1
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Jeschke G. Protein ensemble modeling and analysis with MMMx. Protein Sci 2024; 33:e4906. [PMID: 38358120 PMCID: PMC10868441 DOI: 10.1002/pro.4906] [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: 08/04/2023] [Revised: 01/04/2024] [Accepted: 01/06/2024] [Indexed: 02/16/2024]
Abstract
Proteins, especially of eukaryotes, often have disordered domains and may contain multiple folded domains whose relative spatial arrangement is distributed. The MMMx ensemble modeling and analysis toolbox (https://github.com/gjeschke/MMMx) can support the design of experiments to characterize the distributed structure of such proteins, starting from AlphaFold2 predictions or folded domain structures. Weak order can be analyzed with reference to a random coil model or to peptide chains that match the residue-specific Ramachandran angle distribution of the loop regions and are otherwise unrestrained. The deviation of the mean square end-to-end distance of chain sections from their average over sections of the same sequence length reveals localized compaction or expansion of the chain. The shape sampled by disordered chains is visualized by superposition in the principal axes frame of their inertia tensor. Ensembles of different sizes and with weighted conformers can be compared based on a similarity parameter that abstracts from the ensemble width.
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Affiliation(s)
- Gunnar Jeschke
- Department of Chemistry and Applied BiosciencesETH ZürichZürichSwitzerland
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2
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Dorn G, Gmeiner C, de Vries T, Dedic E, Novakovic M, Damberger FF, Maris C, Finol E, Sarnowski CP, Kohlbrecher J, Welsh TJ, Bolisetty S, Mezzenga R, Aebersold R, Leitner A, Yulikov M, Jeschke G, Allain FHT. Integrative solution structure of PTBP1-IRES complex reveals strong compaction and ordering with residual conformational flexibility. Nat Commun 2023; 14:6429. [PMID: 37833274 PMCID: PMC10576089 DOI: 10.1038/s41467-023-42012-z] [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: 09/16/2022] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
RNA-binding proteins (RBPs) are crucial regulators of gene expression, often composed of defined domains interspersed with flexible, intrinsically disordered regions. Determining the structure of ribonucleoprotein (RNP) complexes involving such RBPs necessitates integrative structural modeling due to their lack of a single stable state. In this study, we integrate magnetic resonance, mass spectrometry, and small-angle scattering data to determine the solution structure of the polypyrimidine-tract binding protein 1 (PTBP1/hnRNP I) bound to an RNA fragment from the internal ribosome entry site (IRES) of the encephalomyocarditis virus (EMCV). This binding, essential for enhancing the translation of viral RNA, leads to a complex structure that demonstrates RNA and protein compaction, while maintaining pronounced conformational flexibility. Acting as an RNA chaperone, PTBP1 orchestrates the IRES RNA into a few distinct conformations, exposing the RNA stems outward. This conformational diversity is likely common among RNP structures and functionally important. Our approach enables atomic-level characterization of heterogeneous RNP structures.
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Affiliation(s)
- Georg Dorn
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Christoph Gmeiner
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | - Tebbe de Vries
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Emil Dedic
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Mihajlo Novakovic
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Fred F Damberger
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Christophe Maris
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Esteban Finol
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Chris P Sarnowski
- Institute of Molecular Systems Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Joachim Kohlbrecher
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Villigen, Switzerland
| | - Timothy J Welsh
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | - Sreenath Bolisetty
- Laboratory of Food & Soft Materials, Institute of Food, Nutrition and Health, Department for Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - Raffaele Mezzenga
- Laboratory of Food & Soft Materials, Institute of Food, Nutrition and Health, Department for Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - Ruedi Aebersold
- Institute of Molecular Systems Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Alexander Leitner
- Institute of Molecular Systems Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Maxim Yulikov
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland.
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland.
| | - Frédéric H-T Allain
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland.
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3
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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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4
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Guidelines for the Simulations of Nitroxide X-Band cw EPR Spectra from Site-Directed Spin Labeling Experiments Using S imLabel. Molecules 2023; 28:molecules28031348. [PMID: 36771013 PMCID: PMC9919594 DOI: 10.3390/molecules28031348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 02/04/2023] Open
Abstract
Site-directed spin labeling (SDSL) combined with continuous wave electron paramagnetic resonance (cw EPR) spectroscopy is a powerful technique to reveal, at the local level, the dynamics of structural transitions in proteins. Here, we consider SDSL-EPR based on the selective grafting of a nitroxide on the protein under study, followed by X-band cw EPR analysis. To extract valuable quantitative information from SDSL-EPR spectra and thus give a reliable interpretation on biological system dynamics, a numerical simulation of the spectra is required. However, regardless of the numerical tool chosen to perform such simulations, the number of parameters is often too high to provide unambiguous results. In this study, we have chosen SimLabel to perform such simulations. SimLabel is a graphical user interface (GUI) of Matlab, using some functions of Easyspin. An exhaustive review of the parameters used in this GUI has enabled to define the adjustable parameters during the simulation fitting and to fix the others prior to the simulation fitting. Among them, some are set once and for all (gy, gz) and others are determined (Az, gx) thanks to a supplementary X-band spectrum recorded on a frozen solution. Finally, we propose guidelines to perform the simulation of X-band cw-EPR spectra of nitroxide labeled proteins at room temperature, with no need of uncommon higher frequency spectrometry and with the minimal number of variable parameters.
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5
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Ossadnik D, Kuzin S, Qi M, Yulikov M, Godt A. A Gd III-Based Spin Label at the Limits for Linewidth Reduction through Zero-Field Splitting Optimization. Inorg Chem 2023; 62:408-432. [PMID: 36525400 DOI: 10.1021/acs.inorgchem.2c03531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The remarkably narrow central line in the electron paramagnetic resonance spectrum and the very weak zero-field splitting (ZFS) make [GdIII(NO3Pic)] ([GdIII(TPATCN)]) an attractive starting point for the development of spin labels. For retaining the narrow line of this parent complex when modifying it with a substituent enabling bioconjugation, alkyl with a somehow remote functional group as a substituent at the picolinate moiety was found to be highly suitable because ZFS stayed weak, even if the threefold axial symmetry was broken. The ZFS is so weak that hyperfine coupling and/or g-value variations noticeably determine the linewidth in Q band and higher fields when the biomolecule is protonated, which is the standard situation, and in W band and higher fields for the protonated complex in a fully deuterated surrounding. Clearly, [NDSE-{GdIII(NO3Pic)}], a spin label targeting the cysteines in a peptide, is at a limit of linewidth narrowing through ZFS minimization. The labeling reaction is highly chemoselective and, applied to a polyproline with two cysteine units, it took no more than a minute at 7 °C and pH 7.8. Subsequent disulfide scrambling is very slow and can therefore be prevented. Double electron-electron resonance and relaxation-induced dipolar modulation enhancement applied to the spin-labeled polyproline proved the spin label useful for distance determination in peptides.
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Affiliation(s)
- Daniel Ossadnik
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615Bielefeld, Germany
| | - Sergei Kuzin
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093Zurich, Switzerland
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615Bielefeld, Germany
| | - Maxim Yulikov
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093Zurich, Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615Bielefeld, Germany
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6
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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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7
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Abstract
Different types of spin labels are currently available for structural studies of biomolecules both in vitro and in cells using Electron Paramagnetic Resonance (EPR) and pulse dipolar spectroscopy (PDS). Each type of label has its own advantages and disadvantages, that will be addressed in this chapter. The spectroscopically distinct properties of the labels have fostered new applications of PDS aimed to simultaneously extract multiple inter-label distances on the same sample. In fact, combining different labels and choosing the optimal strategy to address their inter-label distances can increase the information content per sample, and this is pivotal to better characterize complex multi-component biomolecular systems. In this review, we provide a brief background of the spectroscopic properties of the four most common orthogonal spin labels for PDS measurements and focus on the various methods at disposal to extract homo- and hetero-label distances in proteins. We also devote a section to possible artifacts arising from channel crosstalk and provide few examples of applications in structural biology.
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8
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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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9
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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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10
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Soetbeer J, Millen M, Zouboulis K, Hülsmann M, Godt A, Polyhach Y, Jeschke G. Dynamical decoupling in water-glycerol glasses: a comparison of nitroxides, trityl radicals and gadolinium complexes. Phys Chem Chem Phys 2021; 23:5352-5369. [PMID: 33635938 DOI: 10.1039/d1cp00055a] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Our previous study on nitroxides in o-terphenyl (OTP) revealed two separable decoherence processes at low temperatures, best captured by the sum of two stretched exponentials (SSE) model. Dynamical decoupling (DD) extends both associated dephasing times linearly for 1 to 5 refocusing pulses [Soetbeer et al., Phys. Chem. Chem. Phys., 2018, 20, 1615]. Here we demonstrate an analogous DD behavior of water-soluble nitroxides in water-glycerol glass by using nitroxide and/or solvent deuteration for component assignment. Compared to the conventional Hahn experiment, we show that Carr-Purcell and Uhrig DD schemes are superior in resolving and identifying active dephasing mechanisms. Thereby, we observe a partial coherence loss to intramolecular nitroxide and trityl nuclei that can be alleviated, while the zero field splitting-induced losses for gadolinium labels cannot be refocused and contribute even at the central transition of this spin-7/2 system. Independent of the studied spin system, Uhrig DD leads to a characteristic convex dephasing envelope in both protonated water-glycerol and OTP glass, thus outperforming the Carr-Purcell scheme.
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Affiliation(s)
- Janne Soetbeer
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland.
| | - Marthe Millen
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland.
| | - Konstantin Zouboulis
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland.
| | - Miriam Hülsmann
- Bielefeld University, Department of Chemistry, Universitätsstr. 25, D-33615 Bielefeld, Germany
| | - Adelheid Godt
- Bielefeld University, Department of Chemistry, Universitätsstr. 25, D-33615 Bielefeld, Germany
| | - Yevhen Polyhach
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland.
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland.
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11
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Teucher M, Qi M, Cati N, Hintz H, Godt A, Bordignon E. Strategies to identify and suppress crosstalk signals in double electron-electron resonance (DEER) experiments with gadolinium III and nitroxide spin-labeled compounds. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2020; 1:285-299. [PMID: 37904822 PMCID: PMC10500692 DOI: 10.5194/mr-1-285-2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 10/31/2020] [Indexed: 11/01/2023]
Abstract
Double electron-electron resonance (DEER) spectroscopy applied to orthogonally spin-labeled biomolecular complexes simplifies the assignment of intra- and intermolecular distances, thereby increasing the information content per sample. In fact, various spin labels can be addressed independently in DEER experiments due to spectroscopically nonoverlapping central transitions, distinct relaxation times, and/or transition moments; hence, they are referred to as spectroscopically orthogonal. Molecular complexes which are, for example, orthogonally spin-labeled with nitroxide (NO) and gadolinium (Gd) labels give access to three distinct DEER channels that are optimized to selectively probe NO-NO, NO-Gd, and Gd-Gd distances. Nevertheless, it has been previously recognized that crosstalk signals between individual DEER channels can occur, for example, when a Gd-Gd distance appears in a DEER channel optimized to detect NO-Gd distances. This is caused by residual spectral overlap between NO and Gd spins which, therefore, cannot be considered as perfectly orthogonal. Here, we present a systematic study on how to identify and suppress crosstalk signals that can appear in DEER experiments using mixtures of NO-NO, NO-Gd, and Gd-Gd molecular rulers characterized by distinct, nonoverlapping distance distributions. This study will help to correctly assign the distance peaks in homo- and heterocomplexes of biomolecules carrying not perfectly orthogonal spin labels.
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Affiliation(s)
- Markus Teucher
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Ninive Cati
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Henrik Hintz
- 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
| | - Enrica Bordignon
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstraße 150, 44801 Bochum, Germany
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12
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Galazzo L, Meier G, Timachi MH, Hutter CAJ, Seeger MA, Bordignon E. Spin-labeled nanobodies as protein conformational reporters for electron paramagnetic resonance in cellular membranes. Proc Natl Acad Sci U S A 2020; 117:2441-2448. [PMID: 31964841 PMCID: PMC7007536 DOI: 10.1073/pnas.1913737117] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Nanobodies are emerging tools in a variety of fields such as structural biology, cell imaging, and drug discovery. Here we pioneer the use of their spin-labeled variants as reporters of conformational dynamics of membrane proteins using DEER spectroscopy. At the example of the bacterial ABC transporter TM287/288, we show that two gadolinium-labeled nanobodies allow us to quantify, via analysis of the modulation depth of DEER traces, the fraction of transporters adopting the outward-facing state under different experimental conditions. Additionally, we quantitatively follow the interconversion from the outward- to the inward-facing state in the conformational ensemble under ATP turnover conditions. We finally show that the specificity of the nanobodies for the target protein allows the direct attainment of structural information on the wild-type TM287/288 expressed in cellular membranes without the need to purify or label the investigated membrane protein.
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Affiliation(s)
- Laura Galazzo
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Gianmarco Meier
- Institute of Medical Microbiology, University of Zürich, 8006 Zürich, Switzerland
| | - M Hadi Timachi
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Cedric A J Hutter
- Institute of Medical Microbiology, University of Zürich, 8006 Zürich, Switzerland
| | - Markus A Seeger
- Institute of Medical Microbiology, University of Zürich, 8006 Zürich, Switzerland
| | - Enrica Bordignon
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44801 Bochum, Germany;
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13
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Teucher M, Zhang H, Bader V, Winklhofer KF, García-Sáez AJ, Rajca A, Bleicken S, Bordignon E. A new perspective on membrane-embedded Bax oligomers using DEER and bioresistant orthogonal spin labels. Sci Rep 2019; 9:13013. [PMID: 31506457 PMCID: PMC6737250 DOI: 10.1038/s41598-019-49370-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 08/20/2019] [Indexed: 12/23/2022] Open
Abstract
Bax is a Bcl-2 protein crucial for apoptosis initiation and execution, whose active conformation is only partially understood. Dipolar EPR spectroscopy has proven to be a valuable tool to determine coarse-grained models of membrane-embedded Bcl-2 proteins. Here we show how the combination of spectroscopically distinguishable nitroxide and gadolinium spin labels and Double Electron-Electron Resonance can help to gain new insights into the quaternary structure of active, membrane-embedded Bax oligomers. We show that attaching labels bulkier than the conventional MTSL may affect Bax fold and activity, depending on the protein/label combination. However, we identified a suitable pair of spectroscopically distinguishable labels, which allows to study complex distance networks in the oligomers that could not be disentangled before. Additionally, we compared the stability of the different spin-labeled protein variants in E. coli and HeLa cell extracts. We found that the gem-diethyl nitroxide-labeled Bax variants were reasonably stable in HeLa cell extracts. However, when transferred into human cells, Bax was found to be mislocalized, thus preventing its characterization in a physiological environment. The successful use of spectroscopically distinguishable labels on membrane-embedded Bax-oligomers opens an exciting new path towards structure determination of membrane-embedded homo- or hetero-oligomeric Bcl-2 proteins via EPR.
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Affiliation(s)
- Markus Teucher
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Hui Zhang
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska, USA
| | - Verian Bader
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Konstanze F Winklhofer
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska, USA
| | - Stephanie Bleicken
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany.
- ZEMOS, Ruhr University Bochum, Bochum, Germany.
| | - Enrica Bordignon
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany.
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14
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Yardeni EH, Bahrenberg T, Stein RA, Mishra S, Zomot E, Graham B, Tuck KL, Huber T, Bibi E, Mchaourab HS, Goldfarb D. Probing the solution structure of the E. coli multidrug transporter MdfA using DEER distance measurements with nitroxide and Gd(III) spin labels. Sci Rep 2019; 9:12528. [PMID: 31467343 PMCID: PMC6715713 DOI: 10.1038/s41598-019-48694-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 08/08/2019] [Indexed: 11/09/2022] Open
Abstract
Methodological and technological advances in EPR spectroscopy have enabled novel insight into the structural and dynamic aspects of integral membrane proteins. In addition to an extensive toolkit of EPR methods, multiple spin labels have been developed and utilized, among them Gd(III)-chelates which offer high sensitivity at high magnetic fields. Here, we applied a dual labeling approach, employing nitroxide and Gd(III) spin labels, in conjunction with Q-band and W-band double electron-electron resonance (DEER) measurements to characterize the solution structure of the detergent-solubilized multidrug transporter MdfA from E. coli. Our results identify highly flexible regions of MdfA, which may play an important role in its functional dynamics. Comparison of distance distribution of spin label pairs on the periplasm with those calculated using inward- and outward-facing crystal structures of MdfA, show that in detergent micelles, the protein adopts a predominantly outward-facing conformation, although more closed than the crystal structure. The cytoplasmic pairs suggest a small preference to the outward-facing crystal structure, with a somewhat more open conformation than the crystal structure. Parallel DEER measurements with the two types of labels led to similar distance distributions, demonstrating the feasibility of using W-band spectroscopy with a Gd(III) label for investigation of the structural dynamics of membrane proteins.
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Affiliation(s)
- Eliane H Yardeni
- Department of Biomolecular Sciences, Weizmann Institute of Science Rehovot, Rehovot, 76100, Israel
| | - Thorsten Bahrenberg
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Richard A Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Smriti Mishra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Elia Zomot
- Department of Biomolecular Sciences, Weizmann Institute of Science Rehovot, Rehovot, 76100, Israel
| | - Bim Graham
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Kellie L Tuck
- School of Chemistry, Monash University, Wellington Road, Clayton, Victoria, Australia
| | - Thomas Huber
- Research School of Chemistry, The Australian National University, Canberra, ACT 2601, Australia
| | - Eitan Bibi
- Department of Biomolecular Sciences, Weizmann Institute of Science Rehovot, Rehovot, 76100, Israel.
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
| | - Daniella Goldfarb
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100, Israel.
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15
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Shah A, Roux A, Starck M, Mosely JA, Stevens M, Norman DG, Hunter RI, El Mkami H, Smith GM, Parker D, Lovett JE. A Gadolinium Spin Label with Both a Narrow Central Transition and Short Tether for Use in Double Electron Electron Resonance Distance Measurements. Inorg Chem 2019; 58:3015-3025. [DOI: 10.1021/acs.inorgchem.8b02892] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Anokhi Shah
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, U.K
- BSRC, University of St Andrews, St Andrews KY16 9ST, U.K
| | - Amandine Roux
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
| | - Matthieu Starck
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
| | - Jackie A. Mosely
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
| | - Michael Stevens
- College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - David G. Norman
- College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Robert I. Hunter
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, U.K
| | - Hassane El Mkami
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, U.K
| | - Graham M. Smith
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, U.K
| | - David Parker
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
| | - Janet E. Lovett
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, U.K
- BSRC, University of St Andrews, St Andrews KY16 9ST, U.K
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16
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Ritsch I, Hintz H, Jeschke G, Godt A, Yulikov M. Improving the accuracy of Cu(ii)–nitroxide RIDME in the presence of orientation correlation in water-soluble Cu(ii)–nitroxide rulers. Phys Chem Chem Phys 2019; 21:9810-9830. [DOI: 10.1039/c8cp06573j] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Detailed analysis of artefacts in the Cu(ii)–nitroxide RIDME experiments, related to orientation averaging, echo-crossing, ESEEM and background-correction is presented.
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Affiliation(s)
- Irina Ritsch
- Laboratory of Physical Chemistry
- Department of Chemistry and Applied Bioscience
- ETH Zurich
- 8093 Zurich
- Switzerland
| | - Henrik Hintz
- Faculty of Chemistry and Center for Molecular Materials (CM2)
- Bielefeld University
- 33615 Bielefeld
- Germany
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry
- Department of Chemistry and Applied Bioscience
- ETH Zurich
- 8093 Zurich
- Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials (CM2)
- Bielefeld University
- 33615 Bielefeld
- Germany
| | - Maxim Yulikov
- Laboratory of Physical Chemistry
- Department of Chemistry and Applied Bioscience
- ETH Zurich
- 8093 Zurich
- Switzerland
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17
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Keller K, Qi M, Gmeiner C, Ritsch I, Godt A, Jeschke G, Savitsky A, Yulikov M. Intermolecular background decay in RIDME experiments. Phys Chem Chem Phys 2019; 21:8228-8245. [DOI: 10.1039/c8cp07815g] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Theoretical and experimental studies of the RIDME background reveal electron and nuclear spectral diffusion contributions.
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Affiliation(s)
- Katharina Keller
- Laboratory of Physical Chemistry
- Department of Chemistry and Applied Biosciences
- ETH Zurich
- 8093 Zurich
- Switzerland
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials (CM2)
- Bielefeld University
- 33615 Bielefeld
- Germany
| | - Christoph Gmeiner
- Laboratory of Physical Chemistry
- Department of Chemistry and Applied Biosciences
- ETH Zurich
- 8093 Zurich
- Switzerland
| | - Irina Ritsch
- Laboratory of Physical Chemistry
- Department of Chemistry and Applied Biosciences
- ETH Zurich
- 8093 Zurich
- Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials (CM2)
- Bielefeld University
- 33615 Bielefeld
- Germany
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry
- Department of Chemistry and Applied Biosciences
- ETH Zurich
- 8093 Zurich
- Switzerland
| | - Anton Savitsky
- Physics Department
- Technical University Dortmund
- Dortmund
- Germany
| | - Maxim Yulikov
- Laboratory of Physical Chemistry
- Department of Chemistry and Applied Biosciences
- ETH Zurich
- 8093 Zurich
- Switzerland
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18
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Weinrich T, Jaumann EA, Scheffer UM, Prisner TF, Göbel MW. Phosphoramidite building blocks with protected nitroxides for the synthesis of spin-labeled DNA and RNA. Beilstein J Org Chem 2018; 14:1563-1569. [PMID: 30013683 PMCID: PMC6036967 DOI: 10.3762/bjoc.14.133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/14/2018] [Indexed: 12/23/2022] Open
Abstract
TEMPO spin labels protected with 2-nitrobenzyloxymethyl groups were attached to the amino residues of three different nucleosides: deoxycytidine, deoxyadenosine, and adenosine. The corresponding phosphoramidites could be incorporated by unmodified standard procedures into four different self-complementary DNA and two RNA oligonucleotides. After photochemical removal of the protective group, elimination of formic aldehyde and spontaneous air oxidation, the nitroxide radicals were regenerated in high yield. The resulting spin-labeled palindromic duplexes could be directly investigated by PELDOR spectroscopy without further purification steps. Spin–spin distances measured by PELDOR correspond well to the values obtained from molecular models.
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Affiliation(s)
- Timo Weinrich
- Institute of Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany
| | - Eva A Jaumann
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany
| | - Ute M Scheffer
- Institute of Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany
| | - Michael W Göbel
- Institute of Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany
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19
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Kuzhelev AA, Krumkacheva OA, Shevelev GY, Yulikov M, Fedin MV, Bagryanskaya EG. Room-temperature distance measurements using RIDME and the orthogonal spin labels trityl/nitroxide. Phys Chem Chem Phys 2018; 20:10224-10230. [PMID: 29594278 DOI: 10.1039/c8cp01093e] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron paramagnetic resonance (EPR) based nanometer distance measurements at ambient temperatures are of particular interest for structural biology applications. The nitroxide spin labels commonly used in EPR reveal relatively short transverse relaxation under these conditions, which limits their use for detecting static dipolar interactions. At the same time, the longitudinal relaxation of nitroxide spin labels is still long enough to allow using them as 'pumped' species in the relaxation induced dipolar modulation enhancement (RIDME) experiment where the detection is carried out on the slower relaxing triarylmethyl (TAM) spin labels. In the present study, we report the first demonstration of room-temperature RIDME distance measurements in nucleic acids using TAM as the slow-relaxing detected species and traditional nitroxide as the fast-relaxing partner spin. Two types of immobilizers, glassy trehalose and the modified silica gel Nucleosil, were used for immobilization of the spin-labeled biomolecules. The room-temperature RIDME-based distance distributions are in good agreement with those measured at 80 K by other techniques. Room-temperature RIDME on the spin pairs trityl/nitroxide may become a useful method for the structural characterization of biomacromolecules and biomolecular complexes at near physiological temperatures.
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Affiliation(s)
- Andrey A Kuzhelev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia.
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20
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Weinrich T, Jaumann EA, Scheffer U, Prisner TF, Göbel MW. A Cytidine Phosphoramidite with Protected Nitroxide Spin Label: Synthesis of a Full-Length TAR RNA and Investigation by In-Line Probing and EPR Spectroscopy. Chemistry 2018; 24:6202-6207. [PMID: 29485736 DOI: 10.1002/chem.201800167] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/23/2018] [Indexed: 01/20/2023]
Abstract
EPR studies on RNA are complicated by three major obstacles related to the chemical nature of nitroxide spin labels: Decomposition while oligonucleotides are chemically synthesized, further decay during enzymatic strand ligation, and undetected changes in conformational equilibria due to the steric demand of the label. Herein possible solutions for all three problems are presented: A 2-nitrobenzyloxymethyl protective group for nitroxides that is stable under all conditions of chemical RNA synthesis and can be removed photochemically. By careful selection of ligation sites and splint oligonucleotides, high yields were achieved in the assembly of a full-length HIV-1 TAR RNA labeled with two protected nitroxide groups. PELDOR measurements on spin-labeled TAR in the absence and presence of arginine amide indicated arrest of interhelical motions on ligand binding. Finally, even minor changes in conformation due to the presence of spin labels are detected with high sensitivity by in-line probing.
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Affiliation(s)
- Timo Weinrich
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
| | - Eva A Jaumann
- Institute for Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
| | - Ute Scheffer
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
| | - Thomas F Prisner
- Institute for Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
| | - Michael W Göbel
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
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21
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Affiliation(s)
- Katrin Ackermann
- Biomedical Sciences Research Complex, Centre of Magnetic Resonance and EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, Scotland
| | - Bela E. Bode
- Biomedical Sciences Research Complex, Centre of Magnetic Resonance and EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, Scotland
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