1
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Ackermann K, Wu D, Stewart AJ, Bode BE. EPR spectroscopic characterisation of native Cu II-binding sites in human serum albumin. Dalton Trans 2024; 53:13529-13536. [PMID: 39072685 PMCID: PMC11320662 DOI: 10.1039/d4dt00892h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 07/17/2024] [Indexed: 07/30/2024]
Abstract
Human serum albumin (HSA) is the most abundant plasma protein, which functions to transport a large range of ligands within the circulation. These interactions have important implications for human health and disease. The primary binding site for CuII ions on HSA is known to be the so-called amino-terminal CuII and NiII binding (ATCUN) motif. However, the number and identity of secondary binding sites is currently not understood. In this study, we harnessed a suite of contemporary electron paramagnetic resonance (EPR) spectroscopy methods to investigate recombinantly produced constructs of HSA bearing single-histidine knockouts, with the aim to characterise its endogenous CuII ion binding sites.
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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, St Andrews, KY16 9ST, UK
| | - Dongmei Wu
- School of Medicine, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews, St Andrews, KY16 9TF, UK.
| | - Alan J Stewart
- School of Medicine, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews, St Andrews, KY16 9TF, UK.
| | - Bela E Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews, St Andrews, KY16 9ST, UK
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2
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Torricella F, Vitali V, Banci L. A systematic study on the effect of protonation and deuteration on electron spin Tm/ T2 in a cellular context. Phys Chem Chem Phys 2024. [PMID: 39037427 DOI: 10.1039/d4cp00599f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2024]
Abstract
In recent years, DEER experiments in pulsed EPR have garnered interest for their precise distance distribution insights in cellular and buffer setups. These measurements linked to electron spin Tm/T2 values of the labelled sample are impacted by the cellular environment being fully protonated or deuterated, as demonstrated in the present study.
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Affiliation(s)
- Francesco Torricella
- Magnetic Resonance Center, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy.
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, Bethesda, Maryland 20892-0520, USA
| | - Valentina Vitali
- Magnetic Resonance Center, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy.
- Dipartimento di Chimica, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy
| | - Lucia Banci
- Magnetic Resonance Center, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy.
- Consorzio Interuniversitario Risonanza Magnetiche di Metallo Proteine, 50019 Sesto Fiorentino, Italy
- Dipartimento di Chimica, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy
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3
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Schmidt T, Kubatova N, Clore GM. Deconvoluting Monomer- and Dimer-Specific Distance Distributions between Spin Labels in a Monomer/Dimer Mixture Using T1-Edited DEER EPR Spectroscopy. J Am Chem Soc 2024; 146:17964-17973. [PMID: 38888555 DOI: 10.1021/jacs.4c03916] [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: 06/20/2024]
Abstract
Double electron-electron resonance (DEER) EPR is a powerful tool in structural biology, providing distances between pairs of spin labels. When the sample consists of a mixture of oligomeric species (e.g., monomer and dimer), the question arises as to how to assign the peaks in the DEER-derived probability distance distribution to the individual species. Here, we propose incorporating an EPR longitudinal electron relaxation (T1) inversion recovery experiment within a DEER pulse sequence to resolve this problem. The apparent T1 between dipolar coupled electron spins measured from the inversion recovery time (τinv) dependence of the peak intensities in the T1-edited DEER-derived probability P(r) distance distribution will be affected by the number of nitroxide labels attached to the biomolecule of interest, for example, two for a monomer and four for a dimer. We show that global fitting of all the T1-edited DEER echo curves, recorded over a range of τinv values, permits the deconvolution of distances between spin labels originating from monomeric (longer T1) and dimeric (shorter T1) species. This is especially useful when the trapping of spin labels in different conformational states during freezing gives rise to complex P(r) distance distributions. The utility of this approach is demonstrated for two systems, the β1 adrenergic receptor and a construct of the huntingtin exon-1 protein fused to the immunoglobulin domain of protein G, both of which exist in a monomer-dimer equilibrium.
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Affiliation(s)
- Thomas Schmidt
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, United States
| | - Nina Kubatova
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, United States
| | - G Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, United States
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4
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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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5
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Kashnik AS, Baranov DS, Dzuba SA. Spatial Arrangement of the Drug Ibuprofen in a Model Membrane in the Presence of Lipid Rafts. J Phys Chem B 2024; 128:3652-3661. [PMID: 38576273 DOI: 10.1021/acs.jpcb.4c01507] [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: 04/06/2024]
Abstract
Many pharmaceutical drugs are known to interact with lipid membranes through nonspecific molecular interactions, which affect their therapeutic effect. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) and one of the most commonly prescribed. In the presence of cholesterol, lipid bilayers can separate into nanoscale liquid-disordered and liquid-ordered structures, the latter known as lipid rafts. Here, we study spin-labeled ibuprofen (ibuprofen-SL) in the model membrane consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and cholesterol in the molar ratio of (0.5-0.5xchol)/(0.5-0.5xchol)/xchol. Electron paramagnetic resonance (EPR) spectroscopy is employed, along with its pulsed version of double electron-electron resonance (DEER, also known as PELDOR). The data obtained indicate lateral lipid-mediated clustering of ibuprofen-SL molecules with a local surface density noticeably larger than that expected for random lateral distribution. In the absence of cholesterol, the data can be interpreted as indicating alternating clustering in two opposing leaflets of the bilayer. In the presence of cholesterol, for xchol ≥ 20 mol %, the results show that ibuprofen-SL molecules have a quasi-regular lateral distribution, with a "superlattice" parameter of ∼3.0 nm. This regularity can be explained by the entrapment of ibuprofen-SL molecules by lipid rafts known to exist in this system with the additional assumption that lipid rafts have a nanoscale substructure.
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Affiliation(s)
- Anna S Kashnik
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Denis S Baranov
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Sergei A Dzuba
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
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6
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Sicoli G, Sieme D, Overkamp K, Khalil M, Backer R, Griesinger C, Willbold D, Rezaei-Ghaleh N. Large dynamics of a phase separating arginine-glycine-rich domain revealed via nuclear and electron spins. Nat Commun 2024; 15:1610. [PMID: 38383529 PMCID: PMC10881997 DOI: 10.1038/s41467-024-45788-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 02/05/2024] [Indexed: 02/23/2024] Open
Abstract
Liquid-liquid phase separation is the key process underlying formation of membrane-less compartments in cells. A highly dynamic cellular body with rapid component exchange is Cajal body (CB), which supports the extensive compositional dynamics of the RNA splicing machinery, spliceosome. Here, we select an arginine-glycine (RG)-rich segment of coilin, the major component of CB, establish its RNA-induced phase separation, and through combined use of nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) probes, interrogate its dynamics within the crowded interior of formed droplets. Taking advantage of glycine-based singlet-states, we show that glycines retain a large level of sub-nanoseconds dynamics inside the coilin droplets. Furthermore, the continuous-wave (CW) and electron-electron dipolar (PELDOR) and electron-nucleus hyperfine coupling EPR data (HYSCORE) support the RNA-induced formation of dynamic coilin droplets with high coilin peptide concentrations. The combined NMR and EPR data reveal the high dynamics of the RG-rich coilin within droplets and suggest its potential role in the large dynamics of CBs.
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Affiliation(s)
- Giuseppe Sicoli
- CNRS UMR 8516, University of Lille, LASIRE, C4 Building, Avenue Paul Langevin, F-59655, Villeneuve d'Ascq, France
| | - Daniel Sieme
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, D-37077, Göttingen, Germany
| | - Kerstin Overkamp
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, D-37077, Göttingen, Germany
| | - Mahdi Khalil
- CNRS UMR 8516, University of Lille, LASIRE, C4 Building, Avenue Paul Langevin, F-59655, Villeneuve d'Ascq, France
| | - Robin Backer
- Heinrich Heine University (HHU) Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute of Physical Biology, Universitätsstrasse 1, D-40225, Düsseldorf, Germany
| | - Christian Griesinger
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, D-37077, Göttingen, Germany
| | - Dieter Willbold
- Heinrich Heine University (HHU) Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute of Physical Biology, Universitätsstrasse 1, D-40225, Düsseldorf, Germany
- Institute of Biological Information Processing, IBI-7: Structural Biochemistry, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, D-52428, Jülich, Germany
| | - Nasrollah Rezaei-Ghaleh
- Heinrich Heine University (HHU) Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute of Physical Biology, Universitätsstrasse 1, D-40225, Düsseldorf, Germany.
- Institute of Biological Information Processing, IBI-7: Structural Biochemistry, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, D-52428, Jülich, Germany.
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7
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Bertran A, De Zotti M, Timmel CR, Di Valentin M, Bowen AM. Determining and controlling conformational information from orientationally selective light-induced triplet-triplet electron resonance spectroscopy for a set of bis-porphyrin rulers. Phys Chem Chem Phys 2024; 26:2589-2602. [PMID: 38170870 PMCID: PMC10793979 DOI: 10.1039/d3cp03454b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 10/31/2023] [Indexed: 01/05/2024]
Abstract
We recently reported a new technique, light-induced triplet-triplet electron resonance (LITTER) spectroscopy, which allows quantification of the dipolar interaction between the photogenerated triplet states of two chromophores. Here we carry out a systematic LITTER study, considering orientation selection by the detection pulses, of a series of bis-porphyrin model peptides with different porphyrin-porphyrin distances and relative orientations. Orientation-dependent analysis of the dipolar datasets yields conformational information of the molecules in frozen solution which is in good agreement with density functional theory predictions. Additionally, a fast partial orientational-averaging treatment produces distance distributions with minimized orientational artefacts. Finally, by direct comparison of LITTER data to double electron-electron resonance (DEER) measured on a system with Cu(II) coordinated into the porphyrins, we demonstrate the advantages of the LITTER technique over the standard DEER methodology. This is due to the remarkable spectroscopic properties of the photogenerated porphyrin triplet state. This work sets the basis for the use of LITTER in structural investigations of unmodified complex biological macromolecules, which could be combined with Förster resonance energy transfer and microscopy inside cells.
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Affiliation(s)
- Arnau Bertran
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, UK.
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
- Centro Interdipartimentale di Ricerca "Centro Studi di Economia e Tecnica dell'energia Giorgio Levi Cases", 35131 Padova, Italy.
| | - Christiane R Timmel
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, UK.
| | - Marilena Di Valentin
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
- Centro Interdipartimentale di Ricerca "Centro Studi di Economia e Tecnica dell'energia Giorgio Levi Cases", 35131 Padova, Italy.
| | - Alice M Bowen
- The National Research Facility for Electron Paramagnetic Resonance, Department of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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8
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Abdullin D, Rauh Corro P, Hett T, Schiemann O. PDSFit: PDS data analysis in the presence of orientation selectivity, g-anisotropy, and exchange coupling. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2024; 62:37-60. [PMID: 38130168 DOI: 10.1002/mrc.5415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/24/2023] [Accepted: 11/01/2023] [Indexed: 12/23/2023]
Abstract
Pulsed dipolar electron paramagnetic resonance spectroscopy (PDS), encompassing techniques such as pulsed electron-electron double resonance (PELDOR or DEER) and relaxation-induced dipolar modulation enhancement (RIDME), is a valuable method in structural biology and materials science for obtaining nanometer-scale distance distributions between electron spin centers. An important aspect of PDS is the extraction of distance distributions from the measured time traces. Most software used for this PDS data analysis relies on simplifying assumptions, such as assuming isotropic g-factors of ~2 and neglecting orientation selectivity and exchange coupling. Here, the program PDSFit is introduced, which enables the analysis of PELDOR and RIDME time traces with or without orientation selectivity. It can be applied to spin systems consisting of up to two spin centers with anisotropic g-factors and to spin systems with exchange coupling. It employs a model-based fitting of the time traces using parametrized distance and angular distributions, and parametrized PDS background functions. The fitting procedure is followed by an error analysis for the optimized parameters of the distributions and backgrounds. Using five different experimental data sets published previously, the performance of PDSFit is tested and found to provide reliable solutions.
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Affiliation(s)
- Dinar Abdullin
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Pablo Rauh Corro
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Tobias Hett
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Olav Schiemann
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
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9
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Awad SI, Smadi OA, Tomeh MF, Alzghoul SM. A guideline for the distance measurement plans of site-directed spin labels for structural prediction of nucleic acids. J Mol Model 2023; 30:16. [PMID: 38157075 DOI: 10.1007/s00894-023-05808-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 12/11/2023] [Indexed: 01/03/2024]
Abstract
CONTEXT AND RESULTS Site-directed spin labeling (SDSL) combined with electron paramagnetic resonance spectroscopy methods has been successfully used to predict the structures of nucleic acids. These methods measure the distances between spin labels yielding distance equations that are solved using numerical algorithms to provide one or several structural predictions. In this work, the minimum number of SDSL distance measurements and distance measurement types required to predict a unique nucleic acid structure were investigated. Our results indicate that at least six distance measurements should be obtained given that the distance measurements do not connect one SDSL on one arm with more than three SDSLs on the other arm. Moreover, there may be a preference for 1-to-1 SLs distance measurements rather than 1-to-many SLs as the latter was linked to undefined structures discussed in this study. METHODS Pairs of double-helical arms of nucleic acid were simulated using the finite element software Pro/ENGINEER (PTC Inc., Boston, MA). In each simulation, a specific SDSL distance measurement plan was adopted and the resulting structure was tested for movability. Immovable structures indicate that this plan will potentially result in a unique structural prediction of the nucleic acid. All the possible plans for SDSL distance measurements were investigated either by direct measurement or by extrapolation.
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Affiliation(s)
- Samer I Awad
- Department of Biomedical Engineering, Faculty of Engineering, The Hashemite University, P.O. Box 330127, Zarqa, 13133, Jordan.
| | - Othman A Smadi
- Department of Biomedical Engineering, Faculty of Engineering, The Hashemite University, P.O. Box 330127, Zarqa, 13133, Jordan
| | - Mohammed F Tomeh
- Department of Industrial Engineering, Faculty of Engineering, The Hashemite University, P.O. Box 330127, Zarqa, 13133, Jordan
| | - Salah M Alzghoul
- Department of Biomedical Engineering, Faculty of Engineering, The Hashemite University, P.O. Box 330127, Zarqa, 13133, Jordan
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10
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Heubach CA, Hasanbasri Z, Abdullin D, Reuter A, Korzekwa B, Saxena S, Schiemann O. Differentiating between Label and Protein Conformers in Pulsed Dipolar EPR Spectroscopy with the dHis-Cu 2+ (NTA) Motif. Chemistry 2023; 29:e202302541. [PMID: 37755452 DOI: 10.1002/chem.202302541] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/26/2023] [Accepted: 09/27/2023] [Indexed: 09/28/2023]
Abstract
Pulsed dipolar EPR spectroscopy (PDS) in combination with site-directed spin labeling is a powerful tool in structural biology. However, the commonly used spin labels are conjugated to biomolecules via rather long and flexible linkers, which hampers the translation of distance distributions into biomolecular conformations. In contrast, the spin label copper(II)-nitrilotriacetic acid [Cu2+ (NTA)] bound to two histidines (dHis) is rigid and yields narrow distance distributions, which can be more easily translated into biomolecular conformations. Here, we use this label on the 71 kDa Yersinia outer protein O (YopO) to decipher whether a previously experimentally observed bimodal distance distribution is due to two conformations of the biomolecule or of the flexible spin labels. Two different PDS experiments, that is, pulsed electron-electron double resonance (PELDOR aka DEER) and relaxation-induced dipolar modulation enhancement (RIDME), yield unimodal distance distribution with the dHis-Cu2+ (NTA) motif; this result suggests that the α-helical backbone of YopO adopts a single conformation in frozen solution. In addition, we show that the Cu2+ (NTA) label preferentially binds to the target double histidine (dHis) sites even in the presence of 22 competing native histidine residues. Our results therefore suggest that the generation of a His-null background is not required for this spin labeling methodology. Together these results highlight the value of the dHis-Cu2+ (NTA) motif in PDS experiments.
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Affiliation(s)
- Caspar A Heubach
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Zikri Hasanbasri
- Department of Chemistry, Chevron Science Center, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA, 15260, USA
| | - Dinar Abdullin
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Arne Reuter
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Benedict Korzekwa
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
- Leibniz-Center for Diabetes Research, University of Düsseldorf, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
| | - Sunil Saxena
- Department of Chemistry, Chevron Science Center, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA, 15260, USA
| | - Olav Schiemann
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
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11
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Denysenkov V, Prisner TF, Neugebauer P, Stoll S, Marko A. Macroscopic sample shape effect on pulse electron double resonance (PELDOR) signal. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 356:107564. [PMID: 37852111 DOI: 10.1016/j.jmr.2023.107564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/20/2023]
Abstract
Pulse electron double resonance (PELDOR), also called double electron-electron resonance (DEER), is a technique capable of measuring the strength of electron spin dipolar interactions, revealing spin-spin distance distributions in ordered and disordered solid materials. Previous work has shown that PELDOR signals acquire an out-of-phase component under conditions of high electron spin polarization, such as at low temperatures and high fields. In this paper, we show theoretically and experimentally that the size and sign of this effect depends on the macroscopic shape of the sample and its orientation in the external magnetic field. This effect is caused by dipolar interactions between distant spins and provides new insights into the fundamental physics of PELDOR.
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Affiliation(s)
- Vasyl Denysenkov
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7, 60437, 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, 60437, Frankfurt am Main, Germany
| | - Petr Neugebauer
- Central European Institute of Technology and Brno University of Technology, Purkynova 123, Brno, 61200, Czech Republic
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
| | - Andriy Marko
- Central European Institute of Technology and Brno University of Technology, Purkynova 123, Brno, 61200, Czech Republic.
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12
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Bertran A, Morbiato L, Sawyer J, Dalla Torre C, Heyes DJ, Hay S, Timmel CR, Di Valentin M, De Zotti M, Bowen AM. Direct Comparison between Förster Resonance Energy Transfer and Light-Induced Triplet-Triplet Electron Resonance Spectroscopy. J Am Chem Soc 2023; 145:22859-22865. [PMID: 37839071 PMCID: PMC10603778 DOI: 10.1021/jacs.3c04685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Indexed: 10/17/2023]
Abstract
To carry out reliable and comprehensive structural investigations, the exploitation of different complementary techniques is required. Here, we report that dual triplet-spin/fluorescent labels enable the first parallel distance measurements by electron spin resonance (ESR) and Förster resonance energy transfer (FRET) on exactly the same molecules with orthogonal chromophores, allowing for direct comparison. An improved light-induced triplet-triplet electron resonance method with 2-color excitation is used, improving the signal-to-noise ratio of the data and yielding a distance distribution that provides greater insight than the single distance resulting from FRET.
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Affiliation(s)
- Arnau Bertran
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, Oxford OX1 3QR, United Kingdom
| | - Laura Morbiato
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Jack Sawyer
- The
National Research Facility for Electron Paramagnetic Resonance, Department
of Chemistry, Manchester Institute of Biotechnology and Photon Science
Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Chiara Dalla Torre
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Derren J. Heyes
- The
National Research Facility for Electron Paramagnetic Resonance, Department
of Chemistry, Manchester Institute of Biotechnology and Photon Science
Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Sam Hay
- The
National Research Facility for Electron Paramagnetic Resonance, Department
of Chemistry, Manchester Institute of Biotechnology and Photon Science
Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Christiane R. Timmel
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, Oxford OX1 3QR, United Kingdom
| | - Marilena Di Valentin
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Centro
Interdipartimentale di Ricerca “Centro Studi di Economia e
Tecnica dell’energia Giorgio Levi Cases”, 35131 Padova, Italy
| | - Marta De Zotti
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Centro
Interdipartimentale di Ricerca “Centro Studi di Economia e
Tecnica dell’energia Giorgio Levi Cases”, 35131 Padova, Italy
| | - Alice M. Bowen
- The
National Research Facility for Electron Paramagnetic Resonance, Department
of Chemistry, Manchester Institute of Biotechnology and Photon Science
Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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13
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Uvarov MN, Kulik LV, Dzuba SA. Assembly of galvinoxyl doped in polymer-fullerene photovoltaic blends. Phys Chem Chem Phys 2023; 25:26219-26224. [PMID: 37740340 DOI: 10.1039/d3cp02513f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
Galvinoxyl (Gx) is a stable free radical used as a dopant in active layers of organic solar cells. Here, the nanoscale arrangement of Gx molecules in a composite of the PCDTBT polymer and modified C60 fullerene, PCBM, was studied using a two-pulse electron spin echo (ESE) technique. The results show that the Gx molecules assemble into clusters, which can be described by the model of 8 molecules on the surface of a sphere with a radius of 2.0 nm. Such a structure can arise due to the octahedral packing of 6 PCBM molecules surrounded by 8 Gx molecules. ESE decays also indicate that these clusters repel each other, forming a quasi-regular nanostructure in the matrix. The Gx concentration of 2 wt% at which clusters appear correlates with the literature data on the Gx-induced enhancement of photocurrent, which provides structural insight into the possible molecular mechanism of this enhancement.
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Affiliation(s)
- Mikhail N Uvarov
- Voevodsky Institute of Chemical Kinetics and Combustion, RAS, Novosibirsk 630090, Russian Federation.
| | - Leonid V Kulik
- Voevodsky Institute of Chemical Kinetics and Combustion, RAS, Novosibirsk 630090, Russian Federation.
| | - Sergei A Dzuba
- Voevodsky Institute of Chemical Kinetics and Combustion, RAS, Novosibirsk 630090, Russian Federation.
- Department of Physics, Novosibirsk State University, 630090 Novosibirsk, Russian Federation
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14
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Vitali V, Ackermann K, Hagelueken G, Bode BE. Spectroscopically Orthogonal Labelling to Disentangle Site-Specific Nitroxide Label Distributions. APPLIED MAGNETIC RESONANCE 2023; 55:187-205. [PMID: 38357007 PMCID: PMC10861635 DOI: 10.1007/s00723-023-01611-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/23/2023] [Accepted: 08/25/2023] [Indexed: 02/16/2024]
Abstract
Biomolecular applications of pulse dipolar electron paramagnetic resonance spectroscopy (PDS) are becoming increasingly valuable in structural biology. Site-directed spin labelling of proteins is routinely performed using nitroxides, with paramagnetic metal ions and other organic radicals gaining popularity as alternative spin centres. Spectroscopically orthogonal spin labelling using different types of labels potentially increases the information content available from a single sample. When analysing experimental distance distributions between two nitroxide spin labels, the site-specific rotamer information has been projected into the distance and is not readily available, and the contributions of individual labelling sites to the width of the distance distribution are not obvious from the PDS data. Here, we exploit the exquisite precision of labelling double-histidine (dHis) motifs with CuII chelate complexes. The contribution of this label to the distance distribution widths in model protein GB1 has been shown to be negligible. By combining a dHis CuII labelling site with cysteine-specific nitroxide labelling, we gather insights on the label rotamers at two distinct sites, comparing their contributions to distance distributions based on different in silico modelling approaches and structural models. From this study, it seems advisable to consider discrepancies between different in silico modelling approaches when selecting labelling sites for PDS studies. Supplementary Information The online version contains supplementary material available at 10.1007/s00723-023-01611-1.
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Affiliation(s)
- Valentina Vitali
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST Scotland
- Magnetic Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
- Department of Chemistry “Ugo Schiff”, University of Florence, Via Della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - 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
| | - Gregor Hagelueken
- Institute of Structural Biology, Biomedical Center, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - 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
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15
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Wang XW, Zhang X, Cui CY, Li B, Goldfarb D, Yang Y, Su XC. Stabilizing Nitroxide Spin Labels for Structural and Conformational Studies of Biomolecules by Maleimide Treatment. Chemistry 2023; 29:e202301350. [PMID: 37354082 DOI: 10.1002/chem.202301350] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/21/2023] [Accepted: 06/22/2023] [Indexed: 06/26/2023]
Abstract
Nitroxide (NO) spin radicals are effective in characterizing structures, interactions and dynamics of biomolecules. The EPR applications in cell lysates or intracellular milieu require stable spin labels, but NO radicals are unstable in such conditions. We showed that the destabilization of NO radicals in cell lysates or even in cells is caused by NADPH/NADH related enzymes, but not by the commonly believed reducing reagents such as GSH. Maleimide stabilizes the NO radicals in the cell lysates by consumption of the NADPH/NADH that are essential for the enzymes involved in destabilizing NO radicals, instead of serving as the solo thiol scavenger. The maleimide treatment retains the crowding properties of the intracellular components and allows to perform long-time EPR measurements of NO labeled biomolecules close to the intracellular conditions. The strategy of maleimide treatment on cell lysates for the EPR applications has been demonstrated on double electron-electron resonance (DEER) measurements on a number of NO labeled protein samples. The method opens a broad application range for the NO labeled biomolecules by EPR in conditions that resemble the intracellular milieu.
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Affiliation(s)
- Xi-Wei Wang
- State Key Laboratory of Elemento-organic Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Xing Zhang
- State Key Laboratory of Elemento-organic Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Chao-Yu Cui
- State Key Laboratory of Elemento-organic Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Bin Li
- State Key Laboratory of Elemento-organic Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Daniella Goldfarb
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Yin Yang
- State Key Laboratory of Elemento-organic Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Xun-Cheng Su
- State Key Laboratory of Elemento-organic Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, China
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16
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Postnikov EB, Wasiak M, Bartoszek M, Polak J, Zyubin A, Lavrova AI, Chora̧żewski M. Accessing Properties of Molecular Compounds Involved in Cellular Metabolic Processes with Electron Paramagnetic Resonance, Raman Spectroscopy, and Differential Scanning Calorimetry. Molecules 2023; 28:6417. [PMID: 37687246 PMCID: PMC10490169 DOI: 10.3390/molecules28176417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/29/2023] [Accepted: 09/01/2023] [Indexed: 09/10/2023] Open
Abstract
In this work, we review some physical methods of macroscopic experiments, which have been recently argued to be promising for the acquisition of valuable characteristics of biomolecular structures and interactions. The methods we focused on are electron paramagnetic resonance spectroscopy, Raman spectroscopy, and differential scanning calorimetry. They were chosen since it can be shown that they are able to provide a mutually complementary picture of the composition of cellular envelopes (with special attention paid to mycobacteria), transitions between their molecular patterning, and the response to biologically active substances (reactive oxygen species and their antagonists-antioxidants-as considered in our case study).
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Affiliation(s)
- Eugene B. Postnikov
- Theoretical Physics Department, Kursk State University, Radishcheva St. 33, 305000 Kursk, Russia
| | - Michał Wasiak
- Department of Physical Chemistry, University of Lódź, ul. Pomorska 165, 90-236 Lódź, Poland;
| | - Mariola Bartoszek
- Institute of Chemistry, University of Silesia in Katowice, ul. Szkolna 9, 40-006 Katowice, Poland; (M.B.); (J.P.)
| | - Justyna Polak
- Institute of Chemistry, University of Silesia in Katowice, ul. Szkolna 9, 40-006 Katowice, Poland; (M.B.); (J.P.)
| | - Andrey Zyubin
- Sophya Kovalevskaya North-West Mathematical Research Center, Immanuel Kant Baltic Federal University, Nevskogo St. 14, 236041 Kaliningrad, Russia; (A.Z.); (A.I.L.)
| | - Anastasia I. Lavrova
- Sophya Kovalevskaya North-West Mathematical Research Center, Immanuel Kant Baltic Federal University, Nevskogo St. 14, 236041 Kaliningrad, Russia; (A.Z.); (A.I.L.)
- Saint-Petersburg State Research Institute of Phthisiopulmonology, Ligovskiy Prospect 2-4, 194064 Saint Petersburg, Russia
| | - Mirosław Chora̧żewski
- Institute of Chemistry, University of Silesia in Katowice, ul. Szkolna 9, 40-006 Katowice, Poland; (M.B.); (J.P.)
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17
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Deng J, Fang X, Huang L, Li S, Xu L, Ye K, Zhang J, Zhang K, Zhang QC. RNA structure determination: From 2D to 3D. FUNDAMENTAL RESEARCH 2023; 3:727-737. [PMID: 38933295 PMCID: PMC11197651 DOI: 10.1016/j.fmre.2023.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 06/04/2023] [Accepted: 06/05/2023] [Indexed: 06/28/2024] Open
Abstract
RNA molecules serve a wide range of functions that are closely linked to their structures. The basic structural units of RNA consist of single- and double-stranded regions. In order to carry out advanced functions such as catalysis and ligand binding, certain types of RNAs can adopt higher-order structures. The analysis of RNA structures has progressed alongside advancements in structural biology techniques, but it comes with its own set of challenges and corresponding solutions. In this review, we will discuss recent advances in RNA structure analysis techniques, including structural probing methods, X-ray crystallography, nuclear magnetic resonance, cryo-electron microscopy, and small-angle X-ray scattering. Often, a combination of multiple techniques is employed for the integrated analysis of RNA structures. We also survey important RNA structures that have been recently determined using various techniques.
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Affiliation(s)
- Jie Deng
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Xianyang Fang
- Beijing Frontier Research Center for Biological Structure, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Lin Huang
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Shanshan Li
- MOE Key Laboratory for Cellular Dynamics and Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Lilei Xu
- Beijing Frontier Research Center for Biological Structure, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Keqiong Ye
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinsong Zhang
- MOE Key Laboratory of Bioinformatics, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing 100084, China
| | - Kaiming Zhang
- MOE Key Laboratory for Cellular Dynamics and Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Qiangfeng Cliff Zhang
- MOE Key Laboratory of Bioinformatics, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing 100084, China
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18
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Haysom SF, Machin J, Whitehouse JM, Horne JE, Fenn K, Ma Y, El Mkami H, Böhringer N, Schäberle TF, Ranson NA, Radford SE, Pliotas C. Darobactin B Stabilises a Lateral-Closed Conformation of the BAM Complex in E. coli Cells. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 135:e202218783. [PMID: 38515502 PMCID: PMC10952338 DOI: 10.1002/ange.202218783] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Indexed: 03/23/2024]
Abstract
The β-barrel assembly machinery (BAM complex) is essential for outer membrane protein (OMP) folding in Gram-negative bacteria, and represents a promising antimicrobial target. Several conformational states of BAM have been reported, but all have been obtained under conditions which lack the unique features and complexity of the outer membrane (OM). Here, we use Pulsed Electron-Electron Double Resonance (PELDOR, or DEER) spectroscopy distance measurements to interrogate the conformational ensemble of the BAM complex in E. coli cells. We show that BAM adopts a broad ensemble of conformations in the OM, while in the presence of the antibiotic darobactin B (DAR-B), BAM's conformational equilibrium shifts to a restricted ensemble consistent with the lateral closed state. Our in-cell PELDOR findings are supported by new cryoEM structures of BAM in the presence and absence of DAR-B. This work demonstrates the utility of PELDOR to map conformational changes in BAM within its native cellular environment.
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Affiliation(s)
- Samuel F. Haysom
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Jonathan Machin
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - James M. Whitehouse
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Jim E. Horne
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Katherine Fenn
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Yue Ma
- Astbury Centre for Structural Molecular BiologySchool of Biomedical SciencesUniversity of LeedsLeedsLS2 9JTUK
- School of Biological Sciences, Faculty of Biology, Medicine and HealthManchester Academic and Health Science CentreThe University of ManchesterManchesterM13 9PTUK
- Manchester Institute of BiotechnologyThe University of ManchesterManchesterM1 7DNUK
| | - Hassane El Mkami
- School of Physics and AstronomyUniversity of St. AndrewsSt. AndrewsKY16 9SSUK
| | - Nils Böhringer
- Institute for Insect BiotechnologyNatural Product ResearchJustus-Liebig-University GiessenOhlebergsweg 1235392GiessenGermany
- German Center for Infection Research (DZIF)Partner Site Giessen-Marburg-LangenOhlebergsweg 1235392GiessenGermany
| | - Till F. Schäberle
- Institute for Insect BiotechnologyNatural Product ResearchJustus-Liebig-University GiessenOhlebergsweg 1235392GiessenGermany
- German Center for Infection Research (DZIF)Partner Site Giessen-Marburg-LangenOhlebergsweg 1235392GiessenGermany
- Natural Product DepartmentFraunhofer-Institute for Molecular Biology and Applied Ecology (IME)Ohlebergsweg 1235392GiessenGermany
| | - Neil A. Ranson
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Sheena E. Radford
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Christos Pliotas
- Astbury Centre for Structural Molecular BiologySchool of Biomedical SciencesUniversity of LeedsLeedsLS2 9JTUK
- School of Biological Sciences, Faculty of Biology, Medicine and HealthManchester Academic and Health Science CentreThe University of ManchesterManchesterM13 9PTUK
- Manchester Institute of BiotechnologyThe University of ManchesterManchesterM1 7DNUK
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19
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Haysom SF, Machin J, Whitehouse JM, Horne JE, Fenn K, Ma Y, El Mkami H, Böhringer N, Schäberle TF, Ranson NA, Radford SE, Pliotas C. Darobactin B Stabilises a Lateral-Closed Conformation of the BAM Complex in E. coli Cells. Angew Chem Int Ed Engl 2023; 62:e202218783. [PMID: 37162386 PMCID: PMC10952311 DOI: 10.1002/anie.202218783] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 04/26/2023] [Accepted: 05/09/2023] [Indexed: 05/11/2023]
Abstract
The β-barrel assembly machinery (BAM complex) is essential for outer membrane protein (OMP) folding in Gram-negative bacteria, and represents a promising antimicrobial target. Several conformational states of BAM have been reported, but all have been obtained under conditions which lack the unique features and complexity of the outer membrane (OM). Here, we use Pulsed Electron-Electron Double Resonance (PELDOR, or DEER) spectroscopy distance measurements to interrogate the conformational ensemble of the BAM complex in E. coli cells. We show that BAM adopts a broad ensemble of conformations in the OM, while in the presence of the antibiotic darobactin B (DAR-B), BAM's conformational equilibrium shifts to a restricted ensemble consistent with the lateral closed state. Our in-cell PELDOR findings are supported by new cryoEM structures of BAM in the presence and absence of DAR-B. This work demonstrates the utility of PELDOR to map conformational changes in BAM within its native cellular environment.
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Affiliation(s)
- Samuel F. Haysom
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Jonathan Machin
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - James M. Whitehouse
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Jim E. Horne
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Katherine Fenn
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Yue Ma
- Astbury Centre for Structural Molecular BiologySchool of Biomedical SciencesUniversity of LeedsLeedsLS2 9JTUK
- School of Biological Sciences, Faculty of Biology, Medicine and HealthManchester Academic and Health Science CentreThe University of ManchesterManchesterM13 9PTUK
- Manchester Institute of BiotechnologyThe University of ManchesterManchesterM1 7DNUK
| | - Hassane El Mkami
- School of Physics and AstronomyUniversity of St. AndrewsSt. AndrewsKY16 9SSUK
| | - Nils Böhringer
- Institute for Insect BiotechnologyNatural Product ResearchJustus-Liebig-University GiessenOhlebergsweg 1235392GiessenGermany
- German Center for Infection Research (DZIF)Partner Site Giessen-Marburg-LangenOhlebergsweg 1235392GiessenGermany
| | - Till F. Schäberle
- Institute for Insect BiotechnologyNatural Product ResearchJustus-Liebig-University GiessenOhlebergsweg 1235392GiessenGermany
- German Center for Infection Research (DZIF)Partner Site Giessen-Marburg-LangenOhlebergsweg 1235392GiessenGermany
- Natural Product DepartmentFraunhofer-Institute for Molecular Biology and Applied Ecology (IME)Ohlebergsweg 1235392GiessenGermany
| | - Neil A. Ranson
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Sheena E. Radford
- Astbury Centre for Structural Molecular BiologySchool of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Christos Pliotas
- Astbury Centre for Structural Molecular BiologySchool of Biomedical SciencesUniversity of LeedsLeedsLS2 9JTUK
- School of Biological Sciences, Faculty of Biology, Medicine and HealthManchester Academic and Health Science CentreThe University of ManchesterManchesterM13 9PTUK
- Manchester Institute of BiotechnologyThe University of ManchesterManchesterM1 7DNUK
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20
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Wort JL, Ackermann K, Giannoulis A, Bode BE. Enhanced sensitivity for pulse dipolar EPR spectroscopy using variable-time RIDME. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 352:107460. [PMID: 37167826 DOI: 10.1016/j.jmr.2023.107460] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 04/03/2023] [Accepted: 04/19/2023] [Indexed: 05/13/2023]
Abstract
Pulse dipolar EPR spectroscopy (PDS) measurements are an important complementary tool in structural biology and are increasingly applied to macromolecular assemblies implicated in human health and disease at physiological concentrations. This requires ever higher sensitivity, and recent advances have driven PDS measurements into the mid-nanomolar concentration regime, though optimization and acquisition of such measurements remains experimentally demanding and time expensive. One important consideration is that constant-time acquisition represents a hard limit for measurement sensitivity, depending on the maximum measured distance. Determining this distance a priori has been facilitated by machine-learning structure prediction (AlphaFold2 and RoseTTAFold) but is often confounded by non-representative behaviour in frozen solution that may mandate multiple rounds of optimization and acquisition. Herein, we endeavour to simultaneously enhance sensitivity and streamline PDS measurement optimization to one-step by benchmarking a variable-time acquisition RIDME experiment applied to CuII-nitroxide and CuII-CuII model systems. Results demonstrate marked sensitivity improvements of both 5- and 6-pulse variable-time RIDME of between 2- and 5-fold over the constant-time analogues.
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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, Scotland
| | - Katrin Ackermann
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland
| | - Angeliki Giannoulis
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland
| | - Bela E Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland.
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21
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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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22
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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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23
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Vanas A, Soetbeer J, Breitgoff FD, Hintz H, Sajid M, Polyhach Y, Godt A, Jeschke G, Yulikov M, Klose D. Intermolecular contributions, filtration effects and signal composition of SIFTER (single-frequency technique for refocusing). MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2023; 4:1-18. [PMID: 38269110 PMCID: PMC10807728 DOI: 10.5194/mr-4-1-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 12/14/2022] [Indexed: 01/26/2024]
Abstract
To characterize structure and molecular order in the nanometre range, distances between electron spins and their distributions can be measured via dipolar spin-spin interactions by different pulsed electron paramagnetic resonance experiments. Here, for the single-frequency technique for refocusing dipolar couplings (SIFTER), the buildup of dipolar modulation signal and intermolecular contributions is analysed for a uniform random distribution of monoradicals and biradicals in frozen glassy solvent by using the product operator formalism for electron spin S = 1 / 2 . A dipolar oscillation artefact appearing at both ends of the SIFTER time trace is predicted, which originates from the weak coherence transfer between biradicals. The relative intensity of this artefact is predicted to be temperature independent but to increase with the spin concentration in the sample. Different compositions of the intermolecular background are predicted in the case of biradicals and in the case of monoradicals. Our theoretical account suggests that the appropriate procedure of extracting the intramolecular dipolar contribution (form factor) requires fitting and subtracting the unmodulated part, followed by division by an intermolecular background function that is different in shape. This scheme differs from the previously used heuristic background division approach. We compare our theoretical derivations to experimental SIFTER traces for nitroxide and trityl monoradicals and biradicals. Our analysis demonstrates a good qualitative match with the proposed theoretical description. The resulting perspectives for a quantitative analysis of SIFTER data are discussed.
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Affiliation(s)
- Agathe Vanas
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg
2, 8093 Zurich, Switzerland
| | - Janne Soetbeer
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg
2, 8093 Zurich, Switzerland
| | - Frauke Diana Breitgoff
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg
2, 8093 Zurich, Switzerland
| | - Henrik Hintz
- Department of Chemistry, Bielefeld University, Universitätsstrasse
25, 33615 Bielefeld, Germany
| | - Muhammad Sajid
- Department of Chemistry, Bielefeld University, Universitätsstrasse
25, 33615 Bielefeld, Germany
| | - Yevhen Polyhach
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg
2, 8093 Zurich, Switzerland
| | - Adelheid Godt
- Department of Chemistry, Bielefeld University, Universitätsstrasse
25, 33615 Bielefeld, Germany
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg
2, 8093 Zurich, Switzerland
| | - Maxim Yulikov
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg
2, 8093 Zurich, Switzerland
| | - Daniel Klose
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg
2, 8093 Zurich, Switzerland
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24
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Bertran A, Morbiato L, Aquilia S, Gabbatore L, De Zotti M, Timmel CR, Di Valentin M, Bowen AM. Erythrosin B as a New Photoswitchable Spin Label for Light-Induced Pulsed EPR Dipolar Spectroscopy. Molecules 2022; 27:molecules27217526. [PMID: 36364348 PMCID: PMC9657417 DOI: 10.3390/molecules27217526] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/27/2022] [Accepted: 10/29/2022] [Indexed: 11/06/2022] Open
Abstract
We present a new photoswitchable spin label for light-induced pulsed electron paramagnetic resonance dipolar spectroscopy (LiPDS), the photoexcited triplet state of erythrosin B (EB), which is ideal for biological applications. With this label, we perform an in-depth study of the orientational effects in dipolar traces acquired using the refocused laser-induced magnetic dipole technique to obtain information on the distance and relative orientation between the EB and nitroxide labels in a rigid model peptide, in good agreement with density functional theory predictions. Additionally, we show that these orientational effects can be averaged to enable an orientation-independent analysis to determine the distance distribution. Furthermore, we demonstrate the feasibility of these experiments above liquid nitrogen temperatures, removing the need for expensive liquid helium or cryogen-free cryostats. The variety of choices in photoswitchable spin labels and the affordability of the experiments are critical for LiPDS to become a widespread methodology in structural biology.
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Affiliation(s)
- Arnau Bertran
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QR, UK
| | - Laura Morbiato
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Sara Aquilia
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Laura Gabbatore
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Centro Interdipartimentale di Ricerca “Centro Studi di Economia e Tecnica dell’Energia Giorgio Levi Cases”, University of Padova, 35131 Padova, Italy
| | - Christiane R. Timmel
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QR, UK
| | - Marilena Di Valentin
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Centro Interdipartimentale di Ricerca “Centro Studi di Economia e Tecnica dell’Energia Giorgio Levi Cases”, University of Padova, 35131 Padova, Italy
- Correspondence: (M.D.V.); (A.M.B.)
| | - Alice M. Bowen
- The National Research Facility for Electron Paramagnetic Resonance, Department of Chemistry and Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK
- Correspondence: (M.D.V.); (A.M.B.)
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25
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Queen A, Bhutto HN, Yousuf M, Syed MA, Hassan MI. Carbonic anhydrase IX: A tumor acidification switch in heterogeneity and chemokine regulation. Semin Cancer Biol 2022; 86:899-913. [PMID: 34998944 DOI: 10.1016/j.semcancer.2022.01.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/30/2021] [Accepted: 01/03/2022] [Indexed: 02/07/2023]
Abstract
The primary physiological process of respiration produces carbon dioxide (CO2) that reacts with water molecules which subsequently liberates bicarbonate (HCO-3) and protons. Carbonic anhydrases (CAs) are the primary catalyst involved in this conversion. More than 16 isoforms of human CAs show organ or subcellular specific activity. Dysregulation of each CA is associated with multiple pathologies. Out of these members, the overexpression of membrane-bound carbonic anhydrase IX (CAIX) is associated explicitly with hypoxic tumors or various solid cancers. CAIX helps tumors deal with higher CO2 by sequestering it with bicarbonate ions and helping cancer cells to grow in a comparatively hypoxic or acidic environment, thus acting as a pH adaptation switch. CAIX-mediated adaptations in cancer cells include angiogenesis, metabolic alterations, tumor heterogeneity, drug resistance, and regulation of cancer-specific chemokines. This review comprehensively collects and describe the cancer-specific expression mechanism and role of CAIX in cancer growth, progression, heterogeneity, and its structural insight to develop future combinatorial targeted cancer therapies.
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Affiliation(s)
- Aarfa Queen
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Humaira Naaz Bhutto
- Department of Biotechnology, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Mohd Yousuf
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Mansoor Ali Syed
- Department of Biotechnology, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Md Imtaiyaz Hassan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India.
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26
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Kashnik AS, Baranov DS, Dzuba SA. Ibuprofen in a Lipid Bilayer: Nanoscale Spatial Arrangement. MEMBRANES 2022; 12:1077. [PMID: 36363632 PMCID: PMC9693523 DOI: 10.3390/membranes12111077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 10/20/2022] [Accepted: 10/29/2022] [Indexed: 06/16/2023]
Abstract
Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID) with analgesic and antipyretic effects. Understanding the molecular mechanisms of drug interaction with cell membranes is important to improving drug delivery, uptake by cells, possible side effects, etc. Double electron-electron resonance spectroscopy (DEER, also known as PELDOR) provides information on the nanoscale spatial arrangement of spin-labeled molecules. Here, DEER was applied to study (mono-)spin-labeled ibuprofen (ibuprofen-SL) in a bilayer of palmitoyl-oleoyl-sn-glycerophosphocholine (POPC). The results obtained show that the ibuprofen-SL molecules are located within a plane in each bilayer leaflet. At their low molar concentration in the bilayer χ, the found surface concentration of ibuprofen-SL is two times higher than χ, which can be explained by alternative assembling in the two leaflets of the bilayer. When χ > 2 mol%, these assemblies merge. The findings shed new light on the nanoscale spatial arrangement of ibuprofen in biological membranes.
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27
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Kaiser F, Endeward B, Collauto A, Scheffer U, Prisner TF, Göbel MW. Spin-Labeled Riboswitch Synthesized from a Protected TPA Phosphoramidite Building Block. Chemistry 2022; 28:e202201822. [PMID: 35903916 PMCID: PMC9804336 DOI: 10.1002/chem.202201822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Indexed: 01/05/2023]
Abstract
The nitroxide TPA (2,2,5,5-tetramethyl-pyrrolin-1-oxyl-3-acetylene) is an excellent spin label for EPR studies of RNA. Previous synthetic methods, however, are complicated and require special equipment. Herein, we describe a uridine derived phosphoramidite with a photocaged TPA unit attached. The light sensitive 2-nitrobenzyloxymethyl group can be removed in high yield by short irradiation at 365 nm. Based on this approach, a doubly spin-labeled 27mer neomycin sensing riboswitch was synthesized and studied by PELDOR. The overall thermal stability of the fold is not much reduced by TPA. In-line probing nevertheless detected changes in local mobility.
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Affiliation(s)
- Frank Kaiser
- Institute for Organic Chemistry and Chemical BiologyGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Burkhard Endeward
- Institute for Physical and Theoretical ChemistryGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Alberto Collauto
- Institute for Physical and Theoretical ChemistryGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Ute Scheffer
- Institute for Organic Chemistry and Chemical BiologyGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Thomas F. Prisner
- Institute for Physical and Theoretical ChemistryGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Michael W. Göbel
- Institute for Organic Chemistry and Chemical BiologyGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
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28
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Fábregas-Ibáñez L, Mertens V, Ritsch I, von Hagens T, Stoll S, Jeschke G. Dipolar pathways in multi-spin and multi-dimensional dipolar EPR spectroscopy. Phys Chem Chem Phys 2022; 24:22645-22660. [PMID: 36106486 PMCID: PMC9516884 DOI: 10.1039/d2cp03048a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 09/07/2022] [Indexed: 11/24/2022]
Abstract
Dipolar electron paramagnetic resonance (EPR) experiments, such as double electron-electron resonance (DEER), measure distributions of nanometer-scale distances between unpaired electrons, which provide valuable information for structural characterization of proteins and other macromolecular systems. We present an extension to our previously published general model based on dipolar pathways valid for multi-dimensional dipolar EPR experiments with more than two spin-1/2 labels. We examine the 4-pulse DEER and TRIER experiments in terms of dipolar pathways and show experimental results confirming the theoretical predictions. This extension to the dipolar pathways model allows the analysis of previously challenging datasets and the extraction of multivariate distance distributions.
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Affiliation(s)
- Luis Fábregas-Ibáñez
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Valerie Mertens
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Irina Ritsch
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Tona von Hagens
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, WA 98195, Washington, USA
| | - Gunnar Jeschke
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
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29
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Lane BJ, Wang B, Ma Y, Calabrese AN, El Mkami H, Pliotas C. HDX-guided EPR spectroscopy to interrogate membrane protein dynamics. STAR Protoc 2022; 3:101562. [PMID: 35874470 PMCID: PMC9304679 DOI: 10.1016/j.xpro.2022.101562] [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] [Indexed: 11/26/2022] Open
Abstract
Solvent accessibilities of and distances between protein residues measured by pulsed-EPR approaches provide high-resolution information on dynamic protein motions. We describe protocols for the purification and site-directed spin labeling of integral membrane proteins. In our protocol, peptide-level HDX-MS is used as a precursor to guide single-residue resolution ESEEM accessibility measurements and spin labeling strategies for EPR applications. Exploiting the pentameric MscL channel as a model, we discuss the use of cwEPR, DEER/PELDOR, and ESEEM spectroscopies to interrogate membrane protein dynamics. For complete details on the use and execution of this protocol, please refer to Wang et al. (2022). Protocols for an integrated EPR-based approach to study membrane protein dynamics Instructions for the sample preparation of spin-labeled membrane proteins Used HDX-MS as a precursor to guide spin labeling strategies for EPR methods Probed solvent accessibility at the single-residue level by ESEEM
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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30
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Peter MF, Gebhardt C, Mächtel R, Muñoz GGM, Glaenzer J, Narducci A, Thomas GH, Cordes T, Hagelueken G. Cross-validation of distance measurements in proteins by PELDOR/DEER and single-molecule FRET. Nat Commun 2022; 13:4396. [PMID: 35906222 PMCID: PMC9338047 DOI: 10.1038/s41467-022-31945-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 07/11/2022] [Indexed: 11/09/2022] Open
Abstract
Pulsed electron-electron double resonance spectroscopy (PELDOR/DEER) and single-molecule Förster resonance energy transfer spectroscopy (smFRET) are frequently used to determine conformational changes, structural heterogeneity, and inter probe distances in biological macromolecules. They provide qualitative information that facilitates mechanistic understanding of biochemical processes and quantitative data for structural modelling. To provide a comprehensive comparison of the accuracy of PELDOR/DEER and smFRET, we use a library of double cysteine variants of four proteins that undergo large-scale conformational changes upon ligand binding. With either method, we use established standard experimental protocols and data analysis routines to determine inter-probe distances in the presence and absence of ligands. The results are compared to distance predictions from structural models. Despite an overall satisfying and similar distance accuracy, some inconsistencies are identified, which we attribute to the use of cryoprotectants for PELDOR/DEER and label-protein interactions for smFRET. This large-scale cross-validation of PELDOR/DEER and smFRET highlights the strengths, weaknesses, and synergies of these two important and complementary tools in integrative structural biology.
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Affiliation(s)
- Martin F Peter
- Institute of Structural Biology, University of Bonn, Bonn, Germany
| | - Christian Gebhardt
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Rebecca Mächtel
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Gabriel G Moya Muñoz
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Janin Glaenzer
- Institute of Structural Biology, University of Bonn, Bonn, Germany
| | - Alessandra Narducci
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Gavin H Thomas
- Department of Biology (Area 10), University of York, York, UK
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.
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31
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Sweger S, Denysenkov V, Maibaum L, Prisner T, Stoll S. The effect of spin polarization on double electron-electron resonance (DEER) spectroscopy. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2022; 3:101-110. [PMID: 37905182 PMCID: PMC10583274 DOI: 10.5194/mr-3-101-2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 06/17/2022] [Indexed: 11/02/2023]
Abstract
Double electron-electron resonance (DEER) spectroscopy measures the distribution of distances between two electron spins in the nanometer range, often on doubly spin-labeled proteins, via the modulation of a refocused spin echo by the dipolar interaction between the spins. DEER is commonly conducted under conditions where the polarization of the spins is small. Here, we examine the DEER signal under conditions of high spin polarization, thermally obtainable at low temperatures and high magnetic fields, and show that the signal acquires a polarization-dependent out-of-phase component both for the intramolecular and intermolecular contributions. For the latter, this corresponds to a phase shift of the spin echo that is linear in the pump pulse position. We derive a compact analytical form of this phase shift and show experimental measurements using monoradical and biradical nitroxides at several fields and temperatures. The effect highlights a novel aspect of the fundamental spin physics underlying DEER spectroscopy.
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Affiliation(s)
- Sarah R. Sweger
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Vasyl P. Denysenkov
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt am Main, Frankfurt, Germany
| | - Lutz Maibaum
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Thomas F. Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt am Main, Frankfurt, Germany
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
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32
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Synthesis of Spin-Labeled Ibuprofen and Its Interaction with Lipid Membranes. Molecules 2022; 27:molecules27134127. [PMID: 35807376 PMCID: PMC9268589 DOI: 10.3390/molecules27134127] [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: 06/04/2022] [Revised: 06/22/2022] [Accepted: 06/24/2022] [Indexed: 02/04/2023] Open
Abstract
Ibuprofen is a non-steroidal anti-inflammatory drug possessing analgesic and antipyretic activity. Electron paramagnetic resonance (EPR) spectroscopy could be applied to study its interaction with biological membranes and proteins if its spin-labeled analogs were synthesized. Here, a simple sequence of ibuprofen transformations—nitration, esterification, reduction, Sandmeyer reaction, Sonogashira cross-coupling, oxidation and saponification—was developed to attain this goal. The synthesis resulted in spin-labeled ibuprofen (ibuprofen-SL) in which the spin label TEMPOL is attached to the benzene ring. EPR spectra confirmed interaction of ibuprofen-SL with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayers. Using 2H electron spin echo envelope modulation (ESEEM) spectroscopy, ibuprofen-SL was found to be embedded into the hydrophobic bilayer interior.
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33
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Al Said T, Weber S, Schleicher E. OOP-ESEEM Spectroscopy: Accuracies of Distances of Spin-Correlated Radical Pairs in Biomolecules. Front Mol Biosci 2022; 9:890826. [PMID: 35813811 PMCID: PMC9262093 DOI: 10.3389/fmolb.2022.890826] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 05/05/2022] [Indexed: 11/30/2022] Open
Abstract
In addition to the commonly used electron–electron double resonance (ELDOR) technique, there are several other electron paramagnetic resonance (EPR) methods by which structure information can be obtained by exploiting the dipolar coupling between two radicals based on its characteristic r−3 dependence. In this contribution, we explore the potential of out-of-phase-electron-spin echo envelope modulation (OOP-ESEEM) spectroscopy to collect accurate distance information in photo-sensitive (bio) molecules. Although the method has already been applied to spin-correlated radical pairs in several classes of light-active proteins, the accuracy of the information obtained has not yet been extensively evaluated. To do this in a system-independent fashion, OOP-ESEEM time traces simulated with different values of the dipolar and exchange couplings were generated and analyzed in a best-possible way. Excellent agreement between calculated and numerically fitted values over a wide range of distances (between 15 and 45 Å) was obtained. Furthermore, the limitations of the method and the dependence on various experimental parameters could be evaluated.
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34
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Azarkh M, Keller K, Qi M, Godt A, Yulikov M. How accurately defined are the overtone coefficients in Gd(III)-Gd(III) RIDME? JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 339:107217. [PMID: 35453095 DOI: 10.1016/j.jmr.2022.107217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/04/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
Relaxation-induced dipolar modulation enhancement (RIDME) is a pulse EPR technique that is particularly suitable to determine distances between paramagnetic centers with a broad EPR spectrum, e.g. metal-ion-based ones. As far as high-spin systems (S > ½) are concerned, the RIDME experiment provides not only the basic dipolar frequency but also its overtones, which complicates the determination of interspin distances. Here, we present and discuss in a step-by-step fashion an r.m.s.d.-based approach for the calibration of the overtone coefficients for a series of molecular rulers doubly labeled with Gd(III)-PyMTA tags. The constructed 2D total-penalty diagrams help revealing that there is no unique set of overtone coefficients but rather a certain pool, which can be used to extract distance distributions between high-spin paramagnetic centers, as determined from the RIDME experiment. This is of particular importance for comparing RIDME overtone calibration and distance distributions obtained in different labs.
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Affiliation(s)
- Mykhailo Azarkh
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
| | - Katharina Keller
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Maxim Yulikov
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland.
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35
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A Low-Spin CoII/Nitroxide Complex for Distance Measurements at Q-Band Frequencies. MAGNETOCHEMISTRY 2022. [DOI: 10.3390/magnetochemistry8040043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pulse dipolar electron paramagnetic resonance spectroscopy (PDS) is continuously furthering the understanding of chemical and biological assemblies through distance measurements in the nanometer range. New paramagnets and pulse sequences can provide structural insights not accessible through other techniques. In the pursuit of alternative spin centers for PDS, we synthesized a low-spin CoII complex bearing a nitroxide (NO) moiety, where both the CoII and NO have an electron spin S of 1/2. We measured CoII-NO distances with the well-established double electron–electron resonance (DEER aka PELDOR) experiment, as well as with the five- and six-pulse relaxation-induced dipolar modulation enhancement (RIDME) spectroscopies at Q-band frequencies (34 GHz). We first identified challenges related to the stability of the complex in solution via DEER and X-ray crystallography and showed that even in cases where complex disproportionation is unavoidable, CoII-NO PDS measurements are feasible and give good signal-to-noise (SNR) ratios. Specifically, DEER and five-pulse RIDME exhibited an SNR of ~100, and while the six-pulse RIDME exhibited compromised SNR, it helped us minimize unwanted signals from the RIDME traces. Last, we demonstrated RIDME at a 10 μM sample concentration. Our results demonstrate paramagnetic CoII to be a feasible spin center in medium magnetic fields with opportunities for PDS studies involving CoII ions.
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36
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Hett T, Schiemann O. PELDOR Measurements on Nitroxide-Labeled Oligonucleotides. Methods Mol Biol 2022; 2439:241-274. [PMID: 35226326 DOI: 10.1007/978-1-0716-2047-2_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In the past decades, pulsed dipolar electron paramagnetic resonance spectroscopy (PDS) has emerged as a powerful tool in biophysical chemistry to study the structure, dynamics, and function of biomolecules like oligonucleotides and proteins. Structural information is obtained from PDS methods in form of a distribution of distances between spin centers. Such spin centers can either be intrinsically present paramagnetic metal ions and organic radicals or may be attached to the biomolecule by means of site-directed spin labeling. The most common PDS experiment for probing interspin distances in the nanometer range is pulsed electron-electron double resonance (PELDOR or DEER). In the protocol presented here, we provide a step-by-step workflow on how to set up a PELDOR experiment on a commercially available pulsed EPR spectrometer, outline the data analysis, and highlight potential pitfalls. We suggest PELDOR measurements on nitroxide-labeled oligonucleotides to study the structure of either RNA-cleaving DNAzymes in complex with their RNA targets or modified DNAzymes with different functions and targets, in which deoxynucleotides are substituted by nitroxide-labeled nucleotides.
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Affiliation(s)
- Tobias Hett
- Institute of Physical and Theoretical Chemistry, Rheinische Friedrich-Wilhelms-University, Bonn, Germany
| | - Olav Schiemann
- Institute of Physical and Theoretical Chemistry, Rheinische Friedrich-Wilhelms-University, Bonn, Germany.
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37
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Ackermann K, Chapman A, Bode BE. A Comparison of Cysteine-Conjugated Nitroxide Spin Labels for Pulse Dipolar EPR Spectroscopy. Molecules 2021; 26:7534. [PMID: 34946616 PMCID: PMC8706713 DOI: 10.3390/molecules26247534] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/30/2021] [Accepted: 12/03/2021] [Indexed: 11/23/2022] Open
Abstract
The structure-function and materials paradigms drive research on the understanding of structures and structural heterogeneity of molecules and solids from materials science to structural biology. Functional insights into complex architectures are often gained from a suite of complementary physicochemical methods. In the context of biomacromolecular structures, the use of pulse dipolar electron paramagnetic resonance spectroscopy (PDS) has become increasingly popular. The main interest in PDS is providing long-range nanometre distance distributions that allow for identifying macromolecular topologies, validating structural models and conformational transitions as well as docking of quaternary complexes. Most commonly, cysteines are introduced into protein structures by site-directed mutagenesis and modified site-specifically to a spin-labelled side-chain such as a stable nitroxide radical. In this contribution, we investigate labelling by four different commercial labelling agents that react through different sulfur-specific reactions. Further, the distance distributions obtained are between spin-bearing moieties and need to be related to the protein structure via modelling approaches. Here, we compare two different approaches to modelling these distributions for all four side-chains. The results indicate that there are significant differences in the optimum labelling procedure. All four spin-labels show differences in the ease of labelling and purification. Further challenges arise from the different tether lengths and rotamers of spin-labelled side-chains; both influence the modelling and translation into structures. Our comparison indicates that the spin-label with the shortest tether in the spin-labelled side-group, (bis-(2,2,5,5-Tetramethyl-3-imidazoline-1-oxyl-4-yl) disulfide, may be underappreciated and could increase the resolution of structural studies by PDS if labelling conditions are optimised accordingly.
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Affiliation(s)
| | | | - 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; (K.A.); (A.C.)
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38
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Seal M, Jash C, Jacob RS, Feintuch A, Harel YS, Albeck S, Unger T, Goldfarb D. Evolution of CPEB4 Dynamics Across its Liquid-Liquid Phase Separation Transition. J Phys Chem B 2021; 125:12947-12957. [PMID: 34787433 PMCID: PMC8647080 DOI: 10.1021/acs.jpcb.1c06696] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 10/13/2021] [Indexed: 12/31/2022]
Abstract
Knowledge about the structural and dynamic properties of proteins that form membrane-less organelles in cells via liquid-liquid phase separation (LLPS) is required for understanding the process at a molecular level. We used spin labeling and electron paramagnetic resonance (EPR) spectroscopy to investigate the dynamic properties (rotational diffusion) of the low complexity N-terminal domain of cytoplasmic polyadenylation element binding-4 protein (CPEB4NTD) across its LLPS transition, which takes place with increasing temperature. We report the coexistence of three spin labeled CPEB4NTD (CPEB4*) populations with distinct dynamic properties representing different conformational spaces, both before and within the LLPS state. Monomeric CPEB4* exhibiting fast motion defines population I and shows low abundance prior to and following LLPS. Populations II and III are part of CPEB4* assemblies where II corresponds to loose conformations with intermediate range motions and population III represents compact conformations with strongly attenuated motions. As the temperature increased the population of component II increased reversibly at the expense of component III, indicating the existence of an III ⇌ II equilibrium. We correlated the macroscopic LLPS properties with the III ⇌ II exchange process upon varying temperature and CPEB4* and salt concentrations. We hypothesized that weak transient intermolecular interactions facilitated by component II lead to LLPS, with the small assemblies integrated within the droplets. The LLPS transition, however, was not associated with a clear discontinuity in the correlation times and populations of the three components. Importantly, CPEB4NTD exhibits LLPS properties where droplet formation occurs from a preformed microscopic assembly rather than the monomeric protein molecules.
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Affiliation(s)
- Manas Seal
- Department
of Chemical and Biological Physics, Department of Biological Regulation, Department of Structural
Biology, and Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Chandrima Jash
- Department
of Chemical and Biological Physics, Department of Biological Regulation, Department of Structural
Biology, and Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Reeba Susan Jacob
- Department
of Chemical and Biological Physics, Department of Biological Regulation, Department of Structural
Biology, and Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Akiva Feintuch
- Department
of Chemical and Biological Physics, Department of Biological Regulation, Department of Structural
Biology, and Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Yair Shalom Harel
- Department
of Chemical and Biological Physics, Department of Biological Regulation, Department of Structural
Biology, and Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Shira Albeck
- Department
of Chemical and Biological Physics, Department of Biological Regulation, Department of Structural
Biology, and Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Tamar Unger
- Department
of Chemical and Biological Physics, Department of Biological Regulation, Department of Structural
Biology, and Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Daniella Goldfarb
- Department
of Chemical and Biological Physics, Department of Biological Regulation, Department of Structural
Biology, and Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
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39
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Smorygina AS, Golysheva EA, Dzuba SA. Clustering of Stearic Acids in Model Phospholipid Membranes Revealed by Double Electron-Electron Resonance. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13909-13916. [PMID: 34787421 DOI: 10.1021/acs.langmuir.1c02460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Free fatty acids play various important roles in biological membranes. Double electron-electron resonance spectroscopy (DEER, also known as PELDOR) of spin-labeled biomolecules is capable of studying magnetic dipole-dipole (d-d) interactions between spin labels at the nanoscale range of distances. Here, DEER is applied to study intermolecular d-d interactions between doxyl-spin-labeled stearic acids (DSA) in gel-phase phospholipid bilayers composed either of an equimolecular mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine or of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. DEER data obtained for different DSA concentrations showed that DSA molecules at their concentration in the bilayer χ larger than 0.5 mol % are assembled into lateral lipid-mediated clusters, with a characteristic intermolecular distance of 2 nm. Some evidences were obtained indicating that clusters may consist of "subclusters", alternatively appearing in two opposite leaflets. Conventional electron paramagnetic resonance (EPR) spectra for the gel-phase bilayers showed that for χ larger than 2 mol % the molecules in the clusters stick together, forming oligomers. Room-temperature EPR spectra for the liquid-crystalline phase were found to change noticeably for χ larger than 0.5 mol %, which may indicate the clustering in a liquid-crystalline phase similar to that observed by DEER in the gel phase.
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Affiliation(s)
- Anna S Smorygina
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Elena A Golysheva
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Sergei A Dzuba
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
- Department of Physics, Novosibirsk State University, Novosibirsk 630090, Russia
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40
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Klose D, Holla A, Gmeiner C, Nettels D, Ritsch I, Bross N, Yulikov M, Allain FHT, Schuler B, Jeschke G. Resolving distance variations by single-molecule FRET and EPR spectroscopy using rotamer libraries. Biophys J 2021; 120:4842-4858. [PMID: 34536387 PMCID: PMC8595751 DOI: 10.1016/j.bpj.2021.09.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/09/2021] [Accepted: 09/13/2021] [Indexed: 01/14/2023] Open
Abstract
Förster resonance energy transfer (FRET) and electron paramagnetic resonance (EPR) spectroscopy are complementary techniques for quantifying distances in the nanometer range. Both approaches are commonly employed for probing the conformations and conformational changes of biological macromolecules based on site-directed fluorescent or paramagnetic labeling. FRET can be applied in solution at ambient temperature and thus provides direct access to dynamics, especially if used at the single-molecule level, whereas EPR requires immobilization or work at cryogenic temperatures but provides data that can be more reliably used to extract distance distributions. However, a combined analysis of the complementary data from the two techniques has been complicated by the lack of a common modeling framework. Here, we demonstrate a systematic analysis approach based on rotamer libraries for both FRET and EPR labels to predict distance distributions between two labels from a structural model. Dynamics of the fluorophores within these distance distributions are taken into account by diffusional averaging, which improves the agreement with experiment. Benchmarking this methodology with a series of surface-exposed pairs of sites in a structured protein domain reveals that the lowest resolved distance differences can be as small as ∼0.25 nm for both techniques, with quantitative agreement between experimental and simulated transfer efficiencies within a range of ±0.045. Rotamer library analysis thus establishes a coherent way of treating experimental data from EPR and FRET and provides a basis for integrative structural modeling, including studies of conformational distributions and dynamics of biological macromolecules using both techniques.
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Affiliation(s)
- Daniel Klose
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.
| | - Andrea Holla
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Christoph Gmeiner
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Irina Ritsch
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Nadja Bross
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Maxim Yulikov
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | | | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland; Department of Physics, University of Zurich, Zurich, Switzerland.
| | - Gunnar Jeschke
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
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41
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Zehnder J, Cadalbert R, Yulikov M, Künze G, Wiegand T. Paramagnetic spin labeling of a bacterial DnaB helicase for solid-state NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 332:107075. [PMID: 34597956 DOI: 10.1016/j.jmr.2021.107075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/16/2021] [Accepted: 09/17/2021] [Indexed: 06/13/2023]
Abstract
Labeling of biomolecules with a paramagnetic probe for nuclear magnetic resonance (NMR) spectroscopy enables determining long-range distance restraints, which are otherwise not accessible by classically used dipolar coupling-based NMR approaches. Distance restraints derived from paramagnetic relaxation enhancements (PREs) can facilitate the structure determination of large proteins and protein complexes. We herein present the site-directed labeling of the large oligomeric bacterial DnaB helicase from Helicobacter pylori with cysteine-reactive maleimide tags carrying either a nitroxide radical or a lanthanide ion. The success of the labeling reaction was followed by quantitative continuous-wave electron paramagnetic resonance (EPR) experiments performed on the nitroxide-labeled protein. PREs were extracted site-specifically from 2D and 3D solid-state NMR spectra. A good agreement with predicted PRE values, derived by computational modeling of nitroxide and Gd3+ tags in the low-resolution DnaB crystal structure, was found. Comparison of experimental PREs and model-predicted spin label-nucleus distances indicated that the size of the "blind sphere" around the paramagnetic center, in which NMR resonances are not detected, is slightly larger for Gd3+ (∼14 Å) than for nitroxide (∼11 Å) in 13C-detected 2D spectra of DnaB. We also present Gd3+-Gd3+ dipolar electron-electron resonance EPR experiments on DnaB supporting the conclusion that DnaB was present as a hexameric assembly.
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Affiliation(s)
| | | | - Maxim Yulikov
- Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Georg Künze
- Institute for Drug Discovery, Medical School, Leipzig University, 04103 Leipzig, Germany.
| | - Thomas Wiegand
- Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland; Max-Planck-Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany; Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
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42
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Nguyen D, Abdullin D, Heubach CA, Pfaffeneder T, Nguyen A, Heine A, Reuter K, Diederich F, Schiemann O, Klebe G. Entschlüsselung der ligandeninduzierten Verdrehung eines homodimeren Enzyms mit Hilfe der gepulsten Elektron‐Elektron‐Doppelresonanz‐Spektroskopie. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Dzung Nguyen
- Institut für Pharmazeutische Chemie Philipps-Universität Marburg Marbacher Weg 8 35032 Marburg Deutschland
| | - Dinar Abdullin
- Institut für Physikalische und Theoretische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn Wegelerstr. 12 53115 Bonn Deutschland
| | - Caspar A. Heubach
- Institut für Physikalische und Theoretische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn Wegelerstr. 12 53115 Bonn Deutschland
| | - Toni Pfaffeneder
- Laboratorium für Organische Chemie ETH Zürich Vladimir-Prelog-Weg 3, HCI 8093 Zürich Schweiz
| | - Andreas Nguyen
- Institut für Pharmazeutische Chemie Philipps-Universität Marburg Marbacher Weg 8 35032 Marburg Deutschland
| | - Andreas Heine
- Institut für Pharmazeutische Chemie Philipps-Universität Marburg Marbacher Weg 8 35032 Marburg Deutschland
| | - Klaus Reuter
- Institut für Pharmazeutische Chemie Philipps-Universität Marburg Marbacher Weg 8 35032 Marburg Deutschland
| | - François Diederich
- Laboratorium für Organische Chemie ETH Zürich Vladimir-Prelog-Weg 3, HCI 8093 Zürich Schweiz
| | - Olav Schiemann
- Institut für Physikalische und Theoretische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn Wegelerstr. 12 53115 Bonn Deutschland
| | - Gerhard Klebe
- Institut für Pharmazeutische Chemie Philipps-Universität Marburg Marbacher Weg 8 35032 Marburg Deutschland
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43
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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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44
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Unguryan VV, Golysheva EA, Dzuba SA. Double Electron-Electron Resonance of Spin-Labeled Cholestane in Model Membranes: Evidence for Substructures inside the Lipid Rafts. J Phys Chem B 2021; 125:9557-9563. [PMID: 34387998 DOI: 10.1021/acs.jpcb.1c05215] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Plasma membranes are assumed to be highly compartmentalized, which is believed to be important for the membrane protein functionality. The liquid ordered-disordered phase segregation in the membranes results in nanoscale liquid-ordered assemblies-lipid rafts. Double electron-electron resonance spectroscopy (DEER, also known as PELDOR) is sensitive to spin-spin dipolar interactions between spin labels at the nanoscale range of distances. Here, DEER is applied to spin-labeled cholestane, 3β-doxyl-5α-cholestane (DChl), diluted in bilayers composed of an equimolar mixture of dioleoyl-glycero-phosphocholine (DOPC) and dipalmitoyl-glycero-phosphocholine (DPPC) phospholipids, with cholesterol (Chol) added. The DEER data allowed us to detect clustering of the DChl molecules. Their lateral distribution in the clusters in the absence of Chol was found to be random, while in the presence of Chol it became quasi-regular. DEER time traces are fairly well simulated within a simple square superlattice model. For the 20 mol % Chol content, for which at physiological temperatures, the lipid rafts are formed, the found superlattice parameter was 3.7 nm. Assuming that lipid rafts are captioned upon shock freezing at the temperature of investigation (80 K), the found regularity of DChl lateral distribution was interpreted by raft substructuring, with the DChl molecules embedded between the substructures.
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Affiliation(s)
- Vasily V Unguryan
- Department of Physics, Novosibirsk State University, Novosibirsk 630090, Russia.,Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Elena A Golysheva
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Sergei A Dzuba
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
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45
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Klebe G, Nguyen D, Abdullin D, Heubach CA, Pfaffeneder T, Nguyen A, Heine A, Reuter K, Diederich F, Schiemann O. Unraveling a ligand-induced twist of a homodimeric enzyme by pulsed electron-electron double resonance. Angew Chem Int Ed Engl 2021; 60:23419-23426. [PMID: 34387025 PMCID: PMC8597004 DOI: 10.1002/anie.202108179] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Indexed: 11/30/2022]
Abstract
Mechanistic insights into protein–ligand interactions can yield chemical tools for modulating protein function and enable their use for therapeutic purposes. For the homodimeric enzyme tRNA‐guanine transglycosylase (TGT), a putative virulence target of shigellosis, ligand binding has been shown by crystallography to transform the functional dimer geometry into an incompetent twisted one. However, crystallographic observation of both end states does neither verify the ligand‐induced transformation of one dimer into the other in solution nor does it shed light on the underlying transformation mechanism. We addressed these questions in an approach that combines site‐directed spin labeling (SDSL) with distance measurements based on pulsed electron–electron double resonance (PELDOR or DEER) spectroscopy. We observed an equilibrium between the functional and twisted dimer that depends on the type of ligand, with a pyranose‐substituted ligand being the most potent one in shifting the equilibrium toward the twisted dimer. Our experiments suggest a dissociation–association mechanism for the formation of the twisted dimer upon ligand binding.
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Affiliation(s)
- Gerhard Klebe
- Univ. of Marburg, Inst. Pharmaceut. Chem., Marbacher Weg 6, D35032, Marburg, GERMANY
| | - Dzung Nguyen
- Philipps-Universität Marburg: Philipps-Universitat Marburg, Pharmaceutical Chemistry, GERMANY
| | - Dinar Abdullin
- Universität Bonn: Rheinische Friedrich-Wilhelms-Universitat Bonn, Physical and Theoretical Chemistry, GERMANY
| | - Caspar A Heubach
- Universität Bonn: Rheinische Friedrich-Wilhelms-Universitat Bonn, Physical and Theoretical Chemistry, GERMANY
| | - Toni Pfaffeneder
- ETH-Zürich LOC: Eidgenossische Technische Hochschule Zurich Laboratorium fur Organische Chemie, Organic Chemistry, SWITZERLAND
| | - Andreas Nguyen
- Philipps-Universität Marburg: Philipps-Universitat Marburg, Pharmaceutical Chemistry, GERMANY
| | - Andreas Heine
- Philipps-Universität Marburg: Philipps-Universitat Marburg, Pharmaceutical Chemistry, GERMANY
| | - Klaus Reuter
- Philipps-Universität Marburg: Philipps-Universitat Marburg, Pharmaceutical Chemistry, GERMANY
| | - Francois Diederich
- ETH Zurich Department of Chemistry and Applied Biosciences: Eidgenossische Technische Hochschule Zurich Departement Chemie und Angewandte Biowissenschaften, Organic Chemistry, SWITZERLAND
| | - Olav Schiemann
- Universität Bonn: Rheinische Friedrich-Wilhelms-Universitat Bonn, Physical and Theoretical Chemistry, GERMANY
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46
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Casto J, Mandato A, Saxena S. dHis-troying Barriers: Deuteration Provides a Pathway to Increase Sensitivity and Accessible Distances for Cu 2+ Labels. J Phys Chem Lett 2021; 12:4681-4685. [PMID: 33979151 DOI: 10.1021/acs.jpclett.1c01002] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Recently, site-directed Cu2+ labeling has emerged as an incisive biophysical tool to directly report on distance constraints that pertain to the structure, conformational transitions, and dynamics of proteins and nucleic acids. However, short phase memory times inherent to the Cu2+ labels limit measurable distances to 4-5 nm. In this work we systematically examine different methods to dampen electron-nuclear and electron-electron coupled interactions to decrease rapid relaxation. We show that using Cu2+ spin concentrations up to ca. 800 μM has an invariant effect on relaxation and that increasing the cryoprotectant concentration reduces contributions of solvent protons to relaxation. On the other hand, the deuteration of protein and solvent dramatically increases the duration of the dipolar modulated signal by over 6-fold to 32 μs. Based on this increase in signal longevity, distances up to 9 nm and beyond can potentially be measured with Cu2+ labels.
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Affiliation(s)
- Joshua Casto
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Alysia Mandato
- 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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47
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Gualandi L, Franchi P, Mezzina E, Goldup SM, Lucarini M. Spin-labelled mechanically interlocked molecules as models for the interpretation of biradical EPR spectra. Chem Sci 2021; 12:8385-8393. [PMID: 34221319 PMCID: PMC8221063 DOI: 10.1039/d1sc01462e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/14/2021] [Indexed: 12/20/2022] Open
Abstract
Biradical spin probes can provide detailed information about the distances between molecules/regions of molecules because the through-space coupling of radical centres, characterised by J, is strongly distance dependent. However, if the system can adopt multiple configurations, as is common in supramolecular complexes, the shape of the EPR spectrum is influenced not only by J but also the rate of exchange between different states. In practice, it is often hard to separate these variables and as a result, the effect of the latter is sometimes overlooked. To demonstrate this challenge unequivocally we synthesised rotaxane biradicals containing nitronyl nitroxide units at the termini of their axles. The rotaxanes exchange between the available biradical conformations more slowly than the corresponding non-interlocked axles but, despite this, in some cases, the EPR spectra of the axle and rotaxane remain remarkably similar. Detailed analysis allowed us to demonstrate that the similar EPR spectral shapes result from different combinations of J and rates of conformational interconversion, a phenomenon suggested theoretically more than 50 years ago. This work reinforces the idea that thorough analysis must be performed when interpreting the spectra of biradicals employed as spin probes in solution.
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Affiliation(s)
- Lorenzo Gualandi
- Department of Chemistry "Giacomo Ciamician", University of Bologna Via San Giacomo 11 Bologna Italy
| | - Paola Franchi
- Department of Chemistry "Giacomo Ciamician", University of Bologna Via San Giacomo 11 Bologna Italy
| | - Elisabetta Mezzina
- Department of Chemistry "Giacomo Ciamician", University of Bologna Via San Giacomo 11 Bologna Italy
| | - Stephen M Goldup
- Department of Chemistry, University of Southampton University Road, Highfield Southampton UK
| | - Marco Lucarini
- Department of Chemistry "Giacomo Ciamician", University of Bologna Via San Giacomo 11 Bologna Italy
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48
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Vicino MF, Hett T, Schiemann O. Spin Labeling of RNA Using "Click" Chemistry for Coarse-grained Structure Determination via Pulsed Electron-electron Double Resonance Spectroscopy. Bio Protoc 2021; 11:e4004. [PMID: 34150941 PMCID: PMC8187847 DOI: 10.21769/bioprotoc.4004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/18/2021] [Accepted: 02/20/2021] [Indexed: 11/02/2022] Open
Abstract
Understanding the function of oligonucleotides on a molecular level requires methods for studying their structure, conformational changes, and internal dynamics. Various biophysical methods exist to achieve this, including the whole toolbox of Electron Paramagnetic Resonance (EPR or ESR) spectroscopy. An EPR method widely used in this regard is Pulsed Electron-Electron Double Resonance (PELDOR or DEER), which provides distances in the nanometer range between electron spins in biomolecules with Angstrom precision, without restriction to the size of the biomolecule, and in solution. Since oligonucleotides inherently do not contain unpaired electrons, these have to be introduced in the form of so-called spin labels. Firstly, this protocol describes how nitroxide spin labels can be site-specifically attached to oligonucleotides using "Click" chemistry. The reaction provides little byproducts, high yields, and is conveniently performed in aqueous solution. Secondly, the protocol details how to run the PELDOR experiment, analyze the data, and derive a coarse-grained structure. Here, emphasis is placed on the pitfalls, requirements for a good dataset, and limits of interpretation; thus, the protocol gives the user a guideline for the whole experiment i.e., from spin labeling, via the PELDOR measurement and data analysis, to the final coarse-grained structure. Graphical abstract: Schematic overview of the workflow described in this protocol: First, the spin-labeling of RNA is described, which is performed as a "Click"-reaction between the alkyne-functionalized RNA strand and the azide group of the spin label. Next, step-by-step instructions are given for setting up PELDOR/DEER distance measurements on the labeled RNA, and for data analysis. Finally, guidelines are provided for building a structural model from the previously analyzed data.
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Affiliation(s)
- Maria F. Vicino
- Institute of Physical and Theoretical Chemistry, Rheinische Friedrich-Wilhelms-University, Bonn, Germany
| | - Tobias Hett
- Institute of Physical and Theoretical Chemistry, Rheinische Friedrich-Wilhelms-University, Bonn, Germany
| | - Olav Schiemann
- Institute of Physical and Theoretical Chemistry, Rheinische Friedrich-Wilhelms-University, Bonn, Germany
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Bowen AM, Bertran A, Henbest KB, Gobbo M, Timmel CR, Di Valentin M. Orientation-Selective and Frequency-Correlated Light-Induced Pulsed Dipolar Spectroscopy. J Phys Chem Lett 2021; 12:3819-3826. [PMID: 33856805 PMCID: PMC8154851 DOI: 10.1021/acs.jpclett.1c00595] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 03/31/2021] [Indexed: 06/12/2023]
Abstract
We explore the potential of orientation-resolved pulsed dipolar spectroscopy (PDS) in light-induced versions of the experiment. The use of triplets as spin-active moieties for PDS offers an attractive tool for studying biochemical systems containing optically active cofactors. Cofactors are often rigidly bound within the protein structure, providing an accurate positional marker. The rigidity leads to orientation selection effects in PDS, which can be analyzed to give both distance and mutual orientation information. Herein we present a comprehensive analysis of the orientation selection of a full set of light-induced PDS experiments. We exploit the complementary information provided by the different light-induced techniques to yield atomic-level structural information. For the first time, we measure a 2D frequency-correlated laser-induced magnetic dipolar spectrum, and we are able to monitor the complete orientation dependence of the system in a single experiment. Alternatively, the summed spectrum enables an orientation-independent analysis to determine the distance distribution.
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Affiliation(s)
- Alice M. Bowen
- Department
of Chemistry, Photon Science Institute and The National EPR Research
Facility, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Arnau Bertran
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Kevin B. Henbest
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Marina Gobbo
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Christiane R. Timmel
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Marilena Di Valentin
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
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50
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Hilger D. The role of structural dynamics in GPCR‐mediated signaling. FEBS J 2021; 288:2461-2489. [DOI: 10.1111/febs.15841] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/19/2021] [Accepted: 03/24/2021] [Indexed: 12/18/2022]
Affiliation(s)
- Daniel Hilger
- Department of Pharmaceutical Chemistry Philipps‐University Marburg Germany
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