1
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Li M, Xu G, Gong Z, Wu Q, Jiang L, Li C. Simultaneous measurement of multiple fluorine labelling effect on GB1 stability by 19F NMR. Talanta 2025; 292:127959. [PMID: 40112587 DOI: 10.1016/j.talanta.2025.127959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2025] [Revised: 03/09/2025] [Accepted: 03/15/2025] [Indexed: 03/22/2025]
Abstract
The incorporation of fluorinated amino acids into proteins through natural biosynthesis in E. coli often leads to the production of heterogeneous fluorinated proteins. The stabilities of proteins with different 19F labelling states can vary, but these differences are challenging to measure due to the difficulty in separating the fluorinated protein mixtures that differ by only a few 19F atoms. Here, we simultaneously incorporated both fluoro-phenylalanines (3-fluoro-phenylalanine, 3FF; or 4-fluoro-phenylalanine, 4FF) and 5-fluoro-tryptophan (5FW) into GB1 protein. We are able to measure the stability of GB1 protein with different 19F labelling states without the need for sample separation by taking the advantage of 19F NMR. The results showed that 4FF-5FW-GB1 with varying 19F labelling states exhibited significantly different protein stability, with higher 4FF labeling efficiency correlating with decreased stability. Furthermore, residues F30 and F52 show synergistic effects on GB1 stability. In contrast, the 3FF and 5FW substitution exhibits a slightly stabilizing effect on GB1 stability. The present research provides a convenient 19F NMR method to simultaneously measure fluorine labelling effects on protein stability, favouring precise understanding and analysis of fluorine labelling effects.
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Affiliation(s)
- Manman Li
- State Key Laboratory of Magnetic Resonance Spectroscopy and Imaging, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Guohua Xu
- State Key Laboratory of Magnetic Resonance Spectroscopy and Imaging, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
| | - Zhou Gong
- State Key Laboratory of Magnetic Resonance Spectroscopy and Imaging, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Qiong Wu
- State Key Laboratory of Magnetic Resonance Spectroscopy and Imaging, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Ling Jiang
- State Key Laboratory of Magnetic Resonance Spectroscopy and Imaging, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Conggang Li
- State Key Laboratory of Magnetic Resonance Spectroscopy and Imaging, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
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2
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Bogdanov A, Gao L, Dalaloyan A, Zhu W, Seal M, Su XC, Frydman V, Liu Y, Gronenborn AM, Goldfarb D. Spin labels for 19F ENDOR distance determination: resolution, sensitivity and distance predictability. Phys Chem Chem Phys 2024; 26:26921-26932. [PMID: 39417349 DOI: 10.1039/d4cp02996h] [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: 10/19/2024]
Abstract
19F electron-nuclear double resonance (ENDOR) has emerged as an attractive method for determining distance distributions in biomolecules in the range of 0.7-2 nm, which is not easily accessible by pulsed electron dipolar spectroscopy. The 19F ENDOR approach relies on spin labeling, and in this work, we compare various labels' performance. Four protein variants of GB1 and ubiquitin bearing fluorinated residues were labeled at the same site with nitroxide and trityl radicals and a Gd(III) chelate. Additionally, a double-histidine variant of GB1 was labeled with a Cu(II) nitrilotriacetic acid chelate. ENDOR measurements were carried out at W-band (95 GHz) where 19F signals are well separated from 1H signals. Differences in sensitivity were observed, with Gd(III) chelates providing the highest signal-to-noise ratio. The new trityl label, OXMA, devoid of methyl groups, exhibited a sufficiently long phase memory time to provide an acceptable sensitivity. However, the longer tether of this label effectively reduces the maximum accessible distance between the 19F and the Cα of the spin-labeling site. The nitroxide and Cu(II) labels provide valuable additional geometric insights via orientation selection. Prediction of electron-nuclear distances based on the known structures of the proteins were the closest to the experimental values for Gd(III) labels, and distances obtained for Cu(II) labeled GB1 are in good agreement with previously published NMR results. Overall, our results offer valuable guidance for selecting optimal spin labels for 19F ENDOR distance measurement in proteins.
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Affiliation(s)
- Alexey Bogdanov
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, P. O. Box 26, Rehovot, 7610001, Israel.
| | - Longfei Gao
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P. R. China
| | - Arina Dalaloyan
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, P. O. Box 26, Rehovot, 7610001, Israel.
| | - Wenkai Zhu
- Department of Structural Biology, University of Pittsburgh, 4200 Fifth Ave, Pittsburgh, PA 15260, USA
| | - Manas Seal
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, P. O. Box 26, Rehovot, 7610001, Israel.
| | - Xun-Cheng Su
- State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P. R. China
| | - Veronica Frydman
- Department of Chemical Research Support, The Weizmann Institute of Science, P. O. Box 26, Rehovot, 7610001, Israel
| | - Yangping Liu
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P. R. China
| | - Angela M Gronenborn
- Department of Structural Biology, University of Pittsburgh, 4200 Fifth Ave, Pittsburgh, PA 15260, USA
| | - Daniella Goldfarb
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, P. O. Box 26, Rehovot, 7610001, Israel.
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3
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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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Phạm TTT, Murza A, Marsault É, Frampton JP, Rainey JK. Localized apelin-17 analogue-bicelle interactions as a facilitator of membrane-catalyzed receptor recognition and binding. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184289. [PMID: 38278504 DOI: 10.1016/j.bbamem.2024.184289] [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: 11/10/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 01/28/2024]
Abstract
The apelinergic system encompasses two peptide ligand families, apelin and apela, along with the apelin receptor (AR or APJ), a class A G-protein-coupled receptor. This system has diverse physiological effects, including modulating heart contraction, vasodilation/constriction, glucose regulation, and vascular development, with involvement in a variety of pathological conditions. Apelin peptides have been previously shown to interact with and become structured upon binding to anionic micelles, consistent with a membrane-catalyzed mechanism of ligand-receptor binding. To overcome the challenges of observing nuclear magnetic resonance (NMR) spectroscopy signals of a dilute peptide in biological environments, 19F NMR spectroscopy, including diffusion ordered spectroscopy (DOSY) and saturation transfer difference (STD) experiments, was used herein to explore the membrane-interactive behaviour of apelin. NMR-optimized apelin-17 analogues with 4-trifluoromethyl-phenylalanine at various positions were designed and tested for bioactivity through ERK activation in stably-AR transfected HEK 293 T cells. Far-UV circular dichroism (CD) spectropolarimetry and 19F NMR spectroscopy were used to compare the membrane interactions of these analogues with unlabelled apelin-17 in both zwitterionic/neutral and net-negative bicelle conditions. Each analogue binds to bicelles with relatively weak affinity (i.e., in fast exchange on the NMR timescale), with preferential interactions observed at the cationic residue-rich N-terminal and mid-length regions of the peptide leaving the C-terminal end unencumbered for receptor recognition, enabling a membrane-anchored fly-casting mechanism of peptide search for the receptor. In all, this study provides further insight into the membrane-interactive behaviour of an important bioactive peptide, demonstrating interactions and biophysical behaviour that cannot be neglected in therapeutic design.
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Affiliation(s)
- Trần Thanh Tâm Phạm
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Alexandre Murza
- Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Éric Marsault
- Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - John P Frampton
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada; School of Biomedical Engineering, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Jan K Rainey
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada; School of Biomedical Engineering, Dalhousie University, Halifax, NS B3H 4R2, Canada; Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.
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5
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Liu J, Wu XL, Zeng YT, Hu ZH, Lu JX. Solid-state NMR studies of amyloids. Structure 2023; 31:230-243. [PMID: 36750098 DOI: 10.1016/j.str.2023.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 10/10/2022] [Accepted: 01/09/2023] [Indexed: 02/08/2023]
Abstract
Amyloids have special structural properties and are involved in many aspects of biological function. In particular, amyloids are the cause or hallmarks of a group of notorious and incurable neurodegenerative diseases. The extraordinary high molecular weight and aggregation states of amyloids have posed a challenge for researchers studying them. Solid-state NMR (SSNMR) has been extensively applied to study the structures and dynamics of amyloids for the past 20 or more years and brought us tremendous progress in understanding their structure and related diseases. These studies, at the same time, helped to push SSNMR technical developments in sensitivity and resolution. In this review, some interesting research studies and important technical developments are highlighted to give the reader an overview of the current state of this field.
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Affiliation(s)
- Jing Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xia-Lian Wu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yu-Teng Zeng
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Zhi-Heng Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jun-Xia Lu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
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6
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Cell-free synthesis of amyloid fibrils with infectious properties and amenable to sub-milligram magic-angle spinning NMR analysis. Commun Biol 2022; 5:1202. [DOI: 10.1038/s42003-022-04175-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/26/2022] [Indexed: 11/11/2022] Open
Abstract
AbstractStructural investigations of amyloid fibrils often rely on heterologous bacterial overexpression of the protein of interest. Due to their inherent hydrophobicity and tendency to aggregate as inclusion bodies, many amyloid proteins are challenging to express in bacterial systems. Cell-free protein expression is a promising alternative to classical bacterial expression to produce hydrophobic proteins and introduce NMR-active isotopes that can improve and speed up the NMR analysis. Here we implement the cell-free synthesis of the functional amyloid prion HET-s(218-289). We present an interesting case where HET-s(218-289) directly assembles into infectious fibril in the cell-free expression mixture without the requirement of denaturation procedures and purification. By introducing tailored 13C and 15N isotopes or CF3 and 13CH2F labels at strategic amino-acid positions, we demonstrate that cell-free synthesized amyloid fibrils are readily amenable to high-resolution magic-angle spinning NMR at sub-milligram quantity.
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7
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Duan P, Dregni AJ, Hong M. Solid-State NMR 19F- 1H- 15N Correlation Experiments for Resonance Assignment and Distance Measurements of Multifluorinated Proteins. J Phys Chem A 2022; 126:7021-7032. [PMID: 36150071 PMCID: PMC10867861 DOI: 10.1021/acs.jpca.2c05154] [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: 11/28/2022]
Abstract
Several solid-state NMR techniques have been introduced recently to measure nanometer distances involving 19F, whose high gyromagnetic ratio makes it a potent nuclear spin for structural investigation. These solid-state NMR techniques either use 19F correlation with 1H or 13C to obtain qualitative interatomic contacts or use the rotational-echo double-resonance (REDOR) pulse sequence to measure quantitative distances. However, no NMR technique is yet available for disambiguating 1H-19F distances in multiply fluorinated proteins and protein-ligand complexes. Here, we introduce a three-dimensional (3D) 19F-15N-1H correlation experiment that resolves the distances of multiple fluorines to their adjacent amide protons. We show that optimal polarization transfer between 1H and 19F spins is achieved using an out-and-back 1H-19F REDOR sequence. We demonstrate this 3D correlation experiment on the model protein GB1 and apply it to the multidrug-resistance transporter, EmrE, complexed to a tetrafluorinated substrate. This technique should be useful for resolving and assigning distance constraints in multiply fluorinated proteins, leading to significant savings of time and precious samples compared to producing several singly fluorinated samples. Moreover, the method enables structural determination of protein-ligand complexes for ligands that contain multiple fluorines.
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Affiliation(s)
- Pu Duan
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Aurelio J. Dregni
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
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8
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Membranolytic Mechanism of Amphiphilic Antimicrobial β-Stranded [KL]n Peptides. Biomedicines 2022; 10:biomedicines10092071. [PMID: 36140173 PMCID: PMC9495826 DOI: 10.3390/biomedicines10092071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/19/2022] [Accepted: 08/21/2022] [Indexed: 11/17/2022] Open
Abstract
Amphipathic peptides can act as antibiotics due to membrane permeabilization. KL peptides with the repetitive sequence [Lys-Leu]n-NH2 form amphipathic β-strands in the presence of lipid bilayers. As they are known to kill bacteria in a peculiar length-dependent manner, we suggest here several different functional models, all of which seem plausible, including a carpet mechanism, a β-barrel pore, a toroidal wormhole, and a β-helix. To resolve their genuine mechanism, the activity of KL peptides with lengths from 6–26 amino acids (plus some inverted LK analogues) was systematically tested against bacteria and erythrocytes. Vesicle leakage assays served to correlate bilayer thickness and peptide length and to examine the role of membrane curvature and putative pore diameter. KL peptides with 10–12 amino acids showed the best therapeutic potential, i.e., high antimicrobial activity and low hemolytic side effects. Mechanistically, this particular window of an optimum β-strand length around 4 nm (11 amino acids × 3.7 Å) would match the typical thickness of a lipid bilayer, implying the formation of a transmembrane pore. Solid-state 15N- and 19F-NMR structure analysis, however, showed that the KL backbone lies flat on the membrane surface under all conditions. We can thus refute any of the pore models and conclude that the KL peptides rather disrupt membranes by a carpet mechanism. The intriguing length-dependent optimum in activity can be fully explained by two counteracting effects, i.e., membrane binding versus amyloid formation. Very short KL peptides are inactive, because they are unable to bind to the lipid bilayer as flexible β-strands, whereas very long peptides are inactive due to vigorous pre-aggregation into β-sheets in solution.
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9
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Porat-Dahlerbruch G, Struppe J, Quinn CM, Gronenborn AM, Polenova T. Determination of accurate 19F chemical shift tensors with R-symmetry recoupling at high MAS frequencies (60-100 kHz). JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 340:107227. [PMID: 35568013 DOI: 10.1016/j.jmr.2022.107227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/14/2022] [Accepted: 04/17/2022] [Indexed: 06/15/2023]
Abstract
Fluorination is a versatile and valuable modification for numerous systems, and 19F NMR spectroscopy is the premier method for their structural characterization. 19F chemical shift anisotropy is a sensitive probe of structure and dynamics, even though 19F chemical shift tensors have been reported for only a handful of systems to date. Here, we explore γ-encoded R-symmetry based recoupling sequences for the determination of 19F chemical shift tensors in fully protonated organic solids at high, 60-100 kHz MAS frequencies. We show that the performance of 19F-RNCSA experiments improves with increasing MAS frequencies, and that 1H decoupling is required to determine accurate chemical shift tensor parameters. In addition, these sequences are tolerant to B1-field inhomogeneity making them suitable for a wide range of systems and experimental conditions.
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Affiliation(s)
- Gal Porat-Dahlerbruch
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Jochem Struppe
- Bruker Biospin Corporation, 15 Fortune Drive, Billerica, MA 01821, United States
| | - Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Angela M Gronenborn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA 15261, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15261, United States
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA 15261, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15261, United States.
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10
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Shcherbakov AA, Spreacker PJ, Dregni AJ, Henzler-Wildman KA, Hong M. High-pH structure of EmrE reveals the mechanism of proton-coupled substrate transport. Nat Commun 2022; 13:991. [PMID: 35181664 PMCID: PMC8857205 DOI: 10.1038/s41467-022-28556-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 01/27/2022] [Indexed: 12/20/2022] Open
Abstract
The homo-dimeric bacterial membrane protein EmrE effluxes polyaromatic cationic substrates in a proton-coupled manner to cause multidrug resistance. We recently determined the structure of substrate-bound EmrE in phospholipid bilayers by measuring hundreds of protein-ligand HN-F distances for a fluorinated substrate, 4-fluoro-tetraphenylphosphonium (F4-TPP+), using solid-state NMR. This structure was solved at low pH where one of the two proton-binding Glu14 residues is protonated. Here, to understand how substrate transport depends on pH, we determine the structure of the EmrE-TPP complex at high pH, where both Glu14 residues are deprotonated. The high-pH complex exhibits an elongated and hydrated binding pocket in which the substrate is similarly exposed to the two sides of the membrane. In contrast, the low-pH complex asymmetrically exposes the substrate to one side of the membrane. These pH-dependent EmrE conformations provide detailed insights into the alternating-access model, and suggest that the high-pH conformation may facilitate proton binding in the presence of the substrate, thus accelerating the conformational change of EmrE to export the substrate.
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Affiliation(s)
- Alexander A Shcherbakov
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA, 02139, USA
| | - Peyton J Spreacker
- Department of Biochemistry, University of Wisconsin at Madison, Madison, WI, 53706, USA
| | - Aurelio J Dregni
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA, 02139, USA
| | | | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA, 02139, USA.
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11
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Liang L, Ji Y, Chen K, Gao P, Zhao Z, Hou G. Solid-State NMR Dipolar and Chemical Shift Anisotropy Recoupling Techniques for Structural and Dynamical Studies in Biological Systems. Chem Rev 2022; 122:9880-9942. [PMID: 35006680 DOI: 10.1021/acs.chemrev.1c00779] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
With the development of NMR methodology and technology during the past decades, solid-state NMR (ssNMR) has become a particularly important tool for investigating structure and dynamics at atomic scale in biological systems, where the recoupling techniques play pivotal roles in modern high-resolution MAS NMR. In this review, following a brief introduction on the basic theory of recoupling in ssNMR, we highlight the recent advances in dipolar and chemical shift anisotropy recoupling methods, as well as their applications in structural determination and dynamical characterization at multiple time scales (i.e., fast-, intermediate-, and slow-motion). The performances of these prevalent recoupling techniques are compared and discussed in multiple aspects, together with the representative applications in biomolecules. Given the recent emerging advances in NMR technology, new challenges for recoupling methodology development and potential opportunities for biological systems are also discussed.
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Affiliation(s)
- Lixin Liang
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian 116023, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi Ji
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian 116023, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kuizhi Chen
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian 116023, China
| | - Pan Gao
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian 116023, China
| | - Zhenchao Zhao
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian 116023, China
| | - Guangjin Hou
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian 116023, China
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12
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Kehl A, Hiller M, Hecker F, Tkach I, Dechert S, Bennati M, Meyer A. Resolution of chemical shift anisotropy in 19F ENDOR spectroscopy at 263 GHz/9.4 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 333:107091. [PMID: 34749036 DOI: 10.1016/j.jmr.2021.107091] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 06/13/2023]
Abstract
Pulsed 19F ENDOR spectroscopy provides a selective method for measuring angstrom to nanometer distances in structural biology. Here, the performance of 19F ENDOR at fields of 3.4 T and 9.4 T is compared using model compounds containing one to three 19F atoms. CF3 groups are included in two compounds, for which the possible occurrence of uniaxial rotation might affect the distance distribution. At 9.4 T, pronounced asymmetric features are observed in many of the presented 19F ENDOR spectra. Data analysis by spectral simulations shows that these features arise from the chemical shift anisotropy (CSA) of the 19F nuclei. This asymmetry is also observed at 3.4 T, albeit to a much smaller extent, confirming the physical origin of the effect. The CSA parameters are well consistent with DFT predicted values and can be extracted from simulation of the experimental data in favourable cases, thereby providing additional information about the geometrical and electronic structure of the spin system. The feasibility of resolving the CSA at 9.4 T provides important information for the interpretation of line broadening in ENDOR spectra also at lower fields, which is relevant for developing methods to extract distance distributions from 19F ENDOR spectra.
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Affiliation(s)
- Annemarie Kehl
- Research Group EPR Spectroscopy, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Markus Hiller
- Research Group EPR Spectroscopy, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Fabian Hecker
- Research Group EPR Spectroscopy, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Igor Tkach
- Research Group EPR Spectroscopy, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Sebastian Dechert
- Department of Chemistry, Georg August University of Göttingen, Tammannstr. 4, Göttingen, Germany
| | - Marina Bennati
- Research Group EPR Spectroscopy, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Department of Chemistry, Georg August University of Göttingen, Tammannstr. 4, Göttingen, Germany.
| | - Andreas Meyer
- Research Group EPR Spectroscopy, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
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13
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Rüdisser SH, Goldberg N, Ebert MO, Kovacs H, Gossert AD. Efficient affinity ranking of fluorinated ligands by 19F NMR: CSAR and FastCSAR. JOURNAL OF BIOMOLECULAR NMR 2020; 74:579-594. [PMID: 32556806 DOI: 10.1007/s10858-020-00325-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/02/2020] [Indexed: 06/11/2023]
Abstract
Fluorine NMR has recently gained high popularity in drug discovery as it allows efficient and sensitive screening of large numbers of ligands. However, the positive hits found in screening must subsequently be ranked according to their affinity in order to prioritize them for follow-up chemistry. Unfortunately, the primary read-out from the screening experiments, namely the increased relaxation rate upon binding, is not proportional to the affinity of the ligand, as it is polluted by effects such as exchange broadening. Here we present the method CSAR (Chemical Shift-anisotropy-based Affinity Ranking) for reliable ranking of fluorinated ligands by NMR, without the need of isotope labeled protein, titrations or setting up a reporter format. Our strategy is to produce relaxation data that is directly proportional to the binding affinity. This is achieved by removing all other contributions to relaxation as follows: (i) exchange effects are efficiently suppressed by using high power spin lock pulses, (ii) dipolar relaxation effects are approximately subtracted by measuring at two different magnetic fields and (iii) differences in chemical shift anisotropy are normalized using calculated values. A similar ranking can be obtained with the simplified approach FastCSAR that relies on a measurement of a single relaxation experiment at high field (preferably > 600 MHz). An affinity ranking obtained in this simple way will enable prioritizing ligands and thus improve the efficiency of fragment-based drug design.
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Affiliation(s)
- Simon H Rüdisser
- Institute for Molecular Biology and Biophysics, ETH Zürich, 8093, Zürich, Switzerland
- Biomolecular NMR Spectroscopy Platform, ETH Zürich, 8093, Zürich, Switzerland
| | - Nils Goldberg
- Institute for Molecular Biology and Biophysics, ETH Zürich, 8093, Zürich, Switzerland
- Biomolecular NMR Spectroscopy Platform, ETH Zürich, 8093, Zürich, Switzerland
| | - Marc-Olivier Ebert
- Laboratorium für Organische Chemie, ETH Zürich, 8093, Zürich, Switzerland
| | | | - Alvar D Gossert
- Institute for Molecular Biology and Biophysics, ETH Zürich, 8093, Zürich, Switzerland.
- Biomolecular NMR Spectroscopy Platform, ETH Zürich, 8093, Zürich, Switzerland.
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14
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Boeszoermenyi A, Ogórek B, Jain A, Arthanari H, Wagner G. The precious fluorine on the ring: fluorine NMR for biological systems. JOURNAL OF BIOMOLECULAR NMR 2020; 74:365-379. [PMID: 32651751 PMCID: PMC7539674 DOI: 10.1007/s10858-020-00331-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/29/2020] [Indexed: 05/08/2023]
Abstract
The fluorine-19 nucleus was recognized early to harbor exceptional properties for NMR spectroscopy. With 100% natural abundance, a high gyromagnetic ratio (83% sensitivity compared to 1H), a chemical shift that is extremely sensitive to its surroundings and near total absence in biological systems, it was destined to become a favored NMR probe, decorating small and large molecules. However, after early excitement, where uptake of fluorinated aromatic amino acids was explored in a series of animal studies, 19F-NMR lost popularity, especially in large molecular weight systems, due to chemical shift anisotropy (CSA) induced line broadening at high magnetic fields. Recently, two orthogonal approaches, (i) CF3 labeling and (ii) aromatic 19F-13C labeling leveraging the TROSY (Transverse Relaxation Optimized Spectroscopy) effect have been successfully applied to study large biomolecular systems. In this perspective, we will discuss the fascinating early work with fluorinated aromatic amino acids, which reveals the enormous potential of these non-natural amino acids in biological NMR and the potential of 19F-NMR to characterize protein and nucleic acid structure, function and dynamics in the light of recent developments. Finally, we explore how fluorine NMR might be exploited to implement small molecule or fragment screens that resemble physiological conditions and discuss the opportunity to follow the fate of small molecules in living cells.
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Affiliation(s)
- Andras Boeszoermenyi
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA, 02215, USA.
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA.
| | - Barbara Ogórek
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and, Harvard Medical School, Boston, MA, 02115, USA
| | - Akshay Jain
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA, 02215, USA
| | - Haribabu Arthanari
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA, 02215, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA.
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15
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Tressler CM, Zondlo NJ. Perfluoro- tert-Butyl Hydroxyprolines as Sensitive, Conformationally Responsive Molecular Probes: Detection of Protein Kinase Activity by 19F NMR. ACS Chem Biol 2020; 15:1096-1103. [PMID: 32125821 DOI: 10.1021/acschembio.0c00131] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
19F NMR spectroscopy provides the ability to quantitatively analyze single species in complex solutions but is often limited by the modest sensitivity inherent to NMR. 4R- and 4S-Perfluoro-tert-buyl hydroxyproline contain 9 equivalent fluorines, in amino acids with strong conformational preferences. In order to test the ability to use these amino acids as sensitive probes of protein modifications, the perfluoro-tert-buyl hydroxyprolines were incorporated into substrate peptides of the protein kinases PKA and Akt. Peptides containing each diastereomeric proline were rapidly phosphorylated by each protein kinase and exhibited 19F chemical shift changes as a result of phosphorylation. The sensitivity of the perfluoro-tert-butyl group allowed quantitative analysis of the kinetics of phosphorylation over three half-lives at single-digit micromolar concentrations of each species. The distinct conformational preferences of these amino acids allowed the optimization of the substrate with a conformationally matched amino acid, in order to maximize the rate of phosphorylation. PKA preferred the 4R-amino acid at the -1 position, whereas the closely related AGC kinase Akt preferred the 4S-amino acid. These data, combined with analysis of structures of the Michaelis complexes of these kinases in the PDB, suggest that PKA recognizes the PPII conformation at the P-1 position relative to the phosphorylation site, while Akt/PKB recognizes an extended conformation at this position. These results suggest that conformational targeting may be employed to increase specificity in recognition by protein kinases. Perfluoro-tert-butyl hydroxyprolines were applied to the real-time detection and quantification of PKA activity and inhibition of PKA activity in HeLa cell extracts via 19F NMR spectroscopy. The coupling of proline ring pucker with main chain conformation suggests broad application of perfluoro-tert-butyl hydroxyprolines in molecular sensing and imaging.
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Affiliation(s)
- Caitlin M. Tressler
- 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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16
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Shcherbakov AA, Roos M, Kwon B, Hong M. Two-dimensional 19F- 13C correlation NMR for 19F resonance assignment of fluorinated proteins. JOURNAL OF BIOMOLECULAR NMR 2020; 74:193-204. [PMID: 32088840 PMCID: PMC7445029 DOI: 10.1007/s10858-020-00306-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 02/13/2020] [Indexed: 05/09/2023]
Abstract
19F solid-state NMR is an excellent approach for measuring long-range distances for structure determination and for studying molecular motion. For multi-fluorinated proteins, assignment of 19F chemical shifts has been traditionally carried out using mutagenesis. Here we show 2D 19F-13C correlation experiments that allow efficient assignment of the 19F chemical shifts. We have compared several rotational-echo double-resonance-based pulse sequences and 19F-13C cross polarization (CP) for 2D 19F-13C correlation. We found that direct transferred-echo double-resonance (TEDOR) transfer from 19F to 13C and vice versa outperforms out-and-back coherence transfer schemes. 19F detection gives twofold higher sensitivity over 13C detection for the 2D correlation experiment. At MAS frequencies of 25-35 kHz, double-quantum 19F-13C CP has higher coherence transfer efficiencies than zero-quantum CP. The most efficient TEDOR transfer experiment has higher sensitivity than the most efficient double-quantum CP experiment. We demonstrate these 2D 19F-13C correlation experiments on the model compounds t-Boc-4F-phenylalanine and GB1. Application of the 2D 19F-13C TEDOR correlation experiment to the tetrameric influenza BM2 transmembrane peptide shows intermolecular 13C-19F cross peaks that indicate that the BM2 tetramers cluster in the lipid bilayer in an antiparallel fashion. This clustering may be relevant for the virus budding function of this protein.
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Affiliation(s)
- Alexander A Shcherbakov
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA, 02139, USA
| | - Matthias Roos
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA, 02139, USA
| | - Byungsu Kwon
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA, 02139, USA
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA, 02139, USA.
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17
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Welte H, Zhou T, Mihajlenko X, Mayans O, Kovermann M. What does fluorine do to a protein? Thermodynamic, and highly-resolved structural insights into fluorine-labelled variants of the cold shock protein. Sci Rep 2020; 10:2640. [PMID: 32060391 PMCID: PMC7021800 DOI: 10.1038/s41598-020-59446-w] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 01/29/2020] [Indexed: 11/21/2022] Open
Abstract
Fluorine labelling represents one promising approach to study proteins in their native environment due to efficient suppressing of background signals. Here, we systematically probe inherent thermodynamic and structural characteristics of the Cold shock protein B from Bacillus subtilis (BsCspB) upon fluorine labelling. A sophisticated combination of fluorescence and NMR experiments has been applied to elucidate potential perturbations due to insertion of fluorine into the protein. We show that single fluorine labelling of phenylalanine or tryptophan residues has neither significant impact on thermodynamic stability nor on folding kinetics compared to wild type BsCspB. Structure determination of fluorinated phenylalanine and tryptophan labelled BsCspB using X-ray crystallography reveals no displacements even for the orientation of fluorinated aromatic side chains in comparison to wild type BsCspB. Hence we propose that single fluorinated phenylalanine and tryptophan residues used for protein labelling may serve as ideal probes to reliably characterize inherent features of proteins that are present in a highly biological context like the cell.
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Affiliation(s)
- Hannah Welte
- Department of Chemistry, Universitätsstrasse 10, Universität Konstanz, DE-78457, Konstanz, Germany.,Graduate School Chemical Biology KoRS-CB, Universitätsstrasse 10, Universität Konstanz, DE-78457, Konstanz, Germany
| | - Tiankun Zhou
- Department of Biology, Universitätsstrasse 10, Universität Konstanz, DE-78457, Konstanz, Germany
| | - Xenia Mihajlenko
- Department of Chemistry, Universitätsstrasse 10, Universität Konstanz, DE-78457, Konstanz, Germany
| | - Olga Mayans
- Graduate School Chemical Biology KoRS-CB, Universitätsstrasse 10, Universität Konstanz, DE-78457, Konstanz, Germany.,Department of Biology, Universitätsstrasse 10, Universität Konstanz, DE-78457, Konstanz, Germany
| | - Michael Kovermann
- Department of Chemistry, Universitätsstrasse 10, Universität Konstanz, DE-78457, Konstanz, Germany. .,Graduate School Chemical Biology KoRS-CB, Universitätsstrasse 10, Universität Konstanz, DE-78457, Konstanz, Germany. .,Zukunftskolleg, Universitätsstrasse 10, Universität Konstanz, DE-78457, Konstanz, Germany.
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18
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Ycas PD, Wagner N, Olsen NM, Fu R, Pomerantz WCK. 2-Fluorotyrosine is a valuable but understudied amino acid for protein-observed 19F NMR. JOURNAL OF BIOMOLECULAR NMR 2020; 74:61-69. [PMID: 31760571 DOI: 10.1007/s10858-019-00290-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 11/13/2019] [Indexed: 06/10/2023]
Abstract
Incorporation of 19F into proteins allows for the study of their molecular interactions via NMR. The study of 19F labeled aromatic amino acids has largely focused on 4-,5-, or 6-fluorotryptophan, 4-fluorophenylalanine, (4,5, or 6FW) or 3-fluorotyrosine (3FY), whereas 2-fluorotyrosine (2FY) has remained largely understudied. Here we report a comparative analysis with different fluorinated amino acids. We first report the NMR chemical shift responsiveness of five aromatic amino acid mimics to changes in solvent polarity and find that the most responsive, a mimic of 3FY, has a 2.9-fold greater change in chemical shift compared to the other amino acid mimics in aprotic solvents including the 2FY mimic. We also probed the utility of 2FY for 19F NMR by measuring its NMR relaxation properties in solution and the chemical shift anisotropy (CSA) of a polycrystalline sample of the amino acid by magic angle spinning. Using protein-observed fluorine NMR (PrOF NMR), we compared the influence of 2FY and 3FY incorporation on stability and pKa perturbation when incorporated into the KIX domain of CBP/p300. Lastly, we investigated the 19F NMR response of both 2FY and 3FY-labeled proteins to a protein-protein interaction partner, MLL, and discovered that 2FY can report on allosteric interactions that are not observed with 3FY-labeling in this protein complex. The reduced perturbation to pKa and similar but reduced CSA of 2FY to 3FY supports 2FY as a suitable alternative amino acid for incorporation into large proteins for 19F NMR analysis.
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Affiliation(s)
- Peter D Ycas
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Nicole Wagner
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Noelle M Olsen
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Riqiang Fu
- National High Magnetic Field Lab, 1800 East Paul Dirac Dr., Tallahassee, FL, 32310, USA
| | - William C K Pomerantz
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA.
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19
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Lu M, Ishima R, Polenova T, Gronenborn AM. 19F NMR relaxation studies of fluorosubstituted tryptophans. JOURNAL OF BIOMOLECULAR NMR 2019; 73:401-409. [PMID: 31435857 PMCID: PMC6878660 DOI: 10.1007/s10858-019-00268-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 07/05/2019] [Indexed: 05/19/2023]
Abstract
We present 19F longitudinal and transverse relaxation studies for four differently fluorosubstituted L-tryptophans, which carry single F atoms in the indole ring, both in the context of the free amino acid and when located in the cyclophilin A protein. For the free 4F-, 5F-, 6F-, 7F-L-Trp, satisfactory agreement between experimentally measured and calculated relaxation rates was obtained, suggesting that the parameters used for calculating the rates for the indole frame are sufficiently accurate. We also measured and calculated relaxation rates for four differently 19F-tryptophan labeled cyclophilin A proteins, transferring the parameters from the free amino acid to the protein-bound moiety. Our results suggest that 19F relaxation data of the large and rigid indole ring in Trp are only moderately affected by protein motions and provide critical reference points for evaluating fluorine NMR relaxation in the future, especially in fluorotryptophan labeled proteins.
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Affiliation(s)
- Manman Lu
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Rieko Ishima
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Tatyana Polenova
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Angela M Gronenborn
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
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20
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Kwon B, Roos M, Mandala VS, Shcherbakov AA, Hong M. Elucidating Relayed Proton Transfer through a His-Trp-His Triad of a Transmembrane Proton Channel by Solid-State NMR. J Mol Biol 2019; 431:2554-2566. [PMID: 31082440 DOI: 10.1016/j.jmb.2019.05.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/13/2019] [Accepted: 05/05/2019] [Indexed: 01/02/2023]
Abstract
Proton transfer through membrane-bound ion channels is mediated by both water and polar residues of proteins, but the detailed molecular mechanism is challenging to determine. The tetrameric influenza A and B virus M2 proteins form canonical proton channels that use an HxxxW motif for proton selectivity and gating. The BM2 channel also contains a second histidine (His), H27, equidistant from the gating tryptophan, which leads to a symmetric H19xxxW23xxxH27 motif. The proton-dissociation constants (pKa's) of H19 in BM2 were found to be much lower than the pKa's of H37 in AM2. To determine if the lower pKa's result from H27-facilitated proton dissociation of H19, we have now investigated a H27A mutant of BM2 using solid-state NMR. 15N NMR spectra indicate that removal of the second histidine converted the protonation and tautomeric equilibria of H19 to be similar to the H37 behavior in AM2, indicating that the peripheral H27 is indeed the origin of the low pKa's of H19 in wild-type BM2. Measured interhelical distances between W23 sidechains indicate that the pore constriction at W23 increases with the H19 tetrad charge but is independent of the H27A mutation. These results indicate that H27 both accelerates proton dissociation from H19 to increase the inward proton conductance and causes the small reverse conductance of BM2. The proton relay between H19 and H27 is likely mediated by the intervening gating tryptophan through cation-π interactions. This relayed proton transfer may exist in other ion channels and has implications for the design of imidazole-based synthetic proton channels.
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Affiliation(s)
- Byungsu Kwon
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Matthias Roos
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Venkata S Mandala
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Alexander A Shcherbakov
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA.
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21
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Brinkmann A, Sternberg U, Bovee-Geurts PHM, Fernández Fernández I, Lugtenburg J, Kentgens APM, DeGrip WJ. Insight into the chromophore of rhodopsin and its Meta-II photointermediate by 19F solid-state NMR and chemical shift tensor calculations. Phys Chem Chem Phys 2018; 20:30174-30188. [PMID: 30484791 DOI: 10.1039/c8cp05886e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
19F nuclei are useful labels in solid-state NMR studies, since their chemical shift and tensor elements are very sensitive to the electrostatic and space-filling properties of their local environment. In this study we have exploited a fluorine substituent, strategically placed at the C-12-position of 11-cis retinal, the chromophore of visual rhodopsins. This label was used to explore the local environment of the chromophore in the ground state of bovine rhodopsin and its active photo-intermediate Meta II. In addition, the chemical shift and tensor elements of the chromophore in the free state in a membrane environment and the bound state in the protein were determined. Upon binding of the chromophore into rhodopsin and Meta II, the isotropic chemical shift changes in the opposite direction by +9.7 and -8.4 ppm, respectively. An unusually large isotropic shift difference of 35.9 ppm was observed between rhodopsin and Meta II. This partly originates in the light-triggered 11-cis to all-trans isomerization of the chromophore. The other part reflects the local conformational rearrangements in the chromophore and the binding pocket. These NMR data were correlated with the available X-ray structures of rhodopsin and Meta II using bond polarization theory. For this purpose hydrogen atoms have to be inserted and hereto a family of structures were derived that best correlated with the well-established 13C chemical shifts. Based upon these structures, a 12-F derivative was obtained that best corresponded with the experimentally determined 19F chemical shifts and tensor elements. The combined data indicate strong changes in the local environment of the C-12 position and a substantially different interaction pattern with the protein in Meta II as compared to rhodopsin.
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Affiliation(s)
- Andreas Brinkmann
- Metrology, National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario K1A 0R6, Canada.
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22
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Roos M, Mandala VS, Hong M. Determination of Long-Range Distances by Fast Magic-Angle-Spinning Radiofrequency-Driven 19F- 19F Dipolar Recoupling NMR. J Phys Chem B 2018; 122:9302-9313. [PMID: 30211552 DOI: 10.1021/acs.jpcb.8b06878] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nanometer-range distances are important for restraining the three-dimensional structure and oligomeric assembly of proteins and other biological molecules. Solid-state NMR determination of protein structures typically utilizes 13C-13C and 13C-15N distance restraints, which can only be measured up to ∼7 Å because of the low gyromagnetic ratios of these nuclear spins. To extend the distance reach of NMR, one can harvest the power of 19F, whose large gyromagnetic ratio in principle allows distances up to 2 nm to be measured. However, 19F possesses large chemical shift anisotropies (CSAs) as well as large isotropic chemical shift dispersions, which pose challenges to dipolar coupling measurements. Here, we demonstrate 19F-19F distance measurements at high magnetic fields under fast magic-angle spinning (MAS) using radiofrequency-driven dipolar recoupling (RFDR). We show that 19F-19F cross-peaks for distances up to 1 nm can be readily observed in two-dimensional 19F-19F correlation spectra using less than 5 ms of RFDR mixing. This efficient 19F-19F dipolar recoupling is achieved using practically accessible MAS frequencies of 15-55 kHz, moderate 19F radio frequency field strengths, and no 1H decoupling. Experiments and simulations show that the fastest polarization transfer for aromatic fluorines with the highest distance accuracy is achieved using either fast MAS (e.g., 60 kHz) with large pulse duty cycles (>50%) or slow MAS with strong 19F pulses. Fast MAS considerably reduces relaxation losses during the RFDR π-pulse train, making finite-pulse RFDR under fast-MAS the method of choice. Under intermediate MAS frequencies (25-40 kHz) and intermediate pulse duty cycles (15-30%), the 19F CSA tensor orientation has a quantifiable effect on the polarization transfer rate; thus, the RFDR buildup curves encode both distance and orientation information. At fast MAS, the impact of CSA orientation is minimized, allowing pure distance restraints to be extracted. We further investigate how relayed transfer and dipolar truncation in multifluorine environments affect polarization transfer. This fast-MAS 19F RFDR approach is complementary to 19F spin diffusion for distance measurements and will be the method of choice under high-field fast-MAS conditions that are increasingly important for protein structure determination by solid-state NMR.
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Affiliation(s)
- Matthias Roos
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Venkata S Mandala
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Mei Hong
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
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23
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Lu M, Sarkar S, Wang M, Kraus J, Fritz M, Quinn CM, Bai S, Holmes ST, Dybowski C, Yap GPA, Struppe J, Sergeyev IV, Maas W, Gronenborn AM, Polenova T. 19F Magic Angle Spinning NMR Spectroscopy and Density Functional Theory Calculations of Fluorosubstituted Tryptophans: Integrating Experiment and Theory for Accurate Determination of Chemical Shift Tensors. J Phys Chem B 2018; 122:6148-6155. [PMID: 29756776 DOI: 10.1021/acs.jpcb.8b00377] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The 19F chemical shift is a sensitive NMR probe of structure and electronic environment in organic and biological molecules. In this report, we examine chemical shift parameters of 4F-, 5F-, 6F-, and 7F-substituted crystalline tryptophan by magic angle spinning (MAS) solid-state NMR spectroscopy and density functional theory. Significant narrowing of the 19F lines was observed under fast MAS conditions, at spinning frequencies above 50 kHz. The parameters characterizing the 19F chemical shift tensor are sensitive to the position of the fluorine in the aromatic ring and, to a lesser extent, the chirality of the molecule. Accurate calculations of 19F magnetic shielding tensors require the PBE0 functional with a 50% admixture of a Hartree-Fock exchange term, as well as taking account of the local crystal symmetry. The methodology developed will be beneficial for 19F-based MAS NMR structural analysis of proteins and protein assemblies.
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Affiliation(s)
- Manman Lu
- Department of Chemistry and Biochemistry , University of Delaware , Newark , Delaware 19716 , United States.,Pittsburgh Center for HIV Protein Interactions , University of Pittsburgh School of Medicine , 1051 Biomedical Science Tower 3, 3501 Fifth Avenue , Pittsburgh , Pennsylvania 15261 , United States
| | - Sucharita Sarkar
- Department of Chemistry and Biochemistry , University of Delaware , Newark , Delaware 19716 , United States.,Pittsburgh Center for HIV Protein Interactions , University of Pittsburgh School of Medicine , 1051 Biomedical Science Tower 3, 3501 Fifth Avenue , Pittsburgh , Pennsylvania 15261 , United States
| | - Mingzhang Wang
- Department of Chemistry and Biochemistry , University of Delaware , Newark , Delaware 19716 , United States.,Pittsburgh Center for HIV Protein Interactions , University of Pittsburgh School of Medicine , 1051 Biomedical Science Tower 3, 3501 Fifth Avenue , Pittsburgh , Pennsylvania 15261 , United States
| | - Jodi Kraus
- Department of Chemistry and Biochemistry , University of Delaware , Newark , Delaware 19716 , United States
| | - Matthew Fritz
- 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
| | - Sean T Holmes
- Department of Chemistry and Biochemistry , University of Delaware , Newark , Delaware 19716 , United States
| | - Cecil Dybowski
- 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
| | - Jochem Struppe
- Bruker Biospin Corporation , 15 Fortune Drive , Billerica , Massachusetts 01821 , United States
| | - Ivan V Sergeyev
- Bruker Biospin Corporation , 15 Fortune Drive , Billerica , Massachusetts 01821 , United States
| | - Werner Maas
- Bruker Biospin Corporation , 15 Fortune Drive , Billerica , Massachusetts 01821 , United States
| | - Angela M Gronenborn
- Pittsburgh Center for HIV Protein Interactions , University of Pittsburgh School of Medicine , 1051 Biomedical Science Tower 3, 3501 Fifth Avenue , Pittsburgh , Pennsylvania 15261 , United States.,Department of Structural Biology , University of Pittsburgh School of Medicine , 3501 Fifth Avenue , Pittsburgh , Pennsylvania 15261 , United States
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry , University of Delaware , Newark , Delaware 19716 , United States.,Pittsburgh Center for HIV Protein Interactions , University of Pittsburgh School of Medicine , 1051 Biomedical Science Tower 3, 3501 Fifth Avenue , Pittsburgh , Pennsylvania 15261 , United States
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24
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Abstract
The third most abundant polypeptide conformation in nature, the polyproline-II helix, is a polar, extended secondary structure with a local organization stabilized by intercarbonyl interactions within the peptide chain. Here we design a hydrophobic polyproline-II helical peptide based on an oligomeric octahydroindole-2-carboxylic acid scaffold and demonstrate its transmembrane alignment in model lipid bilayers by means of solid-state 19F NMR. As result, we provide a first example of a purely artificial transmembrane peptide with a structural organization that is not based on hydrogen-bonding.
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Affiliation(s)
- Vladimir Kubyshkin
- Institute of Chemistry , Technical University of Berlin , Müller-Breslau-Strasse 10 , Berlin 10623 , Germany
| | - Stephan L Grage
- Institute of Biological Interfaces (IBG-2) , Karlsruhe Institute of Technology (KIT) , P.O.B. 3640, Karlsruhe 76021 , Germany
| | - Jochen Bürck
- Institute of Biological Interfaces (IBG-2) , Karlsruhe Institute of Technology (KIT) , P.O.B. 3640, Karlsruhe 76021 , Germany
| | - Anne S Ulrich
- Institute of Biological Interfaces (IBG-2) , Karlsruhe Institute of Technology (KIT) , P.O.B. 3640, Karlsruhe 76021 , Germany
- Institute of Organic Chemistry , KIT , Fritz-Haber-Weg 6 , Karlsruhe 76131 , Germany
| | - Nediljko Budisa
- Institute of Chemistry , Technical University of Berlin , Müller-Breslau-Strasse 10 , Berlin 10623 , Germany
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25
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Shcherbakov AA, Hong M. Rapid measurement of long-range distances in proteins by multidimensional 13C- 19F REDOR NMR under fast magic-angle spinning. JOURNAL OF BIOMOLECULAR NMR 2018; 71:31-43. [PMID: 29785460 PMCID: PMC6314655 DOI: 10.1007/s10858-018-0187-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/16/2018] [Indexed: 05/24/2023]
Abstract
The ability to simultaneously measure many long-range distances is critical to efficient and accurate determination of protein structures by solid-state NMR (SSNMR). So far, the most common distance constraints for proteins are 13C-15N distances, which are usually measured using the rotational-echo double-resonance (REDOR) technique. However, these measurements are restricted to distances of up to ~ 5 Å due to the low gyromagnetic ratios of 15N and 13C. Here we present a robust 2D 13C-19F REDOR experiment to measure multiple distances to ~ 10 Å. The technique targets proteins that contain a small number of recombinantly or synthetically incorporated fluorines. The 13C-19F REDOR sequence is combined with 2D 13C-13C correlation to resolve multiple distances in highly 13C-labeled proteins. We show that, at the high magnetic fields which are important for obtaining well resolved 13C spectra, the deleterious effect of the large 19F chemical shift anisotropy for REDOR is ameliorated by fast magic-angle spinning and is further taken into account in numerical simulations. We demonstrate this 2D 13C-13C resolved 13C-19F REDOR technique on 13C, 15N-labeled GB1. A 5-19F-Trp tagged GB1 sample shows the extraction of distances to a single fluorine atom, while a 3-19F-Tyr labeled GB1 sample allows us to evaluate the effects of multi-spin coupling and statistical 19F labeling on distance measurement. Finally, we apply this 2D REDOR experiment to membrane-bound influenza B M2 transmembrane peptide, and show that the distance between the proton-selective histidine residue and the gating tryptophan residue differs from the distances in the solution NMR structure of detergent-bound BM2. This 2D 13C-19F REDOR technique should facilitate SSNMR-based protein structure determination by increasing the measurable distances to the ~ 10 Å range.
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Affiliation(s)
- Alexander A Shcherbakov
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA, 02139, USA
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA, 02139, USA.
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26
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Roos M, Wang T, Shcherbakov AA, Hong M. Fast Magic-Angle-Spinning 19F Spin Exchange NMR for Determining Nanometer 19F- 19F Distances in Proteins and Pharmaceutical Compounds. J Phys Chem B 2018; 122:2900-2911. [PMID: 29486126 PMCID: PMC6312665 DOI: 10.1021/acs.jpcb.8b00310] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Internuclear distances measured using NMR provide crucial constraints of three-dimensional structures but are often restricted to about 5 Å due to the weakness of nuclear-spin dipolar couplings. For studying macromolecular assemblies in biology and materials science, distance constraints beyond 1 nm will be extremely valuable. Here we present an extensive and quantitative analysis of the feasibility of 19F spin exchange NMR for precise and robust measurements of interatomic distances up to 1.6 nm at a magnetic field of 14.1 T, under 20-40 kHz magic-angle spinning (MAS). The measured distances are comparable to those achievable from paramagnetic relaxation enhancement but have higher precision, which is better than ±1 Å for short distances and ±2 Å for long distances. For 19F spins with the same isotropic chemical shift but different anisotropic chemical shifts, intermediate MAS frequencies of 15-25 kHz without 1H irradiation accelerate spin exchange. For spectrally resolved 19F-19F spin exchange, 1H-19F dipolar recoupling significantly speeds up 19F-19F spin exchange. On the basis of data from five fluorinated synthetic, pharmaceutical, and biological compounds, we obtained two general curves for spin exchange between CF groups and between CF3 and CF groups. These curves allow 19F-19F distances to be extracted from the measured spin exchange rates after taking into account 19F chemical shifts. These results demonstrate the robustness of 19F spin exchange NMR for distance measurements in a wide range of biological and chemical systems.
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Affiliation(s)
- Matthias Roos
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Tuo Wang
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Alexander A Shcherbakov
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Mei Hong
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
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27
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New insights into the influence of monofluorination on dimyristoylphosphatidylcholine membrane properties: A solid-state NMR study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:654-663. [DOI: 10.1016/j.bbamem.2017.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 11/29/2017] [Accepted: 12/04/2017] [Indexed: 10/18/2022]
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28
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Quantification of size effect on protein rotational mobility in cells by 19F NMR spectroscopy. Anal Bioanal Chem 2017; 410:869-874. [PMID: 29184995 DOI: 10.1007/s00216-017-0745-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 09/21/2017] [Accepted: 11/03/2017] [Indexed: 12/18/2022]
Abstract
Protein diffusion in living cells might differ significantly from that measured in vitro. Little is known about the effect of globular protein size on rotational diffusion in cells because each protein has distinct surface properties, which result in different interactions with cellular components. To overcome this problem, the B1 domain of protein G (GB1) and several concatemers of the protein were labeled with 5-fluorotryptophan and studied by 19F NMR in Escherichia coli cells, Xenopus laevis oocytes, and in aqueous solutions crowded with glycerol, or Ficoll70™ and lysozyme. Relaxation data show that the size dependence of protein rotation in cells is due to weak interactions of the target protein with cellular components, but the effect of these interactions decreases as protein size increases. The results provide valuable information for interpreting protein diffusion data acquired in living cells. Graphical abstract Size matters. The protein rotational mobility in living cells was assessed by 19F NMR. The size dependence effect may arise from weak interactions between protein and cytoplasmic components.
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29
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Sun X, Dyson HJ, Wright PE. Fluorotryptophan Incorporation Modulates the Structure and Stability of Transthyretin in a Site-Specific Manner. Biochemistry 2017; 56:5570-5581. [PMID: 28920433 DOI: 10.1021/acs.biochem.7b00815] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Abnormal deposition of aggregated wild-type (WT) human transthyretin (TTR) and its pathogenic variants is responsible for cardiomyopathy and neuropathy related to TTR amyloidosis. The tryptophan (Trp) fluorescence measurements typically used to study structural changes of TTR do not yield site-specific information on the two Trp residues per TTR protomer. To obtain such information, tryptophan labeled with fluorine at the 5 and 6 positions (5FW and 6FW) was incorporated into TTR. Fluorescence of 5FW and 6FW-labeled WT-TTR (WT-5FW and WT-6FW) and a single-Trp mutant W41Y showed that the photophysics of incorporated fluoro-Trp is consistent with site-specific solvation of the indole ring of W41 and W79. 19F-NMR showed that solvent accessibility depends on both the location of the Trp and the position of the fluorine substituent in the indole ring. Unexpectedly, differences were observed in the rates of aggregation, with WT-6FW aggregating more rapidly than WT-5FW or WT-TTR. Real-time 19F-NMR urea unfolding experiments revealed that WT-5FW is kinetically more stable than WT-6FW, consistent with the aggregation assay. In addition, structural perturbations of residues distant from either Trp site are more extensive in WT-6FW. Notably, residues in the dimer interfaces are perturbed by 6FW at residue 79; pathogenic mutations in these regions are associated with reduced tetramer stability and amyloidogenesis. The differences in behavior that arise from the replacement of a fluorine at the 5-position of a tryptophan with one at the adjacent 6-position emphasize the delicate balance of stability in the TTR tetramer.
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Affiliation(s)
- Xun Sun
- Department of Integrative Structural and Computational Biology and Skaggs Institute of Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - H Jane Dyson
- Department of Integrative Structural and Computational Biology and Skaggs Institute of Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Peter E Wright
- Department of Integrative Structural and Computational Biology and Skaggs Institute of Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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30
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Kirberger SE, Maltseva SD, Manulik JC, Einstein SA, Weegman BP, Garwood M, Pomerantz WCK. Synthesis of Intrinsically Disordered Fluorinated Peptides for Modular Design of High-Signal 19 F MRI Agents. Angew Chem Int Ed Engl 2017; 56:6440-6444. [PMID: 28471097 PMCID: PMC5493043 DOI: 10.1002/anie.201700426] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/13/2017] [Indexed: 12/28/2022]
Abstract
19 F MRI is valuable for in vivo imaging due to the only trace amounts of fluorine in biological systems. Because of the low sensitivity of MRI however, designing new fluorochemicals remains a significant challenge for achieving sufficient 19 F signal. Here, we describe a new class of high-signal, water-soluble fluorochemicals as 19 F MRI imaging agents. A polyamide backbone is used for tuning the proteolytic stability to avoid retention within the body, which is a limitation of current state-of-the-art perfluorochemicals. We show that unstructured peptides containing alternating N-ϵ-trifluoroacetyllysine and lysine provide a degenerate 19 F NMR signal. 19 F MRI phantom images provide sufficient contrast at micromolar concentrations, showing promise for eventual clinical applications. Finally, the degenerate high signal characteristics were retained when conjugated to a large protein, indicating potential for in vivo targeting applications, including molecular imaging and cell tracking.
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Affiliation(s)
- Steven E Kirberger
- Department of Chemistry, University of Minnesota - Twin Cities, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Sofia D Maltseva
- Department of Chemistry, University of Minnesota - Twin Cities, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Joseph C Manulik
- Department of Chemistry, University of Minnesota - Twin Cities, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Samuel A Einstein
- Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota - Twin Cities, 2021 6thSt. SE, Minneapolis, MN, 55455, USA
| | - Bradley P Weegman
- Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota - Twin Cities, 2021 6thSt. SE, Minneapolis, MN, 55455, USA
| | - Michael Garwood
- Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota - Twin Cities, 2021 6thSt. SE, Minneapolis, MN, 55455, USA
| | - William C K Pomerantz
- Department of Chemistry, University of Minnesota - Twin Cities, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
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31
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Kirberger SE, Maltseva SD, Manulik JC, Einstein SA, Weegman BP, Garwood M, Pomerantz WCK. Synthesis of Intrinsically Disordered Fluorinated Peptides for Modular Design of High-Signal 19
F MRI Agents. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201700426] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Steven E. Kirberger
- Department of Chemistry; University of Minnesota - Twin Cities; 207 Pleasant St. SE Minneapolis MN 55455 USA
| | - Sofia D. Maltseva
- Department of Chemistry; University of Minnesota - Twin Cities; 207 Pleasant St. SE Minneapolis MN 55455 USA
| | - Joseph C. Manulik
- Department of Chemistry; University of Minnesota - Twin Cities; 207 Pleasant St. SE Minneapolis MN 55455 USA
| | - Samuel A. Einstein
- Department of Radiology; Center for Magnetic Resonance Research; University of Minnesota - Twin Cities; 2021 6 St. SE Minneapolis MN 55455 USA
| | - Bradley P. Weegman
- Department of Radiology; Center for Magnetic Resonance Research; University of Minnesota - Twin Cities; 2021 6 St. SE Minneapolis MN 55455 USA
| | - Michael Garwood
- Department of Radiology; Center for Magnetic Resonance Research; University of Minnesota - Twin Cities; 2021 6 St. SE Minneapolis MN 55455 USA
| | - William C. K. Pomerantz
- Department of Chemistry; University of Minnesota - Twin Cities; 207 Pleasant St. SE Minneapolis MN 55455 USA
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32
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Dalvit C, Piotto M. 19 F NMR transverse and longitudinal relaxation filter experiments for screening: a theoretical and experimental analysis. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:106-114. [PMID: 27514284 DOI: 10.1002/mrc.4500] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 08/09/2016] [Indexed: 06/06/2023]
Abstract
Ligand-based 19 F NMR screening represents an efficient approach for performing binding assays. The high sensitivity of the methodology to receptor binding allows the detection of weak affinity ligands. The observable NMR parameters that are typically used are the 19 F transverse relaxation rate and isotropic chemical shift. However, there are few cases where the 19 F longitudinal relaxation rate should also be used. A theoretical and experimental analysis of the 19 F NMR transverse and longitudinal relaxation rates at different magnetic fields is presented along with proposed methods for improving the sensitivity and dynamic range of these experiments applied to fragment-based screening. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Claudio Dalvit
- Faculty of Science, University of Neuchatel, Neuchatel, Switzerland
- IDD/SDI, Sanofi, Vitry-sur-Seine, France
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33
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Tressler CM, Zondlo NJ. Synthesis of Perfluoro-tert-butyl Tyrosine, for Application in 19F NMR, via a Diazonium-Coupling Reaction. Org Lett 2016; 18:6240-6243. [PMID: 27978684 DOI: 10.1021/acs.orglett.6b02858] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A practical synthesis of the novel highly fluorinated amino acid Fmoc-perfluoro-tert-butyl tyrosine was developed. The sequence proceeds in two steps from commercially available Fmoc-4-NH2-phenylalanine via diazotization followed by diazonium coupling reaction with perfluoro-tert-butanol. In peptides, perfluoro-tert-butyl tyrosine was detected in 30 s by NMR spectroscopy at 500 nM peptide concentration due to nine chemically equivalent fluorines that are a sharp singlet by 19F NMR. Perfluoro-tert-butyl ether has an estimated σp Hammett substituent constant of +0.30.
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Affiliation(s)
- Caitlin M Tressler
- 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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34
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Buratto R, Mammoli D, Canet E, Bodenhausen G. Ligand–Protein Affinity Studies Using Long-Lived States of Fluorine-19 Nuclei. J Med Chem 2016; 59:1960-6. [DOI: 10.1021/acs.jmedchem.5b01583] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Roberto Buratto
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Daniele Mammoli
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Estel Canet
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Département
de Chimie, Ecole Normale Supérieure−PSL Research University, 24 Rue Lhomond, 75231 Paris Cedex 05, France
- Sorbonne Université, UPMC Univ Paris 06, 4 place Jussieu, 75005 Paris, France
- CNRS, UMR 7203 LBM, 75005 Paris, France
| | - Geoffrey Bodenhausen
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Département
de Chimie, Ecole Normale Supérieure−PSL Research University, 24 Rue Lhomond, 75231 Paris Cedex 05, France
- Sorbonne Université, UPMC Univ Paris 06, 4 place Jussieu, 75005 Paris, France
- CNRS, UMR 7203 LBM, 75005 Paris, France
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35
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Wielgus E, Paluch P, Frelek J, Szczepek WJ, Potrzebowski MJ. Full Characterization of Linezolid and Its Synthetic Precursors by Solid-State Nuclear Magnetic Resonance Spectroscopy and Mass Spectrometry. J Pharm Sci 2015; 104:3883-3892. [DOI: 10.1002/jps.24606] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/14/2015] [Accepted: 07/16/2015] [Indexed: 12/27/2022]
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36
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Fillion M, Auger M. Oriented samples: a tool for determining the membrane topology and the mechanism of action of cationic antimicrobial peptides by solid-state NMR. Biophys Rev 2015; 7:311-320. [PMID: 28510228 PMCID: PMC5425733 DOI: 10.1007/s12551-015-0167-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 02/05/2015] [Indexed: 01/12/2023] Open
Abstract
Overuse and misuse of antibiotics have led bacteria to acquire several mechanisms of resistance. In response to this, researchers have identified natural antimicrobial peptides as promising candidates to fight against multiresistant bacteria. However, their mode of action is still unclear, and a better understanding of the mode of action of these peptides is of primary importance to develop new peptides displaying high antibacterial activity and low hemolytic activity. One of the main features that defines the mechanism of action is the membrane topology of the peptide. Among the spectroscopic techniques, solid-state NMR is the technique of choice for determining the location of the peptide within the membrane. It can be achieved by performing experiments with oriented samples. In the literature, the two most common types of oriented samples are bicelles and phospholipids mechanically oriented between glass plates. The mode of perturbation of the membrane-active peptide can be studied by phosphorus-31 and deuterium NMR. On the other hand, several experiments such as nitrogen-15 and fluorine solid-state NMR, that require labeled peptides, can give valuable information on the membrane topology of the peptide. The combination of the latter techniques allows the determination of a precise topology, thus a better knowledge of the molecular determinants involved in the membrane interactions of antimicrobial peptides.
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Affiliation(s)
- Matthieu Fillion
- Department of Chemistry, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA), Centre québécois sur les matériaux fonctionnels (CQMF), Université Laval, Québec, QC, G1V 0A6, Canada
| | - Michèle Auger
- Department of Chemistry, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA), Centre québécois sur les matériaux fonctionnels (CQMF), Université Laval, Québec, QC, G1V 0A6, Canada.
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37
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3D hydrophobic moment vectors as a tool to characterize the surface polarity of amphiphilic peptides. Biophys J 2015; 106:2385-94. [PMID: 24896117 DOI: 10.1016/j.bpj.2014.04.020] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 04/02/2014] [Accepted: 04/07/2014] [Indexed: 11/22/2022] Open
Abstract
The interaction of membranes with peptides and proteins is largely determined by their amphiphilic character. Hydrophobic moments of helical segments are commonly derived from their two-dimensional helical wheel projections, and the same is true for β-sheets. However, to the best of our knowledge, there exists no method to describe structures in three dimensions or molecules with irregular shape. Here, we define the hydrophobic moment of a molecule as a vector in three dimensions by evaluating the surface distribution of all hydrophilic and lipophilic regions over any given shape. The electrostatic potential on the molecular surface is calculated based on the atomic point charges. The resulting hydrophobic moment vector is specific for the instantaneous conformation, and it takes into account all structural characteristics of the molecule, e.g., partial unfolding, bending, and side-chain torsion angles. Extended all-atom molecular dynamics simulations are then used to calculate the equilibrium hydrophobic moments for two antimicrobial peptides, gramicidin S and PGLa, under different conditions. We show that their effective hydrophobic moment vectors reflect the distribution of polar and nonpolar patches on the molecular surface and the calculated electrostatic surface potential. A comparison of simulations in solution and in lipid membranes shows how the peptides undergo internal conformational rearrangement upon binding to the bilayer surface. A good correlation with solid-state NMR data indicates that the hydrophobic moment vector can be used to predict the membrane binding geometry of peptides. This method is available as a web application on http://www.ibg.kit.edu/HM/.
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38
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Wang Y, Zhao T, Wei D, Strandberg E, Ulrich AS, Ulmschneider JP. How reliable are molecular dynamics simulations of membrane active antimicrobial peptides? BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1838:2280-2288. [PMID: 24747526 DOI: 10.1016/j.bbamem.2014.04.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 03/07/2014] [Accepted: 04/10/2014] [Indexed: 10/25/2022]
Abstract
Membrane-active antimicrobial peptides (AMPs) are challenging to study experimentally, but relatively easy to investigate using molecular dynamics (MD) computer simulations. For this reason, a large number of MD studies of AMPs have been reported over recent years. Yet relatively little effort has focused on the validity of such simulations. Are these results reliable, and do they agree with what is known experimentally? And how much meaningful information can be obtained? To answer these questions, we demonstrate here some of the requirements and limitations of running MD simulations for several common AMPs: PGLa, melittin, maculatin and BP100. The two most important findings are: (a) simulation results depend strongly on force field parameters, making experimental verification of the simulations obligatory, and (b) slow orientational and conformational fluctuations mean that much longer sampling timescales (multi-μs) are needed if quantitative agreement between simulation averages and experimental data is to be achieved. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.
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Affiliation(s)
- Yukun Wang
- The State Key Laboratory of Microbial Metabolism and College of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; College of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Tangzheng Zhao
- The State Key Laboratory of Microbial Metabolism and College of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; College of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dongqing Wei
- The State Key Laboratory of Microbial Metabolism and College of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; College of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Erik Strandberg
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P.O.B. 3640, 76021 Karlsruhe, Germany
| | - Anne S Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P.O.B. 3640, 76021 Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology, Fritz-Haber Weg 6, 76131 Karlsruhe, Germany
| | - Jakob P Ulmschneider
- Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China; The Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China.
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39
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Tressler C, Zondlo NJ. (2S,4R)- and (2S,4S)-perfluoro-tert-butyl 4-hydroxyproline: two conformationally distinct proline amino acids for sensitive application in 19F NMR. J Org Chem 2014; 79:5880-6. [PMID: 24870929 PMCID: PMC4076032 DOI: 10.1021/jo5008674] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Indexed: 01/19/2023]
Abstract
(2S,4R)- and (2S,4S)-perfluoro-tert-butyl 4-hydroxyproline were synthesized (as Fmoc-, Boc-, and free amino acids) in 2-5 steps. The key step of each synthesis was a Mitsunobu reaction with perfluoro-tert-butanol, which incorporated a perfluoro-tert-butyl group, with nine chemically equivalent fluorines. Both amino acids were incorporated in model α-helical and polyproline helix peptides. Each amino acid exhibited distinct conformational preferences, with (2S,4R)-perfluoro-tert-butyl 4-hydroxyproline promoting polyproline helix. Peptides containing these amino acids were sensitively detected by (19)F NMR, suggesting their use in probes and medicinal chemistry.
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Affiliation(s)
- Caitlin
M. Tressler
- 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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40
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Wadhwani P, Strandberg E, van den Berg J, Mink C, Bürck J, Ciriello RA, Ulrich AS. Dynamical structure of the short multifunctional peptide BP100 in membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:940-9. [DOI: 10.1016/j.bbamem.2013.11.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 10/25/2013] [Accepted: 11/01/2013] [Indexed: 11/26/2022]
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41
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Gagnon MC, Turgeon B, Savoie JD, Parent JF, Auger M, Paquin JF. Evaluation of the effect of fluorination on the property of monofluorinated dimyristoylphosphatidylcholines. Org Biomol Chem 2014; 12:5126-35. [DOI: 10.1039/c4ob00934g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The synthesis and characterization of three monofluorinated dimyristoylphosphatidylcholines, with the fluorine atom located at the extremities of the acyl chain in position 2 of the glycerol (sn-2), is described.
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Affiliation(s)
- Marie-Claude Gagnon
- Department of Chemistry
- PROTEO
- CERMA
- Québec, Canada
- Canada Research Chair in Organic and Medicinal Chemistry
| | - Bianka Turgeon
- Department of Chemistry
- PROTEO
- CERMA
- Québec, Canada
- Canada Research Chair in Organic and Medicinal Chemistry
| | - Jean-Daniel Savoie
- Department of Chemistry
- PROTEO
- CERMA
- Québec, Canada
- Canada Research Chair in Organic and Medicinal Chemistry
| | - Jean-François Parent
- Department of Chemistry
- PROTEO
- CERMA
- Québec, Canada
- Canada Research Chair in Organic and Medicinal Chemistry
| | | | - Jean-François Paquin
- Canada Research Chair in Organic and Medicinal Chemistry
- Department of Chemistry
- PROTEO
- CGCC
- Québec, Canada
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42
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Crowley PB, Kyne C, Monteith WB. Simple and inexpensive incorporation of 19F-tryptophan for protein NMR spectroscopy. Chem Commun (Camb) 2013; 48:10681-3. [PMID: 23000821 DOI: 10.1039/c2cc35347d] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Fluorine-containing amino acids are valuable probes for the biophysical characterization of proteins. Current methods for (19)F-labeled protein production involve time-consuming genetic manipulation, compromised expression systems and expensive reagents. We show that Escherichia coli BL21, the workhorse of protein production, can utilise fluoroindole for the biosynthesis of proteins containing (19)F-tryptophan.
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Affiliation(s)
- Peter B Crowley
- School of Chemistry, National University of Ireland Galway, University Road, Galway, Ireland.
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43
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Vinther JM, Khaneja N, Nielsen NC. Robust and efficient 19F heteronuclear dipolar decoupling using refocused continuous-wave rf irradiation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 226:88-92. [PMID: 23220184 DOI: 10.1016/j.jmr.2012.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 11/04/2012] [Accepted: 11/07/2012] [Indexed: 06/01/2023]
Abstract
Refocused continuous wave (rCW) decoupling is presented as an efficient and robust means to obtain well-resolved magic-angle-spinning solid-state NMR spectra of low-γ spins, such as (13)C dipolar coupled to fluorine. The rCW decoupling sequences, recently introduced for (1)H decoupling, are very robust towards large isotropic and anisotropic shift ranges as often encountered for (19)F spins. In rCW decoupling, the so-called refocusing pulses inserted into the CW irradiation eliminate critical residual second- and third-order dipolar coupling and dipolar-coupling against chemical shielding anisotropy cross-terms in the effective Hamiltonian through time-reversal (i.e. refocusing). As important additional assets, the rCW decoupling sequences are robust towards variations in rf amplitudes, operational at low to high spinning speeds, and easy to set-up for optimal performance experimentally. These aspects are demonstrated analytically/numerically and experimentally in comparison to state-of-the-art decoupling sequences such as TPPM, SPINAL-64, and frequency-swept variants of these.
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Affiliation(s)
- Joachim M Vinther
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Aarhus C, Denmark
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44
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Kitevski-LeBlanc JL, Prosser RS. Current applications of 19F NMR to studies of protein structure and dynamics. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 62:1-33. [PMID: 22364614 DOI: 10.1016/j.pnmrs.2011.06.003] [Citation(s) in RCA: 217] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 07/01/2011] [Indexed: 05/20/2023]
Affiliation(s)
- Julianne L Kitevski-LeBlanc
- Department of Chemistry, University of Toronto, UTM, 3359 Mississauga Rd., North Mississauga, Ontario, Canada
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45
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Merkel L, Budisa N. Organic fluorine as a polypeptide building element: in vivo expression of fluorinated peptides, proteins and proteomes. Org Biomol Chem 2012; 10:7241-61. [DOI: 10.1039/c2ob06922a] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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46
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Dalvit C, Vulpetti A. Fluorine-protein interactions and ¹⁹F NMR isotropic chemical shifts: An empirical correlation with implications for drug design. ChemMedChem 2011; 6:104-14. [PMID: 21117131 DOI: 10.1002/cmdc.201000412] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
An empirical correlation between the fluorine isotropic chemical shifts, measured by ¹⁹F NMR spectroscopy, and the type of fluorine-protein interactions observed in crystal structures is presented. The CF, CF₂, and CF₃ groups present in fluorinated ligands found in the Protein Data Bank were classified according to their ¹⁹F NMR chemical shifts and their close intermolecular contacts with the protein atoms. Shielded fluorine atoms, i.e., those with increased electron density, are observed primarily in close contact to hydrogen bond donors within the protein structure, suggesting the possibility of intermolecular hydrogen bond formation. Deshielded fluorines are predominantly found in close contact with hydrophobic side chains and with the carbon of carbonyl groups of the protein backbone. Correlation between the ¹⁹F NMR chemical shift and hydrogen bond distance, both derived experimentally and computed through quantum chemical methods, is also presented. The proposed "rule of shielding" provides some insight into and guidelines for the judicious selection of appropriate fluorinated moieties to be inserted into a molecule for making the most favorable interactions with the receptor.
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Affiliation(s)
- Claudio Dalvit
- Italian Institute of Technology, Drug Discovery and Development Department, Genova, Italy.
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47
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Shi P, Wang H, Xi Z, Shi C, Xiong Y, Tian C. Site-specific ¹⁹F NMR chemical shift and side chain relaxation analysis of a membrane protein labeled with an unnatural amino acid. Protein Sci 2011; 20:224-8. [PMID: 21080424 DOI: 10.1002/pro.545] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Site-specific ¹⁹F chemical shift and side chain relaxation analysis can be applied on large size proteins. Here, one-dimensional ¹⁹F spectra and T₁, T₂ relaxation data were acquired on a SH3 domain in aqueous buffer containing 60% glycerol, and a nine-transmembrane helices membrane protein diacyl-glycerol kinase (DAGK) in dodecyl phosphochoine (DPC) micelles. The high quality of the data indicates that this method can be applied to site-specifically analyze side chain internal mobility of membrane proteins or large size proteins.
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Affiliation(s)
- Pan Shi
- National Laboratory for Physical Science at Microscale and School of Life Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
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48
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Grygorenko OO, Artamonov OS, Komarov IV, Mykhailiuk PK. Trifluoromethyl-substituted cyclopropanes. Tetrahedron 2011. [DOI: 10.1016/j.tet.2010.11.068] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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49
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Fowler DJ, Khalifah PG, Thompson LK. Design and characterization of a calixarene inclusion compound for calibration of long-range carbon-fluorine distance measurements by solid-state NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 207:153-7. [PMID: 20822943 PMCID: PMC2956861 DOI: 10.1016/j.jmr.2010.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 08/01/2010] [Accepted: 08/06/2010] [Indexed: 05/17/2023]
Abstract
An inexpensive, easily synthesized calixarene:fluorotoluene host:guest inclusion complex has been designed for optimization and calibration of solid-state NMR measurements of carbon-fluorine distances using Rotational Echo DOuble Resonance (REDOR). Complexation of the fluorotoluene with the calixarene host separates the molecules such that simple two-spin behavior is observed for one site with a 4.08 Å carbon-fluorine distance. Fluorotoluene dynamics within the calixarene matrix cause motional averaging of the dipolar couplings, which makes it possible to easily optimize REDOR experiments and test their accuracy for relatively long distance measurements (>6.6 Å). This provides a new tool for accurate REDOR measurements of long carbon-fluorine distances, which have important applications in the characterization of fluorine-containing drugs, proteins, and polymers.
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Affiliation(s)
- Daniel J. Fowler
- Department of Chemistry, University of Massachusetts Amherst. 710 N. Pleasant St, Amherst, MA 01003
| | - Peter G. Khalifah
- Department of Chemistry, Stony Brook University, 100 Nicolls Rd., Stony Brook, NY 11794-3400
- Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973-5000
| | - Lynmarie K. Thompson
- Department of Chemistry, University of Massachusetts Amherst. 710 N. Pleasant St, Amherst, MA 01003
- Corresponding author. Department of Chemistry, University of Massachusetts Amherst. 710 N. Pleasant St, Amherst, MA 01003, USA, FAX: +1 413-545-4490,
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50
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Begam Elavarasi S, Kavita Dorai. Characterization of the 19F chemical shielding tensor using cross-correlated spin relaxation measurements and quantum chemical calculations. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.02.078] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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