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Dervişoğlu R, Antonschmidt L, Nimerovsky E, Sant V, Kim M, Ryazanov S, Leonov A, Carlos Fuentes-Monteverde J, Wegstroth M, Giller K, Mathies G, Giese A, Becker S, Griesinger C, Andreas LB. Anle138b interaction in α-synuclein aggregates by dynamic nuclear polarization NMR. Methods 2023; 214:18-27. [PMID: 37037308 DOI: 10.1016/j.ymeth.2023.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/22/2023] [Accepted: 04/06/2023] [Indexed: 04/12/2023] Open
Abstract
Small molecules that bind to oligomeric protein species such as membrane proteins and fibrils are of clinical interest for development of therapeutics and diagnostics. Definition of the binding site at atomic resolution via NMR is often challenging due to low binding stoichiometry of the small molecule. For fibrils and aggregation intermediates grown in the presence of lipids, we report atomic-resolution contacts to the small molecule at sub nm distance via solid-state NMR using dynamic nuclear polarization (DNP) and orthogonally labelled samples of the protein and the small molecule. We apply this approach to α-synuclein (αS) aggregates in complex with the small molecule anle138b, which is a clinical drug candidate for disease modifying therapy. The small central pyrazole moiety of anle138b is detected in close proximity to the protein backbone and differences in the contacts between fibrils and early intermediates are observed. For intermediate species, the 100 K condition for DNP helps to preserve the aggregation state, while for both fibrils and oligomers, the DNP enhancement is essential to obtain sufficient sensitivity.
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Affiliation(s)
- Rıza Dervişoğlu
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Leif Antonschmidt
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Evgeny Nimerovsky
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Vrinda Sant
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Myeongkyu Kim
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Sergey Ryazanov
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Center for Neuropathology and Prion Research, Ludwig-Maximilians University, Munich, Germany
| | - Andrei Leonov
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Center for Neuropathology and Prion Research, Ludwig-Maximilians University, Munich, Germany
| | | | - Melanie Wegstroth
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Karin Giller
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | | | - Armin Giese
- Center for Neuropathology and Prion Research, Ludwig-Maximilians University, Munich, Germany
| | - Stefan Becker
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Christian Griesinger
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Loren B Andreas
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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2
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Harati Taji Z, Bielytskyi P, Shein M, Sani MA, Seitz S, Schütz AK. Transient RNA Interactions Leave a Covalent Imprint on a Viral Capsid Protein. J Am Chem Soc 2022; 144:8536-8550. [PMID: 35512333 PMCID: PMC9121876 DOI: 10.1021/jacs.1c12439] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The hepatitis B virus (HBV) is the leading cause of persistent liver infections. Its DNA-based genome is synthesized through reverse transcription of an RNA template inside the assembled capsid shell. In addition to the structured assembly domain, the capsid protein harbors a C-terminal extension that mediates both the enclosure of RNA during capsid assembly and the nuclear entry of the capsid during infection. The arginine-rich motifs within this extension, though common to many viruses, have largely escaped atomic-scale investigation. Here, we leverage solution and solid-state nuclear magnetic resonance spectroscopy at ambient and cryogenic temperatures, under dynamic nuclear polarization signal enhancement, to investigate the organization of the genome within the capsid. Transient interactions with phosphate groups of the RNA backbone confine the arginine-rich motifs to the interior capsid space. While no secondary structure is induced in the C-terminal extension, interactions with RNA counteract the formation of a disulfide bond, which covalently tethers this peptide arm onto the inner capsid surface. Electrostatic and covalent contributions thus compete in the spatial regulation of capsid architecture. This disulfide switch represents a coupling mechanism between the structured assembly domain of the capsid and the enclosed nucleic acids. In particular, it enables the redox-dependent regulation of the exposure of the C-terminal extension on the capsid surface, which is required for nuclear uptake of the capsid. Phylogenetic analysis of capsid proteins from hepadnaviruses points toward a function of this switch in the persistence of HBV infections.
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Affiliation(s)
- Zahra Harati Taji
- Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Garching 85748, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg 85764, Germany
| | - Pavlo Bielytskyi
- Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Garching 85748, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg 85764, Germany
| | - Mikhail Shein
- Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Garching 85748, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg 85764, Germany
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Stefan Seitz
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg 69120, Germany.,Division of Virus-Associated Carcinogenesis (F170), German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Anne K Schütz
- Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Garching 85748, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg 85764, Germany
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3
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Matsuoka S, Sindelar M, Bansal S, Patti GJ, Schaefer J. Quantitative rotational-echo double resonance for Carbon-13 spin clusters. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 330:107043. [PMID: 34364107 PMCID: PMC9277705 DOI: 10.1016/j.jmr.2021.107043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/17/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
By using only half of the total evolution time for dephasing pulses, C{N} rotational-echo double resonance (REDOR) for clusters of 13C spins (RDX) results in the same universal REDOR behavior as observed for isolated 13C-15N pairs. RDX combines Hahn echoes with solid echoes to suppress interference from scalar J couplings. This is crucial for long evolution times. The modified version (which we call RDX24) makes RDX quantitative for 13C clusters. We apply this scheme to human embryonic kidney cells labeled in culture by L-[13C5 -15N2]-glutamine. We quantitatively characterize three separate nitrogen isotopic enrichments for: (i) the alpha nitrogens of glutamine residues in proteins (including the residues of the five amino acids synthesized from glutamine); (ii) the alpha nitrogens of the five amino-acid residues synthesized from glucose, together with those of the nine essential amino acids added to the growth medium; and (iii) the side-chain nitrogens of glutamine (and of asparagine derived from glutamine).
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Affiliation(s)
- Shigeru Matsuoka
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA; Faculty of Medicine, Oita University, Oita 879-5593, Japan
| | - Miriam Sindelar
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
| | - Sonal Bansal
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
| | - Gary J Patti
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
| | - Jacob Schaefer
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA.
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4
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Gelenter MD, Chen KJ, Hong M. Off-resonance 13C- 2H REDOR NMR for site-resolved studies of molecular motion. JOURNAL OF BIOMOLECULAR NMR 2021; 75:335-345. [PMID: 34342847 PMCID: PMC8830769 DOI: 10.1007/s10858-021-00377-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/19/2021] [Indexed: 06/06/2023]
Abstract
We introduce a 13C-2H Rotational Echo DOuble Resonance (REDOR) technique that uses the difference between on-resonance and off-resonance 2H irradiation to detect dynamic segments in deuterated molecules. By selectively inverting specific regions of the 2H magic-angle spinning (MAS) sideband manifold to recouple some of the deuterons to nearby carbons, we distinguish dynamic and rigid residues in 1D and 2D 13C spectra. We demonstrate this approach on deuterated GB1, H/D exchanged GB1, and perdeuterated bacterial cellulose. Numerical simulations reproduce the measured mixing-time and 2H carrier-frequency dependence of the REDOR dephasing of bacterial cellulose. Combining numerical simulations with experiments thus allow the extraction of motionally averaged quadrupolar couplings from REDOR dephasing values.
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Affiliation(s)
- Martin D Gelenter
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, MA, 02139, Cambridge, USA
| | - Kelly J Chen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, MA, 02139, Cambridge, USA
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, MA, 02139, Cambridge, USA.
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5
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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: 16] [Impact Index Per Article: 4.0] [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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6
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Eddy MT, Yu TY, Wagner G, Griffin RG. Structural characterization of the human membrane protein VDAC2 in lipid bilayers by MAS NMR. JOURNAL OF BIOMOLECULAR NMR 2019; 73:451-460. [PMID: 31407201 PMCID: PMC6819253 DOI: 10.1007/s10858-019-00242-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 03/19/2019] [Indexed: 05/25/2023]
Abstract
The second isoform of the human voltage dependent anion channel (VDAC2) is a mitochondrial porin that translocates calcium and other metabolites across the outer mitochondrial membrane. VDAC2 has been implicated in cardioprotection and plays a critical role in a unique apoptotic pathway in tumor cells. Despite its medical importance, there have been few biophysical studies of VDAC2 in large part due to the difficulty of obtaining homogeneous preparations of the protein for spectroscopic characterization. Here we present high resolution magic angle spinning nuclear magnetic resonance (NMR) data obtained from homogeneous preparation of human VDAC2 in 2D crystalline lipid bilayers. The excellent resolution in the spectra permit several sequence-specific assignments of the signals for a large portion of the VDAC2 N-terminus and several other residues in two- and three-dimensional heteronuclear correlation experiments. The first 12 residues appear to be dynamic, are not visible in cross polarization experiments, and they are not sufficiently mobile on very fast timescales to be visible in 13C INEPT experiments. A comparison of the NMR spectra of VDAC2 and VDAC1 obtained from highly similar preparations demonstrates that the spectral quality, line shapes and peak dispersion exhibited by the two proteins are nearly identical. This suggests an overall similar dynamic behavior and conformational homogeneity, which is in contrast to two earlier reports that suggested an inherent conformational heterogeneity of VDAC2 in membranes. The current data suggest that the sample preparation and spectroscopic methods are likely applicable to studying other human membrane porins, including human VDAC3, which has not yet been structurally characterized.
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Affiliation(s)
- Matthew T Eddy
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Departments of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | - Tsyr-Yan Yu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan, Republic of China
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Robert G Griffin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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7
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Murray DT, Zhou X, Kato M, Xiang S, Tycko R, McKnight SL. Structural characterization of the D290V mutation site in hnRNPA2 low-complexity-domain polymers. Proc Natl Acad Sci U S A 2018; 115:E9782-E9791. [PMID: 30279180 PMCID: PMC6196502 DOI: 10.1073/pnas.1806174115] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Human genetic studies have given evidence of familial, disease-causing mutations in the analogous amino acid residue shared by three related RNA binding proteins causative of three neurological diseases. Alteration of aspartic acid residue 290 of hnRNPA2 to valine is believed to predispose patients to multisystem proteinopathy. Mutation of aspartic acid 262 of hnRNPA1 to either valine or asparagine has been linked to either amyotrophic lateral sclerosis or multisystem proteinopathy. Mutation of aspartic acid 378 of hnRNPDL to either asparagine or histidine has been associated with limb girdle muscular dystrophy. All three of these aspartic acid residues map to evolutionarily conserved regions of low-complexity (LC) sequence that may function in states of either intrinsic disorder or labile self-association. Here, we present a combination of solid-state NMR spectroscopy with segmental isotope labeling and electron microscopy on the LC domain of the hnRNPA2 protein. We show that, for both the wild-type protein and the aspartic acid 290-to-valine mutant, labile polymers are formed in which the LC domain associates into an in-register cross-β conformation. Aspartic acid 290 is shown to be charged at physiological pH and immobilized within the polymer core. Polymers of the aspartic acid 290-to-valine mutant are thermodynamically more stable than wild-type polymers. These observations give evidence that removal of destabilizing electrostatic interactions may be responsible for the increased propensity of the mutated LC domains to self-associate in disease-causing conformations.
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Affiliation(s)
- Dylan T Murray
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Disease, Bethesda, MD 20892
- Postdoctoral Research Associate Training Program, National Institute of General Medical Sciences, Bethesda, MD 20892
| | - Xiaoming Zhou
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Masato Kato
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Siheng Xiang
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Robert Tycko
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Disease, Bethesda, MD 20892;
| | - Steven L McKnight
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390
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8
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Elkins MR, Williams JK, Gelenter MD, Dai P, Kwon B, Sergeyev IV, Pentelute BL, Hong M. Cholesterol-binding site of the influenza M2 protein in lipid bilayers from solid-state NMR. Proc Natl Acad Sci U S A 2017; 114:12946-12951. [PMID: 29158386 PMCID: PMC5724280 DOI: 10.1073/pnas.1715127114] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The influenza M2 protein not only forms a proton channel but also mediates membrane scission in a cholesterol-dependent manner to cause virus budding and release. The atomic interaction of cholesterol with M2, as with most eukaryotic membrane proteins, has long been elusive. We have now determined the cholesterol-binding site of the M2 protein in phospholipid bilayers using solid-state NMR spectroscopy. Chain-fluorinated cholesterol was used to measure cholesterol proximity to M2 while sterol-deuterated cholesterol was used to measure bound-cholesterol orientation in lipid bilayers. Carbon-fluorine distance measurements show that at a cholesterol concentration of 17 mol%, two cholesterol molecules bind each M2 tetramer. Cholesterol binds the C-terminal transmembrane (TM) residues, near an amphipathic helix, without requiring a cholesterol recognition sequence motif. Deuterium NMR spectra indicate that bound cholesterol is approximately parallel to the bilayer normal, with the rough face of the sterol rings apposed to methyl-rich TM residues. The distance- and orientation-restrained cholesterol-binding site structure shows that cholesterol is stabilized by hydrophobic interactions with the TM helix and polar and aromatic interactions with neighboring amphipathic helices. At the 1:2 binding stoichiometry, lipid 31P spectra show an isotropic peak indicative of high membrane curvature. This M2-cholesterol complex structure, together with previously observed M2 localization at phase boundaries, suggests that cholesterol mediates M2 clustering to the neck of the budding virus to cause the necessary curvature for membrane scission. The solid-state NMR approach developed here is generally applicable for elucidating the structural basis of cholesterol's effects on membrane protein function.
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Affiliation(s)
- Matthew R Elkins
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Jonathan K Williams
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Martin D Gelenter
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Peng Dai
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Byungsu Kwon
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | | | - Bradley L Pentelute
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139;
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9
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Zhang Z, Li J, Chen Y, Xie H, Yang J. A robust heteronuclear dipolar recoupling method comparable to TEDOR for proteins in magic-angle spinning solid-state NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 285:79-85. [PMID: 29126001 DOI: 10.1016/j.jmr.2017.10.012] [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: 08/04/2017] [Revised: 10/27/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
In this letter, we propose a robust heteronuclear dipolar recoupling method for proteins in magic-angle spinning (MAS) solid-state NMR. This method is as simple, robust and efficient as the well-known TEDOR in the aspect of magnetization transfer between 15N and 13C. Deriving from our recent band-selective dual back-to-back pulses (DBP) (Zhang et al., 2016), this method uses new phase-cycling schemes to realize broadband DBP (Bro-DBP). For broadband 15N-13C magnetization transfer (simultaneous 15N→13C' and 15N→13Cα), Bro-DBP has almost the same 15N→13Cα efficiency while offers 30-40% enhancement on 15N→13C' transfer, compared to TEDOR. Besides, Bro-DBP can also be used as a carbonyl (13C')-selected method, whose 15N→13C' efficiency is up to 1.7 times that of TEDOR and is also higher than that of band-selective DBP. The performance of Bro-DBP is demonstrated on the N-formyl-[U-13C,15N]-Met-Leu-Phe-OH (fMLF) peptide and the U-13C, 15N labeled β1 immunoglobulin binding domain of protein G (GB1) microcrystalline protein. Since Bro-DBP is as robust, simple and efficient as TEDOR, we believe it is very useful for protein studies in MAS solid-state NMR.
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Affiliation(s)
- Zhengfeng Zhang
- National Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China.
| | - Jianping Li
- National Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Yanke Chen
- National Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Huayong Xie
- National Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Jun Yang
- National Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China.
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10
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Iuga D, Rossi P, Herzfeld J, Griffin RG. Reprint of: Localization of Cl-35 Nuclei in Biological Solids using Rotational-Echo Double-Resonance Experiments. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 84:242-248. [PMID: 28781142 DOI: 10.1016/j.ssnmr.2017.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 12/16/2016] [Accepted: 01/23/2017] [Indexed: 06/07/2023]
Abstract
Chloride ions play important roles in many chemical and biological processes. This paper investigates the possibility of localizing 35Cl nuclei using solid-state NMR. It demonstrates that distances shorter than 3.8Å, between 13C atoms and 35Cl atoms in 10% uniformly labeled 13C L-tyrosine·HCl and natural abundance Glycine·HCl can be measured using rotational-echo (adiabatic passage) double-resonance (RE(AP)DOR). Furthermore the effect of quadrupolar interaction on the REDOR/REAPDOR experiment is quantified. The dephasing curve is plotted in a three dimensional chart as a function of the dephasing time and of the strength of quadrupolar interaction felt by each orientation. During spinning each orientation feels a quadrupolar interaction that varies in time, and therefore at each moment in time we reorder the crystallite orientations as a function of their contribution to the dephasing curve. In this way the effect of quadrupolar interaction on the dipolar dephasing curve can be fitted with a polynomial function. The numerical investigation performed allows us to generate REDOR/REAPDOR curves which are then used to simulate the experimental data.
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Affiliation(s)
- D Iuga
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK.
| | - P Rossi
- Department of Chemistry, Brandeis University, Waltham, MA 02454-9110, USA
| | - J Herzfeld
- Department of Chemistry, Brandeis University, Waltham, MA 02454-9110, USA
| | - R G Griffin
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, 150 Albany Street Cambridge, MA 02139, USA.
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11
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Greenwood AI, Clay MC, Rienstra CM. 31P-dephased, 13C-detected REDOR for NMR crystallography at natural isotopic abundance. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 278:8-17. [PMID: 28319851 PMCID: PMC5478420 DOI: 10.1016/j.jmr.2017.02.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 02/21/2017] [Accepted: 02/26/2017] [Indexed: 05/14/2023]
Abstract
Typically, the process of NMR-based structure determination relies on accurately measuring a large number of internuclear distances to serve as restraints for simulated annealing calculations. In solids, the rotational-echo double-resonance (REDOR) experiment is a widely used approach to determine heteronuclear dipolar couplings corresponding to distances usually in the range of 1.5-8Å. A challenge in the interpretation of REDOR data is the degeneracy of symmetric subunits in an oligomer or equivalent molecules in a crystal lattice, which produce REDOR trajectories that depend explicitly on two or more distances instead of one. This degeneracy cannot be overcome by either spin dilution (for molecules containing 31P, 19F and other highly abundant nuclei) or selective pulses (in the case where there is chemical shift degeneracy). For small, crystalline molecules, such as phosphoserine, we demonstrate that as many as five inter-molecular distances must be considered to model 31P-dephased REDOR data accurately. We report excellent agreement between simulation and experiment once lattice couplings, 31P chemical shift anisotropy, and radio-frequency field inhomogeneity are all taken into account. We also discuss the systematic inaccuracies that may result from approximations that consider only the initial slope of the REDOR trajectory and/or that utilize a two- or three-spin system. Furthermore, we demonstrate the applicability of 31P-dephased REDOR for validation or refinement of candidate crystal structures and show that this approach is especially informative for NMR crystallography of 31P-containing molecules.
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Affiliation(s)
- Alexander I Greenwood
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Mary C Clay
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Chad M Rienstra
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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12
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Iuga D, Rossi P, Herzfeld J, Griffin RG. Localization of Cl-35 nuclei in biological solids using rotational-echo double-resonance experiments. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 82-83:35-41. [PMID: 28187333 PMCID: PMC5378917 DOI: 10.1016/j.ssnmr.2017.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 12/16/2016] [Accepted: 01/23/2017] [Indexed: 06/06/2023]
Abstract
Chloride ions play important roles in many chemical and biological processes. This paper investigates the possibility of localizing 35Cl nuclei using solid-state NMR. It demonstrates that distances shorter than 3.8Å, between 13C atoms and 35Cl atoms in 10% uniformly labeled 13C L-tyrosine·HCl and natural abundance Glycine·HCl can be measured using rotational-echo (adiabatic passage) double-resonance (RE(AP)DOR). Furthermore the effect of quadrupolar interaction on the REDOR/REAPDOR experiment is quantified. The dephasing curve is plotted in a three dimensional chart as a function of the dephasing time and of the strength of quadrupolar interaction felt by each orientation. During spinning each orientation feels a quadrupolar interaction that varies in time, and therefore at each moment in time we reorder the crystallite orientations as a function of their contribution to the dephasing curve. In this way the effect of quadrupolar interaction on the dipolar dephasing curve can be fitted with a polynomial function. The numerical investigation performed allows us to generate REDOR/REAPDOR curves which are then used to simulate the experimental data.
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Affiliation(s)
- D Iuga
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK.
| | - P Rossi
- Department of Chemistry, Brandeis University, Waltham, MA 02454-9110, USA
| | - J Herzfeld
- Department of Chemistry, Brandeis University, Waltham, MA 02454-9110, USA
| | - R G Griffin
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, 150 Albany Street Cambridge, MA 02139, USA.
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13
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Brückner SI, Donets S, Dianat A, Bobeth M, Gutiérrez R, Cuniberti G, Brunner E. Probing Silica-Biomolecule Interactions by Solid-State NMR and Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11698-11705. [PMID: 27759396 DOI: 10.1021/acs.langmuir.6b03311] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Understanding the molecular interactions between inorganic phases such as silica and organic material is fundamental for chromatographic applications, for tailoring silica-enzyme interactions, and for elucidating the mechanisms of biomineralization. The formation, structure, and properties of the organic/inorganic interface is crucial in this context. Here, we investigate the interaction of selectively 13C-labeled choline with 29Si-labeled monosilicic acid/silica at the molecular level. Silica/choline nanocomposites were analyzed by solid-state NMR spectroscopy in combination with extended molecular dynamics (MD) simulations to understand the silica/organic interface. Cross-polarization magic angle spinning (CP MAS)-based NMR experiments like 1H-13C CP-REDOR (rotational-echo double resonance), 1H-13C HETCOR (heteronuclear correlation), and 1H-29Si-1H double CP are employed to determine spatial parameters. The measurement of 29Si-13C internuclear distances for selectively 13C-labeled choline provides an experimental parameter that allows the direct verification of MD simulations. Atomistic modeling using classical MD methodologies is performed using the INTERFACE force field. The modeling results are in excellent agreement with the experimental data and reveal the relevant molecular conformations as well as the nature and interplay of the interactions between the choline cation and the silica surface. Electrostatic interactions and hydrogen bonding are both important and depend strongly on the hydration level as well as the charge state of the silica surface.
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Affiliation(s)
- Stephan Ingmar Brückner
- Chair for Bioanalytical Chemistry, Department of Chemistry and Food Chemistry, TU Dresden , 01062 Dresden, Germany
| | - Sergii Donets
- Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden , 01062 Dresden, Germany
| | - Arezoo Dianat
- Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden , 01062 Dresden, Germany
| | - Manfred Bobeth
- Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden , 01062 Dresden, Germany
| | - Rafael Gutiérrez
- Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden , 01062 Dresden, Germany
| | - Gianaurelio Cuniberti
- Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden , 01062 Dresden, Germany
- Dresden Center for Computational Materials Science (DCMS), TU Dresden , 01062 Dresden, Germany
- Center for Advancing Electronics Dresden, TU Dresden , 01062 Dresden, Germany
| | - Eike Brunner
- Chair for Bioanalytical Chemistry, Department of Chemistry and Food Chemistry, TU Dresden , 01062 Dresden, Germany
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14
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Nishiyama Y, Malon M, Potrzebowski MJ, Paluch P, Amoureux JP. Accurate NMR determination of C-H or N-H distances for unlabeled molecules. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2016; 73:15-21. [PMID: 26169913 DOI: 10.1016/j.ssnmr.2015.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 06/19/2015] [Accepted: 06/28/2015] [Indexed: 06/04/2023]
Abstract
Cross-Polarization with Variable Contact-time (CP-VC) is very efficient at ultra-fast MAS (νR ≥ 60 kHz) to measure accurately the dipolar interactions corresponding to C-H or N-H short distances, which are very useful for resonance assignment and for analysis of dynamics. Here, we demonstrate the CP-VC experiment with (1)H detection. In the case of C-H distances, we compare the CP-VC signals with direct ((13)C) and indirect ((1)H) detection and find that the latter allows a S/N gain of ca. 2.5, which means a gain of ca. 6 in experimental time. The main powerful characteristics of CP-VC methods are related to the ultra-fast spinning speed and to the fact that most of the time only the value of the dipolar peak separation has to be used to obtain the information. As a result, CP-VC methods are: (i) easy to set up and to use, and robust with respect to (ii) rf-inhomogeneity thus allowing the use of full rotor samples, (iii) rf mismatch, and (iv) offsets and chemical shift anisotropies. It must be noted that the CP-VC 2D method with indirect (1)H detection requires the proton resolution and is thus mainly applicable to small or perdeuterated molecules. We also show that an analysis of the dynamics can even be performed, with a reasonable experimental time, on unlabeled samples with (13)C or even (15)N natural abundance.
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Affiliation(s)
- Y Nishiyama
- JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan; RIKEN CLST-JEOL Collaboration Center, Yokohama, Kanagawa 230-0045, Japan
| | - M Malon
- JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan; RIKEN CLST-JEOL Collaboration Center, Yokohama, Kanagawa 230-0045, Japan
| | - M J Potrzebowski
- Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies, 90-363 Lodz, Poland
| | - P Paluch
- Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies, 90-363 Lodz, Poland
| | - J P Amoureux
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China; UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France.
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15
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Paluch P, Trébosc J, Nishiyama Y, Potrzebowski MJ, Malon M, Amoureux JP. Theoretical study of CP-VC: a simple, robust and accurate MAS NMR method for analysis of dipolar C-H interactions under rotation speeds faster than ca. 60 kHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 252:67-77. [PMID: 25662360 DOI: 10.1016/j.jmr.2015.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 12/24/2014] [Accepted: 01/05/2015] [Indexed: 06/04/2023]
Abstract
We show that Cross-Polarization with Variable Contact-time (CP-VC) allows an accurate determination of C-H dipolar interactions, which permits an easy detailed analysis of bond lengths and local dynamics, e.g. in biomolecules. The method presents a large dipolar scaling factor of 1/√2, leading to a better determination of dipolar interactions, especially for long C-H distances, and it allows the observation of very small local details such as those related either to CH(2) three spin systems, or even to hydrogen bonds. CP-VC is very simple to set up and very robust with respect to most experimental parameters, such as: rf-offsets, chemical-shift anisotropies, imperfect Hartmann-Hahn setting, and rf-inhomogeneity. The only required condition is the use of a sufficiently fast MAS spinning speed of at least ca. 60 kHz.
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Affiliation(s)
- P Paluch
- Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies, Lodz 90-363, Poland
| | - J Trébosc
- UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France
| | - Y Nishiyama
- JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan; RIKEN CLST-JEOL Collaboration Center, Yokohama, Kanagawa 230-0045, Japan
| | - M J Potrzebowski
- Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies, Lodz 90-363, Poland
| | - M Malon
- JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan; RIKEN CLST-JEOL Collaboration Center, Yokohama, Kanagawa 230-0045, Japan
| | - J P Amoureux
- UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France; Physics Department, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China.
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16
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Spencer TL, Plagos NW, Brouwer DH, Goward GR. The use of 6Li{7Li}-REDOR NMR spectroscopy to compare the ionic conductivities of solid-state lithium ion electrolytes. Phys Chem Chem Phys 2014; 16:2515-26. [PMID: 24363013 DOI: 10.1039/c3cp55132f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Garnet-like solid-state electrolyte materials for lithium ion batteries are promising replacements for the currently-used liquid electrolytes. This work compares the temperature dependent Li(+) ion hopping rate in Li6BaLa2M2O12 (M = Ta, Nb) using solid-state (6)Li{(7)Li}-REDOR NMR. The slope of the (6)Li{(7)Li}-REDOR curve is highly temperature dependent in these two phases, and a comparison of the changes of the REDOR slopes as a function of temperature has been used to evaluate the Li(+) ion dynamics. Our results indicate that the Nb phase has a higher overall ionic conductivity in the range of 247 K to 350 K, as well as a higher activation energy for lithium ion hopping than the Ta counterpart. For appropriate relative timescales of the dipolar couplings and ion transport processes, this is shown to be a facile method to compare ion dynamics among similar structures.
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Affiliation(s)
- T L Spencer
- McMaster University, Department of Chemistry and Chemical Biology, 1280 Main St. West, Hamilton, Ontario, Canada, L8S 1H2.
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17
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Mithu VS, Tan KO, Madhu PK. Selective inversion of 1H resonances in solid-state nuclear magnetic resonance: Use of double-DANTE pulse sequence. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 237:11-16. [PMID: 24121475 DOI: 10.1016/j.jmr.2013.09.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 09/07/2013] [Accepted: 09/16/2013] [Indexed: 06/02/2023]
Abstract
We here present a method based on DANTE pulses and homonuclear dipolar decoupling scheme to invert selectively any desired resonance in a proton spin system under magic-angle spinning. Experimental results are reported on a sample of L-histidine·HCl·H2O at magic-angle spinning frequencies of 15 and 60kHz. The results are also substantiated numerically.
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Affiliation(s)
- Venus Singh Mithu
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - Kong Ooi Tan
- Department of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland
| | - P K Madhu
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India; TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsinghi, Hyderabad 500 075, India.
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18
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Williams J, Zhang Y, Schmidt-Rohr K, Hong M. pH-dependent conformation, dynamics, and aromatic interaction of the gating tryptophan residue of the influenza M2 proton channel from solid-state NMR. Biophys J 2013; 104:1698-708. [PMID: 23601317 PMCID: PMC3627873 DOI: 10.1016/j.bpj.2013.02.054] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 02/11/2013] [Indexed: 12/19/2022] Open
Abstract
The M2 protein of the influenza virus conducts protons into the virion under external acidic pH. The proton selectivity of the tetrameric channel is controlled by a single histidine (His(37)), whereas channel gating is accomplished by a single tryptophan (Trp(41)) in the transmembrane domain of the protein. Aromatic interaction between these two functional residues has been previously observed in Raman spectra, but atomic-resolution evidence for this interaction remains scarce. Here we use high-resolution solid-state NMR spectroscopy to determine the side-chain conformation and dynamics of Trp(41) in the M2 transmembrane peptide by measuring the Trp chemical shifts, His(37)-Trp(41) distances, and indole dynamics at high and low pH. The interatomic distances constrain the Trp41 side-chain conformation to trans for χ1 and 120-135° for χ2. This t90 rotamer points the Nε1-Cε2-Cζ2 side of the indole toward the aqueous pore. The precise χ1 and χ2 angles differ by ∼20° between high and low pH. These differences, together with the known changes in the helix tilt angle between high and low pH, push the imidazole and indole rings closer together at low pH. Moreover, the measured order parameters indicate that the indole rings undergo simultaneous χ1 and χ2 torsional fluctuations at acidic pH, but only restricted χ1 fluctuations at high pH. As a result, the Trp(41) side chain periodically experiences strong cation-π interactions with His(37) at low pH as the indole sweeps through its trajectory, whereas at high pH the indole ring is further away from the imidazole. These results provide the structural basis for understanding how the His(37)-water proton exchange rate measured by NMR is reduced to the small proton flux measured in biochemical experiments. The indole dynamics, together with the known motion of the imidazolium, indicate that this compact ion channel uses economical side-chain dynamics to regulate proton conduction and gating.
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Affiliation(s)
| | | | | | - Mei Hong
- Department of Chemistry, Iowa State University, Ames, Iowa
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19
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Xie L, Ghosh U, Schmick SD, Weliky DP. Residue-specific membrane location of peptides and proteins using specifically and extensively deuterated lipids and ¹³C-²H rotational-echo double-resonance solid-state NMR. JOURNAL OF BIOMOLECULAR NMR 2013; 55:11-7. [PMID: 23225071 PMCID: PMC3557618 DOI: 10.1007/s10858-012-9692-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 11/28/2012] [Indexed: 05/12/2023]
Abstract
Residue-specific location of peptides in the hydrophobic core of membranes was examined using (13)C-(2)H REDOR and samples in which the lipids were selectively deuterated. The transmembrane topology of the KALP peptide was validated with this approach with substantial dephasing observed for deuteration in the bilayer center and reduced or no dephasing for deuteration closer to the headgroups. Insertion of β sheet HIV and helical and β sheet influenza virus fusion peptides into the hydrophobic core of the membrane was validated in samples with extensively deuterated lipids.
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Affiliation(s)
- Li Xie
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
| | - Ujjayini Ghosh
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
| | - Scott D. Schmick
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
| | - David P. Weliky
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
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20
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Li S, Su Y, Hong M. Intramolecular 1H-13C distance measurement in uniformly 13C, 15N labeled peptides by solid-state NMR. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2012; 45-46:51-58. [PMID: 22749432 PMCID: PMC3414644 DOI: 10.1016/j.ssnmr.2012.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 04/29/2012] [Accepted: 06/05/2012] [Indexed: 06/01/2023]
Abstract
A (1)H-(13)C frequency-selective REDOR (FS-REDOR) experiment is developed for measuring intramolecular (1)H-(13)C distances in uniformly (13)C, (15)N-labeled molecules. Theory and simulations show that the experiment removes the interfering homonuclear (1)H-(1)H, (13)C-(13)C and heteronuclear (1)H-(15)N, (13)C-(15)N dipolar interactions while retaining the desired heteronuclear (1)H-(13)C dipolar interaction. Our results indicate that this technique, combined with the numerical fitting, can be used to measure a (1)H-(13)C distance up to 5Å. We also demonstrate that the measured intramolecular (1)H-(13)C distances are useful to determine dihedral angles in proteins.
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Affiliation(s)
- Shenhui Li
- Wuhan Institute of Physics and Mathematics, the Chinese Academy of Sciences, Wuhan 430071, China
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Yongchao Su
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Mei Hong
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
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21
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Giffard M, Hediger S, Lewandowski JR, Bardet M, Simorre JP, Griffin RG, De Paëpe G. Compensated second-order recoupling: application to third spin assisted recoupling. Phys Chem Chem Phys 2012; 14:7246-55. [PMID: 22513727 PMCID: PMC4440590 DOI: 10.1039/c2cp40406k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We consider the effect of phase shifts in the context of second-order recoupling techniques in solid-state NMR. Notably we highlight conditions leading to significant improvements for the Third Spin Assisted Recoupling (TSAR) mechanism and demonstrate the benefits of resulting techniques for detecting long-distance transfer in biomolecular systems. The modified pulse sequences of PAR and PAIN-CP, Phase-Shifted Proton Assisted Recoupling (AH-PS-PAR) and Phase-Shifted Proton-Assisted Insensitive Nuclei Cross Polarization (ABH-PS-PAIN-CP), still rely on cross terms between heteronuclear dipolar couplings involving assisting protons that mediate zero-quantum polarization transfer between low-γ nuclei ((13)C-(13)C, (15)N-(15)N, (15)N-(13)C polarization transfer). Using Average Hamiltonian Theory we show that phase inversion compensates off-resonance contributions and yields improved polarization transfer as well as substantial broadening of the matching conditions. PS-TSAR greatly improves on the standard TSAR based methods because it alleviates their sensitivity to precise RF settings which significantly enhances robustness of the experiments. We demonstrate these new methods on a 19.6 kDa protein (U-[(15)N, (13)C]-YajG) at high magnetic fields (up to 900 MHz (1)H frequency) and fast sample spinning (up to 65 kHz MAS frequency).
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Affiliation(s)
- Mathilde Giffard
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, CEA/DSM/INAC–38054, Grenoble, France
| | - Sabine Hediger
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, CEA/DSM/INAC–38054, Grenoble, France
| | | | - Michel Bardet
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, CEA/DSM/INAC–38054, Grenoble, France
| | - Jean-Pierre Simorre
- Institut de Biologie Structurale, UMR 5075 (CEA/CNRS/UJF), 38027 Grenoble, France
| | - Robert G. Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Gaël De Paëpe
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, CEA/DSM/INAC–38054, Grenoble, France
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22
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De Paëpe G. Dipolar Recoupling in Magic Angle Spinning Solid-State Nuclear Magnetic Resonance. Annu Rev Phys Chem 2012; 63:661-84. [DOI: 10.1146/annurev-physchem-032511-143726] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Gaël De Paëpe
- Service de Chimie Inorganique et Biologique, UMR-E 3 CEA/UJF-Grenoble 1, Institut Nanosciences et Cryogénie, F-38054 Grenoble, France;
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23
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Hu YY, Rawal A, Schmidt-Rohr K. Strongly bound citrate stabilizes the apatite nanocrystals in bone. Proc Natl Acad Sci U S A 2010; 107:22425-9. [PMID: 21127269 PMCID: PMC3012505 DOI: 10.1073/pnas.1009219107] [Citation(s) in RCA: 320] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nanocrystals of apatitic calcium phosphate impart the organic-inorganic nanocomposite in bone with favorable mechanical properties. So far, the factors preventing crystal growth beyond the favorable thickness of ca. 3 nm have not been identified. Here we show that the apatite surfaces are studded with strongly bound citrate molecules, whose signals have been identified unambiguously by multinuclear magnetic resonance (NMR) analysis. NMR reveals that bound citrate accounts for 5.5 wt% of the organic matter in bone and covers apatite at a density of about 1 molecule per (2 nm)(2), with its three carboxylate groups at distances of 0.3 to 0.45 nm from the apatite surface. Bound citrate is highly conserved, being found in fish, avian, and mammalian bone, which indicates its critical role in interfering with crystal thickening and stabilizing the apatite nanocrystals in bone.
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Affiliation(s)
- Y.-Y. Hu
- Ames Laboratory and Department of Chemistry, Iowa State University, Ames, IA 50011
| | - A. Rawal
- Ames Laboratory and Department of Chemistry, Iowa State University, Ames, IA 50011
| | - K. Schmidt-Rohr
- Ames Laboratory and Department of Chemistry, Iowa State University, Ames, IA 50011
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24
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Zhang Y, Lu W, Hong M. The membrane-bound structure and topology of a human α-defensin indicate a dimer pore mechanism for membrane disruption. Biochemistry 2010; 49:9770-82. [PMID: 20961099 DOI: 10.1021/bi101512j] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Defensins are cationic and disulfide-bonded host defense proteins of many animals that target microbial cell membranes. Elucidating the three-dimensional structure, dynamics, and topology of these proteins in phospholipid bilayers is important for understanding their mechanisms of action. Using solid-state nuclear magnetic resonance spectroscopy, we have now determined the conformation, dynamics, oligomeric state, and topology of a human α-defensin, HNP-1, in DMPC/DMPG bilayers. Two-dimensional correlation spectra show that membrane-bound HNP-1 exhibits a conformation similar to that of the water-soluble state, except for the turn connecting strands β2 and β3, whose side chains exhibit immobilization and conformational perturbation upon membrane binding. At high protein/lipid ratios, rapid (1)H spin diffusion from the lipid chains to the protein was observed, indicating that HNP-1 was well inserted into the hydrocarbon core of the bilayer. Arg Cζ-lipid (31)P distances indicate that only one of the four Arg residues forms tight hydrogen-bonded guanidinium-phosphate complexes. The protein is predominantly dimerized at high protein/lipid molar ratios, as shown by (19)F spin diffusion experiments. The presence of a small fraction of monomers and the shallower insertion at lower protein concentrations suggest that HNP-1 adopts concentration-dependent oligomerization and membrane-bound structure. These data strongly support a "dimer pore" topology of HNP-1 in which the polar top of the dimer lines an aqueous pore while the hydrophobic bottom faces the lipid chains. In this structure, R25 lies closest to the membrane surface among the four Arg residues. The pore does not have a high degree of lipid disorder, in contrast to the toroidal pores formed by protegrin-1, a two-stranded β-hairpin antimicrobial peptide. These results provide the first glimpse into the membrane-bound structure and mechanism of action of human α-defensins.
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Affiliation(s)
- Yuan Zhang
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
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25
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Doherty T, Su Y, Hong M. High-resolution orientation and depth of insertion of the voltage-sensing S4 helix of a potassium channel in lipid bilayers. J Mol Biol 2010; 401:642-52. [PMID: 20600109 PMCID: PMC2918711 DOI: 10.1016/j.jmb.2010.06.048] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 06/17/2010] [Accepted: 06/23/2010] [Indexed: 11/27/2022]
Abstract
The opening and closing of voltage-gated potassium (Kv) channels are controlled by several conserved Arg residues in the S4 helix of the voltage-sensing domain. The interaction of these positively charged Arg residues with the lipid membrane has been of intense interest for understanding how membrane proteins fold to allow charged residues to insert into lipid bilayers against free-energy barriers. Using solid-state NMR, we have now determined the orientation and insertion depth of the S4 peptide of the KvAP channel in lipid bilayers. Two-dimensional (15)N correlation experiments of macroscopically oriented S4 peptide in phospholipid bilayers revealed a tilt angle of 40 degrees and two possible rotation angles differing by 180 degrees around the helix axis. Remarkably, the tilt angle and one of the two rotation angles are identical to those of the S4 helix in the intact voltage-sensing domain, suggesting that interactions between the S4 segment and other helices of the voltage-sensing domain are not essential for the membrane topology of the S4 helix. (13)C-(31)P distances between the S4 backbone and the lipid (31)P indicate a approximately 9 A local thinning and 2 A average thinning of the DMPC (1,2-dimyristoyl-sn-glycero-3-phosphochloline)/DMPG (1,2-dimyristoyl-sn-glycero-3-phosphatidylglycerol) bilayer, consistent with neutron diffraction data. Moreover, a short distance of 4.6 A from the guanidinium C(zeta) of the second Arg to (31)P indicates the existence of guanidinium phosphate hydrogen bonding and salt bridges. These data suggest that the structure of the Kv gating helix is mainly determined by protein-lipid interactions instead of interhelical protein-protein interactions, and the S4 amino acid sequence encodes sufficient information for the membrane topology of this crucial gating helix.
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Affiliation(s)
| | | | - Mei Hong
- Department of Chemistry, Iowa State University, Ames, IA 50011
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26
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Chen L, Wang Q, Hu B, Lafon O, Trébosc J, Deng F, Amoureux JP. Measurement of hetero-nuclear distances using a symmetry-based pulse sequence in solid-state NMR. Phys Chem Chem Phys 2010; 12:9395-405. [PMID: 20577687 DOI: 10.1039/b926546e] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A Symmetry-based Resonance-Echo DOuble-Resonance (S-REDOR) method is proposed for measuring hetero-nuclear dipolar couplings between two different spin-1/2 nuclei, under fast magic-angle spinning. The hetero-nuclear dipolar couplings are restored by employing the SR4 sequence, which requires the rf-field strength to be only twice the spinning frequency. The S-REDOR experiment is extended to S-RESPDOR (Symmetry-based Resonance-Echo Saturation-Pulse DOuble-Resonance) for determining dipolar coupling between a spin-1/2 nucleus (e.g.(13)C) and (14)N. It is demonstrated that S-REDOR and S-RESPDOR methods suppress efficiently the homo-nuclear dipolar interaction of the irradiated nucleus and benefit from high robustness to the rf-field inhomogeneity, chemical shielding and dipolar truncation. Therefore, these methods allow the measurement of (13)C/(14,15)N distances, with (13)C observation, in uniformly (13)C-labeled samples. Furthermore, we provide analytical solutions for the S-REDOR and S-RESPDOR dephasing curves. These solutions facilitate the measurement of hetero-nuclear distances from experimental data.
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Affiliation(s)
- Lei Chen
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, the Chinese Academy of Sciences, Wuhan 430071, China
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27
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Helmus JJ, Surewicz K, Surewicz WK, Jaroniec CP. Conformational flexibility of Y145Stop human prion protein amyloid fibrils probed by solid-state nuclear magnetic resonance spectroscopy. J Am Chem Soc 2010; 132:2393-403. [PMID: 20121096 PMCID: PMC2838504 DOI: 10.1021/ja909827v] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Amyloid aggregates of a C-truncated Y145Stop mutant of human prion protein, huPrP23-144, associated with a heritable amyloid angiopathy, have previously been shown to contain a compact, relatively rigid, and beta-sheet-rich approximately 30-residue amyloid core near the C-terminus under physiologically relevant conditions. In contrast, the remaining huPrP23-144 residues display considerable conformational dynamics, as evidenced by the absence of corresponding signals in cross-polarization (CP)-based solid-state NMR (SSNMR) spectra under ambient conditions and their emergence in analogous spectra recorded at low temperature on frozen fibril samples. Here, we present the direct observation of residues comprising the flexible N-terminal domain of huPrP23-144 amyloid by using 2D J-coupling-based magic-angle spinning (MAS) SSNMR techniques. Chemical shifts for these residues indicate that the N-terminal domain is effectively an ensemble of protein chains with random-coil-like conformations. Interestingly, a detailed analysis of signal intensities in CP-based 3D SSNMR spectra suggests that non-negligible molecular motions may also be occurring on the NMR time scale within the relatively rigid core of huPrP23-144 amyloid. To further investigate this hypothesis, quantitative measurements of backbone dipolar order parameters and transverse spin relaxation rates were performed for the core residues. The observed order parameters indicate that, on the submicrosecond time scale, these residues are effectively rigid and experience only highly restricted and relatively uniform motions similar to those characteristic for well-structured regions of microcrystalline proteins. On the other hand, significant variations in magnitude of transverse spin relaxation rates were noted for residues present at different locations within the core region and correlated with observed differences in spectral intensities. While interpreted only qualitatively at the present time, the extent of the observed variations in transverse relaxation rates is consistent with the presence of relatively slow, microsecond-millisecond time scale chemical exchange type phenomena within the huPrP23-144 amyloid core.
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Affiliation(s)
- Jonathan J. Helmus
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43210
| | - Krystyna Surewicz
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106
| | - Witold K. Surewicz
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106
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28
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Zhang Y, Doherty T, Li J, Lu W, Barinka C, Lubkowski J, Hong M. Resonance assignment and three-dimensional structure determination of a human alpha-defensin, HNP-1, by solid-state NMR. J Mol Biol 2010; 397:408-22. [PMID: 20097206 DOI: 10.1016/j.jmb.2010.01.030] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 12/28/2009] [Accepted: 01/14/2010] [Indexed: 11/26/2022]
Abstract
Human alpha-defensins [human neutrophil peptides (HNPs)] are immune defense mini-proteins that act by disrupting microbial cell membranes. Elucidating the three-dimensional (3D) structures of HNPs in lipid membranes is important for understanding their mechanisms of action. Using solid-state NMR (SSNMR), we have determined the 3D structure of HNP-1 in a microcrystalline state outside the lipid membrane, which provides benchmarks for structure determination and comparison with the membrane-bound state. From a suite of two-dimensional and 3D magic-angle spinning experiments, (13)C and (15)N chemical shifts that yielded torsion angle constraints were obtained, while inter-residue distances were obtained to restrain the 3D fold. Together, these constraints led to the first high-resolution SSNMR structure of a human defensin. The SSNMR structure has close similarity to the crystal structures of the HNP family, with the exception of the loop region between the first and second beta-strands. The difference, which is partially validated by direct torsion angle measurements of selected loop residues, suggests possible conformational variation and flexibility of this segment of the protein, which may regulate HNP interaction with the phospholipid membrane of microbial cells.
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Affiliation(s)
- Yuan Zhang
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
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29
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Bajaj VS, Mak-Jurkauskas ML, Belenky M, Herzfeld J, Griffin RG. DNP enhanced frequency-selective TEDOR experiments in bacteriorhodopsin. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 202:9-13. [PMID: 19854082 PMCID: PMC2818331 DOI: 10.1016/j.jmr.2009.09.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 08/27/2009] [Accepted: 09/03/2009] [Indexed: 05/06/2023]
Abstract
We describe a new approach to multiple (13)C-(15)N distance measurements in uniformly labeled solids, frequency-selective (FS) TEDOR. The method shares features with FS-REDOR and ZF- and BASE-TEDOR, which also provide quantitative (15)N-(13)C spectral assignments and distance measurements in U-[(13)C,(15)N] samples. To demonstrate the validity of the FS-TEDOR sequence, we measured distances in [U-(13)C,(15)N]-asparagine which are in good agreement with other methods. In addition, we integrate high frequency dynamic nuclear polarization (DNP) into the experimental protocol and use FS-TEDOR to record a resolved correlation spectrum of the Arg-(13)C(gamma)-(15)N(epsilon) region in [U-(13)C,(15)N]-bacteriorhodopsin. We resolve six of the seven cross-peaks expected based on the primary sequence of this membrane protein.
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Affiliation(s)
- Vikram S Bajaj
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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30
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Luo W, Cady SD, Hong M. Immobilization of the influenza A M2 transmembrane peptide in virus envelope-mimetic lipid membranes: a solid-state NMR investigation. Biochemistry 2009; 48:6361-8. [PMID: 19489611 PMCID: PMC4082982 DOI: 10.1021/bi900716s] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The dynamic and structural properties of membrane proteins are intimately affected by the lipid bilayer. One property of membrane proteins is uniaxial rotational diffusion, which depends on the membrane viscosity and thickness. This rotational diffusion is readily manifested in solid-state NMR spectra as characteristic line shapes and temperature-dependent line narrowing or broadening. We show here that this whole-body uniaxial diffusion is suppressed in lipid bilayers mimicking the composition of eukaryotic cell membranes, which are rich in cholesterol and sphingomyelin. We demonstrate this membrane-induced immobilization on the transmembrane peptide of the influenza A M2 (AM2-TM) proton channel protein. At physiological temperature, AM2-TM undergoes uniaxial diffusion faster than approximately 10(5) s(-1) in DLPC, DMPC, and POPC bilayers, but the motion is slowed by 2 orders of magnitude, to <10(3) s(-1), in a cholesterol-rich virus envelope-mimetic membrane ("viral membrane"). The immobilization is manifested as near rigid-limit (2)H quadrupolar couplings and (13)C-(1)H, (15)N-(1)H, and (13)C-(15)N dipolar couplings for all labeled residues. The immobilization suppresses intermediate time scale broadening of the NMR spectra, thus allowing high-sensitivity and high-resolution spectra to be measured at physiological temperature. The conformation of the protein in the viral membrane is more homogeneous than in model PC membranes, as evidenced by the narrow (15)N lines. The immobilization of the M2 helical bundle by the membrane composition change indicates the importance of studying membrane proteins in environments as native as possible. It also suggests that eukaryote-mimetic lipid membranes may greatly facilitate structure determination of membrane proteins by solid-state NMR.
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Affiliation(s)
- Wenbin Luo
- Department of Chemistry, Iowa State University, Ames, IA 50011
| | - Sarah D. Cady
- Department of Chemistry, Iowa State University, Ames, IA 50011
| | - Mei Hong
- Department of Chemistry, Iowa State University, Ames, IA 50011
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31
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Lewandowski JR, De Paëpe G, Eddy MT, Griffin RG. (15)N-(15)N proton assisted recoupling in magic angle spinning NMR. J Am Chem Soc 2009; 131:5769-76. [PMID: 19334788 PMCID: PMC2754755 DOI: 10.1021/ja806578y] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe a new magic angle spinning (MAS) NMR experiment for obtaining (15)N-(15)N correlation spectra. The approach yields direct information about the secondary and tertiary structure of proteins, including identification of alpha-helical stretches and interstrand connectivity in antiparallel beta-sheets, which are of major interest for structural studies of membrane proteins and amyloid fibrils. The method, (15)N-(15)N proton assisted recoupling (PAR), relies on a second-order mechanism, third spin assisted recoupling (TSAR), used previously in the context of (15)N-(13)C and (13)C-(13)C polarization transfer schemes. In comparison to (15)N-(15)N proton-driven spin diffusion experiments, the PAR technique accelerates polarization transfer between (15)N's by a factor of approximately 10(2)-10(3) and is furthermore applicable over the entire range of currently available MAS frequencies (10-70 kHz).
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Affiliation(s)
- Józef R Lewandowski
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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32
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Matsuoka S, Inoue M. Application of REDOR NMR in natural product chemistry. Chem Commun (Camb) 2009:5664-75. [DOI: 10.1039/b910230b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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De Paëpe G, Lewandowski JR, Loquet A, Böckmann A, Griffin RG. Proton assisted recoupling and protein structure determination. J Chem Phys 2008; 129:245101. [PMID: 19123534 PMCID: PMC2755343 DOI: 10.1063/1.3036928] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 11/03/2008] [Indexed: 11/14/2022] Open
Abstract
We introduce a homonuclear version of third spin assisted recoupling, a second-order mechanism that can be used for polarization transfer between (13)C or (15)N spins in magic angle spinning (MAS) NMR experiments, particularly at high spinning frequencies employed in contemporary high field MAS experiments. The resulting sequence, which we refer to as proton assisted recoupling (PAR), relies on a cross-term between (1)H-(13)C (or (1)H-(15)N) couplings to mediate zero quantum (13)C-(13)C (or (15)N-(15)N recoupling). In particular, using average Hamiltonian theory we derive an effective Hamiltonian for PAR and show that the transfer is mediated by trilinear terms of the form C(1) (+/-)C(2) (-/+)H(Z) for (13)C-(13)C recoupling experiments (or N(1) (+/-)N(2) (-/+)H(Z) for (15)N-(15)N). We use analytical and numerical simulations to explain the structure of the PAR optimization maps and to delineate the PAR matching conditions. We also detail the PAR polarization transfer dependence with respect to the local molecular geometry and explain the observed reduction in dipolar truncation. Finally, we demonstrate the utility of PAR in structural studies of proteins with (13)C-(13)C spectra of uniformly (13)C, (15)N labeled microcrystalline Crh, a 85 amino acid model protein that forms a domain swapped dimer (MW=2 x 10.4 kDa). The spectra, which were acquired at high MAS frequencies (omega(r)2pi>20 kHz) and magnetic fields (750-900 MHz (1)H frequencies) using moderate rf fields, exhibit numerous cross peaks corresponding to long (up to 6-7 A) (13)C-(13)C distances which are particularly useful in protein structure determination. Using results from PAR spectra we calculate the structure of the Crh protein.
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Affiliation(s)
- Gaël De Paëpe
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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34
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Tang M, Waring AJ, Hong M. Effects of arginine density on the membrane-bound structure of a cationic antimicrobial peptide from solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:514-21. [PMID: 19059201 DOI: 10.1016/j.bbamem.2008.10.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 10/02/2008] [Accepted: 10/30/2008] [Indexed: 11/30/2022]
Abstract
Solid-state NMR spectroscopy is used to determine the membrane-bound topological structure of a cationic beta-hairpin antimicrobial peptide in which the number of Arg residues has been halved. The parent peptide, PG-1, was previously found to form transmembrane beta-barrels in anionic membranes where the Arg residues complex with the lipid phosphate groups to cause toroidal pore defects in the membrane. In comparison, the charge-attenuated and less active mutant studied here forms beta-sheets that lie on the surface of the zwitterionic membrane and only partially insert into the anionic membrane. The mutant also exhibits much looser contact with the lipid headgroups. These results indicate that transmembrane insertion and tight Arg-phosphate association are two important elements for strong antimicrobial activities of this class of peptides. Comparison with other beta-hairpin antimicrobial peptides studied so far further suggests a relative potency scale for the various mechanisms of action for the beta-sheet family of antimicrobial peptides. The transmembrane insertion-toroidal pore mechanism is the most potent in disrupting the lipid bilayer, followed by the large-amplitude in-plane motional mechanism. The carpet model, where peptides aggregate on the membrane surface to cause lateral expansion and eventual micellization of the membrane, is a weaker mechanism of action.
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Affiliation(s)
- Ming Tang
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
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35
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Mihaliuk E, Gullion T. A frequency-selective REDOR experiment for an SI2 spin system. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2008; 193:308-310. [PMID: 18547849 DOI: 10.1016/j.jmr.2008.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Accepted: 05/10/2008] [Indexed: 05/26/2023]
Abstract
A frequency-selective REDOR experiment is described for SI2 spin systems. The experiment causes the net dipolar dephasing of the S spin to evolve only under the influence of one of the I spins. The experiment is based on a single pair of appropriately phased 90 degrees I-spin pulses, and the I spin causing the S-spin dipolar dephasing is determined by the relative phases between the two 90 degrees pulses. The experiment is demonstrated on a sample of 15N2-L-asparagine.
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Affiliation(s)
- Eugene Mihaliuk
- Department of Chemistry, West Virginia University, Clark Hall, P.O. Box 6045, Morgantown, WV 26505, USA
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36
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Su Y, Mani R, Hong M. Asymmetric insertion of membrane proteins in lipid bilayers by solid-state NMR paramagnetic relaxation enhancement: a cell-penetrating Peptide example. J Am Chem Soc 2008; 130:8856-64. [PMID: 18597439 PMCID: PMC4083468 DOI: 10.1021/ja802383t] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A novel solid-state NMR technique for identifying the asymmetric insertion depths of membrane proteins in lipid bilayers is introduced. By applying Mn (2+) ions on the outer but not the inner leaflet of lipid bilayers, the sidedness of protein residues in the lipid bilayer can be determined through paramagnetic relaxation enhancement (PRE) effects. Protein-free lipid membranes with one-side Mn (2+)-bound surfaces exhibit significant residual (31)P and lipid headgroup (13)C intensities, in contrast to two-side Mn (2+)-bound membranes, where lipid headgroup signals are mostly suppressed. Applying this method to a cell-penetrating peptide, penetratin, we found that at low peptide concentrations, penetratin is distributed in both leaflets of the bilayer, in contrast to the prediction of the electroporation model, which predicts that penetratin binds to only the outer lipid leaflet at low peptide concentrations to cause an electric field that drives subsequent peptide translocation. The invalidation of the electroporation model suggests an alternative mechanism for intracellular import of penetratin, which may involve guanidinium-phosphate complexation between the peptide and the lipids.
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Affiliation(s)
- Yongchao Su
- Department of Chemistry, Iowa State University, Ames, Iowa 50011
| | | | - Mei Hong
- Department of Chemistry, Iowa State University, Ames, Iowa 50011
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37
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Helmus JJ, Nadaud PS, Höfer N, Jaroniec CP. Determination of methyl 13C-15N dipolar couplings in peptides and proteins by three-dimensional and four-dimensional magic-angle spinning solid-state NMR spectroscopy. J Chem Phys 2008; 128:052314. [PMID: 18266431 DOI: 10.1063/1.2817638] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We describe three- and four-dimensional semiconstant-time transferred echo double resonance (SCT-TEDOR) magic-angle spinning solid-state nuclear magnetic resonance (NMR) experiments for the simultaneous measurement of multiple long-range (15)N-(13)C(methyl) dipolar couplings in uniformly (13)C, (15)N-enriched peptides and proteins with high resolution and sensitivity. The methods take advantage of (13)C spin topologies characteristic of the side-chain methyl groups in amino acids alanine, isoleucine, leucine, methionine, threonine, and valine to encode up to three distinct frequencies ((15)N-(13)C(methyl) dipolar coupling, (15)N chemical shift, and (13)C(methyl) chemical shift) within a single SCT evolution period of initial duration approximately 1(1)J(CC) (where (1)J(CC) approximately 35 Hz, is the one-bond (13)C(methyl)-(13)C J-coupling) while concurrently suppressing the modulation of NMR coherences due to (13)C-(13)C and (15)N-(13)C J-couplings and transverse relaxation. The SCT-TEDOR schemes offer several important advantages over previous methods of this type. First, significant (approximately twofold to threefold) gains in experimental sensitivity can be realized for weak (15)N-(13)C(methyl) dipolar couplings (corresponding to structurally interesting, approximately 3.5 A or longer, distances) and typical (13)C(methyl) transverse relaxation rates. Second, the entire SCT evolution period can be used for (13)C(methyl) and/or (15)N frequency encoding, leading to increased spectral resolution with minimal additional coherence decay. Third, the experiments are inherently "methyl selective," which results in simplified NMR spectra and obviates the use of frequency-selective pulses or other spectral filtering techniques. Finally, the (15)N-(13)C cross-peak buildup trajectories are purely dipolar in nature (i.e., not influenced by J-couplings or relaxation), which enables the straightforward extraction of (15)N-(13)C(methyl) distances using an analytical model. The SCT-TEDOR experiments are demonstrated on a uniformly (13)C, (15)N-labeled peptide, N-acetyl-valine, and a 56 amino acid protein, B1 immunoglobulin-binding domain of protein G (GB1), where the measured (15)N-(13)C(methyl) dipolar couplings provide site-specific information about side-chain dihedral angles and the packing of protein molecules in the crystal lattice.
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Affiliation(s)
- Jonathan J Helmus
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA
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38
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De Paëpe G, Lewandowski JR, Griffin RG. Spin dynamics in the modulation frame: Application to homonuclear recoupling in magic angle spinning solid-state NMR. J Chem Phys 2008; 128:124503. [DOI: 10.1063/1.2834732] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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39
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Graesser DT, Wylie BJ, Nieuwkoop AJ, Franks WT, Rienstra CM. Long-range 19F-15N distance measurements in highly-13C, 15N-enriched solid proteins with 19F-dephased REDOR shift (FRESH) spectroscopy. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2007; 45 Suppl 1:S129-S134. [PMID: 18157807 DOI: 10.1002/mrc.2126] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We present a novel rotational-echo double resonance (REDOR) method for detection of multiple (19)F-(15)N distances in solid proteins. The method is applicable to protein samples containing a single (19)F label, in addition to high levels of (13)C and (15)N enrichment. REDOR dephasing pulses are applied on the (19)F channel during an indirect constant time chemical shift evolution period on (15)N, and polarization is then transferred to (13)C for detection, with high-power (1)H decoupling throughout the sequence. This four-channel experiment reports site-specifically on (19)F-(15)N distances, with highly accurate determinations of approximately 5 A distances and detection of correlations arising from internuclear distances of at least 8 A. We demonstrate the method on the well-characterized 56-residue model protein GB1, where the sole tryptophan residue (Trp-43) has been labeled with 5-(19)F-Trp, in a bacterial growth medium also including (13)C-glucose and (15)N ammonium chloride. In GB1, 11 distances are determined, all agreeing within 20% of the X-ray structure distances. We envision the experiment will be utilized to measure quantitative long-range distances for protein structure determination.
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Affiliation(s)
- Daniel T Graesser
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 68101, USA
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40
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Matsuoka S, Schaefer J. Dipolar double-quantum filtered rotational-echo double resonance. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2007; 45 Suppl 1:S61-S64. [PMID: 18157803 DOI: 10.1002/mrc.2076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The homonuclear dipolar coupling of a directly bonded (13)C-(13)C pair has been used to create a dipolar double-quantum filter (D-DQF) to remove the natural-abundance (13)C background in (13)C[(2)H] rotational-echo double-resonance (REDOR) experiments. The most efficient version of this experiment has the D-DQF excitation and reconversion preceding the REDOR evolution period. Calculated and observed (13)C[(2)H]D-DQF-REDOR dephasings were in agreement for a test sample of mixed recrystallized labeled alanines.
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Affiliation(s)
- Shigeru Matsuoka
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA
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41
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Gibson JM, Popham JM, Raghunathan V, Stayton PS, Drobny GP. A solid-state NMR study of the dynamics and interactions of phenylalanine rings in a statherin fragment bound to hydroxyapatite crystals. J Am Chem Soc 2007; 128:5364-70. [PMID: 16620107 DOI: 10.1021/ja056731m] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Extracellular matrix proteins regulate hard tissue growth by acting as adhesion sites for cells, by triggering cell signaling pathways, and by directly regulating the primary and/or secondary crystallization of hydroxyapatite, the mineral component of bone and teeth. Despite the key role that these proteins play in the regulation of hard tissue growth in humans, the exact mechanism used by these proteins to recognize mineral surfaces is poorly understood. Interactions between mineral surfaces and proteins very likely involve specific contacts between the lattice and the protein side chains, so elucidation of the nature of interactions between protein side chains and their corresponding inorganic mineral surfaces will provide insight into the recognition and regulation of hard tissue growth. Isotropic chemical shifts, chemical shift anisotropies (CSAs), NMR line-width information, (13)C rotating frame relaxation measurements, as well as direct detection of correlations between (13)C spins on protein side chains and (31)P spins in the crystal surface with REDOR NMR show that, in the peptide fragment derived from the N-terminal 15 amino acids of salivary statherin (i.e., SN-15), the side chain of the phenylalanine nearest the C-terminus of the peptide (F14) is dynamically constrained and oriented near the surface, whereas the side chain of the phenylalanine located nearest to the peptide's N-terminus (F7) is more mobile and is oriented away from the hydroxyapatite surface. The relative dynamics and proximities of F7 and F14 to the surface together with prior data obtained for the side chain of SN-15's unique lysine (i.e., K6) were used to construct a new picture for the structure of the surface-bound peptide and its orientation to the crystal surface.
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Affiliation(s)
- James M Gibson
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
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42
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Andreas LB, Mehta AK, Mehta MA. Determination of Global Structure from Distance and Orientation Constraints in Biological Solids Using Solid-State NMR Spectroscopy. J Am Chem Soc 2007; 129:15233-9. [DOI: 10.1021/ja074789q] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Loren B. Andreas
- Contribution from the Department of Chemistry and Biochemistry, Oberlin College, Oberlin, Ohio 44074, and Department of Chemistry, Emory University, Atlanta, Georgia 30322
| | - Anil K. Mehta
- Contribution from the Department of Chemistry and Biochemistry, Oberlin College, Oberlin, Ohio 44074, and Department of Chemistry, Emory University, Atlanta, Georgia 30322
| | - Manish A. Mehta
- Contribution from the Department of Chemistry and Biochemistry, Oberlin College, Oberlin, Ohio 44074, and Department of Chemistry, Emory University, Atlanta, Georgia 30322
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43
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Tang M, Waring AJ, Hong M. Phosphate-Mediated Arginine Insertion into Lipid Membranes and Pore Formation by a Cationic Membrane Peptide from Solid-State NMR. J Am Chem Soc 2007; 129:11438-46. [PMID: 17705480 DOI: 10.1021/ja072511s] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The insertion of charged amino acid residues into the hydrophobic part of lipid bilayers is energetically unfavorable yet found in many cationic membrane peptides and protein domains. To understand the mechanism of this translocation, we measured the (13)C-(31)P distances for an Arg-rich beta-hairpin antimicrobial peptide, PG-1, in the lipid membrane using solid-state NMR. Four residues, including two Arg's, scattered through the peptide were chosen for the distance measurements. Surprisingly, all residues show short distances to the lipid (31)P: 4.0-6.5 A in anionic POPE/POPG membranes and 6.5-8.0 A in zwitterionic POPC membranes. The shortest distance of 4.0 A, found for a guanidinium Czeta at the beta-turn, suggests N-H...O-P hydrogen bond formation. Torsion angle measurements of the two Arg's quantitatively confirm that the peptide adopts a beta-hairpin conformation in the lipid bilayer, and gel-phase 1H spin diffusion from water to the peptide indicates that PG-1 remains transmembrane in the gel phase of the membrane. For this transmembrane beta-hairpin peptide to have short (13)C-(31)P distances for multiple residues in the molecule, some phosphate groups must be embedded in the hydrophobic part of the membrane, with the local (31)P plane parallel to the beta-strand. This provides direct evidence for toroidal pores, where some lipid molecules change their orientation to merge the two monolayers. We propose that the driving force for this toroidal pore formation is guanidinium-phosphate complexation, where the cationic Arg residues drag the anionic phosphate groups along as they insert into the hydrophobic part of the membrane. This phosphate-mediated translocation of guanidinium ions may underlie the activity of other Arg-rich antimocrobial peptides and may be common among cationic membrane proteins.
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Affiliation(s)
- Ming Tang
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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Lewandowski JR, De Paëpe G, Griffin RG. Proton assisted insensitive nuclei cross polarization. J Am Chem Soc 2007; 129:728-9. [PMID: 17243786 PMCID: PMC2518536 DOI: 10.1021/ja0650394] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Józef R Lewandowski
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Gross BJ, McDermott AE. Locating hydrogen atoms in single crystal and uniaxially aligned amino acids by solid-state NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2007; 185:12-8. [PMID: 17142075 DOI: 10.1016/j.jmr.2006.09.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 09/23/2006] [Accepted: 09/29/2006] [Indexed: 05/12/2023]
Abstract
We demonstrate a novel method to locate hydrogen atoms in amino acids, which involves measuring the C(alpha)H(alpha) bond vector geometry through orientationally dependent dipolar coupling frequencies measured by Lee-Goldburg cross polarization (LGCP). A 2D LGCP experiment is used to measure the polar angle of the C(alpha)H(alpha) bond vector in a single crystal of the model compound L-alanine. It is also demonstrated that by coupling the 13C(alpha)1H(alpha) LGCP experiment to a 13C(alpha)15N REDOR experiment, one can determine the complete three-dimensional geometry of the C(alpha)H(alpha) and C(alpha)N vectors in a single crystal. These measurements allow for location of hydrogen atoms in crystalline biological macromolecules.
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Affiliation(s)
- Benjamin J Gross
- Department of Chemistry, Columbia University, New York, NY 10027, USA.
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Matsuoka S, Ikeuchi H, Umegawa Y, Matsumori N, Murata M. Membrane interaction of amphotericin B as single-length assembly examined by solid state NMR for uniformly 13C-enriched agent. Bioorg Med Chem 2006; 14:6608-14. [PMID: 16782343 DOI: 10.1016/j.bmc.2006.06.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 05/31/2006] [Accepted: 06/01/2006] [Indexed: 11/29/2022]
Abstract
The membrane interaction of amphotericin B (AmB), one of the most important anti-fungal drugs, was investigated by solid state NMR measurements of uniformly 13C-enriched AmB, which was prepared by the culture of the drug-producing microorganism in the presence of [u-13C6]glucose. All the 13C NMR signals of AmB upon binding to DLPC membrane were successfully assigned on the basis of the 13C-13C correlation spectrum. 13C-31P RDX (Rotational-Echo Double Resonance for X-clusters) experiments clearly revealed the REDOR dephasing effects for carbon atoms residing in the both terminal parts, whereas no dephasing was observed for the middle parts including polyolefinic C20-C33 and hydroxyl-bearing C8/C9 parts. These observations suggest that AmB binds to DLPC membrane with a high affinity to the phospholipid and spans the membrane with a single molecular length.
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Affiliation(s)
- Shigeru Matsuoka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-16 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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47
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Li Y, Wylie BJ, Rienstra CM. Selective refocusing pulses in magic-angle spinning NMR: characterization and applications to multi-dimensional protein spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2006; 179:206-16. [PMID: 16406627 DOI: 10.1016/j.jmr.2005.12.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 11/22/2005] [Accepted: 12/10/2005] [Indexed: 05/06/2023]
Abstract
Band-selective pulses are frequently used in multi-dimensional NMR in solution, but have been used relatively less often in solid-state NMR applications because of the complications imposed by magic-angle spinning. In this work, we examine the frequency profiles and the refocusing efficiency of several commonly employed selective general rotation pi pulses through experiments and numerical simulations. We demonstrate that highly efficient refocusing of transverse magnetization can be achieved, with experiments that agree well with numerical simulations. We also show that the rotational echo is shifted by a half rotor period if a selective pulse is applied over an integer number of rotor periods. Appropriately synchronizing indirect evolution periods with selective pulses ensures proper phasing of cross peaks in 2D spectra. The improved performance of selective pulses in multi-dimensional protein spectroscopy is demonstrated on the 56-residue beta1 immunoglobulin binding domain of protein G (GB1).
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Affiliation(s)
- Ying Li
- Department of Chemistry and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
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Hologne M, Raya J, Hirschinger J. 13C/15N distance determination by CPMAS NMR in uniformly 13C labeled molecules. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2006; 44:174-7. [PMID: 16358305 DOI: 10.1002/mrc.1744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The REDOR and CPMAS techniques are applied for measuring 13C-15N dipolar coupling constants in glycine. It is shown that the selective CP or SPECIFIC CP technique removes the coherent evolution of the spin system under homonuclear 13C-13C J couplings. While the large coupling constant (approximately 900 Hz) is readily determined because of the presence of large oscillations in the CPMAS dynamics, their absence precludes the measurement of the small coupling constant (approximately 200 Hz). The experimental results and numerical simulations demonstrate that the determination of 13C-15N coupling constants of medium size (<1 kHz) by the CPMAS technique is mainly limited by the strength of the 1H decoupling field and the size of the 13C and 15N chemical shift anisotropies.
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Affiliation(s)
- Maggy Hologne
- Institut de Chimie, FRE 2446 CNRS, Université Louis Pasteur, BP 296, 67008 Strasbourg Cedex, France
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Gibson JM, Raghunathan V, Popham JM, Stayton PS, Drobny GP. A REDOR NMR study of a phosphorylated statherin fragment bound to hydroxyapatite crystals. J Am Chem Soc 2005; 127:9350-1. [PMID: 15984845 DOI: 10.1021/ja050910m] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hydroxyapatite (HAP) is the main mineral component of teeth. It is well-known that several salivary proteins and peptides bind strongly to HAP to regulate crystal growth. Interactions between a peptide derived from the N-terminal fragment of the salivary protein statherin and HAP were measured utilizing rotational-echo double-resonance (REDOR) nuclear magnetic resonance (NMR). The REDOR measurement from the side chain of the salivary peptide to the HAP surface is complicated by two effects: a possible additional dipolar coupling to a phosphorylated side chain and the potential proximity of phosphorus atoms to each other, resulting in a homonuclear dipolar interaction. Both of these effects were addressed, and the smallest model applicable to our system includes the nitrogen-15 (15N) spin in the lysine side chain and two phosphorus-31 (31P) spins, at least one of which must be from the surface phosphates of the HAP.
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Affiliation(s)
- James M Gibson
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
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Gross BJ, Tanski JM, McDermott AE. Structure determination of aligned systems by solid-state NMR magic angle spinning methods. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 176:223-33. [PMID: 16081308 DOI: 10.1016/j.jmr.2005.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Revised: 06/14/2005] [Accepted: 06/14/2005] [Indexed: 05/03/2023]
Abstract
Single crystal rotational echo double resonance (REDOR) experiments can be used to determine the three-dimensional orientation of heteronuclear bond vectors in an amino acid, as well as the crystal's orientation relative to the rotor fixed frame (RFF). We also demonstrate that for samples uniaxially aligned along the rotor axis, the polar tilt angle of a bond vector relative to the RFF can be measured by use of an analytical expression that describes the REDOR curve for that system. These bond orientations were verified by X-ray indexing of the single crystal sample, and were shown to be as accurate as +/- 1 degrees .
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Affiliation(s)
- Benjamin J Gross
- Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA.
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