1
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Nguyen K, Strauss T, Refaeli B, Hiller R, Vinogradova O, Khananshvili D. 19F-NMR Probing of Ion-Induced Conformational Changes in Detergent-Solubilized and Nanodisc-Reconstituted NCX_Mj. Int J Mol Sci 2024; 25:6909. [PMID: 39000018 PMCID: PMC11241019 DOI: 10.3390/ijms25136909] [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: 06/06/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 07/14/2024] Open
Abstract
Consecutive interactions of 3Na+ or 1Ca2+ with the Na+/Ca2+ exchanger (NCX) result in an alternative exposure (access) of the cytosolic and extracellular vestibules to opposite sides of the membrane, where ion-induced transitions between the outward-facing (OF) and inward-facing (IF) conformational states drive a transport cycle. Here, we investigate sub-state populations of apo and ion-bound species in the OF and IF states by analyzing detergent-solubilized and nanodisc-reconstituted preparations of NCX_Mj with 19F-NMR. The 19F probe was covalently attached to the cysteine residues at entry locations of the cytosolic and extracellular vestibules. Multiple sub-states of apo and ion-bound species were observed in nanodisc-reconstituted (but not in detergent-solubilized) NCX_Mj, meaning that the lipid-membrane environment preconditions multiple sub-state populations toward the OF/IF swapping. Most importantly, ion-induced sub-state redistributions occur within each major (OF or IF) state, where sub-state interconversions may precondition the OF/IF swapping. In contrast with large changes in population redistributions, the sum of sub-state populations within each inherent state (OF or IF) remains nearly unchanged upon ion addition. The present findings allow the further elucidation of structure-dynamic modules underlying ion-induced conformational changes that determine a functional asymmetry of ion access/translocation at opposite sides of the membrane and ion transport rates concurring physiological demands.
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Affiliation(s)
- Khiem Nguyen
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
| | - Tali Strauss
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel Aviv 69978, Israel
| | - Bosmat Refaeli
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel Aviv 69978, Israel
| | - Reuben Hiller
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel Aviv 69978, Israel
| | - Olga Vinogradova
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
| | - Daniel Khananshvili
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel Aviv 69978, Israel
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2
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Ganguly HK, Ludwig BA, Tressler CM, Bhatt MR, Pandey AK, Quinn CM, Bai S, Yap GPA, Zondlo NJ. 4,4-Difluoroproline as a Unique 19F NMR Probe of Proline Conformation. Biochemistry 2024; 63:1131-1146. [PMID: 38598681 DOI: 10.1021/acs.biochem.3c00697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Despite the importance of proline conformational equilibria (trans versus cis amide and exo versus endo ring pucker) on protein structure and function, there is a lack of convenient ways to probe proline conformation. 4,4-Difluoroproline (Dfp) was identified to be a sensitive 19F NMR-based probe of proline conformational biases and cis-trans isomerism. Within model compounds and disordered peptides, the diastereotopic fluorines of Dfp exhibit similar chemical shifts (ΔδFF = 0-3 ppm) when a trans X-Dfp amide bond is present. In contrast, the diastereotopic fluorines exhibit a large (ΔδFF = 5-12 ppm) difference in chemical shift in a cis X-Dfp prolyl amide bond. DFT calculations, X-ray crystallography, and solid-state NMR spectroscopy indicated that ΔδFF directly reports on the relative preference of one proline ring pucker over the other: a fluorine which is pseudo-axial (i.e., the pro-4R-F in an exo ring pucker, or the pro-4S-F in an endo ring pucker) is downfield, while a fluorine which is pseudo-equatorial (i.e., pro-4S-F when exo, or pro-4R-F when endo) is upfield. Thus, when a proline is disordered (a mixture of exo and endo ring puckers, as at trans-Pro in peptides in water), it exhibits a small Δδ. In contrast, when the Pro is ordered (i.e., when one ring pucker is strongly preferred, as in cis-Pro amide bonds, where the endo ring pucker is strongly favored), a large Δδ is observed. Dfp can be used to identify inherent induced order in peptides and to quantify proline cis-trans isomerism. Using Dfp, we discovered that the stable polyproline II helix (PPII) formed in the denatured state (8 M urea) exhibits essentially equal populations of the exo and endo proline ring puckers. In addition, the data with Dfp suggested the specific stabilization of PPII by water over other polar solvents. These data strongly support the importance of carbonyl solvation and n → π* interactions for the stabilization of PPII. Dfp was also employed to quantify proline cis-trans isomerism as a function of phosphorylation and the R406W mutation in peptides derived from the intrinsically disordered protein tau. Dfp is minimally sterically disruptive and can be incorporated in expressed proteins, suggesting its broad application in understanding proline cis-trans isomerization, protein folding, and local order in intrinsically disordered proteins.
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Affiliation(s)
- Himal K Ganguly
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Brice A Ludwig
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Caitlin M Tressler
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Megh R Bhatt
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Anil K Pandey
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Shi Bai
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Glenn P A Yap
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Neal J Zondlo
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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3
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Chai Z, Li C. In-Cell 19F NMR of Proteins: Recent Progress and Future Opportunities. Chemistry 2024; 30:e202303988. [PMID: 38269421 DOI: 10.1002/chem.202303988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/23/2024] [Accepted: 01/24/2024] [Indexed: 01/26/2024]
Abstract
In vitro, 19F NMR methodology is preferably selected as a complementary and straightforward method for unveiling the conformations, dynamics, and interactions of biological molecules. Its effectiveness in vivo has seen continuous improvement, addressing challenges faced by conventional heteronuclear NMR experiments on structured proteins, such as severe line broadening, low signal-to-noise ratio, and background signals. Herein, we summarize the distinctive advantages of 19F NMR, along with recent progress in sample preparation and applications within the realm of in-cell NMR. Additionally, we offer insights into the future directions and prospects of this methodology based on our understanding.
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Affiliation(s)
- Zhaofei Chai
- 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 National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, 430071, Wuhan, China
| | - Conggang Li
- 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 National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, 430071, Wuhan, China
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4
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Nussinov R, Liu Y, Zhang W, Jang H. Protein conformational ensembles in function: roles and mechanisms. RSC Chem Biol 2023; 4:850-864. [PMID: 37920394 PMCID: PMC10619138 DOI: 10.1039/d3cb00114h] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 09/02/2023] [Indexed: 11/04/2023] Open
Abstract
The sequence-structure-function paradigm has dominated twentieth century molecular biology. The paradigm tacitly stipulated that for each sequence there exists a single, well-organized protein structure. Yet, to sustain cell life, function requires (i) that there be more than a single structure, (ii) that there be switching between the structures, and (iii) that the structures be incompletely organized. These fundamental tenets called for an updated sequence-conformational ensemble-function paradigm. The powerful energy landscape idea, which is the foundation of modernized molecular biology, imported the conformational ensemble framework from physics and chemistry. This framework embraces the recognition that proteins are dynamic and are always interconverting between conformational states with varying energies. The more stable the conformation the more populated it is. The changes in the populations of the states are required for cell life. As an example, in vivo, under physiological conditions, wild type kinases commonly populate their more stable "closed", inactive, conformations. However, there are minor populations of the "open", ligand-free states. Upon their stabilization, e.g., by high affinity interactions or mutations, their ensembles shift to occupy the active states. Here we discuss the role of conformational propensities in function. We provide multiple examples of diverse systems, including protein kinases, lipid kinases, and Ras GTPases, discuss diverse conformational mechanisms, and provide a broad outlook on protein ensembles in the cell. We propose that the number of molecules in the active state (inactive for repressors), determine protein function, and that the dynamic, relative conformational propensities, rather than the rigid structures, are the hallmark of cell life.
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Affiliation(s)
- Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research Frederick MD 21702 USA
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University Tel Aviv 69978 Israel
- Cancer Innovation Laboratory, National Cancer Institute Frederick MD 21702 USA
| | - Yonglan Liu
- Cancer Innovation Laboratory, National Cancer Institute Frederick MD 21702 USA
| | - Wengang Zhang
- Cancer Innovation Laboratory, National Cancer Institute Frederick MD 21702 USA
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research Frederick MD 21702 USA
- Cancer Innovation Laboratory, National Cancer Institute Frederick MD 21702 USA
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5
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Prosser RS, Alonzi NA. Discerning conformational dynamics and binding kinetics of GPCRs by 19F NMR. Curr Opin Pharmacol 2023; 72:102377. [PMID: 37612172 DOI: 10.1016/j.coph.2023.102377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 08/25/2023]
Abstract
19F NMR provides a way of monitoring conformational dynamics of G-protein coupled receptors (GPCRs) from the perspective of an ensemble. While X-ray crystallography provides exquisitely resolved high-resolution structures of specific states, it generally does not recapitulate the true ensemble of functional states. Fluorine (19F) NMR provides a highly sensitive spectroscopic window into the conformational ensemble, generally permitting the direct quantification of resolvable states. Moreover, straightforward T1- and T2-based relaxation experiments allow for the study of fluctuations within a given state and exchange between states, on timescales spanning nanoseconds to seconds. Conveniently, most biological systems are free of fluorine. Thus, via fluorinated amino acid analogues or thiol-reactive fluorinated tags, F or CF3 reporters can be site specifically incorporated into proteins of interest. In this review, fluorine labeling protocols and 19F NMR experiments will be presented, from the perspective of small molecule NMR (i.e. drug or small molecule interactions with receptors) or macromolecular NMR (i.e. conformational dynamics of receptors and receptor-G-protein complexes).
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Affiliation(s)
- R S Prosser
- Chemistry Department, University of Toronto, CPS UTM, Davis Building, Rm 4052, 3359 Mississauga Rd North, Mississauga, Ontario, L5L 1C6, Canada; Biochemistry Department, University of Toronto, CPS UTM, Davis Building, Rm 4052, 3359 Mississauga Rd North, Mississauga, Ontario, L5L 1C6, Canada.
| | - Nicholas A Alonzi
- Chemistry Department, University of Toronto, CPS UTM, Davis Building, Rm 4052, 3359 Mississauga Rd North, Mississauga, Ontario, L5L 1C6, Canada
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6
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Puthenveetil R, Christenson ET, Vinogradova O. New Horizons in Structural Biology of Membrane Proteins: Experimental Evaluation of the Role of Conformational Dynamics and Intrinsic Flexibility. MEMBRANES 2022; 12:227. [PMID: 35207148 PMCID: PMC8877495 DOI: 10.3390/membranes12020227] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 02/13/2022] [Accepted: 02/14/2022] [Indexed: 02/08/2023]
Abstract
A plethora of membrane proteins are found along the cell surface and on the convoluted labyrinth of membranes surrounding organelles. Since the advent of various structural biology techniques, a sub-population of these proteins has become accessible to investigation at near-atomic resolutions. The predominant bona fide methods for structure solution, X-ray crystallography and cryo-EM, provide high resolution in three-dimensional space at the cost of neglecting protein motions through time. Though structures provide various rigid snapshots, only an amorphous mechanistic understanding can be inferred from interpolations between these different static states. In this review, we discuss various techniques that have been utilized in observing dynamic conformational intermediaries that remain elusive from rigid structures. More specifically we discuss the application of structural techniques such as NMR, cryo-EM and X-ray crystallography in studying protein dynamics along with complementation by conformational trapping by specific binders such as antibodies. We finally showcase the strength of various biophysical techniques including FRET, EPR and computational approaches using a multitude of succinct examples from GPCRs, transporters and ion channels.
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Affiliation(s)
- Robbins Puthenveetil
- Section on Structural and Chemical Biology of Membrane Proteins, Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 35A Convent Dr., Bethesda, MD 20892, USA
| | | | - Olga Vinogradova
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
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7
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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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8
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The native state conformational heterogeneity in the energy landscape of protein folding. Biophys Chem 2022; 283:106761. [DOI: 10.1016/j.bpc.2022.106761] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 11/18/2022]
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9
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Orton HW, Qianzhu H, Abdelkader EH, Habel EI, Tan YJ, Frkic RL, Jackson CJ, Huber T, Otting G. Through-Space Scalar 19F- 19F Couplings between Fluorinated Noncanonical Amino Acids for the Detection of Specific Contacts in Proteins. J Am Chem Soc 2021; 143:19587-19598. [PMID: 34780162 DOI: 10.1021/jacs.1c10104] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluorine atoms are known to display scalar 19F-19F couplings in nuclear magnetic resonance (NMR) spectra when they are sufficiently close in space for nonbonding orbitals to overlap. We show that fluorinated noncanonical amino acids positioned in the hydrophobic core or on the surface of a protein can be linked by scalar through-space 19F-19F (TSJFF) couplings even if the 19F spins are in the time average separated by more than the van der Waals distance. Using two different aromatic amino acids featuring CF3 groups, O-trifluoromethyl-tyrosine and 4-trifluoromethyl-phenylalanine, we show that 19F-19F TOCSY experiments are sufficiently sensitive to detect TSJFF couplings between 2.5 and 5 Hz in the 19 kDa protein PpiB measured on a two-channel 400 MHz NMR spectrometer with a regular room temperature probe. A quantitative J evolution experiment enables the measurement of TSJFF coupling constants that are up to five times smaller than the 19F NMR line width. In addition, a new aminoacyl-tRNA synthetase was identified for genetic encoding of N6-(trifluoroacetyl)-l-lysine (TFA-Lys) and 19F-19F TOCSY peaks were observed between two TFA-Lys residues incorporated into the proteins AncCDT-1 and mRFP despite high solvent exposure and flexibility of the TFA-Lys side chains. With the ready availability of systems for site-specific incorporation of fluorinated amino acids into proteins by genetic encoding, 19F-19F interactions offer a straightforward way to probe the spatial proximity of selected sites without any assignments of 1H NMR resonances.
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Affiliation(s)
- Henry W Orton
- ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Haocheng Qianzhu
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Elwy H Abdelkader
- ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Edan I Habel
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Yi Jiun Tan
- ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Rebecca L Frkic
- ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Colin J Jackson
- ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Thomas Huber
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Gottfried Otting
- ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
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10
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Varner TA, Mohamed-Raseek N, Miller AF. Assignments of 19F NMR resonances and exploration of dynamics in a long-chain flavodoxin. Arch Biochem Biophys 2021; 703:108839. [PMID: 33727041 DOI: 10.1016/j.abb.2021.108839] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 03/04/2021] [Accepted: 03/09/2021] [Indexed: 12/23/2022]
Abstract
Flavodoxin is a small protein that employs a non-covalently bound flavin to mediate single-electron transfer at low potentials. The long-chain flavodoxins possess a long surface loop that is proposed to interact with partner proteins. We have incorporated 19F-labeled tyrosine in long-chain flavodoxin from Rhodopseudomonas palustris to gain a probe of possible loop dynamics, exploiting the presence of a Tyr in the long loop in addition to Tyr residues near the flavin. We report 19F resonance assignments for all four Tyrs, and demonstration of a pair of resonances in slow exchange, both corresponding to a Tyr adjacent to the flavin. We also provide evidence for dynamics affecting the Tyr in the long loop. Thus, we show that 19F NMR of 19F-Tyr labeled flavodoxin holds promise for monitoring possible changes in conformation upon binding to partner proteins.
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Affiliation(s)
- Taylor A Varner
- Department of Chemistry, University of Kentucky, Lexington, KY, 40506, USA
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11
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Gimenez D, Phelan A, Murphy CD, Cobb SL. 19F NMR as a tool in chemical biology. Beilstein J Org Chem 2021; 17:293-318. [PMID: 33564338 PMCID: PMC7849273 DOI: 10.3762/bjoc.17.28] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 01/07/2021] [Indexed: 12/15/2022] Open
Abstract
We previously reviewed the use of 19F NMR in the broad field of chemical biology [Cobb, S. L.; Murphy, C. D. J. Fluorine Chem. 2009, 130, 132-140] and present here a summary of the literature from the last decade that has the technique as the central method of analysis. The topics covered include the synthesis of new fluorinated probes and their incorporation into macromolecules, the application of 19F NMR to monitor protein-protein interactions, protein-ligand interactions, physiologically relevant ions and in the structural analysis of proteins and nucleic acids. The continued relevance of the technique to investigate biosynthesis and biodegradation of fluorinated organic compounds is also described.
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Affiliation(s)
- Diana Gimenez
- Department of Chemistry, Durham University, South Road, Durham, DH13LE, UK
| | - Aoife Phelan
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Cormac D Murphy
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Steven L Cobb
- Department of Chemistry, Durham University, South Road, Durham, DH13LE, UK
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12
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Wu T, Li A, Chen K, Peng X, Zhang J, Jiang M, Chen S, Zheng X, Zhou X, Jiang ZX. Perfluoro- tert-butanol: a cornerstone for high performance fluorine-19 magnetic resonance imaging. Chem Commun (Camb) 2021; 57:7743-7757. [PMID: 34286714 DOI: 10.1039/d1cc02133h] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
As a versatile quantification and tracking technology, 19F magnetic resonance imaging (19F MRI) provides quantitative "hot-spot" images without ionizing radiation, tissue depth limit, and background interference. However, the lack of suitable imaging agents severely hampers its clinical application. First, because the 19F signals are solely originated from imaging agents, the relatively low sensitivity of MRI technology requires high local 19F concentrations to generate images, which are often beyond the reach of many 19F MRI agents. Second, the peculiar physicochemical properties of many fluorinated compounds usually lead to low 19F signal intensity, tedious formulation, severe organ retention, etc. Therefore, the development of 19F MRI agents with high sensitivity and with suitable physicochemical and biological properties is of great importance. To this end, perfluoro-tert-butanol (PFTB), containing nine equivalent 19F and a modifiable hydroxyl group, has outperformed most perfluorocarbons as a valuable building block for high performance 19F MRI agents. Herein, we summarize the development and application of PFTB-based 19F MRI agents and analyze the strategies to improve their sensitivity and physicochemical and biological properties. In the context of PFC-based 19F MRI agents, we also discuss the challenges and prospects of PFTB-based 19F MRI agents.
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Affiliation(s)
- Tingjuan Wu
- Group of Lead Compound, Department of Pharmacy, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang 421001, Hunan, China.
| | - Anfeng Li
- Group of Lead Compound, Department of Pharmacy, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang 421001, Hunan, China.
| | - Kexin Chen
- Group of Lead Compound, Department of Pharmacy, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang 421001, Hunan, China.
| | - Xingxing Peng
- Group of Lead Compound, Department of Pharmacy, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang 421001, Hunan, China.
| | - Jing Zhang
- Hubei Province Engineering and Technology Research Center for Fluorinated Pharmaceuticals, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China.
| | - Mou Jiang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovative Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Wuhan 430071, China.
| | - Shizhen Chen
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovative Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Wuhan 430071, China.
| | - Xing Zheng
- Group of Lead Compound, Department of Pharmacy, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang 421001, Hunan, China.
| | - Xin Zhou
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovative Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Wuhan 430071, China.
| | - Zhong-Xing Jiang
- Group of Lead Compound, Department of Pharmacy, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang 421001, Hunan, China. and Hubei Province Engineering and Technology Research Center for Fluorinated Pharmaceuticals, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China.
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13
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Miller MA, Sletten EM. Perfluorocarbons in Chemical Biology. Chembiochem 2020; 21:3451-3462. [PMID: 32628804 PMCID: PMC7736518 DOI: 10.1002/cbic.202000297] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/03/2020] [Indexed: 01/10/2023]
Abstract
Perfluorocarbons, saturated carbon chains in which all the hydrogen atoms are replaced with fluorine, form a separate phase from both organic and aqueous solutions. Though perfluorinated compounds are not found in living systems, they can be used to modify biomolecules to confer orthogonal behavior within natural systems, such as improved stability, engineered assembly, and cell-permeability. Perfluorinated groups also provide handles for purification, mass spectrometry, and 19 F NMR studies in complex environments. Herein, we describe how the unique properties of perfluorocarbons have been employed to understand and manipulate biological systems.
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Affiliation(s)
- Margeaux A Miller
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E Young Dr E, Los Angeles, CA, 90095, USA
| | - Ellen M Sletten
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E Young Dr E, Los Angeles, CA, 90095, USA
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14
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Cheng RC, Maduke M. Expanding the membrane-protein NMR toolkit. Nat Chem Biol 2020; 16:937-938. [PMID: 32665639 PMCID: PMC8064024 DOI: 10.1038/s41589-020-0597-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An NMR method to monitor conformational states of challenging large protein targets is described. The method, which can be used to evaluate distances between two labels and to measure conformational exchange rates, revealed an unanticipated outward-facing state in a glutamate transporter.
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Affiliation(s)
- Ricky C Cheng
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Merritt Maduke
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
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15
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Huang Y, Wang X, Lv G, Razavi AM, Huysmans GHM, Weinstein H, Bracken C, Eliezer D, Boudker O. Use of paramagnetic 19F NMR to monitor domain movement in a glutamate transporter homolog. Nat Chem Biol 2020; 16:1006-1012. [PMID: 32514183 PMCID: PMC7442671 DOI: 10.1038/s41589-020-0561-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 05/07/2020] [Indexed: 12/17/2022]
Abstract
In proteins where conformational changes are functionally important, the number of accessible states and their dynamics are often difficult to establish. Here we describe a novel 19F-NMR spectroscopy approach to probe dynamics of large membrane proteins. We labeled a glutamate transporter homolog with a 19F probe via cysteine chemistry and with a Ni2+ ion via chelation by a di-histidine motif. We used distance-dependent enhancement of the longitudinal relaxation of 19F nuclei by the paramagnetic metal to assign the observed resonances. We identified one inward- and two outward-facing states of the transporter, in which the substrate-binding site is near the extracellular and intracellular solutions, respectively. We then resolved the structure of the unanticipated second outward-facing state by cryo-EM. Finally, we showed that the rates of the conformational exchange are accessible from measurements of the metal-enhanced longitudinal relaxation of 19F nuclei.
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Affiliation(s)
- Yun Huang
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, NY, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Xiaoyu Wang
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Guohua Lv
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, USA
- Division of Histology & Embryology, Medical College, Jinan University, Guangzhou, China
| | - Asghar M Razavi
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Gerard H M Huysmans
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Harel Weinstein
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Clay Bracken
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, USA
| | - David Eliezer
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, USA.
| | - Olga Boudker
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, NY, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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16
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Dietschreit JCB, Wagner A, Le TA, Klein P, Schindelin H, Opatz T, Engels B, Hellmich UA, Ochsenfeld C. Predicting
19
F NMR Chemical Shifts: A Combined Computational and Experimental Study of a Trypanosomal Oxidoreductase–Inhibitor Complex. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000539] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Johannes C. B. Dietschreit
- Theoretical Chemistry Department of Chemistry University of Munich (LMU) Butenandtstr. 7 81377 Munich Germany
| | - Annika Wagner
- Dept. Chemistry Section Biochemistry Johannes Gutenberg-Universität Mainz 55128 Mainz Germany
- Centre for Biomolecular Magnetic Resonance (BMRZ) Goethe-University Frankfurt Max-von-Laue Str. 9 60438 Frankfurt Germany
| | - T. Anh Le
- Institute for Physical and Theoretical Chemistry University of Würzburg Emil-Fischer-Straße 42 97074 Würzburg Germany
| | - Philipp Klein
- Dept. Chemistry Section Organic Chemistry Johannes Gutenberg-Universität Mainz 55128 Mainz Germany
| | - Hermann Schindelin
- Institute of Structural Biology Rudolf Virchow Center for Experimental Biomedicine University of Würzburg 97080 Würzburg Germany
| | - Till Opatz
- Dept. Chemistry Section Organic Chemistry Johannes Gutenberg-Universität Mainz 55128 Mainz Germany
| | - Bernd Engels
- Institute for Physical and Theoretical Chemistry University of Würzburg Emil-Fischer-Straße 42 97074 Würzburg Germany
| | - Ute A. Hellmich
- Dept. Chemistry Section Biochemistry Johannes Gutenberg-Universität Mainz 55128 Mainz Germany
- Centre for Biomolecular Magnetic Resonance (BMRZ) Goethe-University Frankfurt Max-von-Laue Str. 9 60438 Frankfurt Germany
| | - Christian Ochsenfeld
- Theoretical Chemistry Department of Chemistry University of Munich (LMU) Butenandtstr. 7 81377 Munich Germany
- Max Planck Institute for Solid State Research 70569 Stuttgart Germany
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17
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Dietschreit JCB, Wagner A, Le TA, Klein P, Schindelin H, Opatz T, Engels B, Hellmich UA, Ochsenfeld C. Predicting 19 F NMR Chemical Shifts: A Combined Computational and Experimental Study of a Trypanosomal Oxidoreductase-Inhibitor Complex. Angew Chem Int Ed Engl 2020; 59:12669-12673. [PMID: 32239740 PMCID: PMC7496126 DOI: 10.1002/anie.202000539] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/22/2020] [Indexed: 02/02/2023]
Abstract
The absence of fluorine from most biomolecules renders it an excellent probe for NMR spectroscopy to monitor inhibitor-protein interactions. However, predicting the binding mode of a fluorinated ligand from a chemical shift (or vice versa) has been challenging due to the high electron density of the fluorine atom. Nonetheless, reliable 19 F chemical-shift predictions to deduce ligand-binding modes hold great potential for in silico drug design. Herein, we present a systematic QM/MM study to predict the 19 F NMR chemical shifts of a covalently bound fluorinated inhibitor to the essential oxidoreductase tryparedoxin (Tpx) from African trypanosomes, the causative agent of African sleeping sickness. We include many protein-inhibitor conformations as well as monomeric and dimeric inhibitor-protein complexes, thus rendering it the largest computational study on chemical shifts of 19 F nuclei in a biological context to date. Our predicted shifts agree well with those obtained experimentally and pave the way for future work in this area.
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Affiliation(s)
| | - Annika Wagner
- Dept. ChemistrySection BiochemistryJohannes Gutenberg-Universität Mainz55128MainzGermany
- Centre for Biomolecular Magnetic Resonance (BMRZ)Goethe-University FrankfurtMax-von-Laue Str. 960438FrankfurtGermany
| | - T. Anh Le
- Institute for Physical and Theoretical ChemistryUniversity of WürzburgEmil-Fischer-Straße 4297074WürzburgGermany
| | - Philipp Klein
- Dept. ChemistrySection Organic ChemistryJohannes Gutenberg-Universität Mainz55128MainzGermany
| | - Hermann Schindelin
- Institute of Structural BiologyRudolf Virchow Center for Experimental BiomedicineUniversity of Würzburg97080WürzburgGermany
| | - Till Opatz
- Dept. ChemistrySection Organic ChemistryJohannes Gutenberg-Universität Mainz55128MainzGermany
| | - Bernd Engels
- Institute for Physical and Theoretical ChemistryUniversity of WürzburgEmil-Fischer-Straße 4297074WürzburgGermany
| | - Ute A. Hellmich
- Dept. ChemistrySection BiochemistryJohannes Gutenberg-Universität Mainz55128MainzGermany
- Centre for Biomolecular Magnetic Resonance (BMRZ)Goethe-University FrankfurtMax-von-Laue Str. 960438FrankfurtGermany
| | - Christian Ochsenfeld
- Theoretical ChemistryDepartment of ChemistryUniversity of Munich (LMU)Butenandtstr. 781377MunichGermany
- Max Planck Institute for Solid State Research70569StuttgartGermany
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18
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Rashid S, Lee BL, Wajda B, Spyracopoulos L. Nucleotide Binding and Active Site Gate Dynamics for the Hsp90 Chaperone ATPase Domain from Benchtop and High Field 19F NMR Spectroscopy. J Phys Chem B 2020; 124:2984-2993. [PMID: 32212608 DOI: 10.1021/acs.jpcb.0c00626] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein turnover in cells is regulated by the ATP dependent activity of the Hsp90 chaperone. In concert with accessory proteins, ATP hydrolysis drives the obligate Hsp90 dimer through a cycle between open and closed states that is critical for assisting the folding and stability of hundreds of proteins. Cycling is initiated by ATP binding to the ATPase domain, with the chaperone and the active site gates in the dimer in open states. The chaperone then adopts a short-lived, ATP bound closed state with a closed active site gate. The structural and dynamic changes induced in the ATPase domain and active site gate upon nucleotide binding, and their impact on dimer closing are not well understood. We site-specifically 19F-labeled the ATPase domain at the active site gate to enable benchtop and high field 19F NMR spectroscopic studies. Combined with MD simulations, this allowed accurate characterization of pico- to nanosecond time scale motions of the active site gate, as well as slower micro- to millisecond time scale processes resulting from nucleotide binding. ATP binding induces increased flexibility at one of the hinges of the active site gate, a necessary prelude to release of the second hinge and eventual gate closure in the intact chaperone.
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Affiliation(s)
- Suad Rashid
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Brian L Lee
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Benjamin Wajda
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Leo Spyracopoulos
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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