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Gauger M, Heinz M, Halbritter ALJ, Stelzl LS, Erlenbach N, Hummer G, Sigurdsson ST, Prisner TF. Structure and Internal Dynamics of Short RNA Duplexes Determined by a Combination of Pulsed EPR Methods and MD Simulations. Angew Chem Int Ed Engl 2024; 63:e202402498. [PMID: 38530284 DOI: 10.1002/anie.202402498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 03/24/2024] [Accepted: 03/25/2024] [Indexed: 03/27/2024]
Abstract
We used EPR spectroscopy to characterize the structure of RNA duplexes and their internal twist, stretch and bending motions. We prepared eight 20-base-pair-long RNA duplexes containing the rigid spin-label Çm, a cytidine analogue, at two positions and acquired orientation-selective PELDOR/DEER data. By using different frequency bands (X-, Q-, G-band), detailed information about the distance and orientation of the labels was obtained and provided insights into the global conformational dynamics of the RNA duplex. We used 19F Mims ENDOR experiments on three singly Çm- and singly fluorine-labeled RNA duplexes to determine the exact position of the Çm spin label in the helix. In a quantitative comparison to MD simulations of RNA with and without Çm spin labels, we found that state-of-the-art force fields with explicit parameterization of the spin label were able to describe the conformational ensemble present in our experiments. The MD simulations further confirmed that the Çm spin labels are excellent mimics of cytidine inducing only small local changes in the RNA structure. Çm spin labels are thus ideally suited for high-precision EPR experiments to probe the structure and, in conjunction with MD simulations, motions of RNA.
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Affiliation(s)
- Maximilian Gauger
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438, Frankfurt am Main, Germany
| | - Marcel Heinz
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany
| | | | - Lukas S Stelzl
- Faculty of Biology, Johannes Gutenberg University, 55128, Mainz, Germany
- KOMET 1, Institute of Physics, Johannes Gutenberg University, Staudingerweg 9, 55128, Mainz, Germany
- Institute of Quantitative and Computational Bioscience (IQCB), Johannes Gutenberg University Mainz, 55128, Mainz, Germany
- Institute of Molecular Biology (IMB), 55128, Mainz, Germany
| | - Nicole Erlenbach
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438, Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany
- Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue Str. 1, 60438, Frankfurt am Main, Germany
| | | | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438, Frankfurt am Main, Germany
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2
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Huang K, Fang X. A review on recent advances in methods for site-directed spin labeling of long RNAs. Int J Biol Macromol 2023; 239:124244. [PMID: 37001783 DOI: 10.1016/j.ijbiomac.2023.124244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 01/12/2023] [Accepted: 03/15/2023] [Indexed: 03/31/2023]
Abstract
RNAs are important biomolecules that play essential roles in various cellular processes and are crucially linked with many human diseases. The key to elucidate the mechanisms underlying their biological functions and develop RNA-based therapeutics is to investigate RNA structure and dynamics and their connections to function in detail using a variety of approaches. Magnetic resonance techniques including paramagnetic nuclear magnetic resonance (NMR) and electron magnetic resonance (EPR) spectroscopies have proved to be powerful tools to gain insights into such properties. The prerequisites for paramagnetic NMR and EPR studies on RNAs are to achieve site-specific spin labeling of the intrinsically diamagnetic RNAs, which however is not trivial, especially for long ones. In this review, we present some covalent labeling strategies that allow site-specific introduction of electron spins to long RNAs. Generally, these strategies include assembly of long RNAs via enzymatic ligation of short oligonucleotides, co- and post-transcriptional site-specific labeling empowered with the unnatural base pair system, and direct enzymatic functionalization of natural RNAs. We introduce a few case studies to discuss the advantages and limitations of each strategy, and to provide a vision for the future development.
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3
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Miao Q, Nitsche C, Orton H, Overhand M, Otting G, Ubbink M. Paramagnetic Chemical Probes for Studying Biological Macromolecules. Chem Rev 2022; 122:9571-9642. [PMID: 35084831 PMCID: PMC9136935 DOI: 10.1021/acs.chemrev.1c00708] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Indexed: 12/11/2022]
Abstract
Paramagnetic chemical probes have been used in electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopy for more than four decades. Recent years witnessed a great increase in the variety of probes for the study of biological macromolecules (proteins, nucleic acids, and oligosaccharides). This Review aims to provide a comprehensive overview of the existing paramagnetic chemical probes, including chemical synthetic approaches, functional properties, and selected applications. Recent developments have seen, in particular, a rapid expansion of the range of lanthanoid probes with anisotropic magnetic susceptibilities for the generation of structural restraints based on residual dipolar couplings and pseudocontact shifts in solution and solid state NMR spectroscopy, mostly for protein studies. Also many new isotropic paramagnetic probes, suitable for NMR measurements of paramagnetic relaxation enhancements, as well as EPR spectroscopic studies (in particular double resonance techniques) have been developed and employed to investigate biological macromolecules. Notwithstanding the large number of reported probes, only few have found broad application and further development of probes for dedicated applications is foreseen.
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Affiliation(s)
- Qing Miao
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands
- School
of Chemistry &Chemical Engineering, Shaanxi University of Science & Technology, Xi’an710021, China
| | - Christoph Nitsche
- Research
School of Chemistry, The Australian National
University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
| | - Henry Orton
- Research
School of Chemistry, The Australian National
University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
- ARC
Centre of Excellence for Innovations in Peptide & Protein Science,
Research School of Chemistry, Australian
National University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
| | - Mark Overhand
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands
| | - Gottfried Otting
- Research
School of Chemistry, The Australian National
University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
- ARC
Centre of Excellence for Innovations in Peptide & Protein Science,
Research School of Chemistry, Australian
National University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
| | - Marcellus Ubbink
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands
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4
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Segler ALJ, Sigurdsson ST. A Carbazole-Derived Nitroxide That Is an Analogue of Cytidine: A Rigid Spin Label for DNA and RNA. J Org Chem 2021; 86:11647-11659. [PMID: 34410721 DOI: 10.1021/acs.joc.1c01176] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A variety of semirigid and rigid spin labels comprise a valuable arsenal for measurements of biomolecular structures and dynamics by electron paramagnetic resonance (EPR) spectroscopy. Here, we report the synthesis and characterization of rigid spin labels Ċ and Ċm for DNA and RNA, respectively, that are carbazole-derived nitroxides and analogues of cytidine. Ċ and Ċm were converted to their phosphoramidites and used for their incorporation into oligonucleotides by solid-phase synthesis. Analysis of Ċ and Ċm by single-crystal X-ray crystallography verified their identity and showed little deviation from planarity of the nucleobase. Analysis of the continuous-wave (CW) EPR spectra of the spin-labeled DNA and RNA duplexes confirmed their incorporation into the nucleic acids and the line-shape was characteristic of rigid spin labels. Circular dichroism (CD) and thermal denaturation studies of the Ċ-labeled DNAs and Ċm-labeled RNAs indicated that the labels are nonperturbing of duplex structure.
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Affiliation(s)
- Anna-Lena Johanna Segler
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
| | - Snorri Th Sigurdsson
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
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5
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Ghosh S, Casto J, Bogetti X, Arora C, Wang J, Saxena S. Orientation and dynamics of Cu 2+ based DNA labels from force field parameterized MD elucidates the relationship between EPR distance constraints and DNA backbone distances. Phys Chem Chem Phys 2020; 22:26707-26719. [PMID: 33159779 PMCID: PMC10521111 DOI: 10.1039/d0cp05016d] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
Pulsed electron paramagnetic resonance (EPR) based distance measurements using the recently developed Cu2+-DPA label present a promising strategy for measuring DNA backbone distance constraints. Herein we develop force field parameters for Cu2+-DPA in order to understand the features of this label at an atomic level. We perform molecular dynamics (MD) simulations using the force field parameters of Cu2+-DPA on four different DNA duplexes. The distance between the Cu2+ centers, extracted from the 2 μs MD trajectories, agrees well with the experimental distance for all the duplexes. Further analyses of the trajectory provide insight into the orientation of the Cu2+-DPA inside the duplex that leads to such agreement with experiments. The MD results also illustrate the ability of the Cu2+-DPA to report on the DNA backbone distance constraints. Furthermore, measurement of fluctuations of individual residues showed that the flexibility of Cu2+-DPA in a DNA depends on the position of the label in the duplex, and a 2 μs MD simulation is not sufficient to fully capture the experimental distribution in some cases. Finally, the MD trajectories were utilized to understand the key aspects of the double electron electron resonance (DEER) results. The lack of orientational selectivity effects of the Cu2+-DPA at Q-band frequency is rationalized in terms of fluctuations in the Cu2+ coordination environment and rotameric fluctuations of the label linker. Overall, a combination of EPR and MD simulations based on the Cu2+-DPA labelling strategy can contribute towards understanding changes in DNA backbone conformations during protein-DNA interactions.
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Affiliation(s)
- Shreya Ghosh
- Department of Chemistry, University of Pittsburgh, PA 15260, USA.
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6
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Ghosh S, Lawless MJ, Brubaker HJ, Singewald K, Kurpiewski MR, Jen-Jacobson L, Saxena S. Cu2+-based distance measurements by pulsed EPR provide distance constraints for DNA backbone conformations in solution. Nucleic Acids Res 2020; 48:e49. [PMID: 32095832 PMCID: PMC7229862 DOI: 10.1093/nar/gkaa133] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/24/2020] [Accepted: 02/17/2020] [Indexed: 11/12/2022] Open
Abstract
Electron paramagnetic resonance (EPR) has become an important tool to probe conformational changes in nucleic acids. An array of EPR labels for nucleic acids are available, but they often come at the cost of long tethers, are dependent on the presence of a particular nucleotide or can be placed only at the termini. Site directed incorporation of Cu2+-chelated to a ligand, 2,2'dipicolylamine (DPA) is potentially an attractive strategy for site-specific, nucleotide independent Cu2+-labelling in DNA. To fully understand the potential of this label, we undertook a systematic and detailed analysis of the Cu2+-DPA motif using EPR and molecular dynamics (MD) simulations. We used continuous wave EPR experiments to characterize Cu2+ binding to DPA as well as optimize Cu2+ loading conditions. We performed double electron-electron resonance (DEER) experiments at two frequencies to elucidate orientational selectivity effects. Furthermore, comparison of DEER and MD simulated distance distributions reveal a remarkable agreement in the most probable distances. The results illustrate the efficacy of the Cu2+-DPA in reporting on DNA backbone conformations for sufficiently long base pair separations. This labelling strategy can serve as an important tool for probing conformational changes in DNA upon interaction with other macromolecules.
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Affiliation(s)
- Shreya Ghosh
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Matthew J Lawless
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Hanna J Brubaker
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Kevin Singewald
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Michael R Kurpiewski
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Linda Jen-Jacobson
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
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7
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Hardwick JS, Haugland MM, El-Sagheer AH, Ptchelkine D, Beierlein FR, Lane AN, Brown T, Lovett JE, Anderson EA. 2'-Alkynyl spin-labelling is a minimally perturbing tool for DNA structural analysis. Nucleic Acids Res 2020; 48:2830-2840. [PMID: 32052020 PMCID: PMC7102949 DOI: 10.1093/nar/gkaa086] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 01/28/2020] [Accepted: 02/10/2020] [Indexed: 02/06/2023] Open
Abstract
The determination of distances between specific points in nucleic acids is essential to understanding their behaviour at the molecular level. The ability to measure distances of 2-10 nm is particularly important: deformations arising from protein binding commonly fall within this range, but the reliable measurement of such distances for a conformational ensemble remains a significant challenge. Using several techniques, we show that electron paramagnetic resonance (EPR) spectroscopy of oligonucleotides spin-labelled with triazole-appended nitroxides at the 2' position offers a robust and minimally perturbing tool for obtaining such measurements. For two nitroxides, we present results from EPR spectroscopy, X-ray crystal structures of B-form spin-labelled DNA duplexes, molecular dynamics simulations and nuclear magnetic resonance spectroscopy. These four methods are mutually supportive, and pinpoint the locations of the spin labels on the duplexes. In doing so, this work establishes 2'-alkynyl nitroxide spin-labelling as a minimally perturbing method for probing DNA conformation.
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Affiliation(s)
- Jack S Hardwick
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Marius M Haugland
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Afaf H El-Sagheer
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
- Chemistry Branch, Department of Science and Mathematics, Faculty of Petroleum and Mining Engineering, Suez University, Suez 43721, Egypt
| | - Denis Ptchelkine
- Weatherall Institute of Molecular Medicine, Department of Oncology, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford OX3 9DS, UK
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0FA, UK
| | - Frank R Beierlein
- Computer-Chemistry-Center and Interdisciplinary Center for Molecular Materials, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstrasse 25, 91052 Erlangen, Germany
| | - Andrew N Lane
- Center for Environmental and Systems Biochemistry and Department of Toxicology & Cancer Biology, The University of Kentucky, 789 S. Limestone St., Lexington, KY 40536, USA
| | - Tom Brown
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Janet E Lovett
- SUPA School of Physics and Astronomy and BSRC, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK
| | - Edward A Anderson
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
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8
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Gustmann H, Segler ALJ, Gophane DB, Reuss AJ, Grünewald C, Braun M, Weigand JE, Sigurdsson ST, Wachtveitl J. Structure guided fluorescence labeling reveals a two-step binding mechanism of neomycin to its RNA aptamer. Nucleic Acids Res 2019; 47:15-28. [PMID: 30462266 PMCID: PMC6326822 DOI: 10.1093/nar/gky1110] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/22/2018] [Indexed: 12/12/2022] Open
Abstract
The ability of the cytidine analog Çmf to act as a position specific reporter of RNA-dynamics was spectroscopically evaluated. Çmf-labeled single- and double-stranded RNAs differ in their fluorescence lifetimes, quantum yields and anisotropies. These observables were also influenced by the nucleobases flanking Çmf. This conformation and position specificity allowed to investigate the binding dynamics and mechanism of neomycin to its aptamer N1 by independently incorporating Çmf at four different positions within the aptamer. Remarkably fast binding kinetics of neomycin binding was observed with stopped-flow measurements, which could be satisfactorily explained with a two-step binding. Conformational selection was identified as the dominant mechanism.
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Affiliation(s)
- Henrik Gustmann
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt, Germany
| | - Anna-Lena J Segler
- Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavik, Iceland
| | | | - Andreas J Reuss
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt, Germany
| | - Christian Grünewald
- Institute for Organic Chemistry and Chemical Biology, Goethe-University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt, Germany
| | - Markus Braun
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt, Germany
| | - Julia E Weigand
- Department of Biology, Technical University Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
| | | | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt, Germany
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9
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Antiviral activity spectrum of phenoxazine nucleoside derivatives. Antiviral Res 2019; 163:117-124. [PMID: 30684562 DOI: 10.1016/j.antiviral.2019.01.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/14/2019] [Accepted: 01/17/2019] [Indexed: 12/13/2022]
Abstract
The phenoxazine scaffold is widely used to stabilize nucleic acid duplexes, as a part of fluorescent probes for the study of nucleic acid structure, recognition, and metabolism, etc. Here we present the synthesis of phenoxazine-based nucleoside derivatives and their antiviral activity against a panel of structurally diverse viruses: enveloped DNA herpesviruses varicella zoster virus (VZV) and human cytomegalovirus, enveloped RNA tick-borne encephalitis virus (TBEV), and non-enveloped RNA enteroviruses. Studied compounds were effective against DNA and RNA viruses reproduction in cell culture. 3-(2'-Deoxy-β-D-ribofuranosyl)-1,3-diaza-2-oxophenoxazine proved to be a potent inhibitor of VZV replication with superior activity against wild type than thymidine kinase deficient strains (EC50 0.06 and 10 μM, respectively). This compound did not show cytotoxicity on all the studied cell lines. Several compounds showed promising activity against TBEV (EC50 0.35-0.91 μM), but the activity was accompanied by pronounced cytotoxicity. These compounds may be considered as a good starting point for further structure optimization as antiherpesviral or antiflaviviral compounds.
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10
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Gränz M, Erlenbach N, Spindler P, Gophane DB, Stelzl LS, Sigurdsson ST, Prisner TF. Dynamics of Nucleic Acids at Room Temperature Revealed by Pulsed EPR Spectroscopy. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201803682] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Markus Gränz
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic ResonanceGoethe University Frankfurt Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
| | - Nicole Erlenbach
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic ResonanceGoethe University Frankfurt Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
| | - Philipp Spindler
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic ResonanceGoethe University Frankfurt Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
| | - Dnyaneshwar B. Gophane
- Department of ChemistryScience InstituteUniversity of Iceland Dunhaga 3 107 Reykjavík Iceland
| | - Lukas S. Stelzl
- Department of Theoretical BiophysicsMax Planck Institute of Biophysics Max-von-Laue-Straße 3 60438 Frankfurt am Main Germany
| | - Snorri Th. Sigurdsson
- Department of ChemistryScience InstituteUniversity of Iceland Dunhaga 3 107 Reykjavík Iceland
| | - Thomas F. Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic ResonanceGoethe University Frankfurt Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
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11
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Gränz M, Erlenbach N, Spindler P, Gophane DB, Stelzl LS, Sigurdsson ST, Prisner TF. Dynamics of Nucleic Acids at Room Temperature Revealed by Pulsed EPR Spectroscopy. Angew Chem Int Ed Engl 2018; 57:10540-10543. [PMID: 29858557 DOI: 10.1002/anie.201803682] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 05/06/2018] [Indexed: 12/16/2022]
Abstract
The investigation of the structure and conformational dynamics of biomolecules under physiological conditions is challenging for structural biology. Although pulsed electron paramagnetic resonance (like PELDOR) techniques provide long-range distance and orientation information with high accuracy, such studies are usually performed at cryogenic temperatures. At room temperature (RT) PELDOR studies are seemingly impossible due to short electronic relaxation times and loss of dipolar interactions through rotational averaging. We incorporated the rigid nitroxide spin label Ç into a DNA duplex and immobilized the sample on a solid support to overcome this limitation. This enabled orientation-selective PELDOR measurements at RT. A comparison with data recorded at 50 K revealed averaging of internal dynamics, which occur on the ns time range at RT. Thus, our approach adds a new method to study structural and dynamical processes at physiological temperature in the <10 μs time range with atomistic resolution.
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Affiliation(s)
- Markus Gränz
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Nicole Erlenbach
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Philipp Spindler
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Dnyaneshwar B Gophane
- Department of Chemistry, Science Institute, University of Iceland, Dunhaga 3, 107, Reykjavík, Iceland
| | - Lukas S Stelzl
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany
| | - Snorri Th Sigurdsson
- Department of Chemistry, Science Institute, University of Iceland, Dunhaga 3, 107, Reykjavík, Iceland
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
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12
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Gustmann H, Lefrancois D, Reuss AJ, Gophane DB, Braun M, Dreuw A, Sigurdsson ST, Wachtveitl J. Spin the light off: rapid internal conversion into a dark doublet state quenches the fluorescence of an RNA spin label. Phys Chem Chem Phys 2018; 19:26255-26264. [PMID: 28933471 DOI: 10.1039/c7cp03975a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The spin label Çm and the fluorophore Çmf are close isosteric relatives: the secondary amine Çmf can be easily oxidized to a nitroxide group to form Çm. Thus, both compounds can serve as EPR and fluorescence labels, respectively, and their high structural similarity allows direct comparison of EPR and fluorescence data, e.g. in the context of investigations of RNA conformation and dynamics. Detailed UV/vis-spectroscopic studies demonstrate that the fluorescence lifetime and the quantum yield of Çmf are directly affected by intermolecular interactions, which makes it a sensitive probe of its microenvironment. On the other hand, Çm undergoes effective fluorescence quenching in the ps-time domain. The established quenching mechanisms that are usually operational for fluorophore-nitroxide compounds, do not explain the spectroscopic data for Çm. Quantum chemical calculations revealed that the lowest excited doublet state D1, which has no equivalent in Çmf, is a key state of the ultrafast quenching mechanism. This dark state is localized on the nitroxide group and is populated via rapid internal conversion.
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Affiliation(s)
- Henrik Gustmann
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt am Main, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany.
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13
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Grytz CM, Kazemi S, Marko A, Cekan P, Güntert P, Sigurdsson ST, Prisner TF. Determination of helix orientations in a flexible DNA by multi-frequency EPR spectroscopy. Phys Chem Chem Phys 2018; 19:29801-29811. [PMID: 29090294 DOI: 10.1039/c7cp04997h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Distance measurements are performed between a pair of spin labels attached to nucleic acids using Pulsed Electron-Electron Double Resonance (PELDOR, also called DEER) spectroscopy which is a complementary tool to other structure determination methods in structural biology. The rigid spin label Ç, when incorporated pairwise into two helical parts of a nucleic acid molecule, allows the determination of both the mutual orientation and the distance between those labels, since Ç moves rigidly with the helix to which it is attached. We have developed a two-step protocol to investigate the conformational flexibility of flexible nucleic acid molecules by multi-frequency PELDOR. In the first step, a library with a broad collection of conformers, which are in agreement with topological constraints, NMR restraints and distances derived from PELDOR, was created. In the second step, a weighted structural ensemble of these conformers was chosen, such that it fits the multi-frequency PELDOR time traces of all doubly Ç-labelled samples simultaneously. This ensemble reflects the global structure and the conformational flexibility of the two-way DNA junction. We demonstrate this approach on a flexible bent DNA molecule, consisting of two short helical parts with a five adenine bulge at the center. The kink and twist motions between both helical parts were quantitatively determined and showed high flexibility, in agreement with a Förster Resonance Energy Transfer (FRET) study on a similar bent DNA motif. The approach presented here should be useful to describe the relative orientation of helical motifs and the conformational flexibility of nucleic acid structures, both alone and in complexes with proteins and other molecules.
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Affiliation(s)
- C M Grytz
- Institute of Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany.
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14
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Stelzl LS, Erlenbach N, Heinz M, Prisner TF, Hummer G. Resolving the Conformational Dynamics of DNA with Ångstrom Resolution by Pulsed Electron-Electron Double Resonance and Molecular Dynamics. J Am Chem Soc 2017; 139:11674-11677. [PMID: 28777549 DOI: 10.1021/jacs.7b05363] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pulsed electron-electron double resonance (PELDOR/DEER) experiments of nucleic acids with rigid spin labels provide highly accurate distance and orientation information. Here we combine PELDOR experiments with molecular dynamics (MD) simulations to arrive at an atomistic view of the conformational dynamics of DNA. The MD simulations closely reproduce the PELDOR time traces, and demonstrate that bending, in addition to twist-stretch motions, underpin the sub-μs dynamics of DNA. PELDOR experiments correctly rank DNA force fields and resolve subtle differences in the conformational ensembles of nucleic acids, on the order of 1-2 Å. Long-range distance and angle measurements with rigid spin labels provide critical input for the refinement of computer models and the elucidation of the structure and dynamics of complex biomolecules.
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Affiliation(s)
- Lukas S Stelzl
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics , 60438 Frankfurt am Main, Germany
| | - Nicole Erlenbach
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt , 60438 Frankfurt am Main, Germany
| | - Marcel Heinz
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics , 60438 Frankfurt am Main, Germany
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt , 60438 Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics , 60438 Frankfurt am Main, Germany.,Institute for Biophysics, Goethe University Frankfurt , 60438 Frankfurt am Main, Germany
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15
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Kerzhner M, Abdullin D, Więcek J, Matsuoka H, Hagelueken G, Schiemann O, Famulok M. Post-synthetic Spin-Labeling of RNA through Click Chemistry for PELDOR Measurements. Chemistry 2016; 22:12113-21. [PMID: 27412453 DOI: 10.1002/chem.201601897] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 01/24/2023]
Abstract
Site-directed spin labeling of RNA based on click chemistry is used in combination with pulsed electron-electron double resonance (PELDOR) to benchmark a nitroxide spin label, called here dŲ. We compare this approach with another established method that employs the rigid spin label Çm for RNA labeling. By using CD spectroscopy, thermal denaturation measurements, CW-EPR as well as PELDOR we analyzed and compared the influence of dŲ and Çm on a self-complementary RNA duplex. Our results demonstrate that the conformational diversity of dŲ is significantly reduced near the freezing temperature of a phosphate buffer, resulting in strongly orientation-selective PELDOR time traces of the dŲ-labeled RNA duplex.
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Affiliation(s)
- Mark Kerzhner
- Life & Medical Sciences Institute, Chemical Biology & Medicinal Chemistry Unit c/o Kekulé-Institut für Organische Chemie und Biochemie, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Dinar Abdullin
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Jennifer Więcek
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Hideto Matsuoka
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Gregor Hagelueken
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Olav Schiemann
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany.
| | - Michael Famulok
- Life & Medical Sciences Institute, Chemical Biology & Medicinal Chemistry Unit c/o Kekulé-Institut für Organische Chemie und Biochemie, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany. .,Max-Planck Fellow Group Chemical Biology, Center of Advanced European Studies and Research, Ludwig-Erhard-Allee 2, 53175, Bonn, Germany.
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17
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Endeward B, Marko A, Denysenkov VP, Sigurdsson ST, Prisner TF. Advanced EPR Methods for Studying Conformational Dynamics of Nucleic Acids. Methods Enzymol 2015; 564:403-25. [PMID: 26477259 DOI: 10.1016/bs.mie.2015.06.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Pulsed electron paramagnetic resonance (EPR) spectroscopy has become an important tool for structural characterization of biomolecules allowing measurement of the distances between two paramagnetic spin labels attached to a biomolecule in the 2-8 nm range. In this chapter, we will focus on applications of this approach to investigate tertiary structure elements as well as conformational dynamics of nucleic acid molecules. Both aspects take advantage of using specific spin labels that are rigidly attached to the nucleobases, as they allow obtaining not only the distance but also the relative orientation between both nitroxide moieties with high accuracy. Thus, not only the distance but additionally the three Euler angles between both the nitroxide axis systems and the two polar angles of the interconnecting vector with respect to the nitroxide axis systems can be extracted from a single pair of spin labels. To extract all these parameters independently and unambiguously, a set of multifrequency/multifield pulsed EPR experiments have to be performed. We will describe the experimental procedure as well as newly developed spin labels, which are helpful to disentangle all these parameters, and tools which we have developed to analyze such data sets. The procedures and analyses will be illustrated by examples from our laboratory.
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Affiliation(s)
- B Endeward
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - A Marko
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - V P Denysenkov
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - S Th Sigurdsson
- Department of Chemistry, Science Institute, University of Iceland, Reykjavık, Iceland
| | - T F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt am Main, Frankfurt am Main, Germany.
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Prisner TF, Marko A, Sigurdsson ST. Conformational dynamics of nucleic acid molecules studied by PELDOR spectroscopy with rigid spin labels. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 252:187-98. [PMID: 25701439 DOI: 10.1016/j.jmr.2014.12.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 12/16/2014] [Accepted: 12/19/2014] [Indexed: 05/22/2023]
Abstract
Nucleic acid molecules can adopt a variety of structures and exhibit a large degree of conformational flexibility to fulfill their various functions in cells. Here we describe the use of Pulsed Electron-Electron Double Resonance (PELDOR or DEER) to investigate nucleic acid molecules where two cytosine analogs have been incorporated as spin probes. Because these new types of spin labels are rigid and incorporated into double stranded DNA and RNA molecules, there is no additional flexibility of the spin label itself present. Therefore the magnetic dipole-dipole interaction between both spin labels encodes for the distance as well as for the mutual orientation between the spin labels. All of this information can be extracted by multi-frequency/multi-field PELDOR experiments, which gives very precise and valuable information about the structure and conformational flexibility of the nucleic acid molecules. We describe in detail our procedure to obtain the conformational ensembles and show the accuracy and limitations with test examples and application to double-stranded DNA.
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Affiliation(s)
- T F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Germany.
| | - A Marko
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Germany
| | - S Th Sigurdsson
- Science Institute, University of Iceland, Reykjavik, Iceland
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Ranis LG, Werellapatha K, Pietrini NJ, Bunker BA, Brown SN. Metal and Ligand Effects on Bonding in Group 6 Complexes of Redox-Active Amidodiphenoxides. Inorg Chem 2014; 53:10203-16. [DOI: 10.1021/ic501222n] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Leila G. Ranis
- Department
of Chemistry and Biochemistry and ‡Department of Physics, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, United States
| | - Kalpani Werellapatha
- Department
of Chemistry and Biochemistry and ‡Department of Physics, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, United States
| | - Nicholas J. Pietrini
- Department
of Chemistry and Biochemistry and ‡Department of Physics, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, United States
| | - Bruce A. Bunker
- Department
of Chemistry and Biochemistry and ‡Department of Physics, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, United States
| | - Seth N. Brown
- Department
of Chemistry and Biochemistry and ‡Department of Physics, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, United States
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Frecus B, Rinkevicius Z, Ågren H. π-Stacking effects on the EPR parameters of a prototypical DNA spin label. Phys Chem Chem Phys 2013; 15:10466-71. [PMID: 23685812 DOI: 10.1039/c3cp51129d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The character and value of spin labels for probing environments like double-stranded DNA depend on the degree of change in the spin Hamiltonian parameters of the spin label induced by the environment. Herein we provide a systematic theoretical investigation of this issue, based on a density functional theory method applied to a spin labeled DNA model system, focusing on the dependence of the EPR properties of the spin label on the π stacking and hydrogen bonding that occur upon incorporating the spin label into the selected base pair inside DNA. It is found that the EPR spin Hamiltonian parameters of the spin label are only negligibly affected by its incorporation into DNA, when compared to its free form. This result gives a theoretical ground for the common empirical assumption regarding the behaviour of spin Hamiltonian parameters made in EPR based measurements of the distance between spin labels incorporated into DNA.
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Affiliation(s)
- Bogdan Frecus
- KTH Royal Institute of Technology, School of Biotechnology, Division of Theoretical Chemistry & Biology, SE-106 91 Stockholm, Sweden.
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Tkach I, Pornsuwan S, Höbartner C, Wachowius F, Sigurdsson ST, Baranova TY, Diederichsen U, Sicoli G, Bennati M. Orientation selection in distance measurements between nitroxide spin labels at 94 GHz EPR with variable dual frequency irradiation. Phys Chem Chem Phys 2013; 15:3433-7. [PMID: 23381580 DOI: 10.1039/c3cp44415e] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pulsed electron-electron double resonance (PELDOR, also known as DEER) has become a method of choice to measure distances in biomolecules. In this work we show how the performance of the method can be improved at high EPR frequencies (94 GHz) using variable dual frequency irradiation in a dual mode cavity in order to obtain enhanced resolution toward orientation selection. Dipolar evolution traces of a representative RNA duplex and an α-helical peptide were analysed in terms of possible bi-radical structures by considering the inherent ambiguity of symmetry-related solutions.
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Affiliation(s)
- Igor Tkach
- Research Group EPR Spectroscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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Cekan P, Sigurdsson ST. Conformation and dynamics of nucleotides in bulges and symmetric internal loops in duplex DNA studied by EPR and fluorescence spectroscopies. Biochem Biophys Res Commun 2012; 420:656-61. [PMID: 22450317 DOI: 10.1016/j.bbrc.2012.03.059] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 03/12/2012] [Indexed: 01/02/2023]
Abstract
The dynamics and conformation of base bulges and internal loops in duplex DNA were studied using the bifunctional spectroscopic probe Ç, which becomes fluorescent (Ç(f)) upon reduction of the nitroxide functional group, along with EPR and fluorescence spectroscopies. A one-base bulge was in a conformational equilibrium between looped-out and stacked states, the former favored at higher temperature and the latter at lower temperature. Stacking of bulge bases was favored in two- and three-base bulges, independent of temperature, resulting in DNA bending as evidenced by increased fluorescence of Ç(f). EPR spectra of Ç-labeled three-, four- and five-base symmetrical interior DNA bulges at 20 °C showed low mobility, indicating that the spin-label was stacked within the loop. The spin-label mobility at 37 °C increased as the loops became larger. A considerable variation in fluorescence between different loops was observed, as well as a temperature-dependence within constructs. Fluorescence unexpectedly increased as the size of the loop decreased at 2 °C. Fluorescence of the smallest loops, where a single T·T mismatch was located between the stem region and the probe, was even larger than for the single strand, indicating a considerable local structural deformation of these loops from regular B-DNA. These results show the value of combining EPR and fluorescence spectroscopy to study non-helical regions of nucleic acids.
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Affiliation(s)
- Pavol Cekan
- University of Iceland, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
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Ming X, Ding P, Leonard P, Budow S, Seela F. Parallel-stranded DNA: Enhancing duplex stability by the ‘G-clamp’ and a pyrrolo-dC derivative. Org Biomol Chem 2012; 10:1861-9. [DOI: 10.1039/c2ob06606h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Shelke SA, Sigurdsson ST. Site-Directed Nitroxide Spin Labeling of Biopolymers. STRUCTURAL INFORMATION FROM SPIN-LABELS AND INTRINSIC PARAMAGNETIC CENTRES IN THE BIOSCIENCES 2011. [DOI: 10.1007/430_2011_62] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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