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Aladin V, Sreemantula AK, Biedenbänder T, Marchanka A, Corzilius B. Specific Signal Enhancement on an RNA-Protein Interface by Dynamic Nuclear Polarization. Chemistry 2023; 29:e202203443. [PMID: 36533705 DOI: 10.1002/chem.202203443] [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: 11/06/2022] [Revised: 12/18/2022] [Accepted: 12/19/2022] [Indexed: 12/23/2022]
Abstract
Sensitivity and specificity are both crucial for the efficient solid-state NMR structure determination of large biomolecules. We present an approach that features both advantages by site-specific enhancement of NMR spectroscopic signals from the protein-RNA binding site within a ribonucleoprotein (RNP) by dynamic nuclear polarization (DNP). This approach uses modern biochemical techniques for sparse isotope labeling and exploits the molecular dynamics of 13 C-labeled methyl groups exclusively present in the protein. These dynamics drive heteronuclear cross relaxation and thus allow specific hyperpolarization transfer across the biomolecular complex's interface. For the example of the L7Ae protein in complex with a 26mer guide RNA minimal construct from the box C/D complex in archaea, we demonstrate that a single methyl-nucleotide contact is responsible for most of the polarization transfer to the RNA, and that this specific transfer can be used to boost both NMR spectral sensitivity and specificity by DNP.
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Affiliation(s)
- Victoria Aladin
- Institute of Chemistry, University of Rostock, Albert-Einstein-Str. 27, 18059, Rostock, Germany
- Department Life, Light & Matter, University of Rostock, Albert-Einstein-Str. 25, 18059, Rostock, Germany
| | - Arun K Sreemantula
- Institute for Organic Chemistry and, Centre of Biomolecular Drug Research (BMWZ), Leibniz University Hannover, Schneiderberg 38, 30167, Hannover, Germany
| | - Thomas Biedenbänder
- Institute of Chemistry, University of Rostock, Albert-Einstein-Str. 27, 18059, Rostock, Germany
- Department Life, Light & Matter, University of Rostock, Albert-Einstein-Str. 25, 18059, Rostock, Germany
| | - Alexander Marchanka
- Institute for Organic Chemistry and, Centre of Biomolecular Drug Research (BMWZ), Leibniz University Hannover, Schneiderberg 38, 30167, Hannover, Germany
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstr. 1, 69117, Heidelberg, Germany
| | - Björn Corzilius
- Institute of Chemistry, University of Rostock, Albert-Einstein-Str. 27, 18059, Rostock, Germany
- Department Life, Light & Matter, University of Rostock, Albert-Einstein-Str. 25, 18059, Rostock, Germany
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29, 18059, Rostock, Germany
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2
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Le Marchand T, Schubeis T, Bonaccorsi M, Paluch P, Lalli D, Pell AJ, Andreas LB, Jaudzems K, Stanek J, Pintacuda G. 1H-Detected Biomolecular NMR under Fast Magic-Angle Spinning. Chem Rev 2022; 122:9943-10018. [PMID: 35536915 PMCID: PMC9136936 DOI: 10.1021/acs.chemrev.1c00918] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Indexed: 02/08/2023]
Abstract
Since the first pioneering studies on small deuterated peptides dating more than 20 years ago, 1H detection has evolved into the most efficient approach for investigation of biomolecular structure, dynamics, and interactions by solid-state NMR. The development of faster and faster magic-angle spinning (MAS) rates (up to 150 kHz today) at ultrahigh magnetic fields has triggered a real revolution in the field. This new spinning regime reduces the 1H-1H dipolar couplings, so that a direct detection of 1H signals, for long impossible without proton dilution, has become possible at high resolution. The switch from the traditional MAS NMR approaches with 13C and 15N detection to 1H boosts the signal by more than an order of magnitude, accelerating the site-specific analysis and opening the way to more complex immobilized biological systems of higher molecular weight and available in limited amounts. This paper reviews the concepts underlying this recent leap forward in sensitivity and resolution, presents a detailed description of the experimental aspects of acquisition of multidimensional correlation spectra with fast MAS, and summarizes the most successful strategies for the assignment of the resonances and for the elucidation of protein structure and conformational dynamics. It finally outlines the many examples where 1H-detected MAS NMR has contributed to the detailed characterization of a variety of crystalline and noncrystalline biomolecular targets involved in biological processes ranging from catalysis through drug binding, viral infectivity, amyloid fibril formation, to transport across lipid membranes.
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Affiliation(s)
- Tanguy Le Marchand
- Centre
de RMN à Très Hauts Champs de Lyon, UMR 5082 CNRS/ENS
Lyon/Université Claude Bernard Lyon 1, Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Tobias Schubeis
- Centre
de RMN à Très Hauts Champs de Lyon, UMR 5082 CNRS/ENS
Lyon/Université Claude Bernard Lyon 1, Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Marta Bonaccorsi
- Centre
de RMN à Très Hauts Champs de Lyon, UMR 5082 CNRS/ENS
Lyon/Université Claude Bernard Lyon 1, Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
- Department
of Biochemistry and Biophysics, Stockholm
University, Svante Arrhenius
väg 16C SE-106 91, Stockholm, Sweden
| | - Piotr Paluch
- Faculty
of Chemistry, University of Warsaw, Pasteura 1, Warsaw 02-093, Poland
| | - Daniela Lalli
- Dipartimento
di Scienze e Innovazione Tecnologica, Università
del Piemonte Orientale “A. Avogadro”, Viale Teresa Michel 11, 15121 Alessandria, Italy
| | - Andrew J. Pell
- Centre
de RMN à Très Hauts Champs de Lyon, UMR 5082 CNRS/ENS
Lyon/Université Claude Bernard Lyon 1, Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Svante Arrhenius väg 16 C, SE-106
91 Stockholm, Sweden
| | - Loren B. Andreas
- Department
for NMR-Based Structural Biology, Max-Planck-Institute
for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Kristaps Jaudzems
- Latvian
Institute of Organic Synthesis, Aizkraukles 21, Riga LV-1006 Latvia
- Faculty
of Chemistry, University of Latvia, Jelgavas 1, Riga LV-1004, Latvia
| | - Jan Stanek
- Faculty
of Chemistry, University of Warsaw, Pasteura 1, Warsaw 02-093, Poland
| | - Guido Pintacuda
- Centre
de RMN à Très Hauts Champs de Lyon, UMR 5082 CNRS/ENS
Lyon/Université Claude Bernard Lyon 1, Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
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3
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Ahlawat S, Mote KR, Lakomek NA, Agarwal V. Solid-State NMR: Methods for Biological Solids. Chem Rev 2022; 122:9643-9737. [PMID: 35238547 DOI: 10.1021/acs.chemrev.1c00852] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In the last two decades, solid-state nuclear magnetic resonance (ssNMR) spectroscopy has transformed from a spectroscopic technique investigating small molecules and industrial polymers to a potent tool decrypting structure and underlying dynamics of complex biological systems, such as membrane proteins, fibrils, and assemblies, in near-physiological environments and temperatures. This transformation can be ascribed to improvements in hardware design, sample preparation, pulsed methods, isotope labeling strategies, resolution, and sensitivity. The fundamental engagement between nuclear spins and radio-frequency pulses in the presence of a strong static magnetic field is identical between solution and ssNMR, but the experimental procedures vastly differ because of the absence of molecular tumbling in solids. This review discusses routinely employed state-of-the-art static and MAS pulsed NMR methods relevant for biological samples with rotational correlation times exceeding 100's of nanoseconds. Recent developments in signal filtering approaches, proton methodologies, and multiple acquisition techniques to boost sensitivity and speed up data acquisition at fast MAS are also discussed. Several examples of protein structures (globular, membrane, fibrils, and assemblies) solved with ssNMR spectroscopy have been considered. We also discuss integrated approaches to structurally characterize challenging biological systems and some newly emanating subdisciplines in ssNMR spectroscopy.
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Affiliation(s)
- Sahil Ahlawat
- Tata Institute of Fundamental Research Hyderabad, Survey No. 36/P Gopanpally, Serilingampally, Ranga Reddy District, Hyderabad 500046, Telangana, India
| | - Kaustubh R Mote
- Tata Institute of Fundamental Research Hyderabad, Survey No. 36/P Gopanpally, Serilingampally, Ranga Reddy District, Hyderabad 500046, Telangana, India
| | - Nils-Alexander Lakomek
- University of Düsseldorf, Institute for Physical Biology, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Vipin Agarwal
- Tata Institute of Fundamental Research Hyderabad, Survey No. 36/P Gopanpally, Serilingampally, Ranga Reddy District, Hyderabad 500046, Telangana, India
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4
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Biedenbänder T, Aladin V, Saeidpour S, Corzilius B. Dynamic Nuclear Polarization for Sensitivity Enhancement in Biomolecular Solid-State NMR. Chem Rev 2022; 122:9738-9794. [PMID: 35099939 DOI: 10.1021/acs.chemrev.1c00776] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Solid-state NMR with magic-angle spinning (MAS) is an important method in structural biology. While NMR can provide invaluable information about local geometry on an atomic scale even for large biomolecular assemblies lacking long-range order, it is often limited by low sensitivity due to small nuclear spin polarization in thermal equilibrium. Dynamic nuclear polarization (DNP) has evolved during the last decades to become a powerful method capable of increasing this sensitivity by two to three orders of magnitude, thereby reducing the valuable experimental time from weeks or months to just hours or days; in many cases, this allows experiments that would be otherwise completely unfeasible. In this review, we give an overview of the developments that have opened the field for DNP-enhanced biomolecular solid-state NMR including state-of-the-art applications at fast MAS and high magnetic field. We present DNP mechanisms, polarizing agents, and sample constitution methods suitable for biomolecules. A wide field of biomolecular NMR applications is covered including membrane proteins, amyloid fibrils, large biomolecular assemblies, and biomaterials. Finally, we present perspectives and recent developments that may shape the field of biomolecular DNP in the future.
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Affiliation(s)
- Thomas Biedenbänder
- Institute of Chemistry, University of Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.,Department Life, Light & Matter, University of Rostock, Albert-Einstein-Straße 25, 18059 Rostock, Germany
| | - Victoria Aladin
- Institute of Chemistry, University of Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.,Department Life, Light & Matter, University of Rostock, Albert-Einstein-Straße 25, 18059 Rostock, Germany
| | - Siavash Saeidpour
- Institute of Chemistry, University of Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.,Department Life, Light & Matter, University of Rostock, Albert-Einstein-Straße 25, 18059 Rostock, Germany
| | - Björn Corzilius
- Institute of Chemistry, University of Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.,Department Life, Light & Matter, University of Rostock, Albert-Einstein-Straße 25, 18059 Rostock, Germany
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5
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Reif B. Deuteration for High-Resolution Detection of Protons in Protein Magic Angle Spinning (MAS) Solid-State NMR. Chem Rev 2021; 122:10019-10035. [PMID: 34870415 DOI: 10.1021/acs.chemrev.1c00681] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proton detection developed in the last 20 years as the method of choice to study biomolecules in the solid state. In perdeuterated proteins, proton dipolar interactions are strongly attenuated, which allows yielding of high-resolution proton spectra. Perdeuteration and backsubstitution of exchangeable protons is essential if samples are rotated with MAS rotation frequencies below 60 kHz. Protonated samples can be investigated directly without spin dilution using proton detection methods in case the MAS frequency exceeds 110 kHz. This review summarizes labeling strategies and the spectroscopic methods to perform experiments that yield assignments, quantitative information on structure, and dynamics using perdeuterated samples. Techniques for solvent suppression, H/D exchange, and deuterium spectroscopy are discussed. Finally, experimental and theoretical results that allow estimation of the sensitivity of proton detected experiments as a function of the MAS frequency and the external B0 field in a perdeuterated environment are compiled.
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Affiliation(s)
- Bernd Reif
- Bayerisches NMR Zentrum (BNMRZ) at the Department of Chemistry, Technische Universität München (TUM), Lichtenbergstr. 4, 85747 Garching, Germany.,Helmholtz-Zentrum München (HMGU), Deutsches Forschungszentrum für Gesundheit und Umwelt, Institute of Structural Biology (STB), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
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6
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Site-specific dynamics of methyl groups probed by temporal evolution of heteronuclear 13C{1H} Overhauser polarisation encoded in 13C – 13C solid-state NMR correlation experiments. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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7
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Exploring Protein Structures by DNP-Enhanced Methyl Solid-State NMR Spectroscopy. J Am Chem Soc 2019; 141:19888-19901. [DOI: 10.1021/jacs.9b11195] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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8
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Phan VC, Fry EA, Zilm KW. Accounting for the temperature dependence of 13C spin-lattice relaxation of methyl groups in the glycyl-alanyl-leucine model system under MAS with spin diffusion. JOURNAL OF BIOMOLECULAR NMR 2019; 73:411-421. [PMID: 31407207 PMCID: PMC6817761 DOI: 10.1007/s10858-019-00261-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 06/19/2019] [Indexed: 06/10/2023]
Abstract
The difficulties in quantitatively modeling the temperature dependence of spin-lattice relaxation in a model isotope-enriched peptide are explored as a prelude to obtaining dynamics parameters for motions in proteins from such measurements. The degree to which this can be handled by adding spin diffusion to a bath in standard rate matrix relaxation theory is studied using a small tri-peptide model system, glycyl-alanyl-leucine (GAL). We observe in this molecule that the relaxation of backbone carbons CO and Cα is not dominated by local fluctuations of the 13C-1H dipolar couplings, but rather by 13C-13C spin diffusion to nearby methyl relaxation sinks. A treatment of the methyl relaxation itself, which ignores 13C-13C spin diffusion effects back to the otherwise slowly relaxing bath, provides poor agreement between theory and experimental data obtained for the temperature dependence of the methyl relaxation rates. Closed form approximate spectral densities and relaxation rates for a methyl group during magic angle spinning are obtained to compute the needed transition rates. These average computed rates, in conjunction with an extended form of the Solomon equations, are found to adequately model the temperature dependence of the methyl relaxation rates when spin diffusion is included. The barrier to rotation for the alanine methyl in GAL is determined to be 3.5 kcal mol-1.
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Affiliation(s)
- Van C Phan
- Natural Science Department, Hostos Community College, 500 Grand Concourse, The Bronx, NY, 10451, USA
| | - Elizabeth A Fry
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT, 06520-8107, USA
| | - Kurt W Zilm
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT, 06520-8107, USA.
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9
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Schanda P, Ernst M. Studying Dynamics by Magic-Angle Spinning Solid-State NMR Spectroscopy: Principles and Applications to Biomolecules. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2016; 96:1-46. [PMID: 27110043 PMCID: PMC4836562 DOI: 10.1016/j.pnmrs.2016.02.001] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Magic-angle spinning solid-state NMR spectroscopy is an important technique to study molecular structure, dynamics and interactions, and is rapidly gaining importance in biomolecular sciences. Here we provide an overview of experimental approaches to study molecular dynamics by MAS solid-state NMR, with an emphasis on the underlying theoretical concepts and differences of MAS solid-state NMR compared to solution-state NMR. The theoretical foundations of nuclear spin relaxation are revisited, focusing on the particularities of spin relaxation in solid samples under magic-angle spinning. We discuss the range of validity of Redfield theory, as well as the inherent multi-exponential behavior of relaxation in solids. Experimental challenges for measuring relaxation parameters in MAS solid-state NMR and a few recently proposed relaxation approaches are discussed, which provide information about time scales and amplitudes of motions ranging from picoseconds to milliseconds. We also discuss the theoretical basis and experimental measurements of anisotropic interactions (chemical-shift anisotropies, dipolar and quadrupolar couplings), which give direct information about the amplitude of motions. The potential of combining relaxation data with such measurements of dynamically-averaged anisotropic interactions is discussed. Although the focus of this review is on the theoretical foundations of dynamics studies rather than their application, we close by discussing a small number of recent dynamics studies, where the dynamic properties of proteins in crystals are compared to those in solution.
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Affiliation(s)
- Paul Schanda
- CEA, Institut de Biologie Structurale (IBS), 38027 Grenoble, France ; CNRS, Institut de Biologie Structurale (IBS), 38027 Grenoble, France ; Université Grenoble Alpes, IBS, 38027 Grenoble, France
| | - Matthias Ernst
- ETH Zürich, Physical Chemistry, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
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10
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Zhang R, Mroue KH, Ramamoorthy A. Hybridizing cross-polarization with NOE or refocused-INEPT enhances the sensitivity of MAS NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 266:59-66. [PMID: 27040936 PMCID: PMC4851575 DOI: 10.1016/j.jmr.2016.03.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 03/13/2016] [Accepted: 03/24/2016] [Indexed: 05/05/2023]
Abstract
Heteronuclear cross polarization (CP) has been commonly used to enhance the sensitivity of dilute low-γ nuclei in almost all solid-state NMR experiments. However, CP relies on heteronuclear dipolar couplings, and therefore the magnetization transfer efficiency becomes inefficient when the dipolar couplings are weak, as is often the case for mobile components in solids. Here, we demonstrate methods that combine CP with heteronuclear Overhauser effect (referred to as CP-NOE) or with refocused-INEPT (referred to as CP-RINEPT) to overcome the efficiency limitation of CP and enhance the signal-to-noise ratio (S/N) for mobile components. Our experimental results reveal that, compared to the conventional CP, significant S/N ratio enhancement can be achieved for resonances originating from mobile components, whereas the resonance signals associated with rigid groups are not significantly affected due to their long spin-lattice relaxation times. In fact, the S/N enhancement factor is also dependent on the temperature, CP contact time as well as on the system under investigation. Furthermore, we also demonstrate that CP-RINEPT experiment can be successfully employed to independently detect mobile and rigid signals in a single experiment without affecting the data collection time. However, the resolution of CP spectrum obtained from the CP-RINEPT experiment could be slightly compromised by the mandatory use of continuous wave (CW) decoupling during the acquisition of signals from rigid components. In addition, CP-RINEPT experiment can be used for spectral editing utilizing the difference in dynamics of different regions of a molecule and/or different components present in the sample, and could also be useful for the assignment of resonances from mobile components in poorly resolved spectra. Therefore, we believe that the proposed approaches are beneficial for the structural characterization of multiphase and heterogeneous systems, and could be used as a building block in multidimensional solid-state NMR experiments.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Kamal H Mroue
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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11
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del Amo JML, Agarwal V, Sarkar R, Porter J, Asami S, Rübbelke M, Fink U, Xue Y, Lange OF, Reif B. Site-specific analysis of heteronuclear Overhauser effects in microcrystalline proteins. JOURNAL OF BIOMOLECULAR NMR 2014; 59:241-9. [PMID: 24989039 DOI: 10.1007/s10858-014-9843-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 06/20/2014] [Indexed: 05/14/2023]
Abstract
Relaxation parameters such as longitudinal relaxation are susceptible to artifacts such as spin diffusion, and can be affected by paramagnetic impurities as e.g. oxygen, which make a quantitative interpretation difficult. We present here the site-specific measurement of [(1)H](13)C and [(1)H](15)N heteronuclear rates in an immobilized protein. For methyls, a strong effect is expected due to the three-fold rotation of the methyl group. Quantification of the [(1)H](13)C heteronuclear NOE in combination with (13)C-R 1 can yield a more accurate analysis of side chain motional parameters. The observation of significant [(1)H](15)N heteronuclear NOEs for certain backbone amides, as well as for specific asparagine/glutamine sidechain amides is consistent with MD simulations. The measurement of site-specific heteronuclear NOEs is enabled by the use of highly deuterated microcrystalline protein samples in which spin diffusion is reduced in comparison to protonated samples.
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Affiliation(s)
- Juan Miguel Lopez del Amo
- Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Lichtenbergstr. 4, 85747, Garching, Germany
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12
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Lewandowski JR. Advances in solid-state relaxation methodology for probing site-specific protein dynamics. Acc Chem Res 2013; 46:2018-27. [PMID: 23621579 DOI: 10.1021/ar300334g] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Dynamics are intimately linked to protein stability and play a crucial role in important biological processes, such as ligand binding, allosteric regulation, protein folding, signaling, and enzymatic catalysis. Solid-state NMR relaxation measurements allow researchers to determine the amplitudes, time scales, and under favorable conditions, directionality of motions at atomic resolution over the entire range of dynamic processes from picoseconds to milliseconds. Because this method allows researchers to examine both the amplitudes and time scales of motions in this range, they can link different tiers of protein motions in protein energy landscapes. As a result, scientists can better understand the relationships between protein motions and functions. Such studies are possible both with the primary targets of solid-state NMR studies, such as amyloid fibrils, membrane proteins, or other heterogeneous systems, and others that researchers typically study by solution NMR and X-ray crystallography. In addition, solid-state NMR, with the absence of tumbling in solution, eliminates the intrinsic size limitation imposed by slow tumbling of large proteins. Thus, this technique allows researchers to characterize interdomain and intermolecular interactions in large complexes at the atomic scale. In this Account, we discuss recent advances in solid-state relaxation methodology for studying widespread site-specific protein dynamics. We focus on applications involving magic angle spinning, one of the primary methods used in high-resolution solid-state NMR. We give an overview of challenges and solutions for measuring (15)N and (13)C spin-lattice relaxation (R1) to characterize fast picosecond-nanosecond motions, spin-lattice in the rotating frame (R1ρ), and other related relaxation rates for characterization of picosecond-millisecond protein motions. In particular, we discuss the problem of separating incoherent effects caused by random motions from coherent effects arising from incomplete averaging of orientation-dependent NMR interactions. We mention a number of quantitative studies of protein dynamics based on solid-state relaxation measurements. Finally, we discuss the potential use of relaxation measurements for extracting the directionality of motions. Using the (15)N and (13)C R1 and R1ρ measurements, we illustrate the backbone and side-chain dynamics in the protein GB1 and comment on this emerging dynamic picture within the context of data from solution NMR measurements and simulations.
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13
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Purusottam RN, Bodenhausen G, Tekely P. Quantitative one- and two-dimensional 13C spectra of microcrystalline proteins with enhanced intensity. JOURNAL OF BIOMOLECULAR NMR 2013; 57:11-9. [PMID: 23812972 DOI: 10.1007/s10858-013-9759-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 06/23/2013] [Indexed: 06/02/2023]
Abstract
We recorded quantitative, uniformly enhanced one- and two-dimensional (13)C spectra of labelled microcrystalline proteins. The approach takes advantage of efficient equilibration of magnetization by low-power proton irradiation using Phase Alternated Recoupling Irradiation Schemes and benefits simultaneously from uniform sensitivity enhancement due to efficient spin exchange that can overcome T1((13)C) constraints and the presence of heteronuclear Overhauser effects.
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Affiliation(s)
- Rudra N Purusottam
- Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005, Paris, France
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14
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Van Melckebeke H, Schanda P, Gath J, Wasmer C, Verel R, Lange A, Meier BH, Böckmann A. Probing Water Accessibility in HET-s(218–289) Amyloid Fibrils by Solid-State NMR. J Mol Biol 2011; 405:765-72. [DOI: 10.1016/j.jmb.2010.11.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 09/28/2010] [Accepted: 11/01/2010] [Indexed: 11/29/2022]
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15
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O’Dell LA, Schurko RW, Harris KJ, Autschbach J, Ratcliffe CI. Interaction Tensors and Local Dynamics in Common Structural Motifs of Nitrogen: A Solid-State 14N NMR and DFT Study. J Am Chem Soc 2010; 133:527-46. [DOI: 10.1021/ja108181y] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Luke A. O’Dell
- Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, K1A 0R6 Ontario, Canada, Department of Chemistry, University of Windsor, 401 Sunset Avenue, Windsor, N9B 3P4 Ontario, Canada, and Department of Chemistry, 312 Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
| | - Robert W. Schurko
- Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, K1A 0R6 Ontario, Canada, Department of Chemistry, University of Windsor, 401 Sunset Avenue, Windsor, N9B 3P4 Ontario, Canada, and Department of Chemistry, 312 Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
| | - Kristopher J. Harris
- Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, K1A 0R6 Ontario, Canada, Department of Chemistry, University of Windsor, 401 Sunset Avenue, Windsor, N9B 3P4 Ontario, Canada, and Department of Chemistry, 312 Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
| | - Jochen Autschbach
- Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, K1A 0R6 Ontario, Canada, Department of Chemistry, University of Windsor, 401 Sunset Avenue, Windsor, N9B 3P4 Ontario, Canada, and Department of Chemistry, 312 Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
| | - Christopher I. Ratcliffe
- Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, K1A 0R6 Ontario, Canada, Department of Chemistry, University of Windsor, 401 Sunset Avenue, Windsor, N9B 3P4 Ontario, Canada, and Department of Chemistry, 312 Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
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Chevelkov V, Fink U, Reif B. Accurate determination of order parameters from 1H,15N dipolar couplings in MAS solid-state NMR experiments. J Am Chem Soc 2009; 131:14018-22. [PMID: 19743845 DOI: 10.1021/ja902649u] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A reliable site-specific estimate of the individual N-H bond lengths in the protein backbone is the fundamental basis of any relaxation experiment in solution and in the solid-state NMR. The N-H bond length can in principle be influenced by hydrogen bonding, which would result in an increased N-H distance. At the same time, dynamics in the backbone induces a reduction of the experimental dipolar coupling due to motional averaging. We present a 3D dipolar recoupling experiment in which the (1)H,(15)N dipolar coupling is reintroduced in the indirect dimension using phase-inverted CP to eliminate effects from rf inhomogeneity. We find no variation of the N-H dipolar coupling as a function of hydrogen bonding. Instead, variations in the (1)H,(15)N dipolar coupling seem to be due to dynamics of the protein backbone. This is supported by the observed correlation between the H(N)-N dipolar coupling and the amide proton chemical shift. The experiment is demonstrated for a perdeuterated sample of the alpha-spectrin SH3 domain. Perdeuteration is a prerequisite to achieve high accuracy. The average error in the analysis of the H-N dipolar couplings is on the order of +/-370 Hz (+/-0.012 A) and can be as small as 150 Hz, corresponding to a variation of the bond length of +/-0.005 A.
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Affiliation(s)
- Veniamin Chevelkov
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, D-13125 Berlin, Germany
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17
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Chevelkov V, Fink U, Reif B. Quantitative analysis of backbone motion in proteins using MAS solid-state NMR spectroscopy. JOURNAL OF BIOMOLECULAR NMR 2009; 45:197-206. [PMID: 19629713 DOI: 10.1007/s10858-009-9348-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2009] [Accepted: 06/26/2009] [Indexed: 05/13/2023]
Abstract
We present a comprehensive analysis of protein dynamics for a micro-crystallin protein in the solid-state. Experimental data include (15)N T (1) relaxation times measured at two different magnetic fields as well as (1)H-(15)N dipole, (15)N CSA cross correlated relaxation rates which are sensitive to the spectral density function J(0) and are thus a measure of T (2) in the solid-state. In addition, global order parameters are included from a (1)H,(15)N dipolar recoupling experiment. The data are analyzed within the framework of the extended model-free Clore-Lipari-Szabo theory. We find slow motional correlation times in the range of 5 and 150 ns. Assuming a wobbling in a cone motion, the amplitude of motion of the respective amide moiety is on the order of 10 degrees for the half-opening angle of the cone in most of the cases. The experiments are demonstrated using a perdeuterated sample of the chicken alpha-spectrin SH3 domain.
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Affiliation(s)
- Veniamin Chevelkov
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, Berlin, Germany
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18
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Agarwal V, Xue Y, Reif B, Skrynnikov NR. Protein Side-Chain Dynamics As Observed by Solution- and Solid-State NMR Spectroscopy: A Similarity Revealed. J Am Chem Soc 2008; 130:16611-21. [PMID: 19049457 DOI: 10.1021/ja804275p] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Vipin Agarwal
- Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany, and Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084
| | - Yi Xue
- Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany, and Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084
| | - Bernd Reif
- Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany, and Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084
| | - Nikolai R. Skrynnikov
- Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany, and Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084
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19
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Lesage A, Gardiennet C, Loquet A, Verel R, Pintacuda G, Emsley L, Meier B, Böckmann A. Polarisationstransfer über die Wasser‐Protein‐Grenzfläche im Festkörper. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200801110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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21
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Zhou DH, Rienstra CM. High-performance solvent suppression for proton detected solid-state NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2008; 192:167-72. [PMID: 18276175 PMCID: PMC2443633 DOI: 10.1016/j.jmr.2008.01.012] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 01/23/2008] [Accepted: 01/29/2008] [Indexed: 05/05/2023]
Abstract
High-sensitivity proton detected experiments in solid-state NMR have been recently demonstrated in proton diluted proteins as well as fully protonated samples under fast magic-angle spinning. One key element for performing successful proton detection is effective solvent suppression achieved by pulsed field gradients (PFG) and/or saturation pulses. Here we report a high-performance solvent suppression method that attenuates multiple solvent signals simultaneously by more than a factor of 10,000, achieved by an optimized combination of homospoil gradients and supercycled saturation pulses. This method, which we call Multiple Intense Solvent Suppression Intended for Sensitive Spectroscopic Investigation of Protonated Proteins, Instantly (MISSISSIPPI), can be applied without a PFG probe. It opens up new opportunities for two-dimensional heteronuclear correlation spectroscopy of hydrated proteins at natural abundance as well as high-sensitivity and multi-dimensional experimental investigation of protein-solvent interactions.
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Affiliation(s)
- Donghua H. Zhou
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana,IL61801,USA
| | - Chad M. Rienstra
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana,IL61801,USA
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana,IL61801,USA
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana,IL61801,USA
- *Corresponding author. Tel: 217-244-4655, Fax: 217-244-3186, e-mail address:
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22
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Gardiennet C, Loquet A, Etzkorn M, Heise H, Baldus M, Böckmann A. Structural constraints for the Crh protein from solid-state NMR experiments. JOURNAL OF BIOMOLECULAR NMR 2008; 40:239-50. [PMID: 18320329 PMCID: PMC2579321 DOI: 10.1007/s10858-008-9229-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 02/06/2008] [Indexed: 05/11/2023]
Abstract
We demonstrate that short, medium and long-range constraints can be extracted from proton mediated, rare-spin detected correlation solid-state NMR experiments for the microcrystalline 10.4 x 2 kDa dimeric model protein Crh. Magnetization build-up curves from cross signals in NHHC and CHHC spectra deliver detailed information on side chain conformers and secondary structure for interactions between spin pairs. A large number of medium and long-range correlations can be observed in the spectra, and an analysis of the resolved signals reveals that the constraints cover the entire sequence, also including inter-monomer contacts between the two molecules forming the domain-swapped Crh dimer. Dynamic behavior is shown to have an impact on cross signals intensities, as indicated for mobile residues or regions by contacts predicted from the crystal structure, but absent in the spectra. Our work validates strategies involving proton distance measurements for large and complex proteins as the Crh dimer, and confirms the magnetization transfer properties previously described for small molecules in solid protein samples.
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Affiliation(s)
- Carole Gardiennet
- Institut de Biologie et Chimie des Protéines, UMR 5086 C.N.R.S./Université de Lyon, 7, passage du Vercors, 69367 Lyon Cedex 07, France
| | - Antoine Loquet
- Institut de Biologie et Chimie des Protéines, UMR 5086 C.N.R.S./Université de Lyon, 7, passage du Vercors, 69367 Lyon Cedex 07, France
| | - Manuel Etzkorn
- Max-Planck-Institute for Biophysical Chemistry, Solid-state NMR, Am Fassberg 11, 37077 Gottingen, Germany
| | - Henrike Heise
- Max-Planck-Institute for Biophysical Chemistry, Solid-state NMR, Am Fassberg 11, 37077 Gottingen, Germany
| | - Marc Baldus
- Max-Planck-Institute for Biophysical Chemistry, Solid-state NMR, Am Fassberg 11, 37077 Gottingen, Germany
| | - Anja Böckmann
- Institut de Biologie et Chimie des Protéines, UMR 5086 C.N.R.S./Université de Lyon, 7, passage du Vercors, 69367 Lyon Cedex 07, France
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23
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Chevelkov V, Diehl A, Reif B. Measurement of N15-T1 relaxation rates in a perdeuterated protein by magic angle spinning solid-state nuclear magnetic resonance spectroscopy. J Chem Phys 2008; 128:052316. [DOI: 10.1063/1.2819311] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Zhou DH, Shea JJ, Nieuwkoop AJ, Franks WT, Wylie BJ, Mullen C, Sandoz D, Rienstra CM. Solid-state protein-structure determination with proton-detected triple-resonance 3D magic-angle-spinning NMR spectroscopy. Angew Chem Int Ed Engl 2008; 46:8380-3. [PMID: 17907259 PMCID: PMC2790053 DOI: 10.1002/anie.200702905] [Citation(s) in RCA: 196] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Donghua H. Zhou
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (USA)
| | - John J. Shea
- Department of Chemistry University of Illinois at Urbana-Champaign Urbana, IL 61801 (USA)
| | - Andrew J. Nieuwkoop
- Department of Chemistry University of Illinois at Urbana-Champaign Urbana, IL 61801 (USA)
| | - W. Trent Franks
- Department of Chemistry University of Illinois at Urbana-Champaign Urbana, IL 61801 (USA)
| | - Benjamin J. Wylie
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (USA)
| | | | | | - Chad M. Rienstra
- Fax: (+1) 217-244-4655, E-mail: , http://www.scs.uiuc.edu/~rienstra
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25
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Chevelkov V, Diehl A, Reif B. Quantitative measurement of differential 15N-H(alpha/beta)T2 relaxation rates in a perdeuterated protein by MAS solid-state NMR spectroscopy. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2007; 45 Suppl 1:S156-60. [PMID: 18157805 DOI: 10.1002/mrc.2129] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Dynamic parameters become more and more accessible in the study of uniformly isotopically enriched proteins by MAS solid-state NMR. We demonstrate that T(2)-related relaxation properties can quantitatively be determined in a sample of a perdeuterated microcrystalline protein by the measurement of (15)N,(1)H dipole, (15)N CSA cross-correlated relaxation rates. We find that the measured cross-correlated relaxation rates are independent of the MAS rotation frequency, and therefore reflect local dynamic fluctuations of the protein structure.
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26
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Böckmann A. High-resolution solid-state MAS NMR of proteins-Crh as an example. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2007; 45 Suppl 1:S24-S31. [PMID: 18081212 DOI: 10.1002/mrc.2106] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Revised: 09/04/2007] [Accepted: 09/12/2007] [Indexed: 05/25/2023]
Abstract
Solid-state NMR spectroscopy provides unique possibilities for the structural investigation of insoluble molecules at the atomic level. Recent efforts aim at solving the complete structures of biological macromolecules using high-resolution magic angle spinning NMR. Structurally homogenous samples of [(13)C,(15)N]-labeled proteins have to be used in this type of studies. Microcrystalline model proteins present valuable tools for the developments of methods towards this goal. This review discusses recent progress in the field, using the Crh protein as an illustrative example. We discuss strategies for resonance assignments and for the determination of structure and dynamics, as well as techniques for the detection of protein interaction partners and folding mechanisms by solid-state NMR methods.
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Affiliation(s)
- Anja Böckmann
- IFR 128 BioSciences Lyon-Gerland, IBCP UMR 5086 CNRS/Université de Lyon Claude Bernard, 7 passage du Vercors, 69367 Lyon, France.
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27
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Zhou D, Shea J, Nieuwkoop A, Franks W, Wylie B, Mullen C, Sandoz D, Rienstra C. Solid-State Protein-Structure Determination with Proton-Detected Triple-Resonance 3D Magic-Angle-Spinning NMR Spectroscopy. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200702905] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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28
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Chevelkov V, Faelber K, Schrey A, Rehbein K, Diehl A, Reif B. Differential Line Broadening in MAS Solid-State NMR due to Dynamic Interference. J Am Chem Soc 2007; 129:10195-200. [PMID: 17663552 DOI: 10.1021/ja072024c] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many MAS (magic angle spinning) solid-state NMR investigations of biologically relevant protein samples are hampered by poor resolution, particularly in the 15N chemical shift dimension. We show that dynamics in the nanosecond-microsecond time scale in solid-state samples can induce significant line broadening of 15N resonances in solid-state NMR experiments. Averaging of 15NH(alpha/beta) multiplet components due to 1H decoupling induces effective relaxation of the 15N coherence in case the N-H spin pair undergoes significant motion. High resolution solid-state NMR spectra can then only be recorded by application of TROSY (Transverse Relaxation Optimized Spectroscopy) type techniques which select the narrow component of the multiplet pattern. We speculate that this effect has been the major obstacle to the NMR spectroscopic characterization of many membrane proteins and fibrillar aggregates so far. Only in very favorable cases, where dynamics are either absent or very fast (picosecond), high-resolution spectra were obtained. We expect that this approach which requires intense deuteration will have a significant impact on the quality and the rate at which solid-state NMR spectroscopic investigations will emerge in the future.
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Affiliation(s)
- Veniamin Chevelkov
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, D-13125 Berlin, Germany, and Charité Universitätsmedizin, D-10115 Berlin, Germany
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29
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Sein J, Giraud N, Blackledge M, Emsley L. The role of (15)N CSA and CSA/dipole cross-correlation in (15)N relaxation in solid proteins. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2007; 186:26-33. [PMID: 17280844 DOI: 10.1016/j.jmr.2007.01.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 01/15/2007] [Accepted: 01/16/2007] [Indexed: 05/13/2023]
Abstract
The influence of the (15)N CSA on (15)N longitudinal relaxation is investigated for an amide group in solid proteins in powder form under MAS. This contribution is determined to be typically 20-33% of the overall longitudinal relaxation rate, at 11.74 and 16.45 T, respectively. The improved treatment is used to analyze the internal dynamics in the protein Crh, in the frame of a motional model of diffusion in a cone, using the explicit average sum approach. Significant variations with respect to the determined dynamics parameters are observed when properly accounting for the contribution of (15)N CSA fluctuations. In general, the fit of experimental data including CSA led to the determination of diffusion times (tau(w)) which are longer than when considering only an (15)N-(1)H dipolar relaxation mechanism. CSA-Dipole cross-correlation is shown to play little or no role in protonated solids, in direct contrast to the liquid state case.
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Affiliation(s)
- Julien Sein
- Laboratoire de Chimie (UMR 5182 CNRS/ENS Lyon), Ecole Normale Supérieure de Lyon, 69364 Lyon, France
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