1
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Sardo M, Morais T, Soares M, Vieira R, Ilkaeva M, Lourenço MAO, Marín-Montesinos I, Mafra L. Unravelling the structure of CO 2 in silica adsorbents: an NMR and computational perspective. Chem Commun (Camb) 2024; 60:4015-4035. [PMID: 38525497 PMCID: PMC11003455 DOI: 10.1039/d3cc05942a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 03/08/2024] [Indexed: 03/26/2024]
Abstract
This comprehensive review describes recent advancements in the use of solid-state NMR-assisted methods and computational modeling strategies to unravel gas adsorption mechanisms and CO2 speciation in porous CO2-adsorbent silica materials at the atomic scale. This work provides new perspectives for the innovative modifications of these materials rendering them more amenable to the use of advanced NMR methods.
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Affiliation(s)
- Mariana Sardo
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Tiago Morais
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
- Department of Chemistry, University of Iceland, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
| | - Márcio Soares
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Ricardo Vieira
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Marina Ilkaeva
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
- Department of Chemical and Environmental Engineering, University of Oviedo, Av. Julián Clavería 8, 33006 Oviedo, Spain
| | - Mirtha A O Lourenço
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Ildefonso Marín-Montesinos
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Luís Mafra
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
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2
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Bakhmutov VI, Elliott DW, Zhou HC. Kinetics of 1H → 31P NMR cross-polarization and dynamics in a layered crystalline α-Sn(IV) phosphate. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2023; 127:101898. [PMID: 37639882 DOI: 10.1016/j.ssnmr.2023.101898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 08/14/2023] [Accepted: 08/21/2023] [Indexed: 08/31/2023]
Abstract
The proton-phosphorus (H-P) cross-polarization (CP) is effective in Sn(HPO4)2·H2O despite of the presence of paramagnetic ion impurities. Polarization constants TH-P and 1H T1ρ times are measured in static Sn(HPO4)2·H2O by the kinetic variable-temperature H-P CP experiments. The temperature dependence of the 1H T1ρ times is interpreted in terms of proton movements in the interlayer space occurring between the phosphate groups without participation of the water molecules. The process requires an activation energy of 8.7 ± 0.7 kcal/mol. The MAS effect on the 1H T1ρ times is shown and discussed.
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Affiliation(s)
- Vladimir I Bakhmutov
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, United States.
| | - Douglas W Elliott
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, United States
| | - Hong-Cai Zhou
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, United States
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3
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Vugmeyster L, Rodgers A, Ostrovsky D, James McKnight C, Fu R. Deuteron off-resonance rotating frame relaxation for the characterization of slow motions in rotating and static solid-state proteins. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 352:107493. [PMID: 37271094 PMCID: PMC10330767 DOI: 10.1016/j.jmr.2023.107493] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/24/2023] [Accepted: 05/25/2023] [Indexed: 06/06/2023]
Abstract
We demonstrate the feasibility of deuterium solid-state NMR off-resonance rotating frame relaxation measurements for studies of slow motions in biomolecular solids. The pulse sequence, which includes adiabatic pulses for magnetization alignment, is illustrated for static and magic-angle spinning conditions away from rotary resonances. We apply the measurements for three systems with selective deuterium labels at methyl groups: a) a model compound, Fluorenylmethyloxycarbonyl methionine-D3 amino acid, for which the principles of the measurements and corresponding motional modeling based on rotameric interconversions are demonstrated; b) amyloid-β1-40 fibrils labeled at a single alanine methyl group located in the disordered N-terminal domain. This system has been extensively studied in prior work and here serves as a test of the method for complex biological systems. The essential features of the dynamics consist of large-scale rearrangements of the disordered N-terminal domain and the conformational exchange between the free and bound forms of the domain, the latter one due to transient interactions with the structured core of the fibrils. and c) a 15-residue helical peptide which belongs to the predicted α-helical domain near the N-terminus of apolipoprotein B. The peptide is solvated with triolein and incorporates a selectively labeled leucine methyl groups. The method permits model refinement, indicating rotameric interconversions with a distribution of rate constants.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204, USA.
| | - Aryana Rodgers
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204, USA
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO 80204, USA
| | - C James McKnight
- Department of Pharmacology, Physiology and Biophysics, Boston University Chobanian and Avedisian School of Medicine, Boston, MA 02118, United States
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL 32310, USA
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4
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Aromatic ring flips in differently packed ubiquitin protein crystals from MAS NMR and MD. J Struct Biol X 2022; 7:100079. [PMID: 36578472 PMCID: PMC9791609 DOI: 10.1016/j.yjsbx.2022.100079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Probing the dynamics of aromatic side chains provides important insights into the behavior of a protein because flips of aromatic rings in a protein's hydrophobic core report on breathing motion involving a large part of the protein. Inherently invisible to crystallography, aromatic motions have been primarily studied by solution NMR. The question how packing of proteins in crystals affects ring flips has, thus, remained largely unexplored. Here we apply magic-angle spinning NMR, advanced phenylalanine 1H-13C/2H isotope labeling and MD simulation to a protein in three different crystal packing environments to shed light onto possible impact of packing on ring flips. The flips of the two Phe residues in ubiquitin, both surface exposed, appear remarkably conserved in the different crystal forms, even though the intermolecular packing is quite different: Phe4 flips on a ca. 10-20 ns time scale, and Phe45 are broadened in all crystals, presumably due to µs motion. Our findings suggest that intramolecular influences are more important for ring flips than intermolecular (packing) effects.
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5
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Keeler EG, McDermott AE. Rotating Frame Relaxation in Magic Angle Spinning Solid State NMR, a Promising Tool for Characterizing Biopolymer Motion. Chem Rev 2022; 122:14940-14953. [PMID: 36099021 PMCID: PMC10122933 DOI: 10.1021/acs.chemrev.2c00442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Magic angle spinning NMR rotating frame relaxation measurements provide a unique experimental window into biomolecules dynamics, as is illustrated by numerous recent applications. We discuss experimental strategies for this class of experiments, with a particular focus on systems where motion-driven modulation of the chemical shift interaction is the main mechanism for relaxation. We also explore and describe common strategies for interpreting the data sets to extract motion time scale, activation energy, and angle or order parameters from rotating frame relaxation data. Using model free analysis and numerical simulations, including time domain treatment, we explore conditions under which it is possible to obtain accurate and precise information about the time scales of motions. Overall, with rapid technical advances in solid state NMR, there is a bright future for this class of studies.
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Affiliation(s)
- Eric G Keeler
- New York Structural Biology Center, New York, New York 10027, United States
| | - Ann E McDermott
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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6
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Callon M, Malär AA, Lecoq L, Dujardin M, Fogeron M, Wang S, Schledorn M, Bauer T, Nassal M, Böckmann A, Meier BH. Fast Magic‐Angle‐Spinning NMR Reveals the Evasive Hepatitis B Virus Capsid C‐Terminal Domain**. Angew Chem Int Ed Engl 2022; 61:e202201083. [PMID: 35653505 PMCID: PMC9400876 DOI: 10.1002/anie.202201083] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Indexed: 11/08/2022]
Abstract
Experimentally determined protein structures often feature missing domains. One example is the C‐terminal domain (CTD) of the hepatitis B virus capsid protein, a functionally central part of this assembly, crucial in regulating nucleic‐acid interactions, cellular trafficking, nuclear import, particle assembly and maturation. However, its structure remained elusive to all current techniques, including NMR. Here we show that the recently developed proton‐detected fast magic‐angle‐spinning solid‐state NMR at >100 kHz MAS allows one to detect this domain and unveil its structural and dynamic behavior. We describe the experimental framework used and compare the domain's behavior in different capsid states. The developed approaches extend solid‐state NMR observations to residues characterized by large‐amplitude motion on the microsecond timescale, and shall allow one to shed light on other flexible protein domains still lacking their structural and dynamic characterization.
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Affiliation(s)
| | | | - Lauriane Lecoq
- Molecular Microbiology and Structural Biochemistry (MMSB) UMR 5086 CNRS/Université de Lyon, Labex Ecofect 7 passage du Vercors 69367 Lyon France
| | - Marie Dujardin
- Molecular Microbiology and Structural Biochemistry (MMSB) UMR 5086 CNRS/Université de Lyon, Labex Ecofect 7 passage du Vercors 69367 Lyon France
| | - Marie‐Laure Fogeron
- Molecular Microbiology and Structural Biochemistry (MMSB) UMR 5086 CNRS/Université de Lyon, Labex Ecofect 7 passage du Vercors 69367 Lyon France
| | - Shishan Wang
- Molecular Microbiology and Structural Biochemistry (MMSB) UMR 5086 CNRS/Université de Lyon, Labex Ecofect 7 passage du Vercors 69367 Lyon France
| | | | - Thomas Bauer
- Physical Chemistry, ETH Zürich 8093 Zürich Switzerland
| | - Michael Nassal
- University Hospital Freiburg Dept. of Medicine II/Molecular Biology Medical Center University of Freiburg Freiburg Germany
| | - Anja Böckmann
- Molecular Microbiology and Structural Biochemistry (MMSB) UMR 5086 CNRS/Université de Lyon, Labex Ecofect 7 passage du Vercors 69367 Lyon France
| | - Beat H. Meier
- Physical Chemistry, ETH Zürich 8093 Zürich Switzerland
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7
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Fonseca R, Vieira R, Sardo M, Marin-Montesinos I, Mafra L. Exploring Molecular Dynamics of Adsorbed CO 2 Species in Amine-Modified Porous Silica by Solid-State NMR Relaxation. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:12582-12591. [PMID: 35968194 PMCID: PMC9358655 DOI: 10.1021/acs.jpcc.2c02656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Previous studies on CO2 adsorbents have mainly addressed the identification and quantification of adsorbed CO2 species in amine-modified porous materials. Investigation of molecular motion of CO2 species in confinement has not been explored in depth yet. This work entails a comprehensive study of molecular dynamics of the different CO2 species chemi- and physisorbed at amine-modified silica materials through the determination of the rotating frame spin-lattice relaxation times (T 1ρ) by solid-state NMR. Rotational correlation times (τC) were also estimated using spin relaxation models based on the Bloch, Wangsness, and Redfield and the Bloembergen-Purcell-Pound theories. As expected, the τC values for the two physisorbed CO2 species are considerably shorter (32 and 20 μs) than for the three identified chemisorbed CO2 species (162, 62, and 123 μs). The differences in molecular dynamics between the different chemisorbed species correlate well with the structures previously proposed. In the case of the physisorbed CO2 species, the τC values of the CO2 species displaying faster molecular dynamics falls in the range of viscous liquids, whereas the species presenting slower dynamics exhibit T 1ρ and τC values compatible with a CO2 layer of weakly interacting molecules with the silica surface. The values for chemical shift anisotropy (CSA) and 1H-13C heteronuclear dipolar couplings have also been estimated from T 1ρ measurements, for each adsorbed CO2 species. The CSA tensor parameters obtained from fitting the relaxation data agree with the experimentally measured CSA values, thus showing that the theories are well suited to study CO2 dynamics in silica surfaces.
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8
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Callon M, Malär AA, Lecoq L, Dujardin M, Fogeron ML, Wang S, Schledorn M, Bauer T, Nassal M, Böckmann A, Meier BH. Fast Magic‐Angle‐Spinning NMR Reveals the Evasive Hepatitis B Virus Capsid C‐Terminal Domain. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202201083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Morgane Callon
- ETH Zurich D-CHAB: Eidgenossische Technische Hochschule Zurich Departement Chemie und Angewandte Biowissenschaften D-CHAB SWITZERLAND
| | - Alexander A. Malär
- ETH Zurich D-CHAB: Eidgenossische Technische Hochschule Zurich Departement Chemie und Angewandte Biowissenschaften D-CHAB SWITZERLAND
| | | | | | | | | | - Maarten Schledorn
- ETH Zurich D-CHAB: Eidgenossische Technische Hochschule Zurich Departement Chemie und Angewandte Biowissenschaften D-CHAB SWITZERLAND
| | - Thomas Bauer
- ETH Zurich D-CHAB: Eidgenossische Technische Hochschule Zurich Departement Chemie und Angewandte Biowissenschaften D-CHAB SWITZERLAND
| | - Michael Nassal
- University of Freiburg Hospital: Universitatsklinikum Freiburg Molecular Biology GERMANY
| | | | - Beat H Meier
- ETH Zurich D-CHAB: Eidgenossische Technische Hochschule Zurich Departement Chemie und Angewandte Biowissenschaften Department of Physical Chemistry Wolfgang-Pauli-Strasse 10 8093 Zürich SWITZERLAND
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9
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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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10
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Gauto DF, Macek P, Malinverni D, Fraga H, Paloni M, Sučec I, Hessel A, Bustamante JP, Barducci A, Schanda P. Functional control of a 0.5 MDa TET aminopeptidase by a flexible loop revealed by MAS NMR. Nat Commun 2022; 13:1927. [PMID: 35395851 PMCID: PMC8993905 DOI: 10.1038/s41467-022-29423-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 03/14/2022] [Indexed: 02/07/2023] Open
Abstract
Large oligomeric enzymes control a myriad of cellular processes, from protein synthesis and degradation to metabolism. The 0.5 MDa large TET2 aminopeptidase, a prototypical protease important for cellular homeostasis, degrades peptides within a ca. 60 Å wide tetrahedral chamber with four lateral openings. The mechanisms of substrate trafficking and processing remain debated. Here, we integrate magic-angle spinning (MAS) NMR, mutagenesis, co-evolution analysis and molecular dynamics simulations and reveal that a loop in the catalytic chamber is a key element for enzymatic function. The loop is able to stabilize ligands in the active site and may additionally have a direct role in activating the catalytic water molecule whereby a conserved histidine plays a key role. Our data provide a strong case for the functional importance of highly dynamic - and often overlooked - parts of an enzyme, and the potential of MAS NMR to investigate their dynamics at atomic resolution.
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Affiliation(s)
- Diego F Gauto
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71, Avenue des Martyrs, F-38044, Grenoble, France.,ICSN, CNRS UPR2301, Univ. Paris-Saclay, Gif-sur-Yvette, France
| | - Pavel Macek
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71, Avenue des Martyrs, F-38044, Grenoble, France.,Celonic AG, Eulerstrasse 55, 4051, Basel, Switzerland
| | - Duccio Malinverni
- Department of Structural Biology and Center for Data Driven Discovery, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Hugo Fraga
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71, Avenue des Martyrs, F-38044, Grenoble, France.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal.,i3S, Instituto de Investigacao e Inovacao em Saude, Universidade do Porto, Porto, Portugal
| | - Matteo Paloni
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, INSERM, Montpellier, France
| | - Iva Sučec
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71, Avenue des Martyrs, F-38044, Grenoble, France
| | - Audrey Hessel
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71, Avenue des Martyrs, F-38044, Grenoble, France
| | - Juan Pablo Bustamante
- Instituto de Bioingenieria y Bioinformatica, IBB (CONICET-UNER), Oro Verde, Entre Rios, Argentina
| | - Alessandro Barducci
- Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal.
| | - Paul Schanda
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71, Avenue des Martyrs, F-38044, Grenoble, France. .,Institute of Science and Technology Austria, Am Campus 1, A-3400, Klosterneuburg, Austria.
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11
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Vugmeyster L, Ostrovsky D, Greenwood A, Fu R. Deuteron rotating frame relaxation for the detection of slow motions in rotating solids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 337:107171. [PMID: 35219160 PMCID: PMC8994516 DOI: 10.1016/j.jmr.2022.107171] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 06/06/2023]
Abstract
We demonstrate experimental and computational approaches for measuring 2H rotating frame NMR relaxation for solid samples under magic angle spinning (MAS) conditions. The relaxation properties of the deuterium spin-1 system are dominated by the reorientation of the anisotropic quadrupolar tensors, with the effective quadrupolar coupling constant around 55 kHz for methyl groups. The technique is demonstrated using the model compound dimethyl-sulfone at MAS rates of 10 and 60 kHz as well as for an amyloid fibril sample comprising an amyloid-β (1-40) protein with a selective methyl group labeled in the disordered domain of the fibrils, at an MAS rate of 8 kHz. For both systems, the motional parameters fall well within the ranges determined by other techniques, thus validating its feasibility. Experimental and computational factors such as i) the probe's radio frequency inhomogeneity profiles, ii) rotary resonances at conditions for which the spin-lock field strength matches the half- or full-integer of the MAS rate, iii) the choice of MAS rates and spin-lock field strengths, and iv) simulations that account for the interconversion of multiple coherences for the spin-1 system under MAS and deviations from the analytical Redfield treatment are thoroughly considered.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204, USA.
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO 80204, USA
| | - Alexander Greenwood
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221-0172, USA
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL 32310, USA
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12
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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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13
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Vugmeyster L, Ostrovsky D, Greenwood A, Fu R. Deuteron Chemical Exchange Saturation Transfer for the Detection of Slow Motions in Rotating Solids. Front Mol Biosci 2021; 8:705572. [PMID: 34386521 PMCID: PMC8353179 DOI: 10.3389/fmolb.2021.705572] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/12/2021] [Indexed: 01/10/2023] Open
Abstract
We utilized the 2H Chemical Exchange Saturation Transfer (CEST) technique under magic angle spinning (MAS) conditions to demonstrate the feasibility of the method for studies of slow motions in the solid state. For the quadrupolar anisotropic interaction, the essence of CEST is to scan the saturation pattern over a range of offsets corresponding to the entire spectral region(s) for all conformational states involved, which translates into a range of −60–+ 60 kHz for methyl groups. Rotary resonances occur when the offsets are at half-and full-integer of the MAS rates. The choice of the optimal MAS rate is governed by the condition to reduce the number of rotary resonances in the CEST profile patterns and retain a sufficiently large quadrupolar interaction active under MAS to maintain sensitivity to motions. As examples, we applied this technique to a well-known model compound dimethyl-sulfone (DMS) as well as amyloid-β fibrils selectively deuterated at a single methyl group of A2 belonging to the disordered domain. It is demonstrated that the obtained exchange rate between the two rotameric states of DMS at elevated temperatures fell within known ranges and the fitted model parameters for the fibrils agree well with the previously obtained value using static 2H NMR techniques. Additionally, for the fibrils we have observed characteristic broadening of rotary resonances in the presence of conformational exchange, which provides implications for model selection and refinement. This work sets the stage for future potential extensions of the 2H CEST under MAS technique to multiple-labeled samples in small molecules and proteins.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO, United States
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO, United States
| | - Alexander Greenwood
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, United States
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL, United States
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14
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Piersanti E, Rezig L, Tranchida F, El-Houri W, Abagana SM, Campredon M, Shintu L, Yemloul M. Evaluation of the Rotating-Frame Relaxation ( T1ρ) Filter and Its Application in Metabolomics as an Alternative to the Transverse Relaxation ( T2) Filter. Anal Chem 2021; 93:8746-8753. [PMID: 34133140 DOI: 10.1021/acs.analchem.0c05251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Nuclear magnetic resonance (NMR)-based metabolomic studies commonly involve the use of T2 filter pulse sequences to eliminate or attenuate the broad signals from large molecules and improve spectral resolution. In this paper, we demonstrate that the T1ρ filter-based pulse sequence represents an interesting alternative because it allows the stability and the reproducibility needed for statistical analysis. The integrity of the samples and the stability of the instruments were assessed for different filter durations and amplitudes. We showed that the T1ρ filter pulse sequence did not induce sample overheating for a filter duration of up to 500 ms. The reproducibility was evaluated and compared with the T2 filter in serum and liver samples. The implementation is relatively simple and provides the same statistical and analytical results as those obtained with the standard filters. Regarding tissues analysis, because the duration of the filter is the same as that of the spin-lock, the synchronization of the echo delays with the magic angle spinning (MAS) rate is no longer necessary as for T2 filter-based sequences. The results presented in this article aim at establishing a new protocol to improve metabolomic studies and pave the way for future developments on T1ρ alternative filters, in liquid and HR-MAS NMR experiments.
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Affiliation(s)
- Elena Piersanti
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2,Marseille, France
| | - Lamya Rezig
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2,Marseille, France
| | - Fabrice Tranchida
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2,Marseille, France
| | - Wael El-Houri
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2,Marseille, France
| | - Seidou M Abagana
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2,Marseille, France
| | - Mylène Campredon
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2,Marseille, France
| | - Laetitia Shintu
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2,Marseille, France
| | - Mehdi Yemloul
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2,Marseille, France
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15
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Akbey Ü. Dynamics of uniformly labelled solid proteins between 100 and 300 K: A 2D 2H- 13C MAS NMR approach. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 327:106974. [PMID: 33823335 DOI: 10.1016/j.jmr.2021.106974] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/20/2021] [Accepted: 03/20/2021] [Indexed: 06/12/2023]
Abstract
We describe a 2H based MAS nuclear magnetic resonance (NMR) method to obtain site-specific molecular dynamics of biomolecules. The method utilizes the use of deuterium nucleus as a spin label that is proven to be very useful in dynamics studies of solid biological and functional materials. The aim is to understand overall characteristics of protein backbone and side-chain motions for CD3, CD2 and CD groups, in terms of timescale, type and activation energy of the underlying processes. Variable temperature two-dimensional (2D) 2H-13C correlation MAS NMR spectra were recorded for the uniformly 2H,13C,15N labelled Alanine and microcrystalline SH3 at a broad temperature range, from 320 K down to 100 K. First, the deuterium quadrupolar-coupling constant from specific D-C sites is obtained with the 2D experiment by utilizing carbon chemical shifts. Second, the static quadrupolar patterns are obtained at 100 K. Third, variable temperature approach enabled the observation of quadrupolar pattern over different motional regimes; slow, intermediate and fast. And finally, the apparent activation energies for C-D sites are determined and compared, by evaluating the temperature induced signal intensities. This information led to the determination of the dynamic processes for different D-C sites at a broad range of temperature and motional timescales. This is a first representation of 2D 2H-13C MAS NMR approach applied to fully isotope labelled deuterated protein covering 220 K temperature range.
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Affiliation(s)
- Ümit Akbey
- Weizmann Institute of Science, Department of Chemical and Biological Physics, Perlman Chemical Sciences Building, P.O. Box 26, Rehovot 76100, Israel.
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16
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Vugmeyster L. Recent developments in deuterium solid-state NMR for the detection of slow motions in proteins. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2021; 111:101710. [PMID: 33450712 PMCID: PMC7903970 DOI: 10.1016/j.ssnmr.2020.101710] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/19/2020] [Accepted: 12/05/2020] [Indexed: 05/14/2023]
Abstract
Slow timescale dynamics in proteins are essential for a variety of biological functions spanning ligand binding, enzymatic catalysis, protein folding and misfolding regulations, as well as protein-protein and protein-nucleic acid interactions. In this review, we focus on the experimental and theoretical developments of 2H static NMR methods applicable for studies of microsecond to millisecond motional modes in proteins, particularly rotating frame relaxation dispersion (R1ρ), quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) relaxation dispersion, and quadrupolar chemical exchange saturation transfer NMR experiments (Q-CEST). With applications chosen from amyloid-β fibrils, we show the complementarity of these approaches for elucidating the complexities of conformational ensembles in disordered domains in the non-crystalline solid state, with the employment of selective deuterium labels. Combined with recent advances in relaxation dispersion backbone measurements for 15N/13C/1H nuclei, these techniques provide powerful tools for studies of biologically relevant timescale dynamics in disordered domains in the solid state.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO, 80204, USA.
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17
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Rovó P. Recent advances in solid-state relaxation dispersion techniques. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2020; 108:101665. [PMID: 32574905 DOI: 10.1016/j.ssnmr.2020.101665] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/11/2020] [Accepted: 04/02/2020] [Indexed: 06/11/2023]
Abstract
This review describes two rotating-frame (R1ρ) relaxation dispersion methods, namely the Bloch-McConnell Relaxation Dispersion and the Near-rotary Resonance Relaxation Dispersion, which enable the study of microsecond time-scale conformational fluctuations in the solid state using magic-angle-spinning nuclear magnetic resonance spectroscopy. The goal is to provide the reader with key ideas, experimental descriptions, and practical considerations associated with R1ρ measurements that are needed for analyzing relaxation dispersion and quantifying conformational exchange. While the focus is on protein motion, many presented concepts can be equally well adapted to study the microsecond time-scale dynamics of other bio- (e.g. lipids, polysaccharides, nucleic acids), organic (e.g. pharmaceutical compounds), or inorganic molecules (e.g., metal organic frameworks). This article summarizes the essential contributions made by recent theoretical and experimental solid-state NMR studies to our understanding of protein motion. Here we discuss recent advances in fast MAS applications that enable the observation and atomic level characterization of sparsely populated conformational states which are otherwise inaccessible for other experimental methods. Such high-energy states are often associated with protein functions such as molecular recognition, ligand binding, or enzymatic catalysis, as well as with disease-related properties such as misfolding and amyloid formation.
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Affiliation(s)
- Petra Rovó
- Department of Chemistry, Ludwig Maximilian University Munich, Butenandtstr. 5-13, 81377, Munich, Germany; Center for NanoScience (CeNS), Schellingstr. 4, 80799, Munich, Germany.
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18
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Gauto DF, Macek P, Barducci A, Fraga H, Hessel A, Terauchi T, Gajan D, Miyanoiri Y, Boisbouvier J, Lichtenecker R, Kainosho M, Schanda P. Aromatic Ring Dynamics, Thermal Activation, and Transient Conformations of a 468 kDa Enzyme by Specific 1H- 13C Labeling and Fast Magic-Angle Spinning NMR. J Am Chem Soc 2019; 141:11183-11195. [PMID: 31199882 DOI: 10.1021/jacs.9b04219] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Aromatic residues are located at structurally important sites of many proteins. Probing their interactions and dynamics can provide important functional insight but is challenging in large proteins. Here, we introduce approaches to characterize the dynamics of phenylalanine residues using 1H-detected fast magic-angle spinning (MAS) NMR combined with a tailored isotope-labeling scheme. Our approach yields isolated two-spin systems that are ideally suited for artifact-free dynamics measurements, and allows probing motions effectively without molecular weight limitations. The application to the TET2 enzyme assembly of ∼0.5 MDa size, the currently largest protein assigned by MAS NMR, provides insights into motions occurring on a wide range of time scales (picoseconds to milliseconds). We quantitatively probe ring-flip motions and show the temperature dependence by MAS NMR measurements down to 100 K. Interestingly, favorable line widths are observed down to 100 K, with potential implications for DNP NMR. Furthermore, we report the first 13C R1ρ MAS NMR relaxation-dispersion measurements and detect structural excursions occurring on a microsecond time scale in the entry pore to the catalytic chamber and at a trimer interface that was proposed as the exit pore. We show that the labeling scheme with deuteration at ca. 50 kHz MAS provides superior resolution compared to 100 kHz MAS experiments with protonated, uniformly 13C-labeled samples.
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Affiliation(s)
- Diego F Gauto
- Univ. Grenoble Alpes, CEA, CNRS , Institut de Biologie Structurale (IBS) , 71, avenue des martyrs , F-38044 Grenoble , France
| | - Pavel Macek
- Univ. Grenoble Alpes, CEA, CNRS , Institut de Biologie Structurale (IBS) , 71, avenue des martyrs , F-38044 Grenoble , France
| | - Alessandro Barducci
- Centre de Biochimie Structurale (CBS) , INSERM, CNRS, Université de Montpellier , Montpellier , France
| | - Hugo Fraga
- Univ. Grenoble Alpes, CEA, CNRS , Institut de Biologie Structurale (IBS) , 71, avenue des martyrs , F-38044 Grenoble , France.,Departamento de Biomedicina , Faculdade de Medicina da Universidade do Porto , Porto , Portugal.,i3S, Instituto de Investigação e Inovação em Saúde , Universidade do Porto , Porto , Portugal
| | - Audrey Hessel
- Univ. Grenoble Alpes, CEA, CNRS , Institut de Biologie Structurale (IBS) , 71, avenue des martyrs , F-38044 Grenoble , France
| | - Tsutomu Terauchi
- Graduate School of Science , Tokyo Metropolitan University , 1-1 Minami-ohsawa , Hachioji , Tokyo 192-0397 , Japan.,SI Innovation Center , Taiyo Nippon Sanso Corp. , 2008-2 Wada , Tama-city , Tokyo 206-0001 , Japan
| | - David Gajan
- Université de Lyon , Centre de RMN à Hauts Champs de Lyon CRMN, FRE 2034, Université de Lyon, CNRS, ENS Lyon, UCB Lyon 1 , 69100 Villeurbanne , France
| | - Yohei Miyanoiri
- Institute of Protein Research , Osaka University , 3-2 Yamadaoka , Suita , Osaka 565-0871 , Japan.,Structural Biology Research Center, Graduate School of Sciences , Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8602 , Japan
| | - Jerome Boisbouvier
- Univ. Grenoble Alpes, CEA, CNRS , Institut de Biologie Structurale (IBS) , 71, avenue des martyrs , F-38044 Grenoble , France
| | - Roman Lichtenecker
- Institute of Organic Chemistry , University of Vienna , Währinger Str. 38 , 1090 Vienna , Austria
| | - Masatsune Kainosho
- Graduate School of Science , Tokyo Metropolitan University , 1-1 Minami-ohsawa , Hachioji , Tokyo 192-0397 , Japan.,Structural Biology Research Center, Graduate School of Sciences , Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8602 , Japan
| | - Paul Schanda
- Univ. Grenoble Alpes, CEA, CNRS , Institut de Biologie Structurale (IBS) , 71, avenue des martyrs , F-38044 Grenoble , France
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19
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Vugmeyster L, Au DF, Ostrovsky D, Fu R. Deuteron Solid-State NMR Relaxation Measurements Reveal Two Distinct Conformational Exchange Processes in the Disordered N-Terminal Domain of Amyloid-β Fibrils. Chemphyschem 2019; 20:1680-1689. [PMID: 31087613 PMCID: PMC6663588 DOI: 10.1002/cphc.201900363] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/12/2019] [Indexed: 12/26/2022]
Abstract
We employed deuterium solid-state NMR techniques under static conditions to discern the details of the μs-ms timescale motions in the flexible N-terminal subdomain of Aβ1-40 amyloid fibrils, which spans residues 1-16. In particular, we utilized a rotating frame (R1ρ ) and the newly developed time domain quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) relaxation measurements at the selectively deuterated side chains of A2, H6, and G9. The two experiments are complementary in terms of probing somewhat different timescales of motions, governed by the tensor parameters and the sampling window of the magnetization decay curves. The results indicated two mobile "free" states of the N-terminal domain undergoing global diffusive motions, with isotropic diffusion coefficients of 0.7-1 ⋅ 108 and 0.3-3 ⋅ 106 ad2 s-1 . The free states are also involved in the conformational exchange with a single bound state, in which the diffusive motions are quenched, likely due to transient interactions with the structured hydrophobic core. The conformational exchange rate constants are 2-3 ⋅ 105 s-1 and 2-3 ⋅ 104 s-1 for the fast and slow diffusion free states, respectively.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver CO, USA, 80204
| | - Dan Fai Au
- Department of Chemistry, University of Colorado Denver, Denver CO, USA, 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver CO, USA, 80204
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL, 32310
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20
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Au DF, Ostrovsky D, Fu R, Vugmeyster L. Solid-state NMR reveals a comprehensive view of the dynamics of the flexible, disordered N-terminal domain of amyloid-β fibrils. J Biol Chem 2019; 294:5840-5853. [PMID: 30737281 DOI: 10.1074/jbc.ra118.006559] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 02/08/2019] [Indexed: 11/06/2022] Open
Abstract
Amyloid fibril deposits observed in Alzheimer's disease comprise amyloid-β (Aβ) protein possessing a structured hydrophobic core and a disordered N-terminal domain (residues 1-16). The internal flexibility of the disordered domain is likely essential for Aβ aggregation. Here, we used 2H static solid-state NMR methods to probe the dynamics of selected side chains of the N-terminal domain of Aβ1-40 fibrils. Line shape and relaxation data suggested a two-state model in which the domain's free state undergoes a diffusive motion that is quenched in the bound state, likely because of transient interactions with the structured C-terminal domain. At 37 °C, we observed freezing of the dynamics progressively along the Aβ sequence, with the fraction of the bound state increasing and the rate of diffusion decreasing. We also found that without solvation, the diffusive motion is quenched. The solvent acted as a plasticizer reminiscent of its role in the onset of global dynamics in globular proteins. As the temperature was lowered, the fraction of the bound state exhibited sigmoidal behavior. The midpoint of the freezing curve coincided with the bulk solvent freezing for the N-terminal residues and increased further along the sequence. Using 2H R 1ρ measurements, we determined the conformational exchange rate constant between the free and bound states under physiological conditions. Zinc-induced aggregation leads to the enhancement of the dynamics, manifested by the faster conformational exchange, faster diffusion, and lower freezing-curve midpoints.
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Affiliation(s)
- Dan Fai Au
- From the Department of Chemistry, University of Colorado, Denver, Colorado 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado, Denver, Colorado 80204
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, Florida 32310
| | - Liliya Vugmeyster
- From the Department of Chemistry, University of Colorado, Denver, Colorado 80204.
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21
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Penzel S, Oss A, Org ML, Samoson A, Böckmann A, Ernst M, Meier BH. Spinning faster: protein NMR at MAS frequencies up to 126 kHz. JOURNAL OF BIOMOLECULAR NMR 2019; 73:19-29. [PMID: 30680507 PMCID: PMC6441448 DOI: 10.1007/s10858-018-0219-9] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 12/05/2018] [Indexed: 05/05/2023]
Abstract
We report linewidth and proton T1, T1ρ and T2' relaxation data of the model protein ubiquitin acquired at MAS frequencies up to 126 kHz. We find a predominantly linear improvement in linewidths and coherence decay times of protons with increasing spinning frequency in the range from 93 to 126 kHz. We further attempt to gain insight into the different contributions to the linewidth at fast MAS using site-specific analysis of proton relaxation parameters and present bulk relaxation times as a function of the MAS frequency. For microcrystalline fully-protonated ubiquitin, inhomogeneous contributions are only a minor part of the proton linewidth, and at 126 kHz MAS coherent effects are still dominating. We furthermore present site-specific proton relaxation rate constants during a spinlock at 126 kHz MAS, as well as MAS-dependent bulk T1ρ (1HN).
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Affiliation(s)
- Susanne Penzel
- Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland
| | - Andres Oss
- NMR Instituut, Tartu Teaduspark, Tehnomeedikum, Tallinn University of Technology, Akadeemia tee 15a, 19086, Tallinn, Estonia
| | - Mai-Liis Org
- NMR Instituut, Tartu Teaduspark, Tehnomeedikum, Tallinn University of Technology, Akadeemia tee 15a, 19086, Tallinn, Estonia
| | - Ago Samoson
- NMR Instituut, Tartu Teaduspark, Tehnomeedikum, Tallinn University of Technology, Akadeemia tee 15a, 19086, Tallinn, Estonia.
| | - Anja Böckmann
- Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS/Université de Lyon 1, Labex ECOFECT, 7, Passage du Vercors, 69367, Lyon, France.
| | - Matthias Ernst
- Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland.
| | - Beat H Meier
- Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland.
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22
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Marion D, Gauto DF, Ayala I, Giandoreggio-Barranco K, Schanda P. Microsecond Protein Dynamics from Combined Bloch-McConnell and Near-Rotary-Resonance R 1p Relaxation-Dispersion MAS NMR. Chemphyschem 2019; 20:276-284. [PMID: 30444575 PMCID: PMC6354937 DOI: 10.1002/cphc.201800935] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 11/15/2018] [Indexed: 12/14/2022]
Abstract
Studying protein dynamics on microsecond-to-millisecond (μs-ms) time scales can provide important insight into protein function. In magic-angle-spinning (MAS) NMR, μs dynamics can be visualized by R 1 ρ rotating-frame relaxation dispersion experiments in different regimes of radio-frequency field strengths: at low RF field strength, isotropic-chemical-shift fluctuation leads to "Bloch-McConnell-type" relaxation dispersion, while when the RF field approaches rotary resonance conditions bond angle fluctuations manifest as increased R 1 ρ rate constants ("Near-Rotary-Resonance Relaxation Dispersion", NERRD). Here we explore the joint analysis of both regimes to gain comprehensive insight into motion in terms of geometric amplitudes, chemical-shift changes, populations and exchange kinetics. We use a numerical simulation procedure to illustrate these effects and the potential of extracting exchange parameters, and apply the methodology to the study of a previously described conformational exchange process in microcrystalline ubiquitin.
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Affiliation(s)
- Dominique Marion
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71 avenue des martyrs, 38000 Grenoble (France)
| | - Diego F. Gauto
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71 avenue des martyrs, 38000 Grenoble (France)
| | - Isabel Ayala
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71 avenue des martyrs, 38000 Grenoble (France)
| | - Karine Giandoreggio-Barranco
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71 avenue des martyrs, 38000 Grenoble (France)
| | - Paul Schanda
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71 avenue des martyrs, 38000 Grenoble (France)
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23
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Liliya V, Dmitry O. Deuterium Rotating Frame NMR Relaxation Measurements in the Solid State under Static Conditions for Quantification of Dynamics. Chemphyschem 2019; 20:333-342. [PMID: 30079456 PMCID: PMC6499496 DOI: 10.1002/cphc.201800454] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Indexed: 11/07/2022]
Abstract
The feasibility of static deuterium rotating frame NMR relaxation measurements for characterization of slow timescale motions in powder systems is demonstrated. Using a model compound dimethyl sulfone-d6 , we show that these measurements yield conformational exchange rates and activation energy values in accordance with results obtained with other techniques. Furthermore, we demonstrate that the full Liouvillian approach as opposed to the Redfield approximation is necessary to analyze the experimental data.
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Affiliation(s)
- Vugmeyster Liliya
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
| | - Ostrovsky Dmitry
- Department of Mathematics, University of Colorado Denver, Denver CO USA 80204
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24
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Krushelnitsky A, Gauto D, Rodriguez Camargo DC, Schanda P, Saalwächter K. Microsecond motions probed by near-rotary-resonance R 1ρ15N MAS NMR experiments: the model case of protein overall-rocking in crystals. JOURNAL OF BIOMOLECULAR NMR 2018; 71:53-67. [PMID: 29845494 PMCID: PMC5986846 DOI: 10.1007/s10858-018-0191-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 05/26/2018] [Indexed: 05/27/2023]
Abstract
Solid-state near-rotary-resonance measurements of the spin-lattice relaxation rate in the rotating frame (R1ρ) is a powerful NMR technique for studying molecular dynamics in the microsecond time scale. The small difference between the spin-lock (SL) and magic-angle-spinning (MAS) frequencies allows sampling very slow motions, at the same time it brings up some methodological challenges. In this work, several issues affecting correct measurements and analysis of 15N R1ρ data are considered in detail. Among them are signal amplitude as a function of the difference between SL and MAS frequencies, "dead time" in the initial part of the relaxation decay caused by transient spin-dynamic oscillations, measurements under HORROR condition and proper treatment of the multi-exponential relaxation decays. The multiple 15N R1ρ measurements at different SL fields and temperatures have been conducted in 1D mode (i.e. without site-specific resolution) for a set of four different microcrystalline protein samples (GB1, SH3, MPD-ubiquitin and cubic-PEG-ubiquitin) to study the overall protein rocking in a crystal. While the amplitude of this motion varies very significantly, its correlation time for all four sample is practically the same, 30-50 μs. The amplitude of the rocking motion correlates with the packing density of a protein crystal. It has been suggested that the rocking motion is not diffusive but likely a jump-like dynamic process.
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Affiliation(s)
| | - Diego Gauto
- Institut de Biologie Structurale (IBS), Grenoble Cedex 9, France
| | | | - Paul Schanda
- Institut de Biologie Structurale (IBS), Grenoble Cedex 9, France
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25
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Awosanya EO, Nevzorov AA. Protein Rotational Dynamics in Aligned Lipid Membranes Probed by Anisotropic T 1ρ NMR Relaxation. Biophys J 2018; 114:392-399. [PMID: 29401436 DOI: 10.1016/j.bpj.2017.11.3740] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/07/2017] [Accepted: 11/20/2017] [Indexed: 11/18/2022] Open
Abstract
A membrane-bound form of Pf1 coat protein reconstituted in magnetically aligned DMPC/DHPC bicelles was used as a molecular probe to quantify for the viscosity of the lipid membrane interior by measuring the uniaxial rotational diffusion coefficient of the protein. Orientationally dependent 15N NMR relaxation times in the rotating frame, or T1ρ, were determined by fitting individually the decay of the resolved NMR peaks corresponding to the transmembrane helix of Pf1 coat protein as a function of the spin-lock time incorporated into the 2D SAMPI4 pulse sequence. The T1ρ relaxation mechanism was modeled by uniaxial rotational diffusion on a cone, which yields a linear correlation with respect to the bond factor sin4θB, where θB is the angle that the NH bond forms with respect to the axis of rotation. Importantly, the bond factors can be independently measured from the dipolar couplings in the separated local-field SAMPI4 spectra. From this dependence, the value of the diffusion coefficient D|| = 8.0 × 105 s-1 was inferred from linear regression of the experimental T1ρ data even without any spectroscopic assignment. Alternatively, a close value of D|| = 7.7 × 105 s-1 was obtained by fitting the T1ρ relaxation data for the assigned NMR peaks of the transmembrane domain of Pf1 to a wavelike pattern as a function of residue number. The method illustrates the use of single-helix transmembrane peptides as molecular probes to assess the dynamic parameters of biological membranes by NMR relaxation in oriented lipid bilayers.
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Affiliation(s)
- Emmanuel O Awosanya
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina
| | - Alexander A Nevzorov
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina.
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Rovó P, Linser R. Microsecond Timescale Protein Dynamics: a Combined Solid-State NMR Approach. Chemphyschem 2017; 19:34-39. [PMID: 29149466 DOI: 10.1002/cphc.201701238] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Indexed: 12/11/2022]
Abstract
Conformational exchange in proteins is a major determinant in protein functionality. In particular, the μs-ms timescale is associated with enzymatic activity and interactions between biological molecules. We show here that a comprehensive data set of R1ρ relaxation dispersion profiles employing multiple effective fields and tilt angles can be easily obtained in perdeuterated, partly back-exchanged proteins at fast magic-angle spinning and further complemented with chemical-exchange saturation transfer NMR experiments. The approach exploits complementary sources of information and enables the extraction of multiple exchange parameters for μs-ms timescale conformational exchange, most notably including the sign of the chemical shift differences between the ground and excited states.
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Affiliation(s)
- Petra Rovó
- Department Chemie und Pharmazie, Ludwig-Maximailians-Universität München, 81377, München, Germany.,Center for Integrated Protein Science (CiPSM), Butenandtstraße 5, 81377, München, Germany
| | - Rasmus Linser
- Department Chemie und Pharmazie, Ludwig-Maximailians-Universität München, 81377, München, Germany.,Center for Integrated Protein Science (CiPSM), Butenandtstraße 5, 81377, München, Germany
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27
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Slow conformational exchange and overall rocking motion in ubiquitin protein crystals. Nat Commun 2017; 8:145. [PMID: 28747759 PMCID: PMC5529581 DOI: 10.1038/s41467-017-00165-8] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 06/07/2017] [Indexed: 01/25/2023] Open
Abstract
Proteins perform their functions in solution but their structures are most frequently studied inside crystals. Here we probe how the crystal packing alters microsecond dynamics, using solid-state NMR measurements and multi-microsecond MD simulations of different crystal forms of ubiquitin. In particular, near-rotary-resonance relaxation dispersion (NERRD) experiments probe angular backbone motion, while Bloch–McConnell relaxation dispersion data report on fluctuations of the local electronic environment. These experiments and simulations reveal that the packing of the protein can significantly alter the thermodynamics and kinetics of local conformational exchange. Moreover, we report small-amplitude reorientational motion of protein molecules in the crystal lattice with an ~3–5° amplitude on a tens-of-microseconds time scale in one of the crystals, but not in others. An intriguing possibility arises that overall motion is to some extent coupled to local dynamics. Our study highlights the importance of considering the packing when analyzing dynamics of crystalline proteins. X-ray crystallography is the main method for protein structure determination. Here the authors combine solid-state NMR measurements and molecular dynamics simulations and show that crystal packing alters the thermodynamics and kinetics of local conformational exchange as well as overall rocking motion of protein molecules in the crystal lattice.
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28
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Lakomek NA, Penzel S, Lends A, Cadalbert R, Ernst M, Meier BH. Microsecond Dynamics in Ubiquitin Probed by Solid-State 15
N NMR Spectroscopy R
1ρ
Relaxation Experiments under Fast MAS (60-110 kHz). Chemistry 2017; 23:9425-9433. [DOI: 10.1002/chem.201701738] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Nils-Alexander Lakomek
- Laboratory of Physical Chemistry; ETH Zurich; Vladimir-Prelog Weg 2 8093 Zurich Switzerland
| | - Susanne Penzel
- Laboratory of Physical Chemistry; ETH Zurich; Vladimir-Prelog Weg 2 8093 Zurich Switzerland
| | - Alons Lends
- Laboratory of Physical Chemistry; ETH Zurich; Vladimir-Prelog Weg 2 8093 Zurich Switzerland
| | - Riccardo Cadalbert
- Laboratory of Physical Chemistry; ETH Zurich; Vladimir-Prelog Weg 2 8093 Zurich Switzerland
| | - Matthias Ernst
- Laboratory of Physical Chemistry; ETH Zurich; Vladimir-Prelog Weg 2 8093 Zurich Switzerland
| | - Beat H. Meier
- Laboratory of Physical Chemistry; ETH Zurich; Vladimir-Prelog Weg 2 8093 Zurich Switzerland
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29
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Rovó P, Linser R. Microsecond Time Scale Proton Rotating-Frame Relaxation under Magic Angle Spinning. J Phys Chem B 2017; 121:6117-6130. [PMID: 28534618 DOI: 10.1021/acs.jpcb.7b03333] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This paper deals with the theoretical foundation of proton magic angle spinning rotating-frame relaxation (R1ρ) and establishes the range of validity and accuracy of the presented approach to describe low-amplitude microsecond time scale motion in the solid state. Beside heteronuclear dipolar and chemical shift anisotropy interactions, a major source of relaxation for protons is the homonuclear dipolar interaction. For this latter relaxation process, no general analytical equation has been published until now, which would describe the R1ρ relaxation at any spinning speed, spin-lock field, or tilt angle. To validate the derived equations, we compared the analytical relaxation rates, obtained by solving the master equation within the framework of Redfield theory, with numerically simulated relaxation rates. We found that for small opening angles (∼10°), the relaxation rates obtained with stochastic Liouville simulations agree well with the analytical Redfield relaxation rates for a large range of motional correlation times. However, deviations around the rotary-resonance conditions highlight the fact that Redfield treatment of the solid-state relaxation rates can only provide qualitative insights into the microsecond time scale motion.
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Affiliation(s)
- Petra Rovó
- Department Chemie und Pharmazie, Ludwig-Maximilians-Universität München , 81377 München, Germany
| | - Rasmus Linser
- Department Chemie und Pharmazie, Ludwig-Maximilians-Universität München , 81377 München, Germany
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30
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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: 143] [Impact Index Per Article: 17.9] [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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31
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Shi X, Rienstra CM. Site-Specific Internal Motions in GB1 Protein Microcrystals Revealed by 3D ²H-¹³C-¹³C Solid-State NMR Spectroscopy. J Am Chem Soc 2016; 138:4105-19. [PMID: 26849428 PMCID: PMC4819898 DOI: 10.1021/jacs.5b12974] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Indexed: 02/04/2023]
Abstract
(2)H quadrupolar line shapes deliver rich information about protein dynamics. A newly designed 3D (2)H-(13)C-(13)C solid-state NMR magic angle spinning (MAS) experiment is presented and demonstrated on the microcrystalline β1 immunoglobulin binding domain of protein G (GB1). The implementation of (2)H-(13)C adiabatic rotor-echo-short-pulse-irradiation cross-polarization (RESPIRATION CP) ensures the accuracy of the extracted line shapes and provides enhanced sensitivity relative to conventional CP methods. The 3D (2)H-(13)C-(13)C spectrum reveals (2)H line shapes for 140 resolved aliphatic deuterium sites. Motional-averaged (2)H quadrupolar parameters obtained from the line-shape fitting identify side-chain motions. Restricted side-chain dynamics are observed for a number of polar residues including K13, D22, E27, K31, D36, N37, D46, D47, K50, and E56, which we attribute to the effects of salt bridges and hydrogen bonds. In contrast, we observe significantly enhanced side-chain flexibility for Q2, K4, K10, E15, E19, N35, N40, and E42, due to solvent exposure and low packing density. T11, T16, and T17 side chains exhibit motions with larger amplitudes than other Thr residues due to solvent interactions. The side chains of L5, V54, and V29 are highly rigid because they are packed in the core of the protein. High correlations were demonstrated between GB1 side-chain dynamics and its biological function. Large-amplitude side-chain motions are observed for regions contacting and interacting with immunoglobulin G (IgG). In contrast, rigid side chains are primarily found for residues in the structural core of the protein that are absent from protein binding and interactions.
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Affiliation(s)
- Xiangyan Shi
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Chad M. Rienstra
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
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Roos M, Hofmann M, Link S, Ott M, Balbach J, Rössler E, Saalwächter K, Krushelnitsky A. The "long tail" of the protein tumbling correlation function: observation by (1)H NMR relaxometry in a wide frequency and concentration range. JOURNAL OF BIOMOLECULAR NMR 2015; 63:403-415. [PMID: 26582718 PMCID: PMC4662726 DOI: 10.1007/s10858-015-0001-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/11/2015] [Indexed: 05/14/2023]
Abstract
Inter-protein interactions in solution affect the auto-correlation function of Brownian tumbling not only in terms of a simple increase of the correlation time, they also lead to the appearance of a weak slow component ("long tail") of the correlation function due to a slowly changing local anisotropy of the microenvironment. The conventional protocol of correlation time estimation from the relaxation rate ratio R1/R2 assumes a single-component tumbling correlation function, and thus can provide incorrect results as soon as the "long tail" is of relevance. This effect, however, has been underestimated in many instances. In this work we present a detailed systematic study of the tumbling correlation function of two proteins, lysozyme and bovine serum albumin, at different concentrations and temperatures using proton field-cycling relaxometry combined with R1ρ and R2 measurements. Unlike high-field NMR relaxation methods, these techniques enable a detailed study of dynamics on a time scale longer than the normal protein tumbling correlation time and, thus, a reliable estimate of the parameters of the "long tail". In this work we analyze the concentration dependence of the intensity and correlation time of the slow component and perform simulations of high-field (15)N NMR relaxation data demonstrating the importance of taking the "long tail" in the analysis into account.
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Affiliation(s)
- Matthias Roos
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120, Halle, Germany
| | - Marius Hofmann
- Universität Bayreuth, Lehrstuhl Experimentalphysik II, Universitätsstr. 30, 95440, Bayreuth, Germany
| | - Susanne Link
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120, Halle, Germany
| | - Maria Ott
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120, Halle, Germany
| | - Jochen Balbach
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120, Halle, Germany
| | - Ernst Rössler
- Universität Bayreuth, Lehrstuhl Experimentalphysik II, Universitätsstr. 30, 95440, Bayreuth, Germany
| | - Kay Saalwächter
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120, Halle, Germany.
| | - Alexey Krushelnitsky
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120, Halle, Germany.
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