1
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Bogetti X, Saxena S. Integrating Electron Paramagnetic Resonance Spectroscopy and Computational Modeling to Measure Protein Structure and Dynamics. Chempluschem 2024; 89:e202300506. [PMID: 37801003 DOI: 10.1002/cplu.202300506] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/07/2023]
Abstract
Electron paramagnetic resonance (EPR) has become a powerful probe of conformational heterogeneity and dynamics of biomolecules. In this Review, we discuss different computational modeling techniques that enrich the interpretation of EPR measurements of dynamics or distance restraints. A variety of spin labels are surveyed to provide a background for the discussion of modeling tools. Molecular dynamics (MD) simulations of models containing spin labels provide dynamical properties of biomolecules and their labels. These simulations can be used to predict EPR spectra, sample stable conformations and sample rotameric preferences of label sidechains. For molecular motions longer than milliseconds, enhanced sampling strategies and de novo prediction software incorporating or validated by EPR measurements are able to efficiently refine or predict protein conformations, respectively. To sample large-amplitude conformational transition, a coarse-grained or an atomistic weighted ensemble (WE) strategy can be guided with EPR insights. Looking forward, we anticipate an integrative strategy for efficient sampling of alternate conformations by de novo predictions, followed by validations by systematic EPR measurements and MD simulations. Continuous pathways between alternate states can be further sampled by WE-MD including all intermediate states.
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Affiliation(s)
- Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA, 15260, USA
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA, 15260, USA
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2
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Schumann SL, Kotnig S, Kutin Y, Drosou M, Stratmann LM, Streltsova Y, Schnegg A, Pantazis DA, Clever GH, Kasanmascheff M. Structure and Flexibility of Copper-Modified DNA G-Quadruplexes Investigated by 19 F ENDOR Experiments at 34 GHz. Chemistry 2023; 29:e202302527. [PMID: 37602522 DOI: 10.1002/chem.202302527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 08/18/2023] [Accepted: 08/21/2023] [Indexed: 08/22/2023]
Abstract
DNA G-quadruplexes (GQs) are of great interest due to their involvement in crucial biological processes such as telomerase maintenance and gene expression. Furthermore, they are reported as catalytically active DNAzymes and building blocks in bio-nanotechnology. GQs exhibit remarkable structural diversity and conformational heterogeneity, necessitating precise and reliable tools to unravel their structure-function relationships. Here, we present insights into the structure and conformational flexibility of a unimolecular GQ with high spatial resolution via electron-nuclear double resonance (ENDOR) experiments combined with Cu(II) and fluorine labeling. These findings showcase the successful application of the 19 F-ENDOR methodology at 34 GHz, overcoming the limitations posed by the complexity and scarcity of higher-frequency spectrometers. Importantly, our approach retains both sensitivity and orientational resolution. This integrated study not only enhances our understanding of GQs but also expands the methodological toolbox for studying other macromolecules.
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Affiliation(s)
- Simon L Schumann
- Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Strasse 6, 44227, Dortmund, Germany
| | - Simon Kotnig
- Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Strasse 6, 44227, Dortmund, Germany
| | - Yury Kutin
- Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Strasse 6, 44227, Dortmund, Germany
| | - Maria Drosou
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Lukas M Stratmann
- Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Strasse 6, 44227, Dortmund, Germany
| | - Yana Streltsova
- Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Strasse 6, 44227, Dortmund, Germany
| | - Alexander Schnegg
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Guido H Clever
- Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Strasse 6, 44227, Dortmund, Germany
| | - Müge Kasanmascheff
- Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Strasse 6, 44227, Dortmund, Germany
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3
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Sannikova NE, Kolokolov MI, Khlynova TA, Chubarov AS, Polienko YF, Fedin MV, Krumkacheva OA. Revealing light-induced structural shifts in G-quadruplex-porphyrin complexes: a pulsed dipolar EPR study. Phys Chem Chem Phys 2023; 25:22455-22466. [PMID: 37581249 DOI: 10.1039/d3cp01775c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The binding of G-quadruplex structures (G4s) with photosensitizers is of considerable importance in medicinal chemistry and drug discovery due to their promising potential in photodynamic therapy applications. G4s can experience structural changes as a result of ligand interactions and light exposure. Understanding these modifications is essential to uncover the fundamental biological roles of the complexes and optimize their therapeutic potential. The structural diversity of G4s makes it challenging to study their complexes with ligands, necessitating the use of various complementary methods to fully understand these interactions. In this study, we introduce, for the first time, the application of laser-induced dipolar EPR as a method to characterize G-quadruplex DNA complexes containing photosensitizers and to investigate light-induced structural modifications in these systems. To demonstrate the feasibility of this approach, we studied complexes of the human telomeric G-quadruplex (HTel-22) with cationic 5,10,15,20-tetrakis(1-methyl-4-pyridinio) porphyrin tetra(p-toluenesulfonate) (TMPyP4). In addition to showcasing a new methodology, we also aimed to provide insights into the mechanisms underlying photoinduced HTel-22/TMPyP4 structural changes, thereby aiding in the advancement of approaches targeting G4s in photodynamic therapy. EPR revealed G-quadruplex unfolding and dimer formation upon light exposure. Our findings demonstrate the potential of EPR spectroscopy for examining G4 complexes with photosensitizers and contribute to a better understanding of G4s' interactions with ligands under light.
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Affiliation(s)
- Natalya E Sannikova
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Mikhail I Kolokolov
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Tamara A Khlynova
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Alexey S Chubarov
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Yuliya F Polienko
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | - Matvey V Fedin
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Olesya A Krumkacheva
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
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4
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Casto J, Bogetti X, Hunter HR, Hasanbasri Z, Saxena S. "Store-bought is fine": Sensitivity considerations using shaped pulses for DEER measurements on Cu(II) labels. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 349:107413. [PMID: 36867974 DOI: 10.1016/j.jmr.2023.107413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/27/2023] [Accepted: 02/22/2023] [Indexed: 06/18/2023]
Abstract
The narrow excitation bandwidth of monochromic pulses is a sensitivity limitation for pulsed dipolar spectroscopy on Cu(II)-based measurements. In response, frequency-swept pulses with large excitation bandwidths have been adopted to probe a greater range of the EPR spectrum. However, much of the work utilizing frequency-swept pulses in Cu(II) distance measurements has been carried out on home-built spectrometers and equipment. Herein, we carry out systematic Cu(II) based distance measurements to demonstrate the capability of chirp pulses on commercial instrumentation. More importantly we delineate sensitivity considerations under acquisition schemes that are necessary for robust distance measurements using Cu(II) labels for proteins. We show that a 200 MHz sweeping bandwidth chirp pulse can improve the sensitivity of long-range distance measurements by factors of three to four. The sensitivity of short-range distances only increases slightly due to special considerations for the chirp pulse duration relative to the period length of the modulated dipolar signal. Enhancements in sensitivity also dramatically reduce measurement collection times enabling rapid collection of orientationally averaged Cu(II) distance measurements in under two hours.
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Affiliation(s)
- Joshua Casto
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Hannah R Hunter
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Zikri Hasanbasri
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States.
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5
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Hasanbasri Z, Moriglioni NA, Saxena S. Efficient sampling of molecular orientations for Cu(II)-based DEER on protein labels. Phys Chem Chem Phys 2023; 25:13275-13288. [PMID: 36939213 DOI: 10.1039/d3cp00404j] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023]
Abstract
Combining rigid Cu(II) labels and pulsed-EPR techniques enables distance constraint measurements that are incisive probes of protein structure and dynamics. However, the labels can lead to a dipolar signal that is biased by the relative orientation of the two spins, which is typically unknown a priori in a bilabeled protein. This effect, dubbed orientational selectivity, becomes a bottleneck in measuring distances. This phenomenon also applies to other pulsed-EPR techniques that probe electron-nucleus interactions. In this work, we dissect orientational selectivity by generating an in silico sample of Cu(II)-labeled proteins to evaluate pulse excitation in the context of double electron-electron resonance (DEER) at Q-band frequencies. This approach enables the observation of the contribution of each protein orientation to the dipolar signal, which provides direct insights into optimizing acquisition schemes to mitigate orientational effects. Furthermore, we incorporate the excitation profile of realistic pulses to identify the excited spins. With this method, we show that rectangular pulses, despite their imperfect inversion capability, can sample similar spin orientations as other sophisticated pulses with the same bandwidth. Additionally, we reveal that the efficiency of exciting spin-pairs in DEER depends on the frequency offset of two pulses used in the experiment and the relative orientation of the two spins. Therefore, we systematically examine the frequency offset of the two pulses used in this double resonance experiment to determine the optimal frequency offset for optimal distance measurements. This procedure leads to a protocol where two measurements are sufficient to acquire orientational-independent DEER at Q-band. Notably, this procedure is feasible with any commercial pulsed-EPR spectrometer. Furthermore, we experimentally validate the computational results using DEER experiments on two different proteins. Finally, we show that increasing the amplitude of the rectangular pulse can increase the efficiency of DEER experiments by almost threefold. Overall, this work provides an attractive new approach for analyzing pulsed-EPR spectroscopy to obtain microscopic nuances that cannot be easily discerned from analytical or numerical calculations.
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Affiliation(s)
- Zikri Hasanbasri
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| | | | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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6
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Ackermann K, Wort JL, Bode BE. Pulse dipolar EPR for determining nanomolar binding affinities. Chem Commun (Camb) 2022; 58:8790-8793. [PMID: 35837993 PMCID: PMC9350988 DOI: 10.1039/d2cc02360a] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Protein interaction studies often require very low concentrations and highly sensitive biophysical methods. Here, we demonstrate that pulse dipolar electron paramagnetic resonance spectroscopy allows measuring dissociation constants in the nanomolar range. This approach is appealing for concentration-limited biomolecular systems and medium-to-high-affinity binding studies, demonstrated here at 50 nanomolar protein concentration. CuII-nitroxide RIDME measurements at 100 nM protein concentration allow reliable extraction of dissociation constants and distances, while measurements at 50 nM protein concentration allow reliable extraction of dissociation constants only.![]()
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Affiliation(s)
- Katrin Ackermann
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST, Scotland, UK.
| | - Joshua L Wort
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST, Scotland, UK.
| | - Bela E Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST, Scotland, UK.
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7
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Bogetti X, Hasanbasri Z, Hunter HR, Saxena S. An optimal acquisition scheme for Q-band EPR distance measurements using Cu 2+-based protein labels. Phys Chem Chem Phys 2022; 24:14727-14739. [PMID: 35574729 DOI: 10.1039/d2cp01032a] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recent advances in site-directed Cu2+ labeling of proteins and nucleic acids have added an attractive new methodology to measure the structure-function relationship in biomolecules. Despite the promise, accessing the higher sensitivity of Q-band Double Electron Electron Resonance (DEER) has been challenging for Cu2+ labels designed for proteins. Q-band DEER experiments on this label typically require many measurements at different magnetic fields, since the pulses can excite only a few orientations at a given magnetic field. Herein, we analyze such orientational effects through simulations and show that three DEER measurements, at strategically selected magnetic fields, are generally sufficient to acquire an orientational-averaged DEER time trace for this spin label at Q-band. The modeling results are experimentally verified on Cu2+ labeled human glutathione S-transferase (hGSTA1-1). The DEER distance distribution measured at the Q-band shows good agreement with the distance distribution sampled by molecular dynamics (MD) simulations and X-band experiments. The concordance of MD sampled distances and experimentally measured distances adds growing evidence that MD simulations can accurately predict distances for the Cu2+ labels, which remains a key bottleneck for the commonly used nitroxide label. In all, this minimal collection scheme reduces data collection time by as much as six-fold and is generally applicable to many octahedrally coordinated Cu2+ systems. Furthermore, the concepts presented here may be applied to other metals and pulsed EPR experiments.
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Affiliation(s)
- Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, PA 15260, USA.
| | - Zikri Hasanbasri
- Department of Chemistry, University of Pittsburgh, PA 15260, USA.
| | - Hannah R Hunter
- Department of Chemistry, University of Pittsburgh, PA 15260, USA.
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, PA 15260, USA.
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8
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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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9
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Abstract
Different types of spin labels are currently available for structural studies of biomolecules both in vitro and in cells using Electron Paramagnetic Resonance (EPR) and pulse dipolar spectroscopy (PDS). Each type of label has its own advantages and disadvantages, that will be addressed in this chapter. The spectroscopically distinct properties of the labels have fostered new applications of PDS aimed to simultaneously extract multiple inter-label distances on the same sample. In fact, combining different labels and choosing the optimal strategy to address their inter-label distances can increase the information content per sample, and this is pivotal to better characterize complex multi-component biomolecular systems. In this review, we provide a brief background of the spectroscopic properties of the four most common orthogonal spin labels for PDS measurements and focus on the various methods at disposal to extract homo- and hetero-label distances in proteins. We also devote a section to possible artifacts arising from channel crosstalk and provide few examples of applications in structural biology.
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10
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Joaqui-Joaqui MA, Maxwell Z, Raju MVR, Jiang M, Srivastava K, Shao F, Arriaga EA, Pierre VC. Metallointercalators-DNA Tetrahedron Supramolecular Self-Assemblies with Increased Serum Stability. ACS NANO 2022; 16:2928-2941. [PMID: 35133785 PMCID: PMC8926058 DOI: 10.1021/acsnano.1c10084] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Self-assembly of metallointercalators into DNA nanocages is a rapid and facile approach to synthesize discrete bioinorganic host/guest structures with a high load of metal complexes. Turberfield's DNA tetrahedron can accommodate one intercalator for every two base pairs, which corresponds to 48 metallointercalators per DNA tetrahedron. The affinity of the metallointercalator for the DNA tetrahedron is a function of both the structure of the intercalating ligand and the overall charge of the complex, with a trend in affinity [Ru(bpy)2(dppz)]2+ > [Tb-DOTAm-Phen]3+ ≫ Tb-DOTA-Phen. Intercalation of the metal complex stabilizes the DNA tetrahedron, resulting in an increase of its melting temperature and, importantly, a significant increase in its stability in the presence of serum. [Ru(bpy)2(dppz)]2+, which has a greater affinity for DNA than [Tb-DOTAm-Phen]3+, increases the melting point and decreases degradation in serum to a greater extent than the TbIII complex. In the presence of Lipofectamine, the metallointercalator@DNA nanocage assemblies substantially increase the cell uptake of their respective metal complex. Altogether, the facile incorporation of a large number of metal complexes per assembly, the higher stability in serum, and the increased cell penetration of metallointercalator@DNA make these self-assemblies well-suited as metallodrugs.
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Affiliation(s)
- M. Andrey Joaqui-Joaqui
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States of America
| | - Zoe Maxwell
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States of America
| | | | - Min Jiang
- Zhejiang University-University of Illinois at Urbana-Champaign Institute, Zhejiang University, Haining, 314400, China
| | - Kriti Srivastava
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States of America
| | - Fangwei Shao
- Zhejiang University-University of Illinois at Urbana-Champaign Institute, Zhejiang University, Haining, 314400, China
| | - Edgar A. Arriaga
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States of America
| | - Valérie C. Pierre
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States of America
- Corresponding Author: Valérie C. Pierre - Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States of America;
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11
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Gamble Jarvi A, Bogetti X, Singewald K, Ghosh S, Saxena S. Going the dHis-tance: Site-Directed Cu 2+ Labeling of Proteins and Nucleic Acids. Acc Chem Res 2021; 54:1481-1491. [PMID: 33476119 DOI: 10.1021/acs.accounts.0c00761] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this Account, we showcase site-directed Cu2+ labeling in proteins and DNA, which has opened new avenues for the measurement of the structure and dynamics of biomolecules using electron paramagnetic resonance (EPR) spectroscopy. In proteins, the spin label is assembled in situ from natural amino acid residues and a metal complex and requires no post-expression synthetic modification or purification procedures. The labeling scheme exploits a double histidine (dHis) motif, which utilizes endogenous or site-specifically mutated histidine residues to coordinate a Cu2+ complex. Pulsed EPR measurements on such Cu2+-labeled proteins potentially yield distance distributions that are up to 5 times narrower than the common protein spin label-the approach, thus, overcomes the inherent limitation of the current technology, which relies on a spin label with a highly flexible side chain. This labeling scheme provides a straightforward method that elucidates biophysical information that is costly, complicated, or simply inaccessible by traditional EPR labels. Examples include the direct measurement of protein backbone dynamics at β-sheet sites, which are largely inaccessible through traditional spin labels, and rigid Cu2+-Cu2+ distance measurements that enable higher precision in the analysis of protein conformations, conformational changes, interactions with other biomolecules, and the relative orientations of two labeled protein subunits. Likewise, a Cu2+ label has been developed for use in DNA, which is small, is nucleotide independent, and is positioned within the DNA helix. The placement of the Cu2+ label directly reports on the biologically relevant backbone distance. Additionally, for both of these labeling techniques, we have developed models for interpretation of the EPR distance information, primarily utilizing molecular dynamics (MD) simulations. Initial results using force fields developed for both protein and DNA labels have agreed with experimental results, which has been a major bottleneck for traditional spin labels. Looking ahead, we anticipate new combinations of MD and EPR to further our understanding of protein and DNA conformational changes, as well as working synergistically to investigate protein-DNA interactions.
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Affiliation(s)
- Austin Gamble Jarvi
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Kevin Singewald
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Shreya Ghosh
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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12
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Punt PM, Langenberg MD, Altan O, Clever GH. Modular Design of G-Quadruplex MetalloDNAzymes for Catalytic C-C Bond Formations with Switchable Enantioselectivity. J Am Chem Soc 2021; 143:3555-3561. [PMID: 33630569 DOI: 10.1021/jacs.0c13251] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Metal-binding DNA structures with catalytic function are receiving increasing interest. Although a number of metalloDNAzymes have been reported to be highly efficient, the exact coordination/position of their catalytic metal center is often unknown. Here, we present a new approach to rationally develop metalloDNAzymes for Lewis acid-catalyzed reactions such as enantioselective Michael additions. Our strategy relies on the predictable folding patterns of unimolecular DNA G-quadruplexes, combined with the concept of metal-mediated base-pairing. Transition-metal coordination environments were created in G-quadruplex loop regions, accessible by substrates. Therefore, protein-inspired imidazole ligandoside L was covalently incorporated into a series of G-rich DNA strands by solid-phase synthesis. Iterative rounds of DNA sequence design and catalytic assays allowed us to select tailored metalloDNAzymes giving high conversions and excellent enantioselectivities (≥99%). Based on their primary sequence, folding pattern, and metal coordination mode, valuable information on structure-activity relationships could be extracted. Variation of the number and position of ligand L within the sequence allowed us to control the formation of (S) and (R) enantiomeric reaction products, respectively.
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Affiliation(s)
- Philip M Punt
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany
| | - Marie D Langenberg
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany
| | - Okan Altan
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany
| | - Guido H Clever
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany
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13
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Stratmann LM, Kutin Y, Kasanmascheff M, Clever GH. Precise Distance Measurements in DNA G-Quadruplex Dimers and Sandwich Complexes by Pulsed Dipolar EPR Spectroscopy. Angew Chem Int Ed Engl 2021; 60:4939-4947. [PMID: 33063395 PMCID: PMC7984025 DOI: 10.1002/anie.202008618] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/12/2020] [Indexed: 12/20/2022]
Abstract
DNA G-quadruplexes show a pronounced tendency to form higher-order structures, such as π-stacked dimers and aggregates with aromatic binding partners. Reliable methods for determining the structure of these non-covalent adducts are scarce. Here, we use artificial square-planar Cu(pyridine)4 complexes, covalently incorporated into tetramolecular G-quadruplexes, as rigid spin labels for detecting dimeric structures and measuring intermolecular Cu2+ -Cu2+ distances via pulsed dipolar EPR spectroscopy. A series of G-quadruplex dimers of different spatial dimensions, formed in tail-to-tail or head-to-head stacking mode, were unambiguously distinguished. Measured distances are in full agreement with results of molecular dynamics simulations. Furthermore, intercalation of two well-known G-quadruplex binders, PIPER and telomestatin, into G-quadruplex dimers resulting in sandwich complexes was investigated, and previously unknown binding modes were discovered. Additionally, we present evidence that free G-tetrads also intercalate into dimers. Our transition metal labeling approach, combined with pulsed EPR spectroscopy, opens new possibilities for examining structures of non-covalent DNA aggregates.
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Affiliation(s)
- Lukas M. Stratmann
- Faculty of Chemistry and Chemical BiologyTU Dortmund UniversityOtto-Hahn-Strasse 644227DortmundGermany
| | - Yury Kutin
- Faculty of Chemistry and Chemical BiologyTU Dortmund UniversityOtto-Hahn-Strasse 644227DortmundGermany
| | - Müge Kasanmascheff
- Faculty of Chemistry and Chemical BiologyTU Dortmund UniversityOtto-Hahn-Strasse 644227DortmundGermany
| | - Guido H. Clever
- Faculty of Chemistry and Chemical BiologyTU Dortmund UniversityOtto-Hahn-Strasse 644227DortmundGermany
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14
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Schulte TR, Holstein JJ, Schneider L, Adam A, Haberhauer G, Clever GH. A New Mechanically-Interlocked [Pd 2 L 4 ] Cage Motif by Dimerization of two Peptide-based Lemniscates. Angew Chem Int Ed Engl 2020; 59:22489-22493. [PMID: 32845570 PMCID: PMC7756597 DOI: 10.1002/anie.202010995] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Indexed: 12/31/2022]
Abstract
Most metallo-supramolecular assemblies of low nuclearity adopt simple topologies, with bridging ligands spanning neighboring metal centers in a direct fashion. Here we contribute a new structural motif to the family of host compounds with low metal count (two) that consists of a pair of doubly-interlocked, Figure-eight-shaped subunits, also termed "lemniscates". Each metal is chelated by two chiral bidentate ligands, composed of a peptidic macrocycle that resembles a natural product with two pyridyl-terminated arms. DFT calculation results suggest that dimerization of the mononuclear halves is driven by a combination of 1) Coulomb interaction with a central anion, 2) π-stacking between intertwined ligand arms and 3) dispersive interactions between the structure's compact inner core bedded into an outer shell composed of the cavitand-type macrocycles. The resulting cage-like architecture was characterized by NMR, MS and X-ray structure analyses. This new mechanically bonded system highlights the scope of structural variety accessible in metal-mediated self-assemblies composed of only a few constituents.
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Affiliation(s)
- Thorben R. Schulte
- Faculty of Chemistry and Chemical BiologyTU Dortmund Univ.Otto-Hahn-Str. 644227DortmundGermany
| | - Julian J. Holstein
- Faculty of Chemistry and Chemical BiologyTU Dortmund Univ.Otto-Hahn-Str. 644227DortmundGermany
| | - Laura Schneider
- Faculty of Chemistry and Chemical BiologyTU Dortmund Univ.Otto-Hahn-Str. 644227DortmundGermany
| | - Abdulselam Adam
- Institute for Organic ChemistryUniv. Duisburg-EssenUniversitätsstr. 745117EssenGermany
| | - Gebhard Haberhauer
- Institute for Organic ChemistryUniv. Duisburg-EssenUniversitätsstr. 745117EssenGermany
| | - Guido H. Clever
- Faculty of Chemistry and Chemical BiologyTU Dortmund Univ.Otto-Hahn-Str. 644227DortmundGermany
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15
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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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16
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Schulte TR, Holstein JJ, Schneider L, Adam A, Haberhauer G, Clever GH. Ein neues, mechanisch verzahntes [Pd
2
L
4
] Käfigmotiv durch Dimerisierung von zwei Peptid‐basierten Lemniskaten. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202010995] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Thorben R. Schulte
- Fakultät für Chemie und Chemische Biologie TU Dortmund Otto-Hahn-Str. 6 44227 Dortmund Deutschland
| | - Julian J. Holstein
- Fakultät für Chemie und Chemische Biologie TU Dortmund Otto-Hahn-Str. 6 44227 Dortmund Deutschland
| | - Laura Schneider
- Fakultät für Chemie und Chemische Biologie TU Dortmund Otto-Hahn-Str. 6 44227 Dortmund Deutschland
| | - Abdulselam Adam
- Institut für Organische Chemie Univ. Duisburg-Essen Universitätsstr. 7 45117 Essen Deutschland
| | - Gebhard Haberhauer
- Institut für Organische Chemie Univ. Duisburg-Essen Universitätsstr. 7 45117 Essen Deutschland
| | - Guido H. Clever
- Fakultät für Chemie und Chemische Biologie TU Dortmund Otto-Hahn-Str. 6 44227 Dortmund Deutschland
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17
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Stratmann LM, Kutin Y, Kasanmascheff M, Clever GH. Präzise Abstandsmessungen in DNA‐G‐Quadruplex‐Dimeren und Sandwichkomplexen über gepulste dipolare EPR‐Spektroskopie. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Lukas M. Stratmann
- Fakultät für Chemie und Chemische Biologie TU Dortmund Otto-Hahn-Straße 6 44227 Dortmund Deutschland
| | - Yury Kutin
- Fakultät für Chemie und Chemische Biologie TU Dortmund Otto-Hahn-Straße 6 44227 Dortmund Deutschland
| | - Müge Kasanmascheff
- Fakultät für Chemie und Chemische Biologie TU Dortmund Otto-Hahn-Straße 6 44227 Dortmund Deutschland
| | - Guido H. Clever
- Fakultät für Chemie und Chemische Biologie TU Dortmund Otto-Hahn-Straße 6 44227 Dortmund Deutschland
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18
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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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19
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Gamble Jarvi A, Sargun A, Bogetti X, Wang J, Achim C, Saxena S. Development of Cu 2+-Based Distance Methods and Force Field Parameters for the Determination of PNA Conformations and Dynamics by EPR and MD Simulations. J Phys Chem B 2020; 124:7544-7556. [PMID: 32790374 DOI: 10.1021/acs.jpcb.0c05509] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Peptide nucleic acids (PNAs) are a promising group of synthetic analogues of DNA and RNA that offer several distinct advantages over the naturally occurring nucleic acids for applications in biosensing, drug delivery, and nanoelectronics. Because of its structural differences from DNA/RNA, methods to analyze and assess the structure, conformations, and dynamics are needed. In this work, we develop synergistic techniques for the study of the PNA conformation. We use CuQ2, a Cu2+ complex with 8-hydroxyquinoline (HQ), as an alternative base pair and as a spin label in electron paramagnetic resonance (EPR) distance methods. We use molecular dynamics (MD) simulations with newly developed force field parameters for the spin labels to interpret the distance constraints determined by EPR. We complement these methods by UV-vis and circular dichroism measurements and assess the efficacy of the Cu2+ label on a PNA duplex whose backbone is based on aminoethylglycine and a duplex with a hydroxymethyl backbone modification. We show that the Cu2+ label functions efficiently within the standard PNA and the hydroxymethyl-modified PNA and that the MD parameters may be used to accurately reproduce our EPR findings. Through the combination of EPR and MD, we gain new insights into the PNA structure and conformations as well as into the mechanism of orientational selectivity in Cu2+ EPR at X-band. These results present for the first time a rigid Cu2+ spin label used for EPR distance measurements in PNA and the accompanying MD force fields for the spin label. Our studies also reveal that the spin labels have a low impact on the structure of the PNA duplexes. The combined MD and EPR approach represents an important new tool for the characterization of the PNA duplex structure and provides valuable information to aid in the rational application of PNA at large.
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Affiliation(s)
- Austin Gamble Jarvi
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Artur Sargun
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Junmei Wang
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15206, United States
| | - Catalina Achim
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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20
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Bogetti X, Ghosh S, Gamble Jarvi A, Wang J, Saxena S. Molecular Dynamics Simulations Based on Newly Developed Force Field Parameters for Cu 2+ Spin Labels Provide Insights into Double-Histidine-Based Double Electron-Electron Resonance. J Phys Chem B 2020; 124:2788-2797. [PMID: 32181671 DOI: 10.1021/acs.jpcb.0c00739] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Electron paramagnetic resonance (EPR) in combination with the recently developed double-histidine (dHis)-based Cu2+ spin labeling has provided valuable insights into protein structure and conformational dynamics. To relate sparse distance constraints measured by EPR to protein fluctuations in solution, modeling techniques are needed. In this work, we have developed force field parameters for Cu2+-nitrilotriacetic and Cu2+-iminodiacetic acid spin labels. We employed molecular dynamics (MD) simulations to capture the atomic-level details of dHis-labeled protein fluctuations. The interspin distances extracted from 200 ns MD trajectories show good agreement with the experimental results. The MD simulations also illustrate the dramatic rigidity of the Cu2+ labels compared to the standard nitroxide spin label. Further, the relative orientations between spin-labeled sites were measured to provide insight into the use of double electron-electron resonance (DEER) methods for such labels. The relative mean angles, as well as the standard deviations of the relative angles, agree well in general with the spectral simulations published previously. The fluctuations of relative orientations help rationalize why orientation selectivity effects are minimal at X-band frequencies, but observable at the Q-band for such labels. In summary, the results show that by combining the experimental results with MD simulations precise information about protein conformations as well as flexibility can be obtained.
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Affiliation(s)
- Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Shreya Ghosh
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Austin Gamble Jarvi
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Junmei Wang
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15206, United States
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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21
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Abdullin D, Schiemann O. Pulsed Dipolar EPR Spectroscopy and Metal Ions: Methodology and Biological Applications. Chempluschem 2020; 85:353-372. [DOI: 10.1002/cplu.201900705] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/16/2020] [Indexed: 01/18/2023]
Affiliation(s)
- Dinar Abdullin
- Institute of Physical and Theoretical ChemistryUniversity of Bonn Wegelerstr. 12 53115 Bonn Germany
| | - Olav Schiemann
- Institute of Physical and Theoretical ChemistryUniversity of Bonn Wegelerstr. 12 53115 Bonn Germany
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22
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Punt PM, Stratmann LM, Sevim S, Knauer L, Strohmann C, Clever GH. Heteroleptic Coordination Environments in Metal-Mediated DNA G-Quadruplexes. Front Chem 2020; 8:26. [PMID: 32064249 PMCID: PMC7000376 DOI: 10.3389/fchem.2020.00026] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/09/2020] [Indexed: 12/28/2022] Open
Abstract
The presence of metal centers with often highly conserved coordination environments is crucial for roughly half of all proteins, having structural, regulatory, or enzymatic function. To understand and mimic the function of metallo-enzymes, bioinorganic chemists pursue the challenge of synthesizing model compounds with well-defined, often heteroleptic metal sites. Recently, we reported the design of tailored homoleptic coordination environments for various transition metal cations based on unimolecular DNA G-quadruplex structures, templating the regioselective positioning of imidazole ligandosides LI. Here, we expand this modular system to more complex, heteroleptic coordination environments by combining LI with a new benzoate ligandoside LB within the same oligonucleotide. The modifications still allow the correct folding of parallel tetramolecular and antiparallel unimolecular G-quadruplexes. Interestingly, the incorporation of LB results in strong destabilization expressed in lower thermal denaturation temperatures Tm. While no transition metal cations could be bound by G-quadruplexes containing only LB, heteroleptic derivatives containing both LI and LB were found to complex CuII, NiII, and ZnII. Especially in case of CuII we found strong stabilizations of up to ΔTm = +34°C. The here shown system represents an important step toward the design of more complex coordination environments inside DNA scaffolds, promising to culminate in the preparation of functional metallo-DNAzymes.
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Affiliation(s)
- Philip M Punt
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Lukas M Stratmann
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Sinem Sevim
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Lena Knauer
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Carsten Strohmann
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Guido H Clever
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
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23
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Keller K, Ritsch I, Hintz H, Hülsmann M, Qi M, Breitgoff FD, Klose D, Polyhach Y, Yulikov M, Godt A, Jeschke G. Accessing distributions of exchange and dipolar couplings in stiff molecular rulers with Cu(ii) centres. Phys Chem Chem Phys 2020; 22:21707-21730. [DOI: 10.1039/d0cp03105d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Novel approaches to quantitatively analyse distributed exchange couplings are described and tested on experimental data sets for stiff synthetic molecules.
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24
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A trade-off for covalent and intercalation binding modes: a case study for Copper (II) ions and singly modified DNA nucleoside. Sci Rep 2019; 9:12602. [PMID: 31467417 PMCID: PMC6715747 DOI: 10.1038/s41598-019-48935-2] [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: 02/14/2019] [Accepted: 07/29/2019] [Indexed: 12/03/2022] Open
Abstract
Selective binding to nucleic acids and, more generally, to biopolymers, very often requires at a minimum the presence of specific functionalities and precise spatial arrangement. DNA can fold into defined 3D structures upon binding to metal centers and/or lanthanides. Binding efficiency can be boosted by modified nucleosides incorporated into DNA sequences. In this work the high selectivity of modified nucleosides towards copper (II) ions, when used in the monomeric form, is unexpectedly and drastically reduced upon being covalently attached to the DNA sequence in single-site scenario. Surprisingly, such selectivity is partially retained upon non-covalent (i.e. intercalation) mixture formed by native DNA duplex and a nucleoside in the monomeric form. Exploiting the electron spin properties of such different and rich binding mode scenarios, 1D/2D pulsed EPR experiments have been used and tailored to differentiate among the different modes. An unusual correlation of dispersion of hyperfine couplings and strength of the binding mode(s) is described.
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25
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Punt PM, Clever GH. Tailored Transition-Metal Coordination Environments in Imidazole-Modified DNA G-Quadruplexes. Chemistry 2019; 25:13987-13993. [PMID: 31468606 PMCID: PMC6899475 DOI: 10.1002/chem.201903445] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/28/2019] [Indexed: 12/18/2022]
Abstract
Two types of imidazole ligands were introduced both at the end of tetramolecular and into the loop region of unimolecular DNA G‐quadruplexes. The modified oligonucleotides were shown to complex a range of different transition‐metal cations including NiII, CuII, ZnII and CoII, as indicated by UV/Vis absorption spectroscopy and ion mobility mass spectrometry. Molecular dynamics simulations were performed to obtain structural insight into the investigated systems. Variation of ligand number and position in the loop region of unimolecular sequences derived from the human telomer region (htel) allows for a controlled design of distinct coordination environments with fine‐tuned metal affinities. It is shown that CuII, which is typically square‐planar coordinated, has a higher affinity for systems offering four ligands, whereas NiII prefers G‐quadruplexes with six ligands. Likewise, the positioning of ligands in a square‐planar versus tetrahedral fashion affects binding affinities of CuII and ZnII cations, respectively. Gaining control over ligand arrangement patterns will spur the rational development of transition‐metal‐modified DNAzymes. Furthermore, this method is suited to combine different types of ligands, for example, those typically found in metalloenzymes, inside a single DNA architecture.
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Affiliation(s)
- Philip M Punt
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 6, 44227, Dortmund, Germany
| | - Guido H Clever
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 6, 44227, Dortmund, Germany
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26
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Naskar S, Guha R, Müller J. Metal-Modified Nucleic Acids: Metal-Mediated Base Pairs, Triples, and Tetrads. Angew Chem Int Ed Engl 2019; 59:1397-1406. [PMID: 31259475 DOI: 10.1002/anie.201905913] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Indexed: 01/02/2023]
Abstract
The incorporation of metal ions into nucleic acids by means of metal-mediated base pairs represents a promising and prominent strategy for the site-specific decoration of these self-assembling supramolecules with metal-based functionality. Over the past 20 years, numerous nucleoside surrogates have been introduced in this respect, broadening the metal scope by providing perfectly tailored metal-binding sites. More recently, artificial nucleosides derived from natural purine or pyrimidine bases have moved into the focus of AgI -mediated base pairing, due to their expected compatibility with regular Watson-Crick base pairs. This minireview summarizes these advances in metal-mediated base pairing but also includes further recent progress in the field. Moreover, it addresses other aspects of metal-modified nucleic acids, highlighting an expansion of the concept to metal-mediated base triples (in triple helices and three-way junctions) and metal-mediated base tetrads (in quadruplexes). For all types of metal-modified nucleic acids, proposed or accomplished applications are briefly mentioned, too.
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Affiliation(s)
- Shuvankar Naskar
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, 48149, Münster, Germany
| | - Rweetuparna Guha
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, 48149, Münster, Germany
| | - Jens Müller
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, 48149, Münster, Germany
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27
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Naskar S, Guha R, Müller J. Metallmodifizierte Nukleinsäuren: Metallvermittelte Basenpaare, ‐tripel und ‐tetraden. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201905913] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Shuvankar Naskar
- Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Corrensstraße 30 48149 Münster Deutschland
| | - Rweetuparna Guha
- Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Corrensstraße 30 48149 Münster Deutschland
| | - Jens Müller
- Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Corrensstraße 30 48149 Münster Deutschland
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28
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Wort JL, Ackermann K, Giannoulis A, Stewart AJ, Norman DG, Bode BE. Sub-Micromolar Pulse Dipolar EPR Spectroscopy Reveals Increasing Cu II -labelling of Double-Histidine Motifs with Lower Temperature. Angew Chem Int Ed Engl 2019; 58:11681-11685. [PMID: 31218813 PMCID: PMC6771633 DOI: 10.1002/anie.201904848] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/03/2019] [Indexed: 12/20/2022]
Abstract
Electron paramagnetic resonance (EPR) distance measurements are making increasingly important contributions to the studies of biomolecules by providing highly accurate geometric constraints. Combining double-histidine motifs with CuII spin labels can further increase the precision of distance measurements. It is also useful for proteins containing essential cysteines that can interfere with thiol-specific labelling. However, the non-covalent CuII coordination approach is vulnerable to low binding-affinity. Herein, dissociation constants (KD ) are investigated directly from the modulation depths of relaxation-induced dipolar modulation enhancement (RIDME) EPR experiments. This reveals low- to sub-μm CuII KD s under EPR distance measurement conditions at cryogenic temperatures. We show the feasibility of exploiting the double-histidine motif for EPR applications even at sub-μm protein concentrations in orthogonally labelled CuII -nitroxide systems using a commercial Q-band EPR instrument.
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Affiliation(s)
- Joshua L. Wort
- EaStCHEM School of ChemistryBiomedical Sciences Research Complex, and Centre of Magnetic ResonanceUniversity of St AndrewsNorth HaughSt AndrewsKY16 9STUK
| | - Katrin Ackermann
- EaStCHEM School of ChemistryBiomedical Sciences Research Complex, and Centre of Magnetic ResonanceUniversity of St AndrewsNorth HaughSt AndrewsKY16 9STUK
| | - Angeliki Giannoulis
- EaStCHEM School of ChemistryBiomedical Sciences Research Complex, and Centre of Magnetic ResonanceUniversity of St AndrewsNorth HaughSt AndrewsKY16 9STUK
| | - Alan J. Stewart
- School of MedicineBiomedical Sciences Research Complex, and Centre of Magnetic ResonanceUniversity of St AndrewsNorth HaughSt AndrewsKY16 9TFUK
| | - David G. Norman
- School of Life SciencesUniversity of Dundee, Medical Sciences InstituteDundeeDD1 5EHUK
| | - Bela E. Bode
- EaStCHEM School of ChemistryBiomedical Sciences Research Complex, and Centre of Magnetic ResonanceUniversity of St AndrewsNorth HaughSt AndrewsKY16 9STUK
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29
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Wort JL, Ackermann K, Giannoulis A, Stewart AJ, Norman DG, Bode BE. Sub‐Micromolar Pulse Dipolar EPR Spectroscopy Reveals Increasing Cu
II
‐labelling of Double‐Histidine Motifs with Lower Temperature. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201904848] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Joshua L. Wort
- EaStCHEM School of Chemistry Biomedical Sciences Research Complex, and Centre of Magnetic Resonance University of St Andrews North Haugh St Andrews KY16 9ST UK
| | - Katrin Ackermann
- EaStCHEM School of Chemistry Biomedical Sciences Research Complex, and Centre of Magnetic Resonance University of St Andrews North Haugh St Andrews KY16 9ST UK
| | - Angeliki Giannoulis
- EaStCHEM School of Chemistry Biomedical Sciences Research Complex, and Centre of Magnetic Resonance University of St Andrews North Haugh St Andrews KY16 9ST UK
| | - Alan J. Stewart
- School of Medicine Biomedical Sciences Research Complex, and Centre of Magnetic Resonance University of St Andrews North Haugh St Andrews KY16 9TF UK
| | - David G. Norman
- School of Life Sciences University of Dundee, Medical Sciences Institute Dundee DD1 5EH UK
| | - Bela E. Bode
- EaStCHEM School of Chemistry Biomedical Sciences Research Complex, and Centre of Magnetic Resonance University of St Andrews North Haugh St Andrews KY16 9ST UK
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30
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Zhu J, Haynes CJE, Kieffer M, Greenfield JL, Greenhalgh RD, Nitschke JR, Keyser UF. Fe II4L 4 Tetrahedron Binds to Nonpaired DNA Bases. J Am Chem Soc 2019; 141:11358-11362. [PMID: 31283214 PMCID: PMC7007224 DOI: 10.1021/jacs.9b03566] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A water-soluble self-assembled supramolecular FeII4L4 tetrahedron binds to single stranded DNA, mismatched DNA base pairs, and three-way DNA junctions. Binding of the coordination cage quenches fluorescent labels on the DNA strand, which provides an optical means to detect the interaction and allows the position of the binding site to be gauged with respect to the fluorescent label. Utilizing the quenching and binding properties of the coordination cage, we developed a simple and rapid detection method based on fluorescence quenching to detect unpaired bases in double-stranded DNA.
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Affiliation(s)
- Jinbo Zhu
- Cavendish Laboratory, University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , United Kingdom
| | - Cally J E Haynes
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom
| | - Marion Kieffer
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom
| | - Jake L Greenfield
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom
| | - Ryan D Greenhalgh
- Cavendish Laboratory, University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , United Kingdom
| | - Jonathan R Nitschke
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom
| | - Ulrich F Keyser
- Cavendish Laboratory, University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , United Kingdom
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31
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Punt PM, Clever GH. Imidazole-modified G-quadruplex DNA as metal-triggered peroxidase. Chem Sci 2019; 10:2513-2518. [PMID: 30931097 PMCID: PMC6399679 DOI: 10.1039/c8sc05020a] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 12/31/2018] [Indexed: 12/30/2022] Open
Abstract
Four imidazoles, serving as metalloprotein-inspired ligands for complexing a range of transition metal cations, were incorporated into tetramolecular G-quadruplex DNA structures. Modified quadruplexes were found to complex Cu(ii), Ni(ii), Zn(ii) and Co(ii) in a 1 : 1 ratio with unprecedented strong thermal stabilizations of up to ΔT 1/2 = +51 °C. Furthermore, addition of Cu(ii) was found to lead to extraordinarily fast G-quadruplex association rates with k on values being ∼100 times higher compared to unmodified G-quadruplexes. This is ascribed to a template effect of Cu(ii), preorganizing the four single strands via coordination, followed by rapid formation of hydrogen-bonded G-quartets. Native electrospray ionization mass spectrometry (ESI), coupled with trapped ion-mobility spectrometry (timsTOF), supports the proposed 1 : 1 G-quadruplex-metal complexes and could further disclose their ability to bind the iron-porphyrin complex hemin in a 1 : 1 stoichiometry. DNA sequence design allowed us to equip this G-quadruplex-hemin complex, known to function as a horseradish peroxidase mimic, with a metal-dependent trigger. A competitive screen of transition metals revealed a high selectivity for Cu(ii), even in mixtures of several divalent metal cations. Once formed, the Cu(ii)-carrying DNAzyme was shown to be preserved in the presence of EDTA, attributed to its remarkable kinetic stability. Stimuli-responsive G-quadruplexes promise application in DNAzymes with switchable activity, adaptive sensors and dynamic DNA origami constructs.
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Affiliation(s)
- Philip M Punt
- TU Dortmund University , Faculty for Chemistry and Chemical Biology , Otto-Hahn-Str. 6 , 44227 Dortmund , Germany .
| | - Guido H Clever
- TU Dortmund University , Faculty for Chemistry and Chemical Biology , Otto-Hahn-Str. 6 , 44227 Dortmund , Germany .
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32
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Gamble Jarvi A, Ranguelova K, Ghosh S, Weber RT, Saxena S. On the Use of Q-Band Double Electron–Electron Resonance To Resolve the Relative Orientations of Two Double Histidine-Bound Cu2+ Ions in a Protein. J Phys Chem B 2018; 122:10669-10677. [DOI: 10.1021/acs.jpcb.8b07727] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Austin Gamble Jarvi
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Kalina Ranguelova
- Bruker BioSpin, Inc., EPR Division, 15 Fortune Drive, Billerica, Massachusetts 01821, United States
| | - Shreya Ghosh
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Ralph T. Weber
- Bruker BioSpin, Inc., EPR Division, 15 Fortune Drive, Billerica, Massachusetts 01821, United States
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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