1
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Grosskopf JD, Sidabras JW, Altenbach C, Anderson JR, Mett RR, Strangeway RA, Hyde JS, Hubbell WL, Lerch MT. A pressure-jump EPR system to monitor millisecond conformational exchange rates of spin-labeled proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.593074. [PMID: 38766191 PMCID: PMC11100676 DOI: 10.1101/2024.05.07.593074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) using nitroxide spin labels is a well-established technology for mapping site-specific secondary and tertiary structure and for monitoring conformational changes in proteins of any degree of complexity, including membrane proteins, with high sensitivity. SDSL-EPR also provides information on protein dynamics in the time scale of ps-µs using continuous wave lineshape analysis and spin lattice relaxation time methods. However, the functionally important time domain of µs-ms, corresponding to large-scale protein motions, is inaccessible to those methods. To extend SDSL-EPR to the longer time domain, the perturbation method of pressure-jump relaxation is implemented. Here, we describe a complete high-pressure EPR system at Q-band for both static pressure and millisecond-timescale pressure-jump measurements on spin-labeled proteins. The instrument enables pressure jumps both up and down from any holding pressure, ranging from atmospheric pressure to the maximum pressure capacity of the system components (~3500 bar). To demonstrate the utility of the system, we characterize a local folding-unfolding equilibrium of T4 lysozyme. The results illustrate the ability of the system to measure thermodynamic and kinetic parameters of protein conformational exchange on the millisecond timescale.
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Affiliation(s)
- Julian D Grosskopf
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Jason W Sidabras
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Christian Altenbach
- Department of Chemistry and Biochemistry and Stein Eye Institute, University of California, Los Angeles, CA 90095, USA
| | - Jim R Anderson
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Richard R Mett
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Robert A Strangeway
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - James S Hyde
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Wayne L Hubbell
- Department of Chemistry and Biochemistry and Stein Eye Institute, University of California, Los Angeles, CA 90095, USA
| | - Michael T Lerch
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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2
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Bogetti X, Saxena S. Integrating Electron Paramagnetic Resonance Spectroscopy and Computational Modeling to Measure Protein Structure and Dynamics. Chempluschem 2024; 89:e202300506. [PMID: 37801003 DOI: 10.1002/cplu.202300506] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/07/2023]
Abstract
Electron paramagnetic resonance (EPR) has become a powerful probe of conformational heterogeneity and dynamics of biomolecules. In this Review, we discuss different computational modeling techniques that enrich the interpretation of EPR measurements of dynamics or distance restraints. A variety of spin labels are surveyed to provide a background for the discussion of modeling tools. Molecular dynamics (MD) simulations of models containing spin labels provide dynamical properties of biomolecules and their labels. These simulations can be used to predict EPR spectra, sample stable conformations and sample rotameric preferences of label sidechains. For molecular motions longer than milliseconds, enhanced sampling strategies and de novo prediction software incorporating or validated by EPR measurements are able to efficiently refine or predict protein conformations, respectively. To sample large-amplitude conformational transition, a coarse-grained or an atomistic weighted ensemble (WE) strategy can be guided with EPR insights. Looking forward, we anticipate an integrative strategy for efficient sampling of alternate conformations by de novo predictions, followed by validations by systematic EPR measurements and MD simulations. Continuous pathways between alternate states can be further sampled by WE-MD including all intermediate states.
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Affiliation(s)
- Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA, 15260, USA
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA, 15260, USA
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3
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Rudolph M, Tampé R, Joseph B. Time-Resolved Mn 2+ -NO and NO-NO Distance Measurements Reveal That Catalytic Asymmetry Regulates Alternating Access in an ABC Transporter. Angew Chem Int Ed Engl 2023; 62:e202307091. [PMID: 37459565 DOI: 10.1002/anie.202307091] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/17/2023] [Indexed: 08/08/2023]
Abstract
ATP-binding cassette (ABC) transporters shuttle diverse substrates across biological membranes. Transport is often achieved through a transition between an inward-facing (IF) and an outward-facing (OF) conformation of the transmembrane domains (TMDs). Asymmetric nucleotide-binding sites (NBSs) are present among several ABC subfamilies and their functional role remains elusive. Here we addressed this question using concomitant NO-NO, Mn2+ -NO, and Mn2+ -Mn2+ pulsed electron-electron double-resonance spectroscopy of TmrAB in a time-resolved manner. This type-IV ABC transporter undergoes a reversible transition in the presence of ATP with a significantly faster forward transition. The impaired degenerate NBS stably binds Mn2+ -ATP, and Mn2+ is preferentially released at the active consensus NBS. ATP hydrolysis at the consensus NBS considerably accelerates the reverse transition. Both NBSs fully open during each conformational cycle and the degenerate NBS may regulate the kinetics of this process.
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Affiliation(s)
- Michael Rudolph
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt/Main, Germany
| | - Benesh Joseph
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
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4
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Fouillen A, Bous J, Granier S, Mouillac B, Sounier R. Bringing GPCR Structural Biology to Medical Applications: Insights from Both V2 Vasopressin and Mu-Opioid Receptors. MEMBRANES 2023; 13:606. [PMID: 37367810 PMCID: PMC10303988 DOI: 10.3390/membranes13060606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/05/2023] [Accepted: 06/14/2023] [Indexed: 06/28/2023]
Abstract
G-protein coupled receptors (GPCRs) are versatile signaling proteins that regulate key physiological processes in response to a wide variety of extracellular stimuli. The last decade has seen a revolution in the structural biology of clinically important GPCRs. Indeed, the improvement in molecular and biochemical methods to study GPCRs and their transducer complexes, together with advances in cryo-electron microscopy, NMR development, and progress in molecular dynamic simulations, have led to a better understanding of their regulation by ligands of different efficacy and bias. This has also renewed a great interest in GPCR drug discovery, such as finding biased ligands that can either promote or not promote specific regulations. In this review, we focus on two therapeutically relevant GPCR targets, the V2 vasopressin receptor (V2R) and the mu-opioid receptor (µOR), to shed light on the recent structural biology studies and show the impact of this integrative approach on the determination of new potential clinical effective compounds.
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Affiliation(s)
- Aurélien Fouillen
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34000 Montpellier, France; (A.F.); (S.G.); (B.M.)
- Centre de Biochimie Structurale (CBS), Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France
| | - Julien Bous
- Section of Receptor Biology & Signaling, Department of Physiology & Pharmacology, Karolinska Institutet, 17165 Stockholm, Sweden;
| | - Sébastien Granier
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34000 Montpellier, France; (A.F.); (S.G.); (B.M.)
| | - Bernard Mouillac
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34000 Montpellier, France; (A.F.); (S.G.); (B.M.)
| | - Remy Sounier
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34000 Montpellier, France; (A.F.); (S.G.); (B.M.)
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5
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Georgieva E, Karamalakova Y, Arabadzhiev G, Atanasov V, Kostandieva R, Mitev M, Tsoneva V, Yovchev Y, Nikolova G. Site-Directed Spin Labeling EPR Spectroscopy for Determination of Albumin Structural Damage and Hypoalbuminemia in Critical COVID-19. Antioxidants (Basel) 2022; 11:antiox11122311. [PMID: 36552520 PMCID: PMC9774111 DOI: 10.3390/antiox11122311] [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: 10/07/2022] [Revised: 11/17/2022] [Accepted: 11/20/2022] [Indexed: 11/24/2022] Open
Abstract
The main factors in the COVID-19 pathology, which can initiate extensive structural changes at the cellular and molecular levels, are the generation of free radicals in abnormal amounts, and oxidative stress. Under "oxidative shock" conditions, the proteins undergo various modifications that affect their function and activity, and as a result distribute malfunctioning protein derivatives in the body. Human serum albumin is a small globular protein characterized by a high overall binding capacity for neutral lipophilic and acidic dosage forms. The albumin concentration is crucial for the maintenance of plasma oncotic pressure, the transport of nutrients, amino acids, and drugs, the effectiveness of drug therapy, and the prevention of drug toxicity. Hypoalbuminemia and structural defects molecule in the protein suggest a risk of changed metabolism and increased plasma concentration of unbound drugs. Therefore, the albumin structural and functional changes accompanied by low protein levels can be a serious prerequisite for ineffective therapy, frequent complications, and high mortality in patients with SARS-CoV-2 infection. The current opinion aims the research community the application of Site-Directed Spin Labeling Electron Paramagnetic Resonance spectroscopy (SDSL-EPR) and 3-Maleimido-PROXYL radical in determining abnormalities of the albumin dynamics and protein concentrations in COVID-19 critical patients.
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Affiliation(s)
- Ekaterina Georgieva
- Department of “General and Clinical Pathology, Forensic Medicine, Deontology and Dermatovenerology”, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
- Department of “Medical Chemistry and Biochemistry”, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
| | - Yanka Karamalakova
- Department of “Medical Chemistry and Biochemistry”, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
| | - Georgi Arabadzhiev
- Department of “Surgery and Anesthesiology”, University Hospital “Prof. Dr. St. Kirkovich”, 6000 Stara Zagora, Bulgaria
| | - Vasil Atanasov
- Forensic Toxicology Laboratory, Military Medical Academy, 3 “Sv. Georgi Sofiiski Str.”, 1606 Sofia, Bulgaria
| | - Rositsa Kostandieva
- Forensic Toxicology Laboratory, Military Medical Academy, 3 “Sv. Georgi Sofiiski Str.”, 1606 Sofia, Bulgaria
| | - Mitko Mitev
- Department of “Diagnostic Imaging”, University Hospital “Prof. Dr. St. Kirkovich”, 6000 Stara Zagora, Bulgaria
| | - Vanya Tsoneva
- Department of Propaedeutics of Internal Medicine and Clinical Laboratory, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
| | - Yovcho Yovchev
- Department of “Surgery and Anesthesiology”, University Hospital “Prof. Dr. St. Kirkovich”, 6000 Stara Zagora, Bulgaria
| | - Galina Nikolova
- Department of “Medical Chemistry and Biochemistry”, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
- Correspondence: ; Tel.: +359-897771301
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6
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Abhyankar N, Agrawal A, Campbell J, Maly T, Shrestha P, Szalai V. Recent advances in microresonators and supporting instrumentation for electron paramagnetic resonance spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:101101. [PMID: 36319314 PMCID: PMC9632321 DOI: 10.1063/5.0097853] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 08/13/2022] [Indexed: 06/16/2023]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy characterizes the magnetic properties of paramagnetic materials at the atomic and molecular levels. Resonators are an enabling technology of EPR spectroscopy. Microresonators, which are miniaturized versions of resonators, have advanced inductive-detection EPR spectroscopy of mass-limited samples. Here, we provide our perspective of the benefits and challenges associated with microresonator use for EPR spectroscopy. To begin, we classify the application space for microresonators and present the conceptual foundation for analysis of resonator sensitivity. We summarize previous work and provide insight into the design and fabrication of microresonators as well as detail the requirements and challenges that arise in incorporating microresonators into EPR spectrometer systems. Finally, we provide our perspective on current challenges and prospective fruitful directions.
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Affiliation(s)
| | - Amit Agrawal
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Jason Campbell
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Thorsten Maly
- Bridge12 Technologies, Inc., Natick, Massachusetts 01760, USA
| | | | - Veronika Szalai
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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7
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Besaw JE, Reichenwallner J, De Guzman P, Tucs A, Kuo A, Morizumi T, Tsuda K, Sljoka A, Miller RJD, Ernst OP. Low pH structure of heliorhodopsin reveals chloride binding site and intramolecular signaling pathway. Sci Rep 2022; 12:13955. [PMID: 35977989 PMCID: PMC9385722 DOI: 10.1038/s41598-022-17716-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 07/29/2022] [Indexed: 11/11/2022] Open
Abstract
Within the microbial rhodopsin family, heliorhodopsins (HeRs) form a phylogenetically distinct group of light-harvesting retinal proteins with largely unknown functions. We have determined the 1.97 Å resolution X-ray crystal structure of Thermoplasmatales archaeon SG8-52-1 heliorhodopsin (TaHeR) in the presence of NaCl under acidic conditions (pH 4.5), which complements the known 2.4 Å TaHeR structure acquired at pH 8.0. The low pH structure revealed that the hydrophilic Schiff base cavity (SBC) accommodates a chloride anion to stabilize the protonated retinal Schiff base when its primary counterion (Glu-108) is neutralized. Comparison of the two structures at different pH revealed conformational changes connecting the SBC and the extracellular loop linking helices A-B. We corroborated this intramolecular signaling transduction pathway with computational studies, which revealed allosteric network changes propagating from the perturbed SBC to the intracellular and extracellular space, suggesting TaHeR may function as a sensory rhodopsin. This intramolecular signaling mechanism may be conserved among HeRs, as similar changes were observed for HeR 48C12 between its pH 8.8 and pH 4.3 structures. We additionally performed DEER experiments, which suggests that TaHeR forms possible dimer-of-dimer associations which may be integral to its putative functionality as a light sensor in binding a transducer protein.
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Affiliation(s)
- Jessica E Besaw
- Department of Chemistry, University of Toronto, Toronto, ON, M5S 3H6, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Jörg Reichenwallner
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Paolo De Guzman
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Department of Laboratory Medicine and Pathology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Andrejs Tucs
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - Anling Kuo
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Takefumi Morizumi
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Koji Tsuda
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
- RIKEN Center for Advanced Intelligence Project, RIKEN, 1-4-1 Nihombashi, Chuo-ku, Tokyo, 103-0027, Japan
- Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0047, Japan
| | - Adnan Sljoka
- RIKEN Center for Advanced Intelligence Project, RIKEN, 1-4-1 Nihombashi, Chuo-ku, Tokyo, 103-0027, Japan.
- Department of Chemistry, York University, Toronto, ON, M3J 1P3, Canada.
| | - R J Dwayne Miller
- Department of Chemistry, University of Toronto, Toronto, ON, M5S 3H6, Canada
- Department of Physics, University of Toronto, Toronto, ON, M5S 3H6, Canada
| | - Oliver P Ernst
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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8
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Huang SK, Prosser RS. Dynamics and Mechanistic Underpinnings to Pharmacology of Class A GPCRs - An NMR Perspective. Am J Physiol Cell Physiol 2022; 322:C739-C753. [PMID: 35235425 DOI: 10.1152/ajpcell.00044.2022] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
One-third of current pharmaceuticals target G protein-coupled receptors (GPCRs), the largest receptor superfamily in humans and mediators of diverse physiological processes. This review summarizes the recent progress in GPCR structural dynamics, focusing on class A receptors and insights derived from nuclear magnetic resonance (NMR) and other spectroscopic techniques. We describe the structural aspects of GPCR activation and the various pharmacological models that capture aspects of receptor signaling behaviour. Spectroscopic studies revealed that receptors and their signaling complexes are dynamic allosteric systems that sample multiple functional states under basal conditions. The distribution of states within the conformational ensemble and the kinetics of transitions between states are regulated through the binding of ligands, allosteric modulators, and the membrane environment. This ensemble view of GPCRs provides a mechanistic framework for understanding many of the pharmacological phenomena associated with receptor signaling, such as basal activity, efficacy, and functional bias.
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Affiliation(s)
- Shuya Kate Huang
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada.,Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - R Scott Prosser
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada.,Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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9
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Kugele A, Uzun B, Müller L, Schott-Verdugo S, Gohlke H, Groth G, Drescher M. Mapping the helix arrangement of the reconstituted ETR1 ethylene receptor transmembrane domain by EPR spectroscopy. RSC Adv 2022; 12:7352-7356. [PMID: 35424698 PMCID: PMC8982231 DOI: 10.1039/d2ra00604a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 02/23/2022] [Indexed: 12/21/2022] Open
Abstract
The plant ethylene receptor ETR1 is a key player in the perception of the phytohormone and subsequent downstream ethylene signal transmission, crucial for processes such as ripening, senescence and abscission. However, to date, there is sparse structural knowledge about the transmembrane sensor domain (TMD) of ETR1 that is responsible for the binding of the plant hormone and initiates the downstream signal transmission. Sequence information and ab initio modelling suggest that the TMD consists of three transmembrane helices. Here, we combined site-directed spin labelling with electron paramagnetic resonance spectroscopy and obtained distance restraints for liposome-reconstituted ETR1_TMD on the orientation and arrangement of the transmembrane helices. We used these data to scrutinize different computational structure predictions of the TMD.
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Affiliation(s)
- Anandi Kugele
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz Universitätsstraße 10 78457 Konstanz Germany
| | - Buket Uzun
- Institute of Biochemical Plant Physiology, Heinrich Heine University Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
| | - Lena Müller
- Institute of Biochemical Plant Physiology, Heinrich Heine University Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
| | - Stephan Schott-Verdugo
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich GmbH 52425 Jülich Germany
| | - Holger Gohlke
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich GmbH 52425 Jülich Germany
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf 40225 Düsseldorf Germany
| | - Georg Groth
- Institute of Biochemical Plant Physiology, Heinrich Heine University Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
| | - Malte Drescher
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz Universitätsstraße 10 78457 Konstanz Germany
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10
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Schultz KM, Klug CS. Use of Site-Directed Spin Labeling EPR Spectroscopy to Study Protein-LPS Interactions. Methods Mol Biol 2022; 2548:83-96. [PMID: 36151493 PMCID: PMC10765611 DOI: 10.1007/978-1-0716-2581-1_6] [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] [Indexed: 06/16/2023]
Abstract
Site-directed spin labeling EPR (electron paramagnetic resonance) spectroscopy is a technique used to identify the local conformational changes at a specific residue of interest within a purified protein in response to a ligand. Here, we describe the site-directed spin labeling EPR spectroscopy methodology to monitor changes in the side-chain motion in soluble lipopolysaccharide transport proteins upon the addition of lipopolysaccharide (LPS). A comparison of the spectral overlays of the spin-labeled protein in the absence and presence of LPS provides a qualitative visualization of how LPS binding affects the motion of each spin-labeled site tested within the protein. No change in the spectral lineshapes of a spin-labeled protein in the absence and presence of LPS indicates that the site is not affected by LPS binding, while differences in the spectral lineshapes indicate that LPS does affect the mobility of the spin label side chain within the protein structure. This is a powerful readout of conformational changes at specific residues of interest that can be used to identify a specific site as a reporter of changes induced by ligand binding and to map out the effects of ligand binding through an array of reporter sites within a protein. With the use of AquaStar tubing, protein concentrations as low as 2 μM allow for up to a 100-fold excess of LPS. This methodology may also be applied to other protein-ligand or protein-protein interactions with minor adaptations.
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Affiliation(s)
- Kathryn M Schultz
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Candice S Klug
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA.
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11
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Sanches K, Wai DCC, Norton RS. Conformational dynamics in peptide toxins: Implications for receptor interactions and molecular design. Toxicon 2021; 201:127-140. [PMID: 34454969 DOI: 10.1016/j.toxicon.2021.08.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/19/2021] [Accepted: 08/23/2021] [Indexed: 10/20/2022]
Abstract
Peptide toxins are potent and often exquisitely selective probes of the structure and function of ion channels and receptors, and are therefore of significant interest to the pharmaceutical and biotech industries as both pharmacological tools and therapeutic leads. The three-dimensional structures of peptide toxins are essential as a basis for understanding their structure-activity relationships and their binding to target receptors, as well as in guiding the design of analogues with modified potency and/or selectivity for key targets. NMR spectroscopy has played a key role in elucidating the structures of peptide toxins and probing their structure-function relationships. In this article, we highlight the additional important contribution of NMR to characterising the dynamics of peptide toxins. We also compare the information available from NMR measurements with that afforded by molecular dynamics simulations. We describe several examples of the importance of dynamics measurements over a range of timescales for understanding the structure-function relationships of peptide toxins and their receptor engagement. Peptide toxins that inhibit the voltage-gated potassium channel KV1.3 with pM affinities display different degrees of conformational flexibility, even though they contain multiple disulfide bonds, and this flexibility can affect the relative orientation of residues that have been shown to be critical for channel binding. Information on the dynamic properties of peptide toxins is important in the design of analogues or mimetics where receptor-bound structures are not available.
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Affiliation(s)
- Karoline Sanches
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia; ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, 3052, Australia
| | - Dorothy C C Wai
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia; ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, 3052, Australia.
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12
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Electron paramagnetic resonance spectroscopy on G-protein-coupled receptors: Adopting strategies from related model systems. Curr Opin Struct Biol 2021; 69:177-186. [PMID: 34304006 DOI: 10.1016/j.sbi.2021.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 05/27/2021] [Accepted: 06/06/2021] [Indexed: 11/23/2022]
Abstract
Membrane proteins, including ion channels, transporters and G-protein-coupled receptors (GPCRs), play a significant role in various physiological processes. Many of these proteins are difficult to express in large quantities, imposing crucial experimental restrictions. Nevertheless, there is now a wide variety of studies available utilizing electron paramagnetic resonance (EPR) spectroscopic techniques that expand experimental accessibility by using relatively small quantities of protein. Here, we give an overview starting from basic strategies in EPR on membrane proteins with a focus on GPCRs, while emphasizing several applications from recent years. We highlight how the arsenal of EPR-based techniques may provide significant further contributions to understanding the complex molecular machinery and energetic phenomena responsible for seamless workflow in essential biological processes.
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13
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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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14
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Probing Structural Dynamics of Membrane Proteins Using Electron Paramagnetic Resonance Spectroscopic Techniques. BIOPHYSICA 2021. [DOI: 10.3390/biophysica1020009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Membrane proteins are essential for the survival of living organisms. They are involved in important biological functions including transportation of ions and molecules across the cell membrane and triggering the signaling pathways. They are targets of more than half of the modern medical drugs. Despite their biological significance, information about the structural dynamics of membrane proteins is lagging when compared to that of globular proteins. The major challenges with these systems are low expression yields and lack of appropriate solubilizing medium required for biophysical techniques. Electron paramagnetic resonance (EPR) spectroscopy coupled with site directed spin labeling (SDSL) is a rapidly growing powerful biophysical technique that can be used to obtain pertinent structural and dynamic information on membrane proteins. In this brief review, we will focus on the overview of the widely used EPR approaches and their emerging applications to answer structural and conformational dynamics related questions on important membrane protein systems.
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15
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Emerging applications of site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) to study food protein structure, dynamics, and interaction. Trends Food Sci Technol 2021. [DOI: 10.1016/j.tifs.2021.01.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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16
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Wili N, Hintz H, Vanas A, Godt A, Jeschke G. Distance measurement between trityl radicals by pulse dressed electron paramagnetic resonance with phase modulation. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2020; 1:75-87. [PMID: 37904888 PMCID: PMC10500722 DOI: 10.5194/mr-1-75-2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 04/29/2020] [Indexed: 11/01/2023]
Abstract
Distance measurement in the nanometre range is among the most important applications of pulse electron paramagnetic resonance today, especially in biological applications. The longest distance that can be measured by all presently used pulse sequences is determined by the phase memory time T m of the observed spins. Here we show that one can measure the dipolar coupling during strong microwave irradiation by using an appropriate frequency- or phase-modulation scheme, i.e. by applying pulse sequences in the nutating frame. This decouples the electron spins from the surrounding nuclear spins and thus leads to significantly longer relaxation times of the microwave-dressed spins (i.e. the rotating frame relaxation times T 1 ρ and T 2 ρ ) compared to T m . The electron-electron dipolar coupling is not decoupled as long as both spins are excited, which can be implemented for trityl radicals at Q-band frequencies (35 GHz, 1.2 T). We show results for two bis-trityl rulers with inter-electron distances of about 4.1 and 5.3 nm and discuss technical challenges and possible next steps.
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Affiliation(s)
- Nino Wili
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Henrik Hintz
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Agathe Vanas
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Gunnar Jeschke
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
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17
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Sahu ID, Lorigan GA. Electron Paramagnetic Resonance as a Tool for Studying Membrane Proteins. Biomolecules 2020; 10:E763. [PMID: 32414134 PMCID: PMC7278021 DOI: 10.3390/biom10050763] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 04/24/2020] [Accepted: 04/24/2020] [Indexed: 12/13/2022] Open
Abstract
Membrane proteins possess a variety of functions essential to the survival of organisms. However, due to their inherent hydrophobic nature, it is extremely difficult to probe the structure and dynamic properties of membrane proteins using traditional biophysical techniques, particularly in their native environments. Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labeling (SDSL) is a very powerful and rapidly growing biophysical technique to study pertinent structural and dynamic properties of membrane proteins with no size restrictions. In this review, we will briefly discuss the most commonly used EPR techniques and their recent applications for answering structure and conformational dynamics related questions of important membrane protein systems.
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Affiliation(s)
- Indra D. Sahu
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Gary A. Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
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18
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Radu V, Price JC, Levett SJ, Narayanasamy KK, Bateman-Price TD, Wilson PB, Mather ML. Dynamic Quantum Sensing of Paramagnetic Species Using Nitrogen-Vacancy Centers in Diamond. ACS Sens 2020; 5:703-710. [PMID: 31867948 PMCID: PMC7106109 DOI: 10.1021/acssensors.9b01903] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 12/23/2019] [Indexed: 12/12/2022]
Abstract
Naturally occurring paramagnetic species (PS), such as free radicals and paramagnetic metalloproteins, play an essential role in a multitude of critical physiological processes including metabolism, cell signaling, and immune response. These highly dynamic species can also act as intrinsic biomarkers for a variety of disease states, while synthetic paramagnetic probes targeted to specific sites on biomolecules enable the study of functional information such as tissue oxygenation and redox status in living systems. The work presented herein describes a new sensing method that exploits the spin-dependent emission of photoluminescence (PL) from an ensemble of nitrogen-vacancy centers in diamond for rapid, nondestructive detection of PS in living systems. Uniquely this approach involves simple measurement protocols that assess PL contrast with and without the application of microwaves. The method is demonstrated to detect concentrations of paramagnetic salts in solution and the widely used magnetic resonance imaging contrast agent gadobutrol with a limit of detection of less than 10 attomol over a 100 μm × 100 μm field of view. Real-time monitoring of changes in the concentration of paramagnetic salts is demonstrated with image exposure times of 20 ms. Further, dynamic tracking of chemical reactions is demonstrated via the conversion of low-spin cyanide-coordinated Fe3+ to hexaaqua Fe3+ under acidic conditions. Finally, the capability to map paramagnetic species in model cells with subcellular resolution is demonstrated using lipid membranes containing gadolinium-labeled phospholipids under ambient conditions in the order of minutes. Overall, this work introduces a new sensing approach for the realization of fast, sensitive imaging of PS in a widefield format that is readily deployable in biomedical settings. Ultimately, this new approach to nitrogen vacancy-based quantum sensing paves the way toward minimally invasive real-time mapping and observation of free radicals in in vitro cellular environments.
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Affiliation(s)
- Valentin Radu
- Optics
and Photonics Research Group, Faculty of Engineering, University Park, University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Joshua Colm Price
- Optics
and Photonics Research Group, Faculty of Engineering, University Park, University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Simon James Levett
- Optics
and Photonics Research Group, Faculty of Engineering, University Park, University of Nottingham, Nottingham NG7 2RD, U.K.
| | | | - Thomas David Bateman-Price
- Optics
and Photonics Research Group, Faculty of Engineering, University Park, University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Philippe Barrie Wilson
- Leicester
School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, U.K.
| | - Melissa Louise Mather
- Optics
and Photonics Research Group, Faculty of Engineering, University Park, University of Nottingham, Nottingham NG7 2RD, U.K.
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19
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Munusamy S, Conde R, Bertrand B, Munoz-Garay C. Biophysical approaches for exploring lipopeptide-lipid interactions. Biochimie 2020; 170:173-202. [PMID: 31978418 PMCID: PMC7116911 DOI: 10.1016/j.biochi.2020.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 01/19/2020] [Indexed: 02/07/2023]
Abstract
In recent years, lipopeptides (LPs) have attracted a lot of attention in the pharmaceutical industry due to their broad-spectrum of antimicrobial activity against a variety of pathogens and their unique mode of action. This class of compounds has enormous potential for application as an alternative to conventional antibiotics and for pest control. Understanding how LPs work from a structural and biophysical standpoint through investigating their interaction with cell membranes is crucial for the rational design of these biomolecules. Various analytical techniques have been developed for studying intramolecular interactions with high resolution. However, these tools have been barely exploited in lipopeptide-lipid interactions studies. These biophysical approaches would give precise insight on these interactions. Here, we reviewed these state-of-the-art analytical techniques. Knowledge at this level is indispensable for understanding LPs activity and particularly their potential specificity, which is relevant information for safe application. Additionally, the principle of each analytical technique is presented and the information acquired is discussed. The key challenges, such as the selection of the membrane model are also been briefly reviewed.
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Affiliation(s)
- Sathishkumar Munusamy
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Mexico
| | - Renaud Conde
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico
| | - Brandt Bertrand
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Mexico
| | - Carlos Munoz-Garay
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Mexico.
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20
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Sicoli G, Vezin H, Ledolter K, Kress T, Kurzbach D. Conformational tuning of a DNA-bound transcription factor. Nucleic Acids Res 2019; 47:5429-5435. [PMID: 31020309 PMCID: PMC6547406 DOI: 10.1093/nar/gkz291] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/05/2019] [Accepted: 04/10/2019] [Indexed: 11/14/2022] Open
Abstract
Transcription factors are involved in many cellular processes that take place remote from their cognate DNA sequences. The efficiencies of these activities are thus in principle counteracted by high binding affinities of the factors to their cognate DNAs. Models such as facilitated diffusion or dissociation address this apparent contradiction. We show that the MYC associated transcription factor X (MAX) undergoes nanoscale conformational fluctuations in the DNA-bound state, which is consistent with facilitated dissociation from or diffusion along DNA strands by transiently reducing binding energies. An integrative approach involving EPR, NMR, crystallographic and molecular dynamics analyses demonstrates that the N-terminal domain of MAX constantly opens and closes around a bound DNA ligand thereby dynamically tuning the binding epitope and the mode of interaction.
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Affiliation(s)
- Giuseppe Sicoli
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France
| | - Hervé Vezin
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France
| | - Karin Ledolter
- University Vienna, Department for Structural and Computational Biology, Max F. Perutz Laboratories, Campus Vienna BioCenter 5, 1030 Vienna, Austria
| | - Thomas Kress
- Laboratoire des biomolécules, LBM, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.,University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Währinger Str. 38, 1090 Vienna, Austria
| | - Dennis Kurzbach
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Währinger Str. 38, 1090 Vienna, Austria
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21
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Kachooei E, Cordina NM, Brown LJ. Constructing a structural model of troponin using site-directed spin labeling: EPR and PRE-NMR. Biophys Rev 2019; 11:621-639. [PMID: 31321733 PMCID: PMC6682194 DOI: 10.1007/s12551-019-00568-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 06/24/2019] [Indexed: 02/05/2023] Open
Abstract
The relative ease of introducing a paramagnetic species onto a protein, and advances in electron paramagnetic resonance (EPR) over the past two decades, have established spin labeling as a vital structural biology technique for revealing the functional workings of the troponin muscle regulatory complex-an ~80 kDa heterotrimeric protein switch for turning on striated muscle contraction. Through the site-directed spin labeling (SDSL) of cysteine residues at key sites in troponin, a molecular-level understanding of the troponin muscle regulatory system across all levels of structural hierarchy has been achieved. Through the application of EPR, mobility and accessibility trends in the EPR signals of the spin labels attached to consecutive residues can reveal the secondary structure of troponin elements and also help map the interaction between subunits. Distance restraints calculated from the interspin interactions between spin label pairs have helped with building a structural model of the troponin complex. Further, when SDSL is paired with NMR, paramagnetic relaxation enhancement (PRE)-NMR has been used to obtain high-resolution structural detail for both intra- and interdomain interactions in troponin and revealed details of protein conformational changes and dynamics accompanying troponin function. In this review, we provide an overview of the SDSL labeling methodology and its application towards building a dynamic structural model of the multi-subunit troponin complex which details the calcium-induced conformational changes intimately linked to muscle regulation. We also describe how the SDSL method, in conjunction with EPR or NMR, can be used to obtain insights into structural perturbations to troponin caused by disease-causing mutations.
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Affiliation(s)
- Ehsan Kachooei
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Nicole M Cordina
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Louise J Brown
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia.
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22
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Joseph B, Jaumann EA, Sikora A, Barth K, Prisner TF, Cafiso DS. In situ observation of conformational dynamics and protein ligand-substrate interactions in outer-membrane proteins with DEER/PELDOR spectroscopy. Nat Protoc 2019; 14:2344-2369. [PMID: 31278399 PMCID: PMC6886689 DOI: 10.1038/s41596-019-0182-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 04/18/2019] [Indexed: 12/01/2022]
Abstract
Observing structure and conformational dynamics of membrane proteins at high-resolution in their native environments is challenging because of the lack of suitable techniques. We have developed an approach for high-precision distance measurements in the nanometer range for outer membrane proteins (OMPs) in intact E. coli and native membranes. OMPs in Gram-negative bacteria rarely have reactive cysteines. This enables in-situ labeling of engineered cysteines with a methanethiosulfonate functionalized nitroxide spin label (MTSL) with minimal background signals. Following overexpression of the target protein, spin labeling is performed with E. coli or isolated outer membranes (OM) under selective conditions. The interspin distances are measured in-situ using pulsed electron-electron double resonance spectroscopy (PELDOR or DEER). The residual background signals, which are problematic for in-situ structural biology, contributes specifically to the intermolecular part of the signal and can be selectively removed to extract the desired interspin distance distribution. The initial cloning stage can take 5–7 d and the subsequent protein expression, OM isolation, spin labeling, PELDOR experiment, and the data analysis typically take 4–5 d. The described protocol provides a general strategy for observing protein-ligand/substrate interactions, oligomerization, and conformational dynamics of OMPs in the native OM and intact E. coli. EDITORIAL SUMMARY This protocol describes how to label bacterial outer membrane proteins with spin labels to study conformational changes and their interaction with ligands and substrates in native membranes and cells using Pulsed Electron-Electron Double Resonance (PELDOR or DEER) spectroscopy. TWEET A new protocol for studying conformational changes and ligand/substrate interactions of bacterial outer membrane proteins in-situ. COVER TEASER Studying membrane protein conformations in-situ
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Affiliation(s)
- Benesh Joseph
- Institute of Biophysics, Department of Physics, University of Frankfurt, Frankfurt am Main, Germany. .,Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, University of Frankfurt, Frankfurt am Main, Germany.
| | - Eva A Jaumann
- Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, University of Frankfurt, Frankfurt am Main, Germany
| | - Arthur Sikora
- Department of Chemistry and Center for Membrane Biology, University of Virginia, Charlottesville, VA, USA
| | - Katja Barth
- Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, University of Frankfurt, Frankfurt am Main, Germany
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, University of Frankfurt, Frankfurt am Main, Germany
| | - David S Cafiso
- Department of Chemistry and Center for Membrane Biology, University of Virginia, Charlottesville, VA, USA
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23
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Chemical Modification of 1-Aminocyclopropane Carboxylic Acid (ACC) Oxidase: Cysteine Mutational Analysis, Characterization, and Bioconjugation with a Nitroxide Spin Label. Mol Biotechnol 2019; 61:650-662. [DOI: 10.1007/s12033-019-00191-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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24
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 184] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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25
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Milikisiyants S, Voinov MA, Marek A, Jafarabadi M, Liu J, Han R, Wang S, Smirnov AI. Enhancing sensitivity of Double Electron-Electron Resonance (DEER) by using Relaxation-Optimized Acquisition Length Distribution (RELOAD) scheme. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 298:115-126. [PMID: 30544015 PMCID: PMC6894391 DOI: 10.1016/j.jmr.2018.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 12/02/2018] [Accepted: 12/04/2018] [Indexed: 05/05/2023]
Abstract
Over the past decades pulsed electron-electron double resonance (PELDOR), often called double electron-electron resonance (DEER), became one of the major spectroscopic tools for measurements of nanometer-scale distances and distance distributions in non-crystalline biological and chemical systems. The method is based on detecting the amplitude of the primary (3-pulse DEER) or refocused (4-pulse DEER) spin echo for the so-called "observer" spins when the other spins coupled to the former by a dipolar interaction are flipped by a "pump" pulse at another EPR frequency. While the timing of the pump pulse is varied in steps, the positions of the observer pulses are typically fixed. For such a detection scheme the total length of the observer pulse train and the electron spin memory time determine the amplitude of the detected echo signal. Usually, the distance range considerations in DEER experiments dictate the total length of the observer pulse train to exceed the phase memory time by a factor of few and this leads to a dramatic loss of the signal-to-noise ratio (SNR). While the acquisition of the DEER signal seems to be irrational under such conditions, it is currently the preferred way to conduct DEER because of an effective filtering out of all other unwanted interactions. Here we propose a novel albeit simple approach to improve DEER sensitivity and decrease data acquisition time by introducing the signal acquisition scheme based on RELaxation Optimized Acquisition (Length) Distribution (DEER-RELOAD). In DEER-RELOAD the dipolar phase evolution signal is acquired in multiple segments in which the observer pulses are fixed at the positions to optimize SNR just for that specific segment. The length of the segment is chosen to maximize the signal acquisition efficiency according the phase relaxation properties of the spin system. The total DEER trace is then obtained by "stitching" the multiple segments into a one continuous trace. The utility of the DEER-RELOAD acquisition scheme has been demonstrated on an example of the standard 4-pulse DEER sequence applied to two membrane protein complexes labeled with nitroxides. While theoretical gains from the DEER-RELOAD scheme increase with the number of stitched segments, in practice, even dividing the acquisition of the DEER trace into two segments may improve SNR by a factor of >3, as it has been demonstrated for one of these two membrane proteins.
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Affiliation(s)
- Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Maxim A Voinov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Antonin Marek
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Morteza Jafarabadi
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Jing Liu
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China
| | - Rong Han
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China
| | - Shenlin Wang
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China
| | - Alex I Smirnov
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China.
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26
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Le Breton N, Longhi S, Rockenbauer A, Guigliarelli B, Marque SRA, Belle V, Martinho M. Probing the dynamic properties of two sites simultaneously in a protein–protein interaction process: a SDSL-EPR study. Phys Chem Chem Phys 2019; 21:22584-22588. [DOI: 10.1039/c9cp04660g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Probing two sites simultaneously in a protein–protein interaction process combining spin labels of different EPR signatures.
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Affiliation(s)
| | - S. Longhi
- Aix Marseille Univ
- CNRS
- AFMB
- Marseille
- France
| | - A. Rockenbauer
- Research Center of Natural Sciences
- Budapest University of Technology and Economics
- Budapest
- Hungary
| | | | | | - V. Belle
- Aix Marseille Univ., CNRS, BIP
- Marseille
- France
| | - M. Martinho
- Aix Marseille Univ., CNRS, BIP
- Marseille
- France
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27
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Ivanov MY, Fedin MV. Nanoscale heterogeneities in ionic liquids: insights from EPR of spin probes. MENDELEEV COMMUNICATIONS 2018. [DOI: 10.1016/j.mencom.2018.11.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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28
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Rein S, Lewe P, Andrade SL, Kacprzak S, Weber S. Global analysis of complex PELDOR time traces. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 295:17-26. [PMID: 30092553 DOI: 10.1016/j.jmr.2018.07.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 07/20/2018] [Accepted: 07/21/2018] [Indexed: 05/24/2023]
Abstract
Pulsed electron-electron double resonance (PELDOR, alternatively called DEER for double electron-electron resonance) pulse sequences allow for the detection of echo decay curves that are modulated by dipole-dipole-coupling frequencies of interacting electron spins. With increasing distance between them, the echo decay needs to be monitored over a progressively extended time period. However, since the echo intensity typically falls off exponentially with increasing time, this might be problematic with respect to the minimum signal-to-noise ratio required for a sound data analysis. In this contribution we present the new PELDOR analysis tool GloPel (Global analysis of PELDOR data), an open-source Python-based application, that allows to extract improved-quality distance distributions from PELDOR data for which no ideal signal-to-noise ratio can be achieved for a very long observation window. By using Tikhonov regularization, GloPel allows for the simultaneous analysis of two time traces acquired for a sample in two different observation time windows, thus taking advantage of both, the typically high signal-to-noise ratio of the time trace acquired at early times of the echo decay, and the best possible background function fitted for the decay at later times, which is in most cases superimposed with considerable noise. In this way, short distances are not overseen in the higher noise of the longer time traces while long distances are not artificially shortened by limiting the observation time window of the experiment. Following our suggested data acquisition procedure, a significant reduction of the measurement time may also be achieved.
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Affiliation(s)
- Stephan Rein
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Philipp Lewe
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Susana L Andrade
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany
| | - Sylwia Kacprzak
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Stefan Weber
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
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Jassoy JJ, Meyer A, Spicher S, Wuebben C, Schiemann O. Synthesis of Nanometer Sized Bis- and Tris-trityl Model Compounds with Different Extent of Spin-Spin Coupling. Molecules 2018; 23:E682. [PMID: 29562622 PMCID: PMC6017437 DOI: 10.3390/molecules23030682] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 03/12/2018] [Accepted: 03/16/2018] [Indexed: 12/29/2022] Open
Abstract
Tris(2,3,5,6-tetrathiaaryl)methyl radicals, so-called trityl radicals, are emerging as spin labels for distance measurements in biological systems based on Electron Paramagnetic Resonance (EPR). Here, the synthesis and characterization of rigid model systems carrying either two or three trityl moieties is reported. The monofunctionalized trityl radicals are connected to the molecular bridging scaffold via an esterification reaction employing the Mukaiyama reagent 2-chloro-methylpyridinium iodide. The bis- and tris-trityl compounds exhibit different inter-spin distances, strength of electron-electron exchange and dipolar coupling and can give rise to multi-spin effects. They are to serve as benchmark systems in comparing EPR distance measurement methods.
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Affiliation(s)
- J Jacques Jassoy
- Institute of Physical and Theoretical Chemistry, University of Bonn, 53115 Bonn, Germany.
| | - Andreas Meyer
- Institute of Physical and Theoretical Chemistry, University of Bonn, 53115 Bonn, Germany.
| | - Sebastian Spicher
- Institute of Physical and Theoretical Chemistry, University of Bonn, 53115 Bonn, Germany.
| | - Christine Wuebben
- Institute of Physical and Theoretical Chemistry, University of Bonn, 53115 Bonn, Germany.
| | - Olav Schiemann
- Institute of Physical and Theoretical Chemistry, University of Bonn, 53115 Bonn, Germany.
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