1
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Costello WN, Xiao Y, Mentink-Vigier F, Kragelj J, Frederick KK. DNP-assisted solid-state NMR enables detection of proteins at nanomolar concentrations in fully protonated cellular milieu. JOURNAL OF BIOMOLECULAR NMR 2024; 78:95-108. [PMID: 38520488 DOI: 10.1007/s10858-024-00436-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/09/2024] [Indexed: 03/25/2024]
Abstract
With the sensitivity enhancements conferred by dynamic nuclear polarization (DNP), magic angle spinning (MAS) solid state NMR spectroscopy experiments can attain the necessary sensitivity to detect very low concentrations of proteins. This potentially enables structural investigations of proteins at their endogenous levels in their biological contexts where their native stoichiometries with potential interactors is maintained. Yet, even with DNP, experiments are still sensitivity limited. Moreover, when an isotopically-enriched target protein is present at physiological levels, which typically range from low micromolar to nanomolar concentrations, the isotope content from the natural abundance isotopes in the cellular milieu can outnumber the isotope content of the target protein. Using isotopically enriched yeast prion protein, Sup35NM, diluted into natural abundance yeast lysates, we optimized sample composition. We found that modest cryoprotectant concentrations and fully protonated environments support efficient DNP. We experimentally validated theoretical calculations of the limit of specificity for an isotopically enriched protein in natural abundance cellular milieu. We establish that, using pulse sequences that are selective for adjacent NMR-active nuclei, proteins can be specifically detected in cellular milieu at concentrations in the hundreds of nanomolar. Finally, we find that maintaining native stoichiometries of the protein of interest to the components of the cellular environment may be important for proteins that make specific interactions with cellular constituents.
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Affiliation(s)
- Whitney N Costello
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX, 75390-8816, USA
| | - Yiling Xiao
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX, 75390-8816, USA
| | | | - Jaka Kragelj
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX, 75390-8816, USA
- Slovenian NMR centre, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| | - Kendra K Frederick
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX, 75390-8816, USA.
- Center for Alzheimer's and Neurodegenerative Disease, UT Southwestern Medical Center, Dallas, TX, 75390, USA.
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2
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Ben‐Ishay Y, Barak Y, Feintuch A, Ouari O, Pierro A, Mileo E, Su X, Goldfarb D. Exploring the dynamics and structure of PpiB in living Escherichia coli cells using electron paramagnetic resonance spectroscopy. Protein Sci 2024; 33:e4903. [PMID: 38358137 PMCID: PMC10868451 DOI: 10.1002/pro.4903] [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: 11/14/2023] [Revised: 12/29/2023] [Accepted: 01/04/2024] [Indexed: 02/16/2024]
Abstract
The combined effects of the cellular environment on proteins led to the definition of a fifth level of protein structural organization termed quinary structure. To explore the implication of potential quinary structure for globular proteins, we studied the dynamics and conformations of Escherichia coli (E. coli) peptidyl-prolyl cis/trans isomerase B (PpiB) in E. coli cells. PpiB plays a major role in maturation and regulation of folded proteins by catalyzing the cis/trans isomerization of the proline imidic peptide bond. We applied electron paramagnetic resonance (EPR) techniques, utilizing both Gadolinium (Gd(III)) and nitroxide spin labels. In addition to using standard spin labeling approaches with genetically engineered cysteines, we incorporated an unnatural amino acid to achieve Gd(III)-nitroxide orthogonal labeling. We probed PpiB's residue-specific dynamics by X-band continuous wave EPR at ambient temperatures and its structure by double electron-electron resonance (DEER) on frozen samples. PpiB was delivered to E. coli cells by electroporation. We report a significant decrease in the dynamics induced by the cellular environment for two chosen labeling positions. These changes could not be reproduced by adding crowding agents and cell extracts. Concomitantly, we report a broadening of the distance distribution in E. coli, determined by Gd(III)-Gd(III) DEER measurements, as compared with solution and human HeLa cells. This suggests an increase in the number of PpiB conformations present in E. coli cells, possibly due to interactions with other cell components, which also contributes to the reduction in mobility and suggests the presence of a quinary structure.
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Affiliation(s)
- Yasmin Ben‐Ishay
- Department of Chemical and Biological PhysicsWeizmann Institute of ScienceRehovotIsrael
| | - Yoav Barak
- Department of Chemical Research SupportWeizmann Institute of ScienceRehovotIsrael
| | - Akiva Feintuch
- Department of Chemical and Biological PhysicsWeizmann Institute of ScienceRehovotIsrael
| | - Olivier Ouari
- CNRS, ICR, Institut de Chimie RadicalaireAix‐Marseille UniversitéMarseilleFrance
| | - Annalisa Pierro
- CNRS, BIP, Laboratoire de Bioénergétique et Ingénierie des ProtéinesAix Marseille UniversitéMarseilleFrance
- Present address:
Konstanz Research School Chemical Biology, Department of ChemistryUniversity of KonstanzKonstanzGermany
| | - Elisabetta Mileo
- CNRS, BIP, Laboratoire de Bioénergétique et Ingénierie des ProtéinesAix Marseille UniversitéMarseilleFrance
| | - Xun‐Cheng Su
- State Key Laboratory of Elemento‐organic Chemistry, Tianjin Key Laboratory of Biosensing and Molecular RecognitionCollege of Chemistry, Nankai UniversityTianjinChina
| | - Daniella Goldfarb
- Department of Chemical and Biological PhysicsWeizmann Institute of ScienceRehovotIsrael
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3
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Zhang A, Guo Z, Ge G, Liu Z. Insights into In Vivo Environmental Effects on Quantitative Biochemistry in Single Cells. Anal Chem 2023; 95:17246-17255. [PMID: 37963214 DOI: 10.1021/acs.analchem.3c03102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
Biomacromolecules exist and function in a crowded and spatially confined intracellular milieu. Single-cell analysis has been an essential tool for deciphering the molecular mechanisms of cell biology and cellular heterogeneity. However, a sound understanding of in vivo environmental effects on single-cell quantification has not been well established. In this study, via cell mimicking with giant unilamellar vesicles and single-cell analysis by an approach called plasmonic immunosandwich assay (PISA) that we developed previously, we investigated the effects of two in vivo environmental factors, i.e., molecular crowding and spatial confinement, on quantitative biochemistry in the cytoplasm of single cells. We find that molecular crowding greatly affects the biomolecular interactions and immunorecognition-based detection while the effect of spatial confinement in cell-sized space is negligible. Without considering the effect of molecular crowding, the results by PISA were found to be apparently under-quantitated, being only 29.5-50.0% of those by the calibration curve considering the effect of molecular crowding. We further demonstrated that the use of a calibration curve established with standard solutions containing 20% (wt) polyethylene glycol 6000 can well offset the effect of intracellular crowding and thereby provide a simple but accurate calibration for the PISA measurement. Thus, this study not only sheds light on how intracellular environmental factors influence biomolecular interactions and immunorecognition-based single-cell quantification but also provides a simple but effective strategy to make the single-cell analysis more accurate.
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Affiliation(s)
- Anqi Zhang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
| | - Zhanchen Guo
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
| | - Ge Ge
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
| | - Zhen Liu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
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4
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Samuel Russell PP, Alaeen S, Pogorelov TV. In-Cell Dynamics: The Next Focus of All-Atom Simulations. J Phys Chem B 2023; 127:9863-9872. [PMID: 37793083 PMCID: PMC10874638 DOI: 10.1021/acs.jpcb.3c05166] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
The cell is a crowded space where large biomolecules and metabolites are in continuous motion. Great strides have been made in in vitro studies of protein dynamics, folding, and protein-protein interactions, and much new data are emerging of how they differ in the cell. In this Perspective, we highlight the current progress in atomistic modeling of in-cell environments, both bacteria and mammals, with emphasis on classical all-atom molecular dynamics simulations. These simulations have been recently used to capture and characterize functional and non-functional protein-protein interactions, protein folding dynamics of small proteins with varied topologies, and dynamics of metabolites. We further discuss the challenges and efforts for updating modern force fields critical to the progress of cellular environment simulations. We also briefly summarize developments in relevant state-of-the-art experimental techniques. As computational and experimental methodologies continue to progress and produce more directly comparable data, we are poised to capture the complex atomistic picture of the cell.
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Affiliation(s)
- Premila P Samuel Russell
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sepehr Alaeen
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Taras V Pogorelov
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- School of Chemical Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- National Center for Supercomputing Applications, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
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5
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Ikari M, Yagi H, Kasai T, Inomata K, Ito M, Higuchi K, Matsuda N, Ito Y, Kigawa T. Direct Observation of Membrane-Associated H-Ras in the Native Cellular Environment by In-Cell 19F-NMR Spectroscopy. JACS AU 2023; 3:1658-1669. [PMID: 37388687 PMCID: PMC10302746 DOI: 10.1021/jacsau.3c00108] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/15/2023] [Accepted: 05/15/2023] [Indexed: 07/01/2023]
Abstract
Ras acts as a molecular switch to control intracellular signaling on the plasma membrane (PM). Elucidating how Ras associates with PM in the native cellular environment is crucial for understanding its control mechanism. Here, we used in-cell nuclear magnetic resonance (NMR) spectroscopy combined with site-specific 19F-labeling to explore the membrane-associated states of H-Ras in living cells. The site-specific incorporation of p-trifluoromethoxyphenylalanine (OCF3Phe) at three different sites of H-Ras, i.e., Tyr32 in switch I, Tyr96 interacting with switch II, and Tyr157 on helix α5, allowed the characterization of their conformational states depending on the nucleotide-bound states and an oncogenic mutational state. Exogenously delivered 19F-labeled H-Ras protein containing a C-terminal hypervariable region was assimilated via endogenous membrane-trafficking, enabling proper association with the cell membrane compartments. Despite poor sensitivity of the in-cell NMR spectra of membrane-associated H-Ras, the Bayesian spectral deconvolution identified distinct signal components on three 19F-labeled sites, thus offering the conformational multiplicity of H-Ras on the PM. Our study may be helpful in elucidating the atomic-scale picture of membrane-associated proteins in living cells.
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Affiliation(s)
- Masaomi Ikari
- RIKEN
Center for Biosystems Dynamics Research, Kanagawa 230-0045, Japan
| | - Hiromasa Yagi
- RIKEN
Center for Biosystems Dynamics Research, Kanagawa 230-0045, Japan
| | - Takuma Kasai
- RIKEN
Center for Biosystems Dynamics Research, Kanagawa 230-0045, Japan
- PRESTO/Japan
Science and Technology Agency, Saitama 332-0012, Japan
| | - Kohsuke Inomata
- RIKEN
Center for Biosystems Dynamics Research, Kanagawa 230-0045, Japan
- PRESTO/Japan
Science and Technology Agency, Saitama 332-0012, Japan
| | - Masahiro Ito
- RIKEN
Center for Biosystems Dynamics Research, Kanagawa 230-0045, Japan
| | - Kae Higuchi
- RIKEN
Center for Biosystems Dynamics Research, Kanagawa 230-0045, Japan
| | - Natsuko Matsuda
- RIKEN
Center for Biosystems Dynamics Research, Kanagawa 230-0045, Japan
- SI Innovation
Center, Taiyo Nippon Sanso Corporation, Tokyo 206-0001, Japan
| | - Yutaka Ito
- Department
of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Takanori Kigawa
- RIKEN
Center for Biosystems Dynamics Research, Kanagawa 230-0045, Japan
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6
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Ayon NJ. High-Throughput Screening of Natural Product and Synthetic Molecule Libraries for Antibacterial Drug Discovery. Metabolites 2023; 13:625. [PMID: 37233666 PMCID: PMC10220967 DOI: 10.3390/metabo13050625] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 04/29/2023] [Accepted: 05/01/2023] [Indexed: 05/27/2023] Open
Abstract
Due to the continued emergence of resistance and a lack of new and promising antibiotics, bacterial infection has become a major public threat. High-throughput screening (HTS) allows rapid screening of a large collection of molecules for bioactivity testing and holds promise in antibacterial drug discovery. More than 50% of the antibiotics that are currently available on the market are derived from natural products. However, with the easily discoverable antibiotics being found, finding new antibiotics from natural sources has seen limited success. Finding new natural sources for antibacterial activity testing has also proven to be challenging. In addition to exploring new sources of natural products and synthetic biology, omics technology helped to study the biosynthetic machinery of existing natural sources enabling the construction of unnatural synthesizers of bioactive molecules and the identification of molecular targets of antibacterial agents. On the other hand, newer and smarter strategies have been continuously pursued to screen synthetic molecule libraries for new antibiotics and new druggable targets. Biomimetic conditions are explored to mimic the real infection model to better study the ligand-target interaction to enable the designing of more effective antibacterial drugs. This narrative review describes various traditional and contemporaneous approaches of high-throughput screening of natural products and synthetic molecule libraries for antibacterial drug discovery. It further discusses critical factors for HTS assay design, makes a general recommendation, and discusses possible alternatives to traditional HTS of natural products and synthetic molecule libraries for antibacterial drug discovery.
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Affiliation(s)
- Navid J Ayon
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA
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7
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Chen ZA, Rappsilber J. Protein structure dynamics by crosslinking mass spectrometry. Curr Opin Struct Biol 2023; 80:102599. [PMID: 37104977 DOI: 10.1016/j.sbi.2023.102599] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/22/2023] [Accepted: 03/27/2023] [Indexed: 04/29/2023]
Abstract
Crosslinking mass spectrometry captures protein structures in solution. The crosslinks reveal spatial proximities as distance restraints, but do not easily reveal which of these restraints derive from the same protein conformation. This superposition can be reduced by photo-crosslinking, and adding information from protein structure models, or quantitative crosslinking reveals conformation-specific crosslinks. As a consequence, crosslinking MS has proven useful already in the context of multiple dynamic protein systems. We foresee a breakthrough in the resolution and scale of studying protein dynamics when crosslinks are used to guide deep-learning-based protein modelling. Advances in crosslinking MS, such as photoactivatable crosslinking and in-situ crosslinking, will then reveal protein conformation dynamics in the cellular context, at a pseudo-atomic resolution, and plausibly in a time-resolved manner.
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Affiliation(s)
- Zhuo Angel Chen
- Technische Universität Berlin, Chair of Bioanalytics, 10623 Berlin, Germany
| | - Juri Rappsilber
- Technische Universität Berlin, Chair of Bioanalytics, 10623 Berlin, Germany; Si-M/"Der Simulierte Mensch", a Science Framework of Technische Universität Berlin and Charité - Universitätsmedizin Berlin, 10623 Berlin, Germany; Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK.
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8
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Gerothanassis IP. Ligand-observed in-tube NMR in natural products research: A review on enzymatic biotransformations, protein-ligand interactions, and in-cell NMR spectroscopy. ARAB J CHEM 2023. [DOI: 10.1016/j.arabjc.2022.104536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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9
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Gerez JA, Prymaczok NC, Kadavath H, Ghosh D, Bütikofer M, Fleischmann Y, Güntert P, Riek R. Protein structure determination in human cells by in-cell NMR and a reporter system to optimize protein delivery or transexpression. Commun Biol 2022; 5:1322. [PMID: 36460747 PMCID: PMC9718737 DOI: 10.1038/s42003-022-04251-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 11/11/2022] [Indexed: 12/03/2022] Open
Abstract
Most experimental methods for structural biology proceed in vitro and therefore the contribution of the intracellular environment on protein structure and dynamics is absent. Studying proteins at atomic resolution in living mammalian cells has been elusive due to the lack of methodologies. In-cell nuclear magnetic resonance spectroscopy (in-cell NMR) is an emerging technique with the power to do so. Here, we improved current methods of in-cell NMR by the development of a reporter system that allows monitoring the delivery of exogenous proteins into mammalian cells, a process that we called here "transexpression". The reporter system was used to develop an efficient protocol for in-cell NMR which enables spectral acquisition with higher quality for both disordered and folded proteins. With this method, the 3D atomic resolution structure of the model protein GB1 in human cells was determined with a backbone root-mean-square deviation (RMSD) of 1.1 Å.
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Affiliation(s)
- Juan A Gerez
- Laboratory of Physical Chemistry, ETH Zürich, 8093, Zürich, Switzerland.
| | | | | | - Dhiman Ghosh
- Laboratory of Physical Chemistry, ETH Zürich, 8093, Zürich, Switzerland
| | | | | | - Peter Güntert
- Laboratory of Physical Chemistry, ETH Zürich, 8093, Zürich, Switzerland
- Institute of Biophysical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt am Main, Germany
- Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, 192-0397, Tokyo, Japan
| | - Roland Riek
- Laboratory of Physical Chemistry, ETH Zürich, 8093, Zürich, Switzerland.
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10
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Döller SC, Gutmann T, Hoffmann M, Buntkowsky G. A case study on the influence of hydrophilicity on the signal enhancement by dynamic nuclear polarization. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2022; 122:101829. [PMID: 36116176 DOI: 10.1016/j.ssnmr.2022.101829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/25/2022] [Accepted: 09/07/2022] [Indexed: 06/15/2023]
Abstract
In this work, the behavior of four different commercially available polarizing agents is investigated employing the non-ionic model surfactant 1-octanol as analyte. A relative method for the comparison of the proportion of the direct and indirect polarization transfer pathways is established, allowing a direct comparison of the polarization efficacy for different radicals and different parts of the 1-octanol molecule despite differences in radical concentration or sample amount. With this approach, it could be demonstrated that the hydrophilicity is a key factor in the way polarization is transferred from the polarizing agent to the analyte. These findings are confirmed by the determination of buildup times Tb, illustrating that the choice of polarizing agent plays an essential role in ensuring an optimal polarization transfer and therefore the maximum amount of enhancement possible for DNP enhanced NMR measurements.
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Affiliation(s)
- Sonja C Döller
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
| | - Torsten Gutmann
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
| | - Markus Hoffmann
- Department of Chemistry and Biochemistry, State University of New York College at Brockport, Brockport, NY, 14420, USA
| | - Gerd Buntkowsky
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany.
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11
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Theillet FX, Luchinat E. In-cell NMR: Why and how? PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2022; 132-133:1-112. [PMID: 36496255 DOI: 10.1016/j.pnmrs.2022.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 04/19/2022] [Accepted: 04/27/2022] [Indexed: 06/17/2023]
Abstract
NMR spectroscopy has been applied to cells and tissues analysis since its beginnings, as early as 1950. We have attempted to gather here in a didactic fashion the broad diversity of data and ideas that emerged from NMR investigations on living cells. Covering a large proportion of the periodic table, NMR spectroscopy permits scrutiny of a great variety of atomic nuclei in all living organisms non-invasively. It has thus provided quantitative information on cellular atoms and their chemical environment, dynamics, or interactions. We will show that NMR studies have generated valuable knowledge on a vast array of cellular molecules and events, from water, salts, metabolites, cell walls, proteins, nucleic acids, drugs and drug targets, to pH, redox equilibria and chemical reactions. The characterization of such a multitude of objects at the atomic scale has thus shaped our mental representation of cellular life at multiple levels, together with major techniques like mass-spectrometry or microscopies. NMR studies on cells has accompanied the developments of MRI and metabolomics, and various subfields have flourished, coined with appealing names: fluxomics, foodomics, MRI and MRS (i.e. imaging and localized spectroscopy of living tissues, respectively), whole-cell NMR, on-cell ligand-based NMR, systems NMR, cellular structural biology, in-cell NMR… All these have not grown separately, but rather by reinforcing each other like a braided trunk. Hence, we try here to provide an analytical account of a large ensemble of intricately linked approaches, whose integration has been and will be key to their success. We present extensive overviews, firstly on the various types of information provided by NMR in a cellular environment (the "why", oriented towards a broad readership), and secondly on the employed NMR techniques and setups (the "how", where we discuss the past, current and future methods). Each subsection is constructed as a historical anthology, showing how the intrinsic properties of NMR spectroscopy and its developments structured the accessible knowledge on cellular phenomena. Using this systematic approach, we sought i) to make this review accessible to the broadest audience and ii) to highlight some early techniques that may find renewed interest. Finally, we present a brief discussion on what may be potential and desirable developments in the context of integrative studies in biology.
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Affiliation(s)
- Francois-Xavier Theillet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
| | - Enrico Luchinat
- Dipartimento di Scienze e Tecnologie Agro-Alimentari, Alma Mater Studiorum - Università di Bologna, Piazza Goidanich 60, 47521 Cesena, Italy; CERM - Magnetic Resonance Center, and Neurofarba Department, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy
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12
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Lutz NW, Bernard M. Methodological Developments for Metabolic NMR Spectroscopy from Cultured Cells to Tissue Extracts: Achievements, Progress and Pitfalls. Molecules 2022; 27:molecules27134214. [PMID: 35807461 PMCID: PMC9268249 DOI: 10.3390/molecules27134214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/08/2022] [Accepted: 06/20/2022] [Indexed: 12/04/2022] Open
Abstract
This is a broad overview and critical review of a particular group of closely related ex vivo and in vitro metabolic NMR spectroscopic methods. The scope of interest comprises studies of cultured cells and excised tissue, either intact or after physicochemical extraction of metabolites. Our detailed discussion includes pitfalls that have led to erroneous statements in the published literature, some of which may cause serious problems in metabolic and biological interpretation of results. To cover a wide range of work from relevant research areas, we consider not only the most recent achievements in the field, but also techniques that proved to be valid and successful in the past, although they may not have generated a very significant number of papers more recently. Thus, this comparative review also aims at providing background information useful for judiciously choosing between the metabolic ex vivo/in vitro NMR methods presented. Finally, the methods of interest are discussed in the context of, and in relation to, other metabolic analysis protocols such as HR-MAS and cell perfusion NMR, as well as the mass spectrometry approach.
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13
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Clore GM. NMR spectroscopy, excited states and relevance to problems in cell biology - transient pre-nucleation tetramerization of huntingtin and insights into Huntington's disease. J Cell Sci 2022; 135:jcs258695. [PMID: 35703323 PMCID: PMC9270955 DOI: 10.1242/jcs.258695] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Solution nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for analyzing three-dimensional structure and dynamics of macromolecules at atomic resolution. Recent advances have exploited the unique properties of NMR in exchanging systems to detect, characterize and visualize excited sparsely populated states of biological macromolecules and their complexes, which are only transient. These states are invisible to conventional biophysical techniques, and play a key role in many processes, including molecular recognition, protein folding, enzyme catalysis, assembly and fibril formation. All the NMR techniques make use of exchange between sparsely populated NMR-invisible and highly populated NMR-visible states to transfer a magnetization property from the invisible state to the visible one where it can be easily detected and quantified. There are three classes of NMR experiments that rely on differences in distance, chemical shift or transverse relaxation (molecular mass) between the NMR-visible and -invisible species. Here, I illustrate the application of these methods to unravel the complex mechanism of sub-millisecond pre-nucleation oligomerization of the N-terminal region of huntingtin, encoded by exon-1 of the huntingtin gene, where CAG expansion leads to Huntington's disease, a fatal autosomal-dominant neurodegenerative condition. I also discuss how inhibition of tetramerization blocks the much slower (by many orders of magnitude) process of fibril formation.
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Affiliation(s)
- G. Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
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14
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Sasikumar PG, Ramachandra M. Small Molecule Agents Targeting PD-1 Checkpoint Pathway for Cancer Immunotherapy: Mechanisms of Action and Other Considerations for Their Advanced Development. Front Immunol 2022; 13:752065. [PMID: 35585982 PMCID: PMC9108255 DOI: 10.3389/fimmu.2022.752065] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 03/29/2022] [Indexed: 12/20/2022] Open
Abstract
Pioneering success of antibodies targeting immune checkpoints such as programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) has changed the outlook of cancer therapy. Although these antibodies show impressive durable clinical activity, low response rates and immune-related adverse events are becoming increasingly evident in antibody-based approaches. For further strides in cancer immunotherapy, novel treatment strategies including combination therapies and alternate therapeutic modalities are highly warranted. Towards this discovery and development of small molecule, checkpoint inhibitors are actively being pursued, and the efforts have culminated in the ongoing clinical testing of orally bioavailable checkpoint inhibitors. This review focuses on the small molecule agents targeting PD-1 checkpoint pathway for cancer immunotherapy and highlights various chemotypes/scaffolds and their characterization including binding and functionality along with reported mechanism of action. The learnings from the ongoing small molecule clinical trials and crucial points to be considered for their clinical development are also discussed.
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15
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Chow WY, De Paëpe G, Hediger S. Biomolecular and Biological Applications of Solid-State NMR with Dynamic Nuclear Polarization Enhancement. Chem Rev 2022; 122:9795-9847. [PMID: 35446555 DOI: 10.1021/acs.chemrev.1c01043] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Solid-state NMR spectroscopy (ssNMR) with magic-angle spinning (MAS) enables the investigation of biological systems within their native context, such as lipid membranes, viral capsid assemblies, and cells. However, such ambitious investigations often suffer from low sensitivity due to the presence of significant amounts of other molecular species, which reduces the effective concentration of the biomolecule or interaction of interest. Certain investigations requiring the detection of very low concentration species remain unfeasible even with increasing experimental time for signal averaging. By applying dynamic nuclear polarization (DNP) to overcome the sensitivity challenge, the experimental time required can be reduced by orders of magnitude, broadening the feasible scope of applications for biological solid-state NMR. In this review, we outline strategies commonly adopted for biological applications of DNP, indicate ongoing challenges, and present a comprehensive overview of biological investigations where MAS-DNP has led to unique insights.
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Affiliation(s)
- Wing Ying Chow
- Univ. Grenoble Alpes, CEA, CNRS, Interdisciplinary Research Institute of Grenoble (IRIG), Modeling and Exploration of Materials Laboratory (MEM), 38054 Grenoble, France.,Univ. Grenoble Alpes, CEA, CNRS, Inst. Biol. Struct. IBS, 38044 Grenoble, France
| | - Gaël De Paëpe
- Univ. Grenoble Alpes, CEA, CNRS, Interdisciplinary Research Institute of Grenoble (IRIG), Modeling and Exploration of Materials Laboratory (MEM), 38054 Grenoble, France
| | - Sabine Hediger
- Univ. Grenoble Alpes, CEA, CNRS, Interdisciplinary Research Institute of Grenoble (IRIG), Modeling and Exploration of Materials Laboratory (MEM), 38054 Grenoble, France
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16
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Bertarello A, Berruyer P, Artelsmair M, Elmore CS, Heydarkhan-Hagvall S, Schade M, Chiarparin E, Schantz S, Emsley L. In-Cell Quantification of Drugs by Magic-Angle Spinning Dynamic Nuclear Polarization NMR. J Am Chem Soc 2022; 144:6734-6741. [PMID: 35385274 PMCID: PMC9026252 DOI: 10.1021/jacs.1c12442] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The determination of intracellular drug concentrations can provide a better understanding of the drug function and efficacy. Ideally, this should be performed nondestructively, with no modification of either the drug or the target, and with the capability to detect low amounts of the molecule of interest, in many cases in the μM to nM range (pmol to fmol per million cells). Unfortunately, it is currently challenging to have an experimental technique that provides direct quantitative measurements of intracellular drug concentrations that simultaneously satisfies these requirements. Here, we show that magic-angle spinning dynamic nuclear polarization (MAS DNP) can be used to fulfill these requirements. We apply a quantitative 15N MAS DNP approach in combination with 15N labeling to quantify the intracellular amount of the drug [15N]CHIR-98014, an activator of the Wingless and Int-1 signaling pathway, determining intracellular drug amounts in the range of tens to hundreds of picomoles per million cells. This is, to our knowledge, the first time that MAS DNP has been used to successfully estimate intracellular drug amounts.
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Affiliation(s)
- Andrea Bertarello
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Pierrick Berruyer
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Markus Artelsmair
- Early Chemical Development, Pharmaceutical Science, R&D, AstraZeneca, SE-431 83 Mölndal, Sweden
| | - Charles S Elmore
- Early Chemical Development, Pharmaceutical Science, R&D, AstraZeneca, SE-431 83 Mölndal, Sweden
| | - Sepideh Heydarkhan-Hagvall
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceutical R&D AstraZeneca, SE-431 83 Mölndal, Sweden
| | - Markus Schade
- Chemistry, Oncology R&D, AstraZeneca, Cambridge CB4 0WG, U.K
| | | | - Staffan Schantz
- Oral Product Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, SE-431 83 Mölndal, Sweden
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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17
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Abstract
In-cell structural biology aims at extracting structural information about proteins or nucleic acids in their native, cellular environment. This emerging field holds great promise and is already providing new facts and outlooks of interest at both fundamental and applied levels. NMR spectroscopy has important contributions on this stage: It brings information on a broad variety of nuclei at the atomic scale, which ensures its great versatility and uniqueness. Here, we detail the methods, the fundamental knowledge, and the applications in biomedical engineering related to in-cell structural biology by NMR. We finally propose a brief overview of the main other techniques in the field (EPR, smFRET, cryo-ET, etc.) to draw some advisable developments for in-cell NMR. In the era of large-scale screenings and deep learning, both accurate and qualitative experimental evidence are as essential as ever to understand the interior life of cells. In-cell structural biology by NMR spectroscopy can generate such a knowledge, and it does so at the atomic scale. This review is meant to deliver comprehensive but accessible information, with advanced technical details and reflections on the methods, the nature of the results, and the future of the field.
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Affiliation(s)
- Francois-Xavier Theillet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
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18
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Nami F, Ferraz MJ, Bakkum T, Aerts JMFG, Pandit A. Real-Time NMR Recording of Fermentation and Lipid Metabolism Processes in Live Microalgae Cells. Angew Chem Int Ed Engl 2022; 61:e202117521. [PMID: 35103372 PMCID: PMC9305762 DOI: 10.1002/anie.202117521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Indexed: 11/10/2022]
Abstract
Non-invasive and real-time recording of processes in living cells has been limited to detection of small cellular components such as soluble proteins and metabolites. Here we report a multiphase NMR approach using magic-angle spinning NMR to synchronously follow microbial processes of fermentation, lipid metabolism and structural dynamic changes in live microalgae cells. Chlamydomonas reinhardtii green algae were highly concentrated, introducing dark fermentation and anoxia conditions. Single-pulse NMR experiments were applied to obtain temperature-dependent kinetic profiles of the formed fermentation products. Through dynamics-based spectral editing NMR, simultaneous conversion of galactolipids into TAG and free fatty acids was observed and rapid loss of rigid lipid structures. This suggests that lipolysis under dark and anoxia conditions finally results in the breakdown of cell and organelle membranes, which could be beneficial for recovery of intracellular microbial useful products.
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Affiliation(s)
- Faezeh Nami
- Dept. of Solid-State NMRLeiden Institute of ChemistryLeiden UniversityEinsteinweg 552333 CCLeidenThe Netherlands
| | - Maria Joao Ferraz
- Dept. of Medicinal BiochemistryLeiden Institute of ChemistryLeiden UniversityEinsteinweg 552333 CCLeidenThe Netherlands
| | - Thomas Bakkum
- Dept. of Bio Organic SynthesisLeiden Institute of ChemistryLeiden UniversityEinsteinweg 552333 CCLeidenThe Netherlands
| | - Johannes M. F. G. Aerts
- Dept. of Medicinal BiochemistryLeiden Institute of ChemistryLeiden UniversityEinsteinweg 552333 CCLeidenThe Netherlands
| | - Anjali Pandit
- Dept. of Solid-State NMRLeiden Institute of ChemistryLeiden UniversityEinsteinweg 552333 CCLeidenThe Netherlands
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19
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Nami F, Ferraz MJ, Bakkum T, Aerts JMFG, Pandit A. Real‐Time NMR Recording of Fermentation and Lipid Metabolism Processes in Live Microalgae Cells. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202117521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Faezeh Nami
- Dept. of Solid-State NMR Leiden Institute of Chemistry Leiden University Einsteinweg 55 2333 CC Leiden The Netherlands
| | - Maria Joao Ferraz
- Dept. of Medicinal Biochemistry Leiden Institute of Chemistry Leiden University Einsteinweg 55 2333 CC Leiden The Netherlands
| | - Thomas Bakkum
- Dept. of Bio Organic Synthesis Leiden Institute of Chemistry Leiden University Einsteinweg 55 2333 CC Leiden The Netherlands
| | - Johannes M. F. G. Aerts
- Dept. of Medicinal Biochemistry Leiden Institute of Chemistry Leiden University Einsteinweg 55 2333 CC Leiden The Netherlands
| | - Anjali Pandit
- Dept. of Solid-State NMR Leiden Institute of Chemistry Leiden University Einsteinweg 55 2333 CC Leiden The Netherlands
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20
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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: 47] [Impact Index Per Article: 23.5] [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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21
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Gronenborn AM. Small, but powerful and attractive: 19F in biomolecular NMR. Structure 2022; 30:6-14. [PMID: 34995480 PMCID: PMC8797020 DOI: 10.1016/j.str.2021.09.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/03/2021] [Accepted: 09/20/2021] [Indexed: 01/09/2023]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is a versatile tool for probing structure, dynamics, folding, and interactions at atomic resolution. While naturally occurring magnetically active isotopes, such as 1H, 13C, or 15N, are most commonly used in biomolecular NMR, with 15N and 13C isotopic labeling routinely employed at the present time, 19F is a very attractive and sensitive alternative nucleus, which offers rich information on biomolecules in solution and in the solid state. This perspective summarizes the unique benefits of solution and solid-state 19F NMR spectroscopy for the study of biological systems. Particular focus is on the most recent studies and on future unique and important potential applications of fluorine NMR methodology.
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22
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Graziadei A, Rappsilber J. Leveraging crosslinking mass spectrometry in structural and cell biology. Structure 2021; 30:37-54. [PMID: 34895473 DOI: 10.1016/j.str.2021.11.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/11/2021] [Accepted: 11/17/2021] [Indexed: 12/18/2022]
Abstract
Crosslinking mass spectrometry (crosslinking-MS) is a versatile tool providing structural insights into protein conformation and protein-protein interactions. Its medium-resolution residue-residue distance restraints have been used to validate protein structures proposed by other methods and have helped derive models of protein complexes by integrative structural biology approaches. The use of crosslinking-MS in integrative approaches is underpinned by progress in estimating error rates in crosslinking-MS data and in combining these data with other information. The flexible and high-throughput nature of crosslinking-MS has allowed it to complement the ongoing resolution revolution in electron microscopy by providing system-wide residue-residue distance restraints, especially for flexible regions or systems. Here, we review how crosslinking-MS information has been leveraged in structural model validation and integrative modeling. Crosslinking-MS has also been a key technology for cell biology studies and structural systems biology where, in conjunction with cryoelectron tomography, it can provide structural and mechanistic insights directly in situ.
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Affiliation(s)
- Andrea Graziadei
- Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany
| | - Juri Rappsilber
- Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany; Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, UK.
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23
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Ghosh R, Xiao Y, Kragelj J, Frederick KK. In-Cell Sensitivity-Enhanced NMR of Intact Viable Mammalian Cells. J Am Chem Soc 2021; 143:18454-18466. [PMID: 34724614 DOI: 10.1021/jacs.1c06680] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
NMR has the resolution and specificity to determine atomic-level protein structures of isotopically labeled proteins in complex environments, and with the sensitivity gains conferred by dynamic nuclear polarization (DNP), NMR has the sensitivity to detect proteins at their endogenous concentrations. However, DNP sensitivity enhancements are critically dependent on experimental conditions and sample composition. While some of these conditions are theoretically compatible with cellular viability, the effects of others on cellular sample integrity are unknown. Uncertainty about the integrity of cellular samples limits the utility of experimental outputs of in-cell experiments. Using several measures, we establish conditions that support DNP enhancements that can enable detection of micromolar concentrations of proteins in experimentally tractable times that are compatible with cellular viability. Taken together, we establish DNP-assisted MAS NMR as a technique for structural investigations of biomolecules in intact viable cells that can be phenotyped both before and after NMR experiments.
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Affiliation(s)
- Rupam Ghosh
- Department of Biophysics, UT Southwestern Medical Center, Dallas, Texas 75390-8816, United States
| | - Yiling Xiao
- Department of Biophysics, UT Southwestern Medical Center, Dallas, Texas 75390-8816, United States
| | - Jaka Kragelj
- Department of Biophysics, UT Southwestern Medical Center, Dallas, Texas 75390-8816, United States
| | - Kendra K Frederick
- Department of Biophysics, UT Southwestern Medical Center, Dallas, Texas 75390-8816, United States.,Center for Alzheimer's and Neurodegenerative Disease, UT Southwestern Medical Center, Dallas, Texas 75390, United States
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24
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Zhu S, Kachooei E, Harmer JR, Brown LJ, Separovic F, Sani MA. TOAC spin-labeled peptides tailored for DNP-NMR studies in lipid membrane environments. Biophys J 2021; 120:4501-4511. [PMID: 34480924 DOI: 10.1016/j.bpj.2021.08.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 07/08/2021] [Accepted: 08/10/2021] [Indexed: 12/15/2022] Open
Abstract
The benefit of combining in-cell solid-state dynamic nuclear polarization (DNP) NMR and cryogenic temperatures is providing sufficient signal/noise and preservation of bacterial integrity via cryoprotection to enable in situ biophysical studies of antimicrobial peptides. The radical source required for DNP was delivered into cells by adding a nitroxide-tagged peptide based on the antimicrobial peptide maculatin 1.1 (Mac1). In this study, the structure, localization, and signal enhancement properties of a single (T-MacW) and double (T-T-MacW) TOAC (2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid) spin-labeled Mac1 analogs were determined within micelles or lipid vesicles. The solution NMR and circular dichroism results showed that the spin-labeled peptides adopted helical structures in contact with micelles. The peptides behaved as an isolated radical source in the presence of multilamellar vesicles, and the electron paramagnetic resonance (EPR) electron-electron distance for the doubly spin-labeled peptide was ∼1 nm. The strongest paramagnetic relaxation enhancement (PRE) was observed for the lipid NMR signals near the glycerol-carbonyl backbone and was stronger for the doubly spin-labeled peptide. Molecular dynamics simulation of the T-T-MacW radical source in phospholipid bilayers supported the EPR and PRE observations while providing further structural insights. Overall, the T-T-MacW peptide achieved better 13C and 15N signal NMR enhancements and 1H spin-lattice T1 relaxation than T-MacW.
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Affiliation(s)
- Shiying Zhu
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Ehsan Kachooei
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia
| | - Louise J Brown
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia.
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25
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Aneskievich BJ, Shamilov R, Vinogradova O. Intrinsic disorder in integral membrane proteins. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 183:101-134. [PMID: 34656327 DOI: 10.1016/bs.pmbts.2021.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The well-defined roles and specific protein-protein interactions of many integral membrane proteins (IMPs), such as those functioning as receptors for extracellular matrix proteins and soluble growth factors, easily align with considering IMP structure as a classical "lock-and-key" concept. Nevertheless, continued advances in understanding protein conformation, such as those which established the widespread existence of intrinsically disordered proteins (IDPs) and especially intrinsically disordered regions (IDRs) in otherwise three-dimensionally organized proteins, call for ongoing reevaluation of transmembrane proteins. Here, we present basic traits of IDPs and IDRs, and, for some select single-span IMPs, consider the potential functional advantages intrinsic disorder might provide and the possible conformational impact of disease-associated mutations. For transmembrane proteins in general, we highlight several investigational approaches, such as biophysical and computational methods, stressing the importance of integrating them to produce a more-complete mechanistic model of disorder-containing IMPs. These procedures, when synergized with in-cell assessments, will likely be key in translating in silico and in vitro results to improved understanding of IMP conformational flexibility in normal cell physiology as well as disease, and will help to extend their potential as therapeutic targets.
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Affiliation(s)
- Brian J Aneskievich
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, United States
| | - Rambon Shamilov
- Graduate Program in Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, United States
| | - Olga Vinogradova
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, United States.
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26
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Sasikumar PG, Sudarshan NS, Adurthi S, Ramachandra RK, Samiulla DS, Lakshminarasimhan A, Ramanathan A, Chandrasekhar T, Dhudashiya AA, Talapati SR, Gowda N, Palakolanu S, Mani J, Srinivasrao B, Joseph D, Kumar N, Nair R, Atreya HS, Gowda N, Ramachandra M. PD-1 derived CA-170 is an oral immune checkpoint inhibitor that exhibits preclinical anti-tumor efficacy. Commun Biol 2021; 4:699. [PMID: 34103659 PMCID: PMC8187357 DOI: 10.1038/s42003-021-02191-1] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 05/05/2021] [Indexed: 12/17/2022] Open
Abstract
Small molecule immune checkpoint inhibitors targeting PD-1 and other pathways may offer advantages including ease of dosing, ability to manage immune-related adverse events (irAEs) due to their shorter pharmacokinetic exposure and opportunity to target more than one pathway for improving efficacy. Here we describe the identification and characterization of CA-170, an amino acid inspired small molecule inhibitor of PD-L1 and VISTA derived from the interface of PD-1 and PD-L1. CA-170 exhibited potent rescue of proliferation and effector functions of T cells inhibited by PD-L1/L2 and VISTA with selectivity over other immune checkpoint proteins as well as a broad panel of receptors and enzymes. Observed blocking of PD-L1 signaling and binding to PD-L1 in the cellular context without preventing the assembly of PD-1:PD-L1 complex support the formation of a defective ternary complex as the mechanism of action of CA-170. Oral administration of CA-170 resulted in increased proliferation and activation of T cells in the tumor, and significant anti-tumor efficacy in a number of immunocompetent mouse tumor models either as a single agent or in combination with approved therapeutics. These results prompted the advancement of CA-170 to human clinical trials.
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Affiliation(s)
| | | | - Srinivas Adurthi
- Aurigene Discovery Technologies Limited, Bangalore, Karnataka, India
| | | | | | | | | | | | - Amit A Dhudashiya
- Aurigene Discovery Technologies Limited, Bangalore, Karnataka, India
| | | | - Nagesh Gowda
- Aurigene Discovery Technologies Limited, Bangalore, Karnataka, India
| | | | - Jiju Mani
- Aurigene Discovery Technologies Limited, Bangalore, Karnataka, India
| | - Bandi Srinivasrao
- Aurigene Discovery Technologies Limited, Bangalore, Karnataka, India
| | - David Joseph
- NMR Research Centre, Indian Institute of Science, Bangalore, Karnataka, India
| | - Nigam Kumar
- Aurigene Discovery Technologies Limited, Bangalore, Karnataka, India
| | - Rashmi Nair
- Aurigene Discovery Technologies Limited, Bangalore, Karnataka, India
| | - Hanudatta S Atreya
- NMR Research Centre, Indian Institute of Science, Bangalore, Karnataka, India
| | - Nagaraj Gowda
- Aurigene Discovery Technologies Limited, Bangalore, Karnataka, India
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27
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Phạm TTT, Rainey JK. On-cell nuclear magnetic resonance spectroscopy to probe cell surface interactions. Biochem Cell Biol 2021; 99:683-692. [PMID: 33945753 DOI: 10.1139/bcb-2021-0052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nuclear magnetic resonance (NMR) spectroscopy allows determination of atomic-level information about intermolecular interactions, molecular structure, and molecular dynamics in the cellular environment. This may be broadly divided into studies focused on obtaining detailed molecular information in the intracellular context ("in-cell") or those focused on characterizing molecules or events at the cell surface ("on-cell"). In this review, we outline some key NMR techniques applied for on-cell NMR studies through both solution-state and solid-state NMR and survey studies that have used these techniques to uncover key information. We particularly focus on application of on-cell NMR spectroscopy to characterize ligand interactions with cell surface membrane proteins such as G-protein coupled receptors (GPCRs), receptor tyrosine kinases, etc. These techniques allow for quantification of binding affinities, competitive binding assays, delineation of portions of ligands involved in binding, ligand bound-state conformational determination, evaluation of receptor structuring and dynamics, and inference of distance constraints characteristic of the ligand-receptor bound state. Excitingly, it is possible to avoid the barriers of production and purification of membrane proteins while obtaining directly physiologically-relevant information through on-cell NMR. We also provide a briefer survey of the applicability of on-cell NMR approaches to other classes of cell surface molecule.
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Affiliation(s)
- Trần Thanh Tâm Phạm
- Dalhousie University, 3688, Department of Biochemistry & Molecular Biology, Halifax, Nova Scotia, Canada;
| | - Jan K Rainey
- Dalhousie University, 3688, Department of Biochemistry & Molecular Biology, Halifax, Canada;
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28
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Reif B, Ashbrook SE, Emsley L, Hong M. Solid-state NMR spectroscopy. NATURE REVIEWS. METHODS PRIMERS 2021; 1:2. [PMID: 34368784 PMCID: PMC8341432 DOI: 10.1038/s43586-020-00002-1] [Citation(s) in RCA: 172] [Impact Index Per Article: 57.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/29/2020] [Indexed: 12/18/2022]
Abstract
Solid-state nuclear magnetic resonance (NMR) spectroscopy is an atomic-level method used to determine the chemical structure, three-dimensional structure, and dynamics of solids and semi-solids. This Primer summarizes the basic principles of NMR as applied to the wide range of solid systems. The fundamental nuclear spin interactions and the effects of magnetic fields and radiofrequency pulses on nuclear spins are the same as in liquid-state NMR. However, because of the anisotropy of the interactions in the solid state, the majority of high-resolution solid-state NMR spectra is measured under magic-angle spinning (MAS), which has profound effects on the types of radiofrequency pulse sequences required to extract structural and dynamical information. We describe the most common MAS NMR experiments and data analysis approaches for investigating biological macromolecules, organic materials, and inorganic solids. Continuing development of sensitivity-enhancement approaches, including 1H-detected fast MAS experiments, dynamic nuclear polarization, and experiments tailored to ultrahigh magnetic fields, is described. We highlight recent applications of solid-state NMR to biological and materials chemistry. The Primer ends with a discussion of current limitations of NMR to study solids, and points to future avenues of development to further enhance the capabilities of this sophisticated spectroscopy for new applications.
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Affiliation(s)
- Bernd Reif
- Technische Universität München, Department Chemie, Lichtenbergstr. 4, D-85747 Garching, Germany
| | - Sharon E. Ashbrook
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, KY16 9ST, UK
| | - Lyndon Emsley
- École Polytechnique Fédérale de Lausanne (EPFL), Institut des sciences et ingénierie chimiques, CH-1015 Lausanne, Switzerland
| | - Mei Hong
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
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29
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In-cell destabilization of a homodimeric protein complex detected by DEER spectroscopy. Proc Natl Acad Sci U S A 2020; 117:20566-20575. [PMID: 32788347 DOI: 10.1073/pnas.2005779117] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The complexity of the cellular medium can affect proteins' properties, and, therefore, in-cell characterization of proteins is essential. We explored the stability and conformation of the first baculoviral IAP repeat (BIR) domain of X chromosome-linked inhibitor of apoptosis (XIAP), BIR1, as a model for a homodimer protein in human HeLa cells. We employed double electron-electron resonance (DEER) spectroscopy and labeling with redox stable and rigid Gd3+ spin labels at three representative protein residues, C12 (flexible region), E22C, and N28C (part of helical residues 26 to 31) in the N-terminal region. In contrast to predictions by excluded-volume crowding theory, the dimer-monomer dissociation constant K D was markedly higher in cells than in solution and dilute cell lysate. As expected, this increase was partially recapitulated under conditions of high salt concentrations, given that conserved salt bridges at the dimer interface are critically required for association. Unexpectedly, however, also the addition of the crowding agent Ficoll destabilized the dimer while the addition of bovine serum albumin (BSA) and lysozyme, often used to represent interaction with charged macromolecules, had no effect. Our results highlight the potential of DEER for in-cell study of proteins as well as the complexities of the effects of the cellular milieu on protein structures and stability.
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30
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Li Q, Kang C. A Practical Perspective on the Roles of Solution NMR Spectroscopy in Drug Discovery. Molecules 2020; 25:molecules25132974. [PMID: 32605297 PMCID: PMC7411973 DOI: 10.3390/molecules25132974] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 06/21/2020] [Accepted: 06/26/2020] [Indexed: 11/26/2022] Open
Abstract
Solution nuclear magnetic resonance (NMR) spectroscopy is a powerful tool to study structures and dynamics of biomolecules under physiological conditions. As there are numerous NMR-derived methods applicable to probe protein–ligand interactions, NMR has been widely utilized in drug discovery, especially in such steps as hit identification and lead optimization. NMR is frequently used to locate ligand-binding sites on a target protein and to determine ligand binding modes. NMR spectroscopy is also a unique tool in fragment-based drug design (FBDD), as it is able to investigate target-ligand interactions with diverse binding affinities. NMR spectroscopy is able to identify fragments that bind weakly to a target, making it valuable for identifying hits targeting undruggable sites. In this review, we summarize the roles of solution NMR spectroscopy in drug discovery. We describe some methods that are used in identifying fragments, understanding the mechanism of action for a ligand, and monitoring the conformational changes of a target induced by ligand binding. A number of studies have proven that 19F-NMR is very powerful in screening fragments and detecting protein conformational changes. In-cell NMR will also play important roles in drug discovery by elucidating protein-ligand interactions in living cells.
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Affiliation(s)
- Qingxin Li
- Guangdong Provincial Engineering Laboratory of Biomass High Value Utilization, Guangdong Provincial Bioengineering Institute (Guangzhou Sugarcane Industry Research Institute), Guangzhou 510316, China
- Correspondence: (Q.L.); (C.K.); Tel.: +86-020-84168436 (Q.L.); +65-64070602 (C.K.)
| | - CongBao Kang
- Experimental Drug Development Centre (EDDC), Agency for Science, Technology and Research (A*STAR), 10 Biopolis Road, Chromos, #05-01, Singapore 138670, Singapore
- Correspondence: (Q.L.); (C.K.); Tel.: +86-020-84168436 (Q.L.); +65-64070602 (C.K.)
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31
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Wang Y, Kim J, Hilty C. Determination of protein-ligand binding modes using fast multi-dimensional NMR with hyperpolarization. Chem Sci 2020; 11:5935-5943. [PMID: 32874513 PMCID: PMC7441707 DOI: 10.1039/d0sc00266f] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/05/2020] [Indexed: 11/21/2022] Open
Abstract
Elucidation of small molecule-protein interactions provides essential information for understanding biological processes such as cellular signaling, as well as for rational drug development. Here, multi-dimensional NMR with sensitivity enhancement by dissolution dynamic nuclear polarization (D-DNP) is shown to allow the determination of the binding epitope of folic acid when complexed with the target dihydrofolate reductase. Protein signals are selectively enhanced by polarization transfer from the hyperpolarized ligand. A pseudo three-dimensional data acquisition with ligand-side Hadamard encoding results in protein-side [13C, 1H] chemical shift correlations that contain intermolecular nuclear Overhauser effect (NOE) information. A scoring function based on this data is used to select pre-docked ligand poses. The top five poses are within 0.76 Å root-mean-square deviation from a reference structure for the encoded five protons, showing improvements compared with the poses selected by an energy-based scoring function without experimental inputs. The sensitivity enhancement provided by the D-DNP combined with multi-dimensional NMR increases the speed and potentially the selectivity of structure elucidation of ligand binding epitopes.
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Affiliation(s)
- Yunyi Wang
- Department of Chemistry , Texas A&M University , 3255 TAMU , College Station , TX 77843 , USA .
| | - Jihyun Kim
- Department of Chemistry , Texas A&M University , 3255 TAMU , College Station , TX 77843 , USA .
| | - Christian Hilty
- Department of Chemistry , Texas A&M University , 3255 TAMU , College Station , TX 77843 , USA .
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32
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Carbajo D, Pérez Y, Bujons J, Alfonso I. Live‐Cell‐Templated Dynamic Combinatorial Chemistry. Angew Chem Int Ed Engl 2020; 59:17202-17206. [DOI: 10.1002/anie.202004745] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Indexed: 12/23/2022]
Affiliation(s)
- Daniel Carbajo
- Department of Biological Chemistry Institute of Advanced Chemistry of Catalonia (IQAC-CSIC) Jordi Girona 18–26 08034 Barcelona Spain
| | - Yolanda Pérez
- NMR Facility (IQAC-CSIC) Jordi Girona 18–26 08034 Barcelona Spain
| | - Jordi Bujons
- Department of Biological Chemistry Institute of Advanced Chemistry of Catalonia (IQAC-CSIC) Jordi Girona 18–26 08034 Barcelona Spain
| | - Ignacio Alfonso
- Department of Biological Chemistry Institute of Advanced Chemistry of Catalonia (IQAC-CSIC) Jordi Girona 18–26 08034 Barcelona Spain
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33
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Carbajo D, Pérez Y, Bujons J, Alfonso I. Live‐Cell‐Templated Dynamic Combinatorial Chemistry. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004745] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Daniel Carbajo
- Department of Biological Chemistry Institute of Advanced Chemistry of Catalonia (IQAC-CSIC) Jordi Girona 18–26 08034 Barcelona Spain
| | - Yolanda Pérez
- NMR Facility (IQAC-CSIC) Jordi Girona 18–26 08034 Barcelona Spain
| | - Jordi Bujons
- Department of Biological Chemistry Institute of Advanced Chemistry of Catalonia (IQAC-CSIC) Jordi Girona 18–26 08034 Barcelona Spain
| | - Ignacio Alfonso
- Department of Biological Chemistry Institute of Advanced Chemistry of Catalonia (IQAC-CSIC) Jordi Girona 18–26 08034 Barcelona Spain
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34
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Mass spectrometry-based methods for structural biology on a proteome-wide scale. Biochem Soc Trans 2020; 48:945-954. [DOI: 10.1042/bst20190794] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/14/2020] [Accepted: 04/16/2020] [Indexed: 11/17/2022]
Abstract
Mass spectrometry (MS) has long been used to study proteins mainly via sequence identification and quantitation of expression abundance. In recent years, MS has emerged as a tool for structural biology. Intact protein structural analysis has been enabled by the development of methods such as native MS, top-down proteomics, and ion mobility MS. Other MS-based structural methods include affinity purification MS, chemical cross-linking, and protein footprinting. These methods have enabled the study of protein–protein and protein–ligand interactions and regions of conformational change. The coupling of MS with liquid chromatography has permitted the analysis of complex samples. This bottom-up proteomics workflow enables the study of protein structure in the native cellular environment and provides structural information across the proteome. It has been demonstrated that the crowded environment of the cell affects protein binding interactions and affinities. Performing studies in this complex environment is essential for understanding the functional roles of proteins. MS-based structural methods permit analysis of samples such as cell lysates, intact cells, and tissue to provide a more physiological view of protein structure. This mini-review discusses the various MS-based methods that can be used for proteome-wide structural studies and highlights some of their application.
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35
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Phosphoprotein Biosensors for Monitoring Pathological Protein Structural Changes. Trends Biotechnol 2020; 38:519-531. [DOI: 10.1016/j.tibtech.2019.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 11/15/2019] [Accepted: 11/15/2019] [Indexed: 12/19/2022]
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36
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Integrating Non-NMR Distance Restraints to Augment NMR Depiction of Protein Structure and Dynamics. J Mol Biol 2020; 432:2913-2929. [DOI: 10.1016/j.jmb.2020.01.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 01/17/2020] [Accepted: 01/17/2020] [Indexed: 11/24/2022]
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37
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Koukos P, Bonvin A. Integrative Modelling of Biomolecular Complexes. J Mol Biol 2020; 432:2861-2881. [DOI: 10.1016/j.jmb.2019.11.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 12/31/2022]
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38
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Juliusson HY, Sigurdsson ST. Reduction Resistant and Rigid Nitroxide Spin-Labels for DNA and RNA. J Org Chem 2020; 85:4036-4046. [PMID: 32103670 DOI: 10.1021/acs.joc.9b02988] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy, coupled with site-directed spin labeling (SDSL), is a useful method for studying conformational changes of biomolecules in cells. To employ in-cell EPR using nitroxide-based spin labels, the structure of the nitroxides must confer reduction resistance to withstand the reductive environment within cells. Here, we report the synthesis of two new spin labels, EÇ and EÇm, both of which possess the rigidity and the reduction resistance needed for extracting detailed structural information by EPR spectroscopy. EÇ and EÇm were incorporated into DNA and RNA, respectively, by oligonucleotide synthesis. Both labels were shown to be nonperturbing of the duplex structure. The partial reduction of EÇm during RNA synthesis was circumvented by the protection of the nitroxide as a benzoylated hydroxylamine.
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Affiliation(s)
- Haraldur Y Juliusson
- Department of Chemistry, Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavik, Iceland
| | - Snorri Th Sigurdsson
- Department of Chemistry, Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavik, Iceland
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39
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Gerez JA, Prymaczok NC, Riek R. In-Cell NMR of Intrinsically Disordered Proteins in Mammalian Cells. Methods Mol Biol 2020; 2141:873-893. [PMID: 32696394 DOI: 10.1007/978-1-0716-0524-0_45] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In-cell NMR enables structural insights at atomic resolution of proteins in their natural environment. To date, very few methods have been developed to study proteins by in-cell NMR in mammalian systems. Here we describe a detailed protocol to conduct in-cell NMR on the intrinsically disordered protein of alpha-Synuclein (αSyn) in mammalian cells. This chapter includes a simplified expression and purification protocol of recombinant αSyn and its delivery into mammalian cells. The chapter also describes how to assess the cell leakage that might occur to the cells, the setup of the instrument, and how to perform basic analyses with the obtained NMR data.
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Affiliation(s)
- Juan A Gerez
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.
| | - Natalia C Prymaczok
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Roland Riek
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.
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40
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Ryl PSJ, Bohlke-Schneider M, Lenz S, Fischer L, Budzinski L, Stuiver M, Mendes MML, Sinn L, O'Reilly FJ, Rappsilber J. In Situ Structural Restraints from Cross-Linking Mass Spectrometry in Human Mitochondria. J Proteome Res 2019; 19:327-336. [PMID: 31746214 PMCID: PMC7010328 DOI: 10.1021/acs.jproteome.9b00541] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The field of structural biology is increasingly focusing on studying proteins in situ, i.e., in their greater biological context. Cross-linking mass spectrometry (CLMS) is contributing to this effort, typically through the use of mass spectrometry (MS)-cleavable cross-linkers. Here, we apply the popular noncleavable cross-linker disuccinimidyl suberate (DSS) to human mitochondria and identify 5518 distance restraints between protein residues. Each distance restraint on proteins or their interactions provides structural information within mitochondria. Comparing these restraints to protein data bank (PDB)-deposited structures and comparative models reveals novel protein conformations. Our data suggest, among others, substrates and protein flexibility of mitochondrial heat shock proteins. Through this study, we bring forward two central points for the progression of CLMS towards large-scale in situ structural biology: First, clustered conflicts of cross-link data reveal in situ protein conformation states in contrast to error-rich individual conflicts. Second, noncleavable cross-linkers are compatible with proteome-wide studies.
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Affiliation(s)
- Petra S J Ryl
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany
| | - Michael Bohlke-Schneider
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany
| | - Swantje Lenz
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany
| | - Lutz Fischer
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany.,Wellcome Centre for Cell Biology, School of Biological Sciences , University of Edinburgh , Edinburgh EH9 3BF , Scotland , United Kingdom
| | - Lisa Budzinski
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany
| | - Marchel Stuiver
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany
| | - Marta M L Mendes
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany
| | - Ludwig Sinn
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany
| | - Francis J O'Reilly
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany
| | - Juri Rappsilber
- Bioanalytics, Institute of Biotechnology , Technische Universität Berlin , 13355 Berlin , Germany.,Wellcome Centre for Cell Biology, School of Biological Sciences , University of Edinburgh , Edinburgh EH9 3BF , Scotland , United Kingdom
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41
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Zheng W, Zhang Z, Ye Y, Wu Q, Liu M, Li C. Phosphorylation dependent α-synuclein degradation monitored by in-cell NMR. Chem Commun (Camb) 2019; 55:11215-11218. [PMID: 31469130 DOI: 10.1039/c9cc05662a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here we report the dephosphorylation and proteolysis of phosphorylated α-synuclein, a Parkinson's disease-related protein, in living cells in a time resolved manner using in-cell NMR.
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Affiliation(s)
- Wenwen Zheng
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
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42
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Puthenveetil R, Vinogradova O. Solution NMR: A powerful tool for structural and functional studies of membrane proteins in reconstituted environments. J Biol Chem 2019; 294:15914-15931. [PMID: 31551353 DOI: 10.1074/jbc.rev119.009178] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A third of the genes in prokaryotic and eukaryotic genomes encode membrane proteins that are either essential for signal transduction and solute transport or function as scaffold structures. Unlike many of their soluble counterparts, the overall structural and functional organization of membrane proteins is sparingly understood. Recent advances in X-ray crystallography, cryo-EM, and nuclear magnetic resonance (NMR) are closing this gap by enabling an in-depth view of these ever-elusive proteins at atomic resolution. Despite substantial technological advancements, however, the overall proportion of membrane protein entries in the Protein Data Bank (PDB) remains <4%. This paucity is mainly attributed to difficulties associated with their expression and purification, propensity to form large multisubunit complexes, and challenges pertinent to identification of an ideal detergent, lipid, or detergent/lipid mixture that closely mimic their native environment. NMR is a powerful technique to obtain atomic-resolution and dynamic details of a protein in solution. This is accomplished through an assortment of isotopic labeling schemes designed to acquire multiple spectra that facilitate deduction of the final protein structure. In this review, we discuss current approaches and technological developments in the determination of membrane protein structures by solution NMR and highlight recent structural and mechanistic insights gained with this technique. We also discuss strategies for overcoming size limitations in NMR applications, and we explore a plethora of membrane mimetics available for the structural and mechanistic understanding of these essential cellular proteins.
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Affiliation(s)
- Robbins Puthenveetil
- Department of Molecular and Cell Biology, college of liberal arts and sciences, University of Connecticut at Storrs, Storrs, Connecticut 06269
| | - Olga Vinogradova
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut at Storrs, Storrs, Connecticut 06269
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43
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Schlagnitweit J, Friebe Sandoz S, Jaworski A, Guzzetti I, Aussenac F, Carbajo RJ, Chiarparin E, Pell AJ, Petzold K. Observing an Antisense Drug Complex in Intact Human Cells by in-Cell NMR Spectroscopy. Chembiochem 2019; 20:2474-2478. [PMID: 31206961 DOI: 10.1002/cbic.201900297] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Indexed: 12/12/2022]
Abstract
Gaining insight into the uptake, trafficking and target engagement of drugs in cells can enhance understanding of a drug's function and efficiency. However, there are currently no reliable methods for studying untagged biomolecules in macromolecular complexes in intact human cells. Here we have studied an antisense oligonucleotide (ASO) drug in HEK 293T and HeLa cells by NMR spectroscopy. Using a combination of transfection, cryoprotection and dynamic nuclear polarization (DNP), we were able to detect the drug directly in intact frozen cells. Activity of the drug was confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). By applying DNP NMR to frozen cells, we overcame limitations both of solution-state in-cell NMR spectroscopy (e.g., size, stability and sensitivity) and of visualization techniques, in which (e.g., fluorescent) tagging of the ASO decreases its activity. The capability to detect an untagged, active drug, interacting in its natural environment, represents a first step towards studying molecular mechanisms in intact cells.
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Affiliation(s)
- Judith Schlagnitweit
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solnavägen 9, 17165, Solna, Sweden
| | - Sarah Friebe Sandoz
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solnavägen 9, 17165, Solna, Sweden
| | - Aleksander Jaworski
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Svante Arrhenius väg 16 C, 106 91, Stockholm, Sweden
| | - Ileana Guzzetti
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solnavägen 9, 17165, Solna, Sweden
| | - Fabien Aussenac
- Bruker BioSpin, 34 Rue de l'Industrie, 67160, Wissembourg, France
| | - Rodrigo J Carbajo
- Analytical and Structural Chemistry Oncology, IMED Biotech Unit, AstraZeneca, Cambridge, CB4 0WG, UK
| | - Elisabetta Chiarparin
- Analytical and Structural Chemistry Oncology, IMED Biotech Unit, AstraZeneca, Cambridge, CB4 0WG, UK
| | - Andrew J Pell
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Svante Arrhenius väg 16 C, 106 91, Stockholm, Sweden
| | - Katja Petzold
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solnavägen 9, 17165, Solna, Sweden
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44
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Siegal G, Selenko P. Cells, drugs and NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 306:202-212. [PMID: 31358370 DOI: 10.1016/j.jmr.2019.07.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 06/08/2019] [Accepted: 07/08/2019] [Indexed: 05/18/2023]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is a versatile tool for investigating cellular structures and their compositions. While in vivo and whole-cell NMR have a long tradition in cell-based approaches, high-resolution in-cell NMR spectroscopy is a new addition to these methods. In recent years, technological advancements in multiple areas provided converging benefits for cellular MR applications, especially in terms of robustness, reproducibility and physiological relevance. Here, we review the use of cellular NMR methods for drug discovery purposes in academia and industry. Specifically, we discuss how developments in NMR technologies such as miniaturized bioreactors and flow-probe perfusion systems have helped to consolidate NMR's role in cell-based drug discovery efforts.
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Affiliation(s)
- Gregg Siegal
- ZoBio B.V., BioPartner 2 Building, J.H. Oortweg 19, 2333 Leiden, the Netherlands
| | - Philipp Selenko
- Department of Biological Regulation, Weizmann Institute of Science, 234 Herzl Street, 761000 Rehovot, Israel.
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45
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Nikolaev Y, Ripin N, Soste M, Picotti P, Iber D, Allain FHT. Systems NMR: single-sample quantification of RNA, proteins and metabolites for biomolecular network analysis. Nat Methods 2019; 16:743-749. [PMID: 31363225 PMCID: PMC6837886 DOI: 10.1038/s41592-019-0495-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 06/17/2019] [Indexed: 12/14/2022]
Abstract
Cellular behavior is controlled by the interplay of diverse biomolecules. Most experimental methods, however, can only monitor a single molecule class or reaction type at a time. We developed an in vitro nuclear magnetic resonance spectroscopy (NMR) approach, which permitted dynamic quantification of an entire 'heterotypic' network-simultaneously monitoring three distinct molecule classes (metabolites, proteins and RNA) and all elementary reaction types (bimolecular interactions, catalysis, unimolecular changes). Focusing on an eight-reaction co-transcriptional RNA folding network, in a single sample we recorded over 35 time points with over 170 observables each, and accurately determined five core reaction constants in multiplex. This reconstruction revealed unexpected cross-talk between the different reactions. We further observed dynamic phase-separation in a system of five distinct RNA-binding domains in the course of the RNA transcription reaction. Our Systems NMR approach provides a deeper understanding of biological network dynamics by combining the dynamic resolution of biochemical assays and the multiplexing ability of 'omics'.
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Affiliation(s)
- Yaroslav Nikolaev
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zurich, Zurich, Switzerland.
| | - Nina Ripin
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zurich, Zurich, Switzerland
| | - Martin Soste
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Paola Picotti
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Dagmar Iber
- Department of Biosystems Science and Engineering, ETH Zurich, Zurich, Switzerland
| | - Frédéric H-T Allain
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zurich, Zurich, Switzerland.
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46
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Schramm A, Bignon C, Brocca S, Grandori R, Santambrogio C, Longhi S. An arsenal of methods for the experimental characterization of intrinsically disordered proteins - How to choose and combine them? Arch Biochem Biophys 2019; 676:108055. [PMID: 31356778 DOI: 10.1016/j.abb.2019.07.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 07/16/2019] [Accepted: 07/24/2019] [Indexed: 12/12/2022]
Abstract
In this review, we detail the most common experimental approaches to assess and characterize protein intrinsic structural disorder, with the notable exception of NMR and EPR spectroscopy, two ideally suited approaches that will be described in depth in two other reviews within this special issue. We discuss the advantages, the limitations, as well as the caveats of the various methods. We also describe less common and more demanding approaches that enable achieving further insights into the conformational properties of IDPs. Finally, we present recent developments that have enabled assessment of structural disorder in living cells, and discuss the currently available methods to model IDPs as conformational ensembles.
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Affiliation(s)
- Antoine Schramm
- CNRS and Aix-Marseille Univ, Laboratoire Architecture et Fonction des Macromolecules Biologiques (AFMB), UMR 7257, Marseille, France
| | - Christophe Bignon
- CNRS and Aix-Marseille Univ, Laboratoire Architecture et Fonction des Macromolecules Biologiques (AFMB), UMR 7257, Marseille, France
| | - Stefania Brocca
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Rita Grandori
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Carlo Santambrogio
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Sonia Longhi
- CNRS and Aix-Marseille Univ, Laboratoire Architecture et Fonction des Macromolecules Biologiques (AFMB), UMR 7257, Marseille, France.
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47
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Dalaloyan A, Martorana A, Barak Y, Gataulin D, Reuveny E, Howe A, Elbaum M, Albeck S, Unger T, Frydman V, Abdelkader EH, Otting G, Goldfarb D. Tracking Conformational Changes in Calmodulin in vitro, in Cell Extract, and in Cells by Electron Paramagnetic Resonance Distance Measurements. Chemphyschem 2019; 20:1860-1868. [PMID: 31054266 DOI: 10.1002/cphc.201900341] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Indexed: 12/12/2022]
Abstract
It is an open question whether the conformations of proteins sampled in dilute solutions are the same as in the cellular environment. Here we address this question by double electron-electron resonance (DEER) distance measurements with Gd(III) spin labels to probe the conformations of calmodulin (CaM) in vitro, in cell extract, and in human HeLa cells. Using the CaM mutants N53C/T110C and T34C/T117C labeled with maleimide-DOTA-Gd(III) in the N- and C-terminal domains, we observed broad and varied interdomain distance distributions. The in vitro distance distributions of apo-CaM and holo-CaM in the presence and absence of the IQ target peptide can be described by combinations of closed, open, and collapsed conformations. In cell extract, apo- and holo-CaM bind to target proteins in a similar way as apo- and holo-CaM bind to IQ peptide in vitro. In HeLa cells, however, in the presence or absence of elevated in-cell Ca2+ levels CaM unexpectedly produced more open conformations and very broad distance distributions indicative of many different interactions with in-cell components. These results show-case the importance of in-cell analyses of protein structures.
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Affiliation(s)
| | | | | | | | | | - Andrew Howe
- Department of Chemical and Biological Physics
| | | | - Shira Albeck
- Department of Life Sciences Core Facilities, The Weizmann Institute of Science, Rehovot, Israel
| | - Tamar Unger
- Department of Life Sciences Core Facilities, The Weizmann Institute of Science, Rehovot, Israel
| | | | - Elwy H Abdelkader
- Research School of Chemistry, Australian National University, Canberra, Australia
| | - Gottfried Otting
- Research School of Chemistry, Australian National University, Canberra, Australia
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Su XC, Chen JL. Site-Specific Tagging of Proteins with Paramagnetic Ions for Determination of Protein Structures in Solution and in Cells. Acc Chem Res 2019; 52:1675-1686. [PMID: 31150202 DOI: 10.1021/acs.accounts.9b00132] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
High-resolution NMR spectroscopy is sensitive to local structural variations and subtle dynamics of biomolecules and is an important technique for studying the structures, dynamics, and interactions of these molecules. Small-molecule probes, including paramagnetic tags, have been developed for this purpose. Paramagnetic effects manifested in magnetic resonance spectra have long been recognized as valuable tools for chemical analysis of small molecules, and these effects were later applied in the fields of chemical biology and structural biology. However, such applications require the installation of a paramagnetic center in the biomolecules of interest. Paramagnetic metal ions and stable free radicals are the most widely used paramagnetic probes for biological magnetic resonance spectroscopy, and therefore mild, high-yielding approaches for chemically attaching paramagnetic tags to biomolecules are in high demand. In this Account, we begin by discussing paramagnetic species, especially transition metal ions and lanthanide ions, that are suitable for NMR and EPR studies, particularly for in-cell applications. Thereafter, we describe approaches for site-specific tagging of proteins with paramagnetic ions and discuss considerations involved in designing high-quality paramagnetic tags, including the strength of the binding between the metal-chelating moiety and the paramagnetic ion, the chemical stability, and the flexibility of the tether between the paramagnetic tag and the target protein. The flexibility of a tag correlates strongly with the averaging of paramagnetic effects observed in NMR spectra, and we describe methods for increasing tag rigidity and applications of such tags in biological systems. We also describe specific applications of established site-specific tagging approaches and newly developed paramagnetic tags for the elucidation of protein structures and dynamics at atomic resolution both in solution and in cells. First, we describe the determination of the 3D structure of a short-lived, low-abundance enzyme intermediate complex in real time by using pseudocontact shifts as structural restraints. Second, we demonstrate the utility of stable paramagnetic tags for determining 3D structures of proteins in live cells, and pseudocontact shifts are shown to be valuable structural restraints for in-cell protein analysis. Third, we show that a NMR optimized paramagnetic tag allows one to determine distance restraints on proteins by double electron-electron resonance (DEER) measurements with high spatial resolution both in vitro and in cells. Finally, we summarize recent advances in site-specific tagging of proteins to achieve atomic-resolution information about structural changes of proteins, and the advantages and challenges of magnetic resonance spectroscopy in biological systems.
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Affiliation(s)
- Xun-Cheng Su
- State Key Laboratory of Elemento-organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Jia-Liang Chen
- State Key Laboratory of Elemento-organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
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Abstract
AbstractThe dynamics of proteins in solution includes a variety of processes, such as backbone and side-chain fluctuations, interdomain motions, as well as global rotational and translational (i.e. center of mass) diffusion. Since protein dynamics is related to protein function and essential transport processes, a detailed mechanistic understanding and monitoring of protein dynamics in solution is highly desirable. The hierarchical character of protein dynamics requires experimental tools addressing a broad range of time- and length scales. We discuss how different techniques contribute to a comprehensive picture of protein dynamics, and focus in particular on results from neutron spectroscopy. We outline the underlying principles and review available instrumentation as well as related analysis frameworks.
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50
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Ikeya T, Güntert P, Ito Y. Protein Structure Determination in Living Cells. Int J Mol Sci 2019; 20:E2442. [PMID: 31108891 PMCID: PMC6567067 DOI: 10.3390/ijms20102442] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 11/16/2022] Open
Abstract
To date, in-cell NMR has elucidated various aspects of protein behaviour by associating structures in physiological conditions. Meanwhile, current studies of this method mostly have deduced protein states in cells exclusively based on 'indirect' structural information from peak patterns and chemical shift changes but not 'direct' data explicitly including interatomic distances and angles. To fully understand the functions and physical properties of proteins inside cells, it is indispensable to obtain explicit structural data or determine three-dimensional (3D) structures of proteins in cells. Whilst the short lifetime of cells in a sample tube, low sample concentrations, and massive background signals make it difficult to observe NMR signals from proteins inside cells, several methodological advances help to overcome the problems. Paramagnetic effects have an outstanding potential for in-cell structural analysis. The combination of a limited amount of experimental in-cell data with software for ab initio protein structure prediction opens an avenue to visualise 3D protein structures inside cells. Conventional nuclear Overhauser effect spectroscopy (NOESY)-based structure determination is advantageous to elucidate the conformations of side-chain atoms of proteins as well as global structures. In this article, we review current progress for the structure analysis of proteins in living systems and discuss the feasibility of its future works.
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Affiliation(s)
- Teppei Ikeya
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minamiosawa, Hachioji, Tokyo 192-0397, Japan.
| | - Peter Güntert
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minamiosawa, Hachioji, Tokyo 192-0397, Japan.
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany.
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland; .
| | - Yutaka Ito
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minamiosawa, Hachioji, Tokyo 192-0397, Japan.
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