysis tools for direct visual inspection of two-dimensional diagrams of FRET efficiency versus donor lifetime are presented for the cases of static and dynamic FRET. Finally these new techniques are compared with fluorescence correlation spectroscopy.
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Affiliation(s)
- Stanislav Kalinin
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Universitätsstrasse 1, Geb 26.32, 40225 Düsseldorf, Germany.
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Liu B, Mazouchi A, Gradinaru CC. Trapping single molecules in liposomes: surface interactions and freeze-thaw effects. J Phys Chem B 2010; 114:15191-8. [PMID: 20979387 DOI: 10.1021/jp104614d] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report on an improved method to encapsulate proteins and other macromolecules inside surface-tethered liposomes to reduce or eliminate environmental interference for single-molecule investigations. These lipid vesicles are large enough for the molecule to experience free diffusion but sufficiently small so that the molecule appears effectively immobile under the fluorescence microscope. Single-molecule fluorescence experiments were used to characterize this anchoring method relative to direct immobilization via biotin-streptavidin linkers. Multidimensional histograms of intensity, polarization, and lifetime revealed that molecules trapped in liposomes display a narrow distribution around a single peak, while the molecules directly immobilized on surface show highly dispersed values for all parameters. By hydrating the lipid film at low volumes, high encapsulation efficiencies can be achieved with ~10 times less biological material than previous protocols. We measured vesicle size distributions and found no significant advantage for using freeze-thaw cycles during vesicle preparation. On the contrary, the temperature jump can induce irreversible damage of fluorophores and it reduces significantly the functionality of proteins, as demonstrated on single-molecule binding experiments on STAT3. Our improved and biologically gentle molecule encapsulation protocol has a great potential for widespread applications in single-molecule fluorescence spectroscopy.
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Affiliation(s)
- Baoxu Liu
- Department of Physics and Institute for Optical Sciences, University of Toronto, Toronto, Ontario, Canada, M5S 1A7
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35
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The Effect of dye-dye interactions on the spatial resolution of single-molecule FRET measurements in nucleic acids. Biophys J 2010; 98:2265-72. [PMID: 20483335 DOI: 10.1016/j.bpj.2010.02.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 01/18/2010] [Accepted: 02/02/2010] [Indexed: 11/22/2022] Open
Abstract
We study the effect of dye-dye interactions in labeled double-stranded DNA molecules on the Förster resonance energy transfer (FRET) efficiency at the single-molecule level. An extensive analysis of internally labeled double-stranded DNA molecules in bulk and at the single-molecule level reveals that donor-acceptor absolute distances can be reliably extracted down to approximately 3-nm separation, provided that dye-dye quenching is accounted for. At these short separations, we find significant long-lived fluorescence fluctuations among discrete levels originating from the simultaneous and synchronous quenching of both dyes. By comparing four different donor-acceptor dye pairs (TMR-ATTO647N, Cy3-ATTO647N, TMR-Cy5, and Cy3-Cy5), we find that this phenomenon depends on the nature of the dye pair used, with the cyanine pair Cy3-Cy5 showing the least amount of fluctuations. The significance of these results is twofold: First, they illustrate that when dye-dye quenching is accounted for, single-molecule FRET can be used to accurately measure inter-dye distances, even at short separations. Second, these results are useful when deciding which dye pairs to use for nucleic acids analyses using FRET.
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36
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Wang Y, Clark TB, Goodson T. Two-photon and time-resolved fluorescence conformational studies of aggregation in amyloid peptides. J Phys Chem B 2010; 114:7112-20. [PMID: 20429591 DOI: 10.1021/jp101496y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conformational changes associated with the aggregation of proteins are critical to the understanding of fundamental molecular events involved in early processes of neurodegenerative diseases. A detailed investigation of these processes requires the development of new approaches that allow for sensitive measurements of protein interactions. In this paper, we applied two-photon spectroscopy coupled with time-resolved fluorescence measurements to analyze amyloid peptide interactions through aggregation-dependent concentration effects. Labeled amyloid-beta peptide (TAMRA-Abeta1-42) was used in our investigation, and measurements of two-photon-excited fluorescence of the free and covalently conjugated peptide structure were carried out. The peptide secondary structure was correlated with a short fluorescence lifetime component, and this was associated with intramolecular interactions. Comparison of the fractional occupancy of the fluorescence lifetime measured at different excitation modes demonstrates the high sensitivity of the two-photon method in comparison to one-photon excitation (OPE). These results give strong justification for the development of fluorescence-lifetime-based multiphoton imaging and assays.
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Affiliation(s)
- Ying Wang
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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37
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Cherkasov D, Biet T, Bäuml E, Traut W, Lohoff M. New nucleotide analogues with enhanced signal properties. Bioconjug Chem 2010; 21:122-9. [PMID: 20047309 DOI: 10.1021/bc900364f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We describe synthesis and testing of a novel type of dye-modified nucleotides which we call macromolecular nucleotides (m-Nucs). Macromolecular nucleotides comprise a nucleotide moiety, a macromolecular linear linker, and a large macromolecular ligand carrying multiple fluorescent dyes. With incorporation of the nucleotide moiety into the growing nucleic acid strand during enzymatic synthesis, the macromolecular ligand together with the coupled dyes is bound to the nucleic acid. By the use of this new class of modified nucleotides, signals from multiple dye molecules can be obtained after a single enzymatic incorporation event. The modified nucleotides are considered especially useful in the fields of nanobiotechnology, where signal stability and intensity is a limiting factor.
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Affiliation(s)
- Dmitry Cherkasov
- Institute for Medical Microbiology, Philipps University of Marburg, Hans-Meerweinstrasse 2, 35043 Marburg, Germany.
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FRET measurements of kinesin neck orientation reveal a structural basis for processivity and asymmetry. Proc Natl Acad Sci U S A 2010; 107:5453-8. [PMID: 20212149 DOI: 10.1073/pnas.0914924107] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
As the smallest and simplest motor enzymes, kinesins have served as the prototype for understanding the relationship between protein structure and mechanochemical function of enzymes in this class. Conventional kinesin (kinesin-1) is a motor enzyme that transports cargo toward the plus end of microtubules by a processive, asymmetric hand-over-hand mechanism. The coiled-coil neck domain, which connects the two kinesin motor domains, contributes to kinesin processivity (the ability to take many steps in a row) and is proposed to be a key determinant of the asymmetry in the kinesin mechanism. While previous studies have defined the orientation and position of microtubule-bound kinesin motor domains, the disposition of the neck coiled-coil remains uncertain. We determined the neck coiled-coil orientation using a multidonor fluorescence resonance energy transfer (FRET) technique to measure distances between microtubules and bound kinesin molecules. Microtubules were labeled with a new fluorescent taxol donor, TAMRA-X-taxol, and kinesin derivatives with an acceptor fluorophore attached at positions on the motor and neck coiled-coil domains were used to reconstruct the positions and orientations of the domains. FRET measurements to positions on the motor domain were largely consistent with the domain orientation determined in previous studies, validating the technique. Measurements to positions on the neck coiled-coil were inconsistent with a radial orientation and instead demonstrated that the neck coiled-coil is parallel to the microtubule surface. The measured orientation provides a structural explanation for how neck surface residues enhance processivity and suggests a simple hypothesis for the origin of kinesin step asymmetry and "limping."
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39
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Delgadillo RF, Parkhurst LJ. Spectroscopic Properties of Fluorescein and Rhodamine Dyes Attached to DNA. Photochem Photobiol 2010; 86:261-72. [DOI: 10.1111/j.1751-1097.2009.00663.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Kaji T, Ito S, Iwai S, Miyasaka H. Nanosecond to submillisecond dynamics in dye-labeled single-stranded DNA, as revealed by ensemble measurements and photon statistics at single-molecule level. J Phys Chem B 2010; 113:13917-25. [PMID: 19780517 DOI: 10.1021/jp811122a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single-molecule and ensemble time-resolved fluorescence measurements were applied for the investigation of the conformational dynamics of single-stranded DNA, ssDNA, connected with a fluorescein dye by a C6 linker, where the motions both of DNA and the C6 linker affect the geometry of the system. From the ensemble measurement of the fluorescence quenching via photoinduced electron transfer with a guanine base in the DNA sequence, three main conformations were found in aqueous solution: a conformation unaffected by the guanine base in the excited state lifetime of fluorescein, a conformation in which the fluorescence is dynamically quenched in the excited-state lifetime, and a conformation leading to rapid quenching via nonfluorescent complex. The analysis by using the parameters acquired from the ensemble measurements for interphoton time distribution histograms and FCS autocorrelations by the single-molecule measurement revealed that interconversion in these three conformations took place with two characteristic time constants of several hundreds of nanoseconds and tens of microseconds. The advantage of the combination use of the ensemble measurements with the single-molecule detections for rather complex dynamic motions is discussed by integrating the experimental results with those obtained by molecular dynamics simulation.
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Affiliation(s)
- Takahiro Kaji
- Division of Frontier Materials Science and Division of Chemistry, Graduate School of Engineering Science and Center for Quantum Materials Science under Extreme Conditions, Osaka University, Machikaneyama1-3, Toyonaka, Osaka 560-8531, Japan
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41
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Doose S, Neuweiler H, Sauer M. Fluorescence quenching by photoinduced electron transfer: a reporter for conformational dynamics of macromolecules. Chemphyschem 2009; 10:1389-98. [PMID: 19475638 DOI: 10.1002/cphc.200900238] [Citation(s) in RCA: 373] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Photoinduced electron transfer (PET) between organic fluorophores and suitable electron donating moieties, for example, the amino acid tryptophan or the nucleobase guanine, can quench fluorescence upon van der Waals contact and thus report on molecular contact. PET-quenching has been used as reporter for monitoring conformational dynamics in polypeptides, proteins, and oligonucleotides. Whereas dynamic quenching transiently influences quantum yield and fluorescence lifetime of the fluorophore, static quenching in pi-stacked complexes efficiently suppresses fluorescence emission over time scales longer than the fluorescence lifetime. Static quenching therefore provides sufficient contrast to be observed at the single-molecule level. Here, we review complex formation and static quenching of different fluorophores by various molecular compounds, discuss applications as reporter system for macromolecular dynamics, and give illustrating examples.
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Affiliation(s)
- Sören Doose
- Applied Laser Physics and Laser Spectroscopy, Bielefeld University, Universitätsstr. 25, 33619 Bielefeld, Germany
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42
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Liu P, Meng X, Qu P, Zhao XS, Wang CC. Subdomain-Specific Collapse of Denatured Staphylococcal Nuclease Revealed by Single Molecule Fluorescence Resonance Energy Transfer Measurements. J Phys Chem B 2009; 113:12030-6. [PMID: 19678648 DOI: 10.1021/jp809825x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pengcheng Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China, Graduate School of the Chinese Academy of Sciences, Beijing 100049, China, Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Xianglan Meng
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China, Graduate School of the Chinese Academy of Sciences, Beijing 100049, China, Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Peng Qu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China, Graduate School of the Chinese Academy of Sciences, Beijing 100049, China, Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Xin Sheng Zhao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China, Graduate School of the Chinese Academy of Sciences, Beijing 100049, China, Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Chih-chen Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China, Graduate School of the Chinese Academy of Sciences, Beijing 100049, China, Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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Andrecka J, Treutlein B, Arcusa MAI, Muschielok A, Lewis R, Cheung ACM, Cramer P, Michaelis J. Nano positioning system reveals the course of upstream and nontemplate DNA within the RNA polymerase II elongation complex. Nucleic Acids Res 2009; 37:5803-9. [PMID: 19620213 PMCID: PMC2761271 DOI: 10.1093/nar/gkp601] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Crystallographic studies of the RNA polymerase II (Pol II) elongation complex (EC) revealed the locations of downstream DNA and the DNA-RNA hybrid, but not the course of the nontemplate DNA strand in the transcription bubble and the upstream DNA duplex. Here we used single-molecule Fluorescence Resonance Energy Transfer (smFRET) experiments to locate nontemplate and upstream DNA with our recently developed Nano Positioning System (NPS). In the resulting complete model of the Pol II EC, separation of the nontemplate from the template strand at position +2 involves interaction with fork loop 2. The nontemplate strand passes loop β10-β11 on the Pol II lobe, and then turns to the other side of the cleft above the rudder. The upstream DNA duplex exits at an approximately right angle from the incoming downstream DNA, and emanates from the cleft between the protrusion and clamp. Comparison with published data suggests that the architecture of the complete EC is conserved from bacteria to eukaryotes and that upstream DNA is relocated during the initiation–elongation transition.
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Affiliation(s)
- Joanna Andrecka
- Department of Chemistry and Biochemistry and Center for Integrated Protein Science München, Ludwig-Maximilians-Universität München, Butenandtstr.11, 81377 München, Germany
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Kvach MV, Stepanova IA, Prokhorenko IA, Stupak AP, Bolibrukh DA, Korshun VA, Shmanai VV. Practical Synthesis of Isomerically Pure 5- and 6-Carboxytetramethylrhodamines, Useful Dyes for DNA Probes. Bioconjug Chem 2009; 20:1673-82. [DOI: 10.1021/bc900037b] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Maksim V. Kvach
- Institute of Physical Organic Chemistry, Surganova 13, 220072 Minsk, Belarus, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia, Institute of Physics, Nezavisimosti av. 70, 220072 Minsk, Belarus, and Institute of Bioorganic Chemistry, Kuprevicha 5/2, 220141, Minsk, Belarus
| | - Irina A. Stepanova
- Institute of Physical Organic Chemistry, Surganova 13, 220072 Minsk, Belarus, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia, Institute of Physics, Nezavisimosti av. 70, 220072 Minsk, Belarus, and Institute of Bioorganic Chemistry, Kuprevicha 5/2, 220141, Minsk, Belarus
| | - Igor A. Prokhorenko
- Institute of Physical Organic Chemistry, Surganova 13, 220072 Minsk, Belarus, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia, Institute of Physics, Nezavisimosti av. 70, 220072 Minsk, Belarus, and Institute of Bioorganic Chemistry, Kuprevicha 5/2, 220141, Minsk, Belarus
| | - Aleksander P. Stupak
- Institute of Physical Organic Chemistry, Surganova 13, 220072 Minsk, Belarus, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia, Institute of Physics, Nezavisimosti av. 70, 220072 Minsk, Belarus, and Institute of Bioorganic Chemistry, Kuprevicha 5/2, 220141, Minsk, Belarus
| | - Dmitry A. Bolibrukh
- Institute of Physical Organic Chemistry, Surganova 13, 220072 Minsk, Belarus, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia, Institute of Physics, Nezavisimosti av. 70, 220072 Minsk, Belarus, and Institute of Bioorganic Chemistry, Kuprevicha 5/2, 220141, Minsk, Belarus
| | - Vladimir A. Korshun
- Institute of Physical Organic Chemistry, Surganova 13, 220072 Minsk, Belarus, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia, Institute of Physics, Nezavisimosti av. 70, 220072 Minsk, Belarus, and Institute of Bioorganic Chemistry, Kuprevicha 5/2, 220141, Minsk, Belarus
| | - Vadim V. Shmanai
- Institute of Physical Organic Chemistry, Surganova 13, 220072 Minsk, Belarus, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia, Institute of Physics, Nezavisimosti av. 70, 220072 Minsk, Belarus, and Institute of Bioorganic Chemistry, Kuprevicha 5/2, 220141, Minsk, Belarus
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Ranjit S, Gurunathan K, Levitus M. Photophysics of Backbone Fluorescent DNA Modifications: Reducing Uncertainties in FRET. J Phys Chem B 2009; 113:7861-6. [DOI: 10.1021/jp810842u] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Suman Ranjit
- Department of Chemistry and Biochemistry, Department of Physics and The Biodesign Institute, Arizona State University, Tempe, Arizona 85287-5601
| | - Kaushik Gurunathan
- Department of Chemistry and Biochemistry, Department of Physics and The Biodesign Institute, Arizona State University, Tempe, Arizona 85287-5601
| | - Marcia Levitus
- Department of Chemistry and Biochemistry, Department of Physics and The Biodesign Institute, Arizona State University, Tempe, Arizona 85287-5601
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Vladimirov E, Ivanova A, Rösch N. Solvent Reorganization Energies in A-DNA, B-DNA, and Rhodamine 6G−DNA Complexes from Molecular Dynamics Simulations with a Polarizable Force Field. J Phys Chem B 2009; 113:4425-34. [DOI: 10.1021/jp809774q] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Egor Vladimirov
- Theoretische Chemie, Department Chemie, Technische Universität München, 85748 Garching, Germany, and Department of Physical Chemistry, Faculty of Chemistry, University of Sofia, 1 J. Bourchier Ave., 1164 Sofia, Bulgaria
| | - Anela Ivanova
- Theoretische Chemie, Department Chemie, Technische Universität München, 85748 Garching, Germany, and Department of Physical Chemistry, Faculty of Chemistry, University of Sofia, 1 J. Bourchier Ave., 1164 Sofia, Bulgaria
| | - Notker Rösch
- Theoretische Chemie, Department Chemie, Technische Universität München, 85748 Garching, Germany, and Department of Physical Chemistry, Faculty of Chemistry, University of Sofia, 1 J. Bourchier Ave., 1164 Sofia, Bulgaria
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Lilley DMJ. The structure and folding of branched RNA analyzed by fluorescence resonance energy transfer. Methods Enzymol 2009; 469:159-87. [PMID: 20946789 DOI: 10.1016/s0076-6879(09)69008-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Fluorescence resonance energy transfer (FRET) is a spectroscopic means of obtaining distance information over a range up to ~80Å in solution. It is based on the dipolar coupling between the electronic transition moments of a donor and acceptor fluorophore attached at known positions on the RNA species of interest. It can be applied in ensembles of molecules, either by steady-state fluorescence or by lifetime measurements, but it is also very appropriate for single-molecule studies. In addition to the provision of distance information, recent studies have emphasized the orientation dependence of energy transfer.
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Affiliation(s)
- David M J Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee, United Kingdom
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48
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Vámosi G, Clegg RM. Helix−Coil Transition of a Four-Way DNA Junction Observed by Multiple Fluorescence Parameters. J Phys Chem B 2008; 112:13136-48. [DOI: 10.1021/jp8034055] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- György Vámosi
- Cell Biology and Signaling Research Group of the Hungarian Academy of Sciences, Department of Biophysics and Cell Biology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary HU H-4012, and Department of Physics, University of Illinois at Urbana−Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080
| | - Robert M. Clegg
- Cell Biology and Signaling Research Group of the Hungarian Academy of Sciences, Department of Biophysics and Cell Biology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary HU H-4012, and Department of Physics, University of Illinois at Urbana−Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080
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Abstract
This chapter is focused on the fluorescent pteridine guanine analogs, 3MI and 6MI and on the pteridine adenine analog, 6MAP. A brief overview of commonly used methods to fluorescently label oligonucleotides reveals the role the pteridines play in the extensive variety of available probes. We describe the fluorescence characteristics of the pteridine probes as monomers and incorporated into DNA and review a variety of applications including changes in fluorescence intensity, anisotropies, time resolved studies, two photon excitation and single molecule detection.
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50
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Using fluorophore-labeled oligonucleotides to measure affinities of protein-DNA interactions. Methods Enzymol 2008; 450:253-72. [PMID: 19152864 DOI: 10.1016/s0076-6879(08)03412-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Changes in fluorescence emission intensity and anisotropy can reflect changes in the environment and molecular motion of a fluorophore. Researchers can capitalize on these characteristics to assess the affinity and specificity of DNA-binding proteins using fluorophore-labeled oligonucleotides. While there are many advantages to measuring binding using fluorescent oligonucleotides, there are also some distinct disadvantages. Here we describe some of the relevant issues for the novice, illustrating key points using data collected with a variety of labeled oligonucleotides and the relaxase domain of F plasmid TraI. Topics include selection of a fluorophore, experimental design using a fluorometer equipped with an automatic titrating unit, and analysis of direct binding and competition assays.
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