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Zhang Z, Jiang J, Xiao Liu X, Wang X, Wang L, Qiu Y, Zhang Z, Zheng Y, Wu X, Liang J, Tian C, Chen CC. Surface-Anchored Acetylcholine Regulates Band-Edge States and Suppresses Ion Migration in a 21%-Efficient Quadruple-Cation Perovskite Solar Cell. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2105184. [PMID: 34851037 DOI: 10.1002/smll.202105184] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/21/2021] [Indexed: 06/13/2023]
Abstract
Although incorporating multiple halogen (bromine) anions and alkali (rubidium) cations can improve the open-circuit voltage (Voc ) of perovskite solar cells (PSCs), severe voltage loss and poor stability have remained pivotal limitations to their further commercialization. In this study, acetylcholine (ACh+ ) is anchored to the surface of a quadruple-cation perovskite to provide additional electron states near the valence band maximum of the perovskite surface, thereby enhancing the band alignment and minimizing the Voc loss significantly. Moreover, the quaternary ammonium and carbonyl units of ACh+ passivate the antisite and vacancy defects of the organic/inorganic hybrid perovskite. Because of strong interactions between ACh+ and the perovskite, the formation of lead clusters and the migration of halogen anions in the perovskite film are suppressed. As a result, the device prepared with ACh+ post-treatment delivers a power conversion efficiency (PCE) (21.56%) and a value of Voc (1.21 V) that are much higher than those of the pristine device, along with a twofold decrease in the hysteresis index. After storage for 720 h in humid air, the device subjected to ACh+ treatment maintained 70% of its initial PCE. Thus, post-treatment with ACh+ appears to be a useful strategy for preparing efficient and stable PSCs.
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Affiliation(s)
- Zhiang Zhang
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Jikun Jiang
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Xiao Xiao Liu
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Xin Wang
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Luyao Wang
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Yuankun Qiu
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Zhanfei Zhang
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Yiting Zheng
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Xueyun Wu
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Jianghu Liang
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Congcong Tian
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Chun-Chao Chen
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
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Saidijam M, Karimi Dermani F, Sohrabi S, Patching SG. Efflux proteins at the blood-brain barrier: review and bioinformatics analysis. Xenobiotica 2017; 48:506-532. [PMID: 28481715 DOI: 10.1080/00498254.2017.1328148] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
1. Efflux proteins at the blood-brain barrier provide a mechanism for export of waste products of normal metabolism from the brain and help to maintain brain homeostasis. They also prevent entry into the brain of a wide range of potentially harmful compounds such as drugs and xenobiotics. 2. Conversely, efflux proteins also hinder delivery of therapeutic drugs to the brain and central nervous system used to treat brain tumours and neurological disorders. For bypassing efflux proteins, a comprehensive understanding of their structures, functions and molecular mechanisms is necessary, along with new strategies and technologies for delivery of drugs across the blood-brain barrier. 3. We review efflux proteins at the blood-brain barrier, classified as either ATP-binding cassette (ABC) transporters (P-gp, BCRP, MRPs) or solute carrier (SLC) transporters (OATP1A2, OATP1A4, OATP1C1, OATP2B1, OAT3, EAATs, PMAT/hENT4 and MATE1). 4. This includes information about substrate and inhibitor specificity, structural organisation and mechanism, membrane localisation, regulation of expression and activity, effects of diseases and conditions and the principal technique used for in vivo analysis of efflux protein activity: positron emission tomography (PET). 5. We also performed analyses of evolutionary relationships, membrane topologies and amino acid compositions of the proteins, and linked these to structure and function.
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Affiliation(s)
- Massoud Saidijam
- a Department of Molecular Medicine and Genetics , Research Centre for Molecular Medicine, School of Medicine, Hamadan University of Medical Sciences , Hamadan , Iran and
| | - Fatemeh Karimi Dermani
- a Department of Molecular Medicine and Genetics , Research Centre for Molecular Medicine, School of Medicine, Hamadan University of Medical Sciences , Hamadan , Iran and
| | - Sareh Sohrabi
- a Department of Molecular Medicine and Genetics , Research Centre for Molecular Medicine, School of Medicine, Hamadan University of Medical Sciences , Hamadan , Iran and
| | - Simon G Patching
- b School of BioMedical Sciences and the Astbury Centre for Structural Molecular Biology, University of Leeds , Leeds , UK
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3
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Rao Z, Hu H, Tang J, Liu Z, Yang Y, Qiu G, Xiao Y, Liu P, Hu X, Zhou X, Hong X. Steroidal Ammonium Compounds as New Neuromuscular Blocking Agents. Chem Biol Drug Des 2016; 87:773-83. [DOI: 10.1111/cbdd.12711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 11/02/2015] [Accepted: 12/03/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Zhigang Rao
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Hao Hu
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Jiazhi Tang
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Zhiying Liu
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Yue Yang
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Guofu Qiu
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Yuling Xiao
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Peng Liu
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Xianming Hu
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Xiaoju Zhou
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
| | - Xuechuan Hong
- State Key Laboratory of Virology; Ministry of Education Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Wuhan University School of Pharmaceutical Sciences; Wuhan 430071 China
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NMR of Membrane Proteins: Beyond Crystals. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 922:29-42. [DOI: 10.1007/978-3-319-35072-1_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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6
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Rudd D, Ronci M, Johnston MR, Guinan T, Voelcker NH, Benkendorff K. Mass spectrometry imaging reveals new biological roles for choline esters and Tyrian purple precursors in muricid molluscs. Sci Rep 2015; 5:13408. [PMID: 26324173 PMCID: PMC4555103 DOI: 10.1038/srep13408] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 07/27/2015] [Indexed: 12/29/2022] Open
Abstract
Despite significant advances in chemical ecology, the biodistribution, temporal changes and ecological function of most marine secondary metabolites remain unknown. One such example is the association between choline esters and Tyrian purple precursors in muricid molluscs. Mass spectrometry imaging (MSI) on nano-structured surfaces has emerged as a sophisticated platform for spatial analysis of low molecular mass metabolites in heterogeneous tissues, ideal for low abundant secondary metabolites. Here we applied desorption-ionisation on porous silicon (DIOS) to examine in situ changes in biodistribution over the reproductive cycle. DIOS-MSI showed muscle-relaxing choline ester murexine to co-localise with tyrindoxyl sulfate in the biosynthetic hypobranchial glands. But during egg-laying, murexine was transferred to the capsule gland, and then to the egg capsules, where chemical ripening resulted in Tyrian purple formation. Murexine was found to tranquilise the larvae and may relax the reproductive tract. This study shows that DIOS-MSI is a powerful tool that can provide new insights into marine chemo-ecology.
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Affiliation(s)
- David Rudd
- School of Biological Sciences, Flinders University, Bedford Park, SA 5042, Australia
| | - Maurizio Ronci
- Mawson Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.,Department of Medical, Oral and Biotechnological Sciences, University G. D'Annunzio, Chieti-Pescara, Italy
| | - Martin R Johnston
- Flinders Centre for Nanoscale Science and Technology, School of Chemical and Physical Sciences, Flinders University, Bedford Park, SA 5042, Australia
| | - Taryn Guinan
- Mawson Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Nicolas H Voelcker
- Mawson Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Kirsten Benkendorff
- Marine Ecology Research Centre, Southern Cross University, P.O. Box 157, Lismore, NSW 2480, Australia
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Eddy MT, Su Y, Silvers R, Andreas L, Clark L, Wagner G, Pintacuda G, Emsley L, Griffin RG. Lipid bilayer-bound conformation of an integral membrane beta barrel protein by multidimensional MAS NMR. JOURNAL OF BIOMOLECULAR NMR 2015; 61:299-310. [PMID: 25634301 PMCID: PMC4398622 DOI: 10.1007/s10858-015-9903-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 01/20/2015] [Indexed: 05/09/2023]
Abstract
The human voltage dependent anion channel 1 (VDAC) is a 32 kDa β-barrel integral membrane protein that controls the transport of ions across the outer mitochondrial membrane. Despite the determination of VDAC solution and diffraction structures, a structural basis for the mechanism of its function is not yet fully understood. Biophysical studies suggest VDAC requires a lipid bilayer to achieve full function, motivating the need for atomic resolution structural information of VDAC in a membrane environment. Here we report an essential step toward that goal: extensive assignments of backbone and side chain resonances for VDAC in DMPC lipid bilayers via magic angle spinning nuclear magnetic resonance (MAS NMR). VDAC reconstituted into DMPC lipid bilayers spontaneously forms two-dimensional lipid crystals, showing remarkable spectral resolution (0.5-0.3 ppm for (13)C line widths and <0.5 ppm (15)N line widths at 750 MHz). In addition to the benefits of working in a lipid bilayer, several distinct advantages are observed with the lipid crystalline preparation. First, the strong signals and sharp line widths facilitated extensive NMR resonance assignments for an integral membrane β-barrel protein in lipid bilayers by MAS NMR. Second, a large number of residues in loop regions were readily observed and assigned, which can be challenging in detergent-solubilized membrane proteins where loop regions are often not detected due to line broadening from conformational exchange. Third, complete backbone and side chain chemical shift assignments could be obtained for the first 25 residues, which comprise the functionally important N-terminus. The reported assignments allow us to compare predicted torsion angles for VDAC prepared in DMPC 2D lipid crystals, DMPC liposomes, and LDAO-solubilized samples to address the possible effects of the membrane mimetic environment on the conformation of the protein. Concluding, we discuss the strengths and weaknesses of the reported assignment approach and the great potential for even more complete assignment studies and de novo structure determination via (1)H detected MAS NMR.
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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
| | - Yongchao Su
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert Silvers
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Loren Andreas
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Lindsay Clark
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA
| | - Guido Pintacuda
- Centre de RMN à Tres̀ Hauts Champs, Institut des Sciences Analytiques (CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 69100 Villeurbanne, France
| | - Lyndon Emsley
- Centre de RMN à Tres̀ Hauts Champs, Institut des Sciences Analytiques (CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 69100 Villeurbanne, France
| | - 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
- Corresponding Author:
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8
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Beinat C, Reekie T, Banister SD, O'Brien-Brown J, Xie T, Olson TT, Xiao Y, Harvey A, O'Connor S, Coles C, Grishin A, Kolesik P, Tsanaktsidis J, Kassiou M. Structure-activity relationship studies of SEN12333 analogues: determination of the optimal requirements for binding affinities at α7 nAChRs through incorporation of known structural motifs. Eur J Med Chem 2015; 95:277-301. [PMID: 25827398 DOI: 10.1016/j.ejmech.2015.03.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 03/11/2015] [Accepted: 03/12/2015] [Indexed: 12/27/2022]
Abstract
Alpha7 nicotinic acetylcholine receptors (nAChRs) have implications in the regulation of cognitive processes such as memory and attention and have been identified as a promising therapeutic target for the treatment of the cognitive deficits associated with schizophrenia and Alzheimer's disease (AD). Structure affinity relationship studies of the previously described α7 agonist SEN12333 (8), have resulted in the identification of compound 45, a potent and selective agonist of the α7 nAChR with enhanced affinity and improved physicochemical properties over the parent compound (SEN12333, 8).
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Affiliation(s)
- Corinne Beinat
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia; Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tristan Reekie
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | - Samuel D Banister
- Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | - Teresa Xie
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC 20057, USA
| | - Thao T Olson
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC 20057, USA
| | - Yingxian Xiao
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC 20057, USA
| | | | | | | | | | | | - John Tsanaktsidis
- CSIRO Materials Science & Engineering, Ian Wark Laboratory, Bayview Avenue, Clayton, Victoria 3168, Australia
| | - Michael Kassiou
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia; Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2006, Australia.
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9
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Asymmetric perturbations of signalling oligomers. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 114:153-69. [PMID: 24650570 DOI: 10.1016/j.pbiomolbio.2014.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 02/26/2014] [Accepted: 03/04/2014] [Indexed: 01/06/2023]
Abstract
This review focuses on rapid and reversible noncovalent interactions for symmetric oligomers of signalling proteins. Symmetry mismatch, transient symmetry breaking and asymmetric perturbations via chemical (ligand binding) and physical (electric or mechanic) effects can initiate the signalling events. Advanced biophysical methods can reveal not only structural symmetries of stable membrane-bound signalling proteins but also asymmetric functional transition states. Relevant techniques amenable to distinguish between symmetric and asymmetric architectures are discussed including those with the capability of capturing low-populated transient conformational states. Typical examples of signalling proteins are overviewed for symmetry breaking in dimers (GPCRs, growth factor receptors, transcription factors); trimers (acid-sensing ion channels); tetramers (voltage-gated cation channels, ionotropic glutamate receptor, CNG and CHN channels); pentameric ligand-gated and mechanosensitive channels; higher order oligomers (gap junction channel, chaperonins, proteasome, virus capsid); as well as primary and secondary transporters. In conclusion, asymmetric perturbations seem to play important functional roles in a broad range of communicating networks.
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Li J, van der Wel PCA. Spinning-rate encoded chemical shift correlations from rotational resonance solid-state NMR experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 230:117-24. [PMID: 23475055 PMCID: PMC3635064 DOI: 10.1016/j.jmr.2013.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 01/22/2013] [Accepted: 02/04/2013] [Indexed: 05/23/2023]
Abstract
Structural measurements in magic-angle-spinning (MAS) solid-state NMR rely heavily on (13)C-(13)C distance measurements. Broadbanded recoupling methods are used to generate many cross-peaks, but have complex polarization transfer mechanisms that limit the precision of distance constraints and can suffer from weak intensities for distant peaks due to relaxation, the broad distribution of polarization, as well as dipolar truncation. Frequency-selective methods that feature narrow-banded recoupling can reduce these effects. Indeed, rotational resonance (R(2)) experiments have found application in many different biological systems, where they have afforded improved precision and accuracy. Unfortunately, a highly selective transfer mechanism also leads to few cross-peaks in the resulting spectra, which complicates the extraction of multiple constraints. R(2)-width (R(2)W) measurements that scan a range of MAS rates to probe the R(2) matching conditions of one or more sites can improve precision, and also permit multiple simultaneous distance measurements. However, multidimensional R(2)W can be very time-consuming. Here, we present an approach that facilitates the acquisition of 2D-like spectra based on a series of 1D R(2)W experiments, by taking advantage of the chemical shift information encoded in the MAS rates where matching occurs. This yields a more time-efficient experiment with many of the benefits of more conventional multidimensional R(2)W measurements. The obtained spectra reveal long-distance (13)C-(13)C cross-peaks resulting from R(2)-mediated polarization transfer. This experiment also enables the efficient setup and targeted implementation of traditional R(2) or R(2)W experiments. Analogous applications may extend to other variable-MAS and frequency-selective solid-state NMR experiments.
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Affiliation(s)
- Jun Li
- Department of Structural Biology, University of Pittsburgh School of Medicine, Biomedical Science Tower 3, 3501 Fifth Ave, Pittsburgh, Pennsylvania 15260, USA
| | - Patrick C. A. van der Wel
- Department of Structural Biology, University of Pittsburgh School of Medicine, Biomedical Science Tower 3, 3501 Fifth Ave, Pittsburgh, Pennsylvania 15260, USA
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How to investigate interactions between membrane proteins and ligands by solid-state NMR. Methods Mol Biol 2013; 914:65-86. [PMID: 22976023 DOI: 10.1007/978-1-62703-023-6_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Solid-state NMR is an established method for biophysical studies of membrane proteins within the lipid bilayers and an emerging technique for structural biology in general. In particular magic angle sample spinning has been found to be very useful for the investigation of large membrane proteins and their interaction with small molecules within the lipid bilayer. Using a number of examples, we illustrate and discuss in this chapter, which information can be gained and which experimental parameters need to be considered when planning such experiments. We focus especially on the interaction of diffusive ligands with membrane proteins.
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PatchinG SG, Henderson PJF, Sharples DJ, Middleton DA. Probing the contacts of a low-affinity substrate with a membrane-embedded transport protein using1H-13C cross-polarisation magic-angle spinning solid-state NMR. Mol Membr Biol 2012; 30:129-37. [DOI: 10.3109/09687688.2012.743193] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
The synapse is a localized neurohumoral contact between a neuron and an effector cell and may be considered the quantum of fast intercellular communication. Analogously, the postsynaptic neurotransmitter receptor may be considered the quantum of fast chemical to electrical transduction. Our understanding of postsynaptic receptors began to develop about a hundred years ago with the demonstration that electrical stimulation of the vagus nerve released acetylcholine and slowed the heart beat. During the past 50 years, advances in understanding postsynaptic receptors increased at a rapid pace, owing largely to studies of the acetylcholine receptor (AChR) at the motor endplate. The endplate AChR belongs to a large superfamily of neurotransmitter receptors, called Cys-loop receptors, and has served as an exemplar receptor for probing fundamental structures and mechanisms that underlie fast synaptic transmission in the central and peripheral nervous systems. Recent studies provide an increasingly detailed picture of the structure of the AChR and the symphony of molecular motions that underpin its remarkably fast and efficient chemoelectrical transduction.
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Affiliation(s)
- Steven M Sine
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
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14
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Carlomagno T. NMR in natural products: understanding conformation, configuration and receptor interactions. Nat Prod Rep 2012; 29:536-54. [PMID: 22456471 DOI: 10.1039/c2np00098a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: up to 2011. Natural products are of tremendous importance in both traditional and modern medicine. For medicinal chemistry natural products represent a challenge, as their chemical synthesis and modification are complex processes, which require many, often stereo-selective, synthetic steps. A prerequisite for the design of analogs of natural products, with more accessible synthetic routes, is the availability of their bioactive conformation. Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray crystallography are the two techniques of choice to investigate the structure of natural products. In this review, I describe the most recent advances in NMR to study the conformation of natural products either free in solution or bound to their cellular receptors. In chapter 2, I focus on the use of residual dipolar couplings (RDC). On the basis of a few examples, I discuss the benefit of complementing classical NMR parameters, such as NOEs and scalar couplings, with dipolar couplings to simultaneously determine both the conformation and the relative configuration of natural products in solution. Chapter 3 is dedicated to the study of the structure of natural products in complex with their cellular receptors and is further divided in two sections. In the first section, I describe two solution-state NMR methodologies to investigate the binding mode of low-affinity ligands to macromolecular receptors. The first approach, INPHARMA (Interligand Noes for PHArmacophore Mapping), is based on the observation of interligand NOEs between two small molecules binding competitively to a common receptor. INPHARMA reveals the relative binding mode of the two ligands, thus allowing ligand superimposition. The second approach is based on paramagnetic relaxation enhancement (PRE) of ligand resonances in the presence of a receptor containing a paramagnetic center. In the second section, I focus on solid-state NMR spectroscopy as a tool to access the bioactive conformation of natural products in complex with macromolecular receptors.
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Affiliation(s)
- Teresa Carlomagno
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg
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15
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Franks WT, Linden AH, Kunert B, van Rossum BJ, Oschkinat H. Solid-state magic-angle spinning NMR of membrane proteins and protein-ligand interactions. Eur J Cell Biol 2011; 91:340-8. [PMID: 22019511 DOI: 10.1016/j.ejcb.2011.09.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 09/09/2011] [Accepted: 09/09/2011] [Indexed: 10/15/2022] Open
Abstract
Structural biology is developing into a universal tool for visualizing biological processes in space and time at atomic resolution. The field has been built by established methodology like X-ray crystallography, electron microscopy and solution NMR and is now incorporating new techniques, such as small-angle X-ray scattering, electron tomography, magic-angle-spinning solid-state NMR and femtosecond X-ray protein nanocrystallography. These new techniques all seek to investigate non-crystalline, native-like biological material. Solid-state NMR is a relatively young technique that has just proven its capabilities for de novo structure determination of model proteins. Further developments promise great potential for investigations on functional biological systems such as membrane-integrated receptors and channels, and macromolecular complexes attached to cytoskeletal proteins. Here, we review the development and applications of solid-state NMR from the first proof-of-principle investigations to mature structure determination projects, including membrane proteins. We describe the development of the methodology by looking at examples in detail and provide an outlook towards future 'big' projects.
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Affiliation(s)
- W Trent Franks
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert Rössle Str. 10, 13125 Berlin, Germany
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16
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Affiliation(s)
- Simon G Patching
- Astbury Centre for Structural Molecular Biology and Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
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17
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Middleton DA, Hughes E, Esmann M. The conformation of ATP within the Na,K-ATPase nucleotide site: a statistically constrained analysis of REDOR solid-state NMR data. Angew Chem Int Ed Engl 2011; 50:7041-4. [PMID: 21671314 DOI: 10.1002/anie.201100736] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 05/05/2011] [Indexed: 11/08/2022]
Affiliation(s)
- David A Middleton
- School of Biological Sciences, University of Liverpool, Liverpool, UK.
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18
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Middleton DA, Hughes E, Esmann M. The Conformation of ATP within the Na,K-ATPase Nucleotide Site: A Statistically Constrained Analysis of REDOR Solid-State NMR Data. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201100736] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Solution- and solid-state NMR studies of GPCRs and their ligands. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1462-75. [DOI: 10.1016/j.bbamem.2010.10.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2010] [Revised: 10/02/2010] [Accepted: 10/05/2010] [Indexed: 12/29/2022]
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20
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Ieronimo M, Afonin S, Koch K, Berditsch M, Wadhwani P, Ulrich AS. 19F NMR Analysis of the Antimicrobial Peptide PGLa Bound to Native Cell Membranes from Bacterial Protoplasts and Human Erythrocytes. J Am Chem Soc 2010; 132:8822-4. [DOI: 10.1021/ja101608z] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marco Ieronimo
- Institute of Organic Chemistry and DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany, and Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P.O. Box 3640,76021 Karlsruhe, Germany
| | - Sergii Afonin
- Institute of Organic Chemistry and DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany, and Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P.O. Box 3640,76021 Karlsruhe, Germany
| | - Katja Koch
- Institute of Organic Chemistry and DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany, and Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P.O. Box 3640,76021 Karlsruhe, Germany
| | - Marina Berditsch
- Institute of Organic Chemistry and DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany, and Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P.O. Box 3640,76021 Karlsruhe, Germany
| | - Parvesh Wadhwani
- Institute of Organic Chemistry and DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany, and Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P.O. Box 3640,76021 Karlsruhe, Germany
| | - Anne S. Ulrich
- Institute of Organic Chemistry and DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany, and Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P.O. Box 3640,76021 Karlsruhe, Germany
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21
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Edwards R, Madine J, Fielding L, Middleton DA. Measurement of multiple torsional angles from one-dimensional solid-state NMR spectra: application to the conformational analysis of a ligand in its biological receptor site. Phys Chem Chem Phys 2010; 12:13999-4008. [DOI: 10.1039/c0cp00326c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Middleton DA, Hughes E, Fedosova NU, Esmann M. Solid-state NMR studies of adenosine 5'-triphosphate freeze-trapped in the nucleotide site of Na,K-ATPase. Chembiochem 2009; 10:1789-92. [PMID: 19565594 DOI: 10.1002/cbic.200900167] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- David A Middleton
- School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK.
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23
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van der Wel PCA, Eddy MT, Ramachandran R, Griffin RG. Targeted 13C-13C distance measurements in a microcrystalline protein via J-decoupled rotational resonance width measurements. Chemphyschem 2009; 10:1656-63. [PMID: 19565580 DOI: 10.1002/cphc.200900102] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Rotational resonance width (R(2)W) magic-angle spinning (MAS) NMR experiments are performed to measure (13)C-(13)C distances in the hydrophobic core of the microcrystalline model protein G(Beta1). Such inter-residue distances are of particular value in NMR structure determinations. The experiments are done at a Larmor frequency of 750 MHz (1)H where the contribution of (13)C chemical shift anisotropy (CSA) to the R(2) transfer mechanism is significant. To minimize line broadening in the 2D spectra, we employ a combination of even/odd isotopic labeling with [1,3-(13)C] glycerol, and J-decoupling in the indirect dimension. This results in high-precision distance measurements between aromatic side chains of three tyrosine residues and distant methyl groups in the hydrophobic core of the protein. Even in the absence of information on the relative orientation of the shift tensors, we obtain relatively high precision data, which can be further improved by additional constraints on the tensor orientations.
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Affiliation(s)
- Patrick C A van der Wel
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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24
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Nicotinic receptors: allosteric transitions and therapeutic targets in the nervous system. Nat Rev Drug Discov 2009; 8:733-50. [PMID: 19721446 DOI: 10.1038/nrd2927] [Citation(s) in RCA: 521] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nicotinic receptors - a family of ligand-gated ion channels that mediate the effects of the neurotransmitter acetylcholine - are among the most well understood allosteric membrane proteins from a structural and functional perspective. There is also considerable interest in modulating nicotinic receptors to treat nervous-system disorders such as Alzheimer's disease, schizophrenia, depression, attention deficit hyperactivity disorder and tobacco addiction. This article describes both recent advances in our understanding of the assembly, activity and conformational transitions of nicotinic receptors, as well as developments in the therapeutic application of nicotinic receptor ligands, with the aim of aiding novel drug discovery by bridging the gap between these two rapidly developing fields.
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25
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Cui T, Canlas CG, Xu Y, Tang P. Anesthetic effects on the structure and dynamics of the second transmembrane domains of nAChR alpha4beta2. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:161-6. [PMID: 19715664 DOI: 10.1016/j.bbamem.2009.08.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 07/31/2009] [Accepted: 08/12/2009] [Indexed: 01/03/2023]
Abstract
Channel functions of the neuronal alpha4beta2 nicotinic acetylcholine receptor (nAChR), one of the most widely expressed subtypes in the brain, can be inhibited by volatile anesthetics. Our Na(+) flux experiments confirmed that the second transmembrane domains (TM2) of alpha4 and beta2 in 2:3 stoichiometry, (alpha4)(2)(beta2)(3), could form pentameric channels, whereas the alpha4 TM2 alone could not. The structure, topology, and dynamics of the alpha4 TM2 and (alpha4)(2)(beta2)(3) TM2 in magnetically aligned phospholipid bicelles were investigated using solid-state NMR spectroscopy in the absence and presence of halothane and isoflurane, two clinically used volatile anesthetics. (2)H NMR demonstrated that anesthetics increased lipid conformational heterogeneity. Such anesthetic effects on lipids became more profound in the presence of transmembrane proteins. PISEMA experiments on the selectively (15)N-labeled alpha4 TM2 showed that the TM2 formed transmembrane helices with tilt angles of 12 degrees +/-1 degrees and 16 degrees +/-1 degrees relative to the bicelle normal for the alpha4 and (alpha4)(2)(beta2)(3) samples, respectively. Anesthetics changed the tilt angle of the alpha4 TM2 from 12 degrees +/-1 degrees to 14 degrees +/-1 degrees , but had only a subtle effect on the tilt angle of the (alpha4)(2)(beta2)(3) TM2. A small degree of wobbling motion of the helix axis occurred in the (alpha4)(2)(beta2)(3) TM2. In addition, a subset of the (alpha4)(2)(beta2)(3) TM2 exhibited counterclockwise rotational motion around the helix axis on a time scale slower than 10(-4) s in the presence of anesthetics. Both helical tilting and rotational motions have been identified computationally as critical elements for ion channel functions. This study suggested that anesthetics could alter these motions to modulate channel functions.
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Affiliation(s)
- Tanxing Cui
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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26
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Patching SG, Edwards R, Middleton DA. Structural analysis of uniformly (13)C-labelled solids from selective angle measurements at rotational resonance. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 199:242-246. [PMID: 19487142 DOI: 10.1016/j.jmr.2009.05.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 04/24/2009] [Accepted: 05/04/2009] [Indexed: 05/27/2023]
Abstract
We demonstrate that individual H-C-C-H torsional angles in uniformly labelled organic solids can be estimated by selective excitation of (13)C double-quantum coherences under magic-angle spinning at rotational resonance. By adapting a straightforward one-dimensional experiment described earlier [T. Karlsson, M. Eden, H. Luhman, M.H. Levitt, J. Magn. Reson. 145 (2000) 95-107], a double-quantum filtered spectrum selective for Calpha and Cbeta of uniformly labelled L-[(13)C,(15)N]valine is obtained with 25% efficiency. The evolution of Calpha-Cbeta double-quantum coherence under the influence of the dipolar fields of bonded protons is monitored to provide a value of the Halpha-Calpha-Cbeta-Hbeta torsional angle that is consistent with the crystal structure. In addition, double-quantum filtration selective for C6 and C1' of uniformly labelled [(13)C,(15)N]uridine is achieved with 12% efficiency for a (13)C-(13)C distance of 2.5A, yielding a reliable estimate of the C6-H and C1'-H projection angle defining the relative orientations of the nucleoside pyrimidine and ribose rings. This procedure will be useful, in favourable cases, for structural analysis of fully labelled small molecules such as receptor ligands that are not readily synthesised with labels placed selectively at structurally diagnostic sites.
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Affiliation(s)
- Simon G Patching
- Astbury Centre for Structural Molecular Biology and Institute of Membrane and Systems Biology, University of Leeds, Leeds, United Kingdom
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27
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McDermott A. Structure and dynamics of membrane proteins by magic angle spinning solid-state NMR. Annu Rev Biophys 2009; 38:385-403. [PMID: 19245337 DOI: 10.1146/annurev.biophys.050708.133719] [Citation(s) in RCA: 288] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Membrane proteins remain difficult to study by traditional methods. Magic angle spinning solid-state NMR (MAS SSNMR) methods present an important approach for studying membrane proteins of moderate size. Emerging MAS SSNMR methods are based on extensive assignments of the nuclei as a basis for structure determination and characterization of function. These methods have already been used to characterize fibrils and globular proteins and are being increasingly used to study membrane proteins embedded in lipids. This review highlights recent applications to intrinsic membrane proteins and summarizes recent technical advances that will enable these methods to be utilized for more complex membrane protein systems in the near future.
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Affiliation(s)
- Ann McDermott
- Department of Chemistry, Columbia University, New York, NY 10027, USA.
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28
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Brown MF, Martínez-Mayorga K, Nakanishi K, Salgado GFJ, Struts AV. Retinal conformation and dynamics in activation of rhodopsin illuminated by solid-state H NMR spectroscopy. Photochem Photobiol 2009; 85:442-53. [PMID: 19267870 DOI: 10.1111/j.1751-1097.2008.00510.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Solid-state NMR spectroscopy gives a powerful avenue for investigating G protein-coupled receptors and other integral membrane proteins in a native-like environment. This article reviews the use of solid-state (2)H NMR to study the retinal cofactor of rhodopsin in the dark state as well as the meta I and meta II photointermediates. Site-specific (2)H NMR labels have been introduced into three regions (methyl groups) of retinal that are crucially important for the photochemical function of rhodopsin. Despite its phenomenal stability (2)H NMR spectroscopy indicates retinal undergoes rapid fluctuations within the protein binding cavity. The spectral lineshapes reveal the methyl groups spin rapidly about their three-fold (C(3)) axes with an order parameter for the off-axial motion of SC(3) approximately 0.9. For the dark state, the (2)H NMR structure of 11-cis-retinal manifests torsional twisting of both the polyene chain and the beta-ionone ring due to steric interactions of the ligand and the protein. Retinal is accommodated within the rhodopsin binding pocket with a negative pretwist about the C11=C12 double bond. Conformational distortion explains its rapid photochemistry and reveals the trajectory of the 11-cis to trans isomerization. In addition, (2)H NMR has been applied to study the retinylidene dynamics in the dark and light-activated states. Upon isomerization there are drastic changes in the mobility of all three methyl groups. The relaxation data support an activation mechanism whereby the beta-ionone ring of retinal stays in nearly the same environment, without a large displacement of the ligand. Interactions of the beta-ionone ring and the retinylidene Schiff base with the protein transmit the force of the retinal isomerization. Solid-state (2)H NMR thus provides information about the flow of energy that triggers changes in hydrogen-bonding networks and helix movements in the activation mechanism of the photoreceptor.
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Affiliation(s)
- Michael F Brown
- Department of Chemistry, University of Arizona, Tucson, AZ, USA.
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29
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Krabben L, van Rossum BJ, Jehle S, Bocharov E, Lyukmanova EN, Schulga AA, Arseniev A, Hucho F, Oschkinat H. Loop 3 of Short Neurotoxin II is an Additional Interaction Site with Membrane-bound Nicotinic Acetylcholine Receptor as Detected by Solid-state NMR Spectroscopy. J Mol Biol 2009; 390:662-71. [DOI: 10.1016/j.jmb.2009.05.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 04/23/2009] [Accepted: 05/12/2009] [Indexed: 11/30/2022]
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Neumoin A, Cohen LS, Arshava B, Tantry S, Becker JM, Zerbe O, Naider F. Structure of a double transmembrane fragment of a G-protein-coupled receptor in micelles. Biophys J 2009; 96:3187-96. [PMID: 19383463 DOI: 10.1016/j.bpj.2009.01.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 01/08/2009] [Accepted: 01/13/2009] [Indexed: 11/29/2022] Open
Abstract
The structure and dynamic properties of an 80-residue fragment of Ste2p, the G-protein-coupled receptor for alpha-factor of Saccharomyces cerevisiae, was studied in LPPG micelles with the use of solution NMR spectroscopy. The fragment Ste2p(G31-T110) (TM1-TM2) consisted of 19 residues from the N-terminal domain, the first TM helix (TM1), the first cytoplasmic loop, the second TM helix (TM2), and seven residues from the first extracellular loop. Multidimensional NMR experiments on [(15)N], [(15)N, (13)C], [(15)N, (13)C, (2)H]-labeled TM1-TM2 and on protein fragments selectively labeled at specific amino acid residues or protonated at selected methyl groups resulted in >95% assignment of backbone and side-chain nuclei. The NMR investigation revealed the secondary structure of specific residues of TM1-TM2. TALOS constraints and NOE connectivities were used to calculate a structure for TM1-TM2 that was highlighted by the presence of three alpha-helices encompassing residues 39-47, 49-72, and 80-103, with higher flexibility around the internal Arg(58) site of TM1. RMSD values of individually superimposed helical segments 39-47, 49-72, and 80-103 were 0.25 +/- 0.10 A, 0.40 +/- 0.13 A, and 0.57 +/- 0.19 A, respectively. Several long-range interhelical connectivities supported the folding of TM1-TM2 into a tertiary structure typified by a crossed helix that splays apart toward the extracellular regions and contains considerable flexibility in the G(56)VRSG(60) region. (15)N-relaxation and hydrogen-deuterium exchange data support a stable fold for the TM parts of TM1-TM2, whereas the solvent-exposed segments are more flexible. The NMR structure is consistent with the results of biochemical experiments that identified the ligand-binding site within this region of the receptor.
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Affiliation(s)
- Alexey Neumoin
- Institute of Organic Chemistry, University of Zurich, Zurich, Switzerland
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31
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Hamouda AK, Jin X, Sanghvi M, Srivastava S, Pandhare A, Duddempudi PK, Steinbach JH, Blanton MP. Photoaffinity labeling the agonist binding domain of alpha4beta4 and alpha4beta2 neuronal nicotinic acetylcholine receptors with [(125)I]epibatidine and 5[(125)I]A-85380. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1987-95. [PMID: 19545536 DOI: 10.1016/j.bbamem.2009.06.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 06/15/2009] [Accepted: 06/16/2009] [Indexed: 11/26/2022]
Abstract
The development of nicotinic acetylcholine receptor (nAChR) agonists, particularly those that discriminate between neuronal nAChR subtypes, holds promise as potential therapeutic agents for many neurological diseases and disorders. To this end, we photoaffinity labeled human alpha4beta2 and rat alpha4beta4 nAChRs affinity-purified from stably transfected HEK-293 cells, with the agonists [(125)I]epibatidine and 5[(125)I]A-85380. Our results show that both agonists photoincorporated into the beta4 subunit with little or no labeling of the beta2 and alpha4 subunits respectively. [(125)I]epibatidine labeling in the beta4 subunit was mapped to two overlapping proteolytic fragments that begin at beta4V102 and contain Loop E (beta4I109-P120) of the agonist binding site. We were unable to identify labeled amino acid(s) in Loop E by protein sequencing, but we were able to demonstrate that beta4Q117 in Loop E is the principal site of [(125)I]epibatidine labeling. This was accomplished by substituting residues in the beta2 subunit with the beta4 homologs and finding [(125)I]epibatidine labeling in beta4 and beta2F119Q subunits with little, if any, labeling in alpha4, beta2, or beta2S113R subunits. Finally, functional studies established that the beta2F119/beta4Q117 position is an important determinant of the receptor subtype-selectivity of the agonist 5I-A-85380, affecting both binding affinity and channel activation.
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Affiliation(s)
- Ayman K Hamouda
- Department of Pharmacology and Neuroscience and the Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430, USA
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32
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Bayro MJ, Huber M, Ramachandran R, Davenport TC, Meier BH, Ernst M, Griffin RG. Dipolar truncation in magic-angle spinning NMR recoupling experiments. J Chem Phys 2009; 130:114506. [PMID: 19317544 DOI: 10.1063/1.3089370] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quantitative solid-state NMR distance measurements in strongly coupled spin systems are often complicated due to the simultaneous presence of multiple noncommuting spin interactions. In the case of zeroth-order homonuclear dipolar recoupling experiments, the recoupled dipolar interaction between distant spins is attenuated by the presence of stronger couplings to nearby spins, an effect known as dipolar truncation. In this article, we quantitatively investigate the effect of dipolar truncation on the polarization-transfer efficiency of various homonuclear recoupling experiments with analytical theory, numerical simulations, and experiments. In particular, using selectively (13)C-labeled tripeptides, we compare the extent of dipolar truncation in model three-spin systems encountered in protein samples produced with uniform and alternating labeling. Our observations indicate that while the extent of dipolar truncation decreases in the absence of directly bonded nuclei, two-bond dipolar couplings can generate significant dipolar truncation of small, long-range couplings. Therefore, while alternating labeling alleviates the effects of dipolar truncation, and thus facilitates the application of recoupling experiments to large spin systems, it does not represent a complete solution to this outstanding problem.
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Affiliation(s)
- Marvin J Bayro
- Department of Chemistry, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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33
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Madine J, Copland A, Serpell LC, Middleton DA. Cross-β Spine Architecture of Fibrils Formed by the Amyloidogenic Segment NFGSVQFV of Medin from Solid-State NMR and X-ray Fiber Diffraction Measurements. Biochemistry 2009; 48:3089-99. [DOI: 10.1021/bi802164e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jillian Madine
- School of Biological Sciences, University of Liverpool,
Crown Street, Liverpool L69 7ZB, United Kingdom, and Department of
Biochemistry, School of Life Sciences, University of Sussex, Falmer,
Brighton BN1 9QG, United Kingdom
| | - Alastair Copland
- School of Biological Sciences, University of Liverpool,
Crown Street, Liverpool L69 7ZB, United Kingdom, and Department of
Biochemistry, School of Life Sciences, University of Sussex, Falmer,
Brighton BN1 9QG, United Kingdom
| | - Louise C. Serpell
- School of Biological Sciences, University of Liverpool,
Crown Street, Liverpool L69 7ZB, United Kingdom, and Department of
Biochemistry, School of Life Sciences, University of Sussex, Falmer,
Brighton BN1 9QG, United Kingdom
| | - David A. Middleton
- School of Biological Sciences, University of Liverpool,
Crown Street, Liverpool L69 7ZB, United Kingdom, and Department of
Biochemistry, School of Life Sciences, University of Sussex, Falmer,
Brighton BN1 9QG, United Kingdom
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Tantama M, Licht S. Use of calculated cation-pi binding energies to predict relative strengths of nicotinic acetylcholine receptor agonists. ACS Chem Biol 2008; 3:693-702. [PMID: 19032090 DOI: 10.1021/cb800189y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Agonists and antagonists of the nicotinic acetylcholine receptor (nAChR) are used to treat nicotine addiction, neuromuscular disorders, and neurological diseases. In designing small molecule therapeutics with the nAChR as a target, it is useful to identify chemical parameters that correlate with ability to activate the receptor. Previous studies have shown that cation-pi interactions at the transmitter binding sites of the nAChR are important for receptor activation by strong agonists such as acetylcholine. We hypothesized that a calculated estimate of cation-pi binding ability could be used to predict the efficiency for channel opening (i.e., the gating efficiency) associated with activation of the acetylcholine receptor by a series of structurally related organic cations. We demonstrate that the calculated cation-pi energy is strongly correlated with gating efficiency but only weakly correlated with closed-state binding affinity. Our results suggest that cation-pi interactions contribute significantly to the open-state affinity of these cations and that the calculated cation-pi energy will be a useful parameter for designing nAChR agonists and antagonists.
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Affiliation(s)
- Mathew Tantama
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building 16, Room 573B, Cambridge, Massachusetts 02139
| | - Stuart Licht
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building 16, Room 573B, Cambridge, Massachusetts 02139
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35
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Bertaccini EJ, Lindahl E, Sixma T, Trudell JR. Effect of cobratoxin binding on the normal mode vibration within acetylcholine binding protein. J Chem Inf Model 2008; 48:855-60. [PMID: 18348519 DOI: 10.1021/ci700456s] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Recent crystal structures of the acetylcholine binding protein (AChBP) have revealed surprisingly small structural alterations upon ligand binding. Here we investigate the extent to which ligand binding may affect receptor dynamics. AChBP is a homologue of the extracellular component of ligand-gated ion channels (LGICs). We have previously used an elastic network normal-mode analysis to propose a gating mechanism for the LGICs and to suggest the effects of various ligands on such motions. However, the difficulties with elastic network methods lie in their inability to account for the modest effects of a small ligand or mutation on ion channel motion. Here, we report the successful application of an elastic network normal mode technique to measure the effects of large ligand binding on receptor dynamics. The present calculations demonstrate a clear alteration in the native symmetric motions of a protein due to the presence of large protein cobratoxin ligands. In particular, normal-mode analysis revealed that cobratoxin binding to this protein significantly dampened the axially symmetric motion of the AChBP that may be associated with channel gating in the full nAChR. The results suggest that alterations in receptor dynamics could be a general feature of ligand binding.
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Affiliation(s)
- Edward J Bertaccini
- Department of Anesthesia, Stanford University School of Medicine and Beckman Center for Molecular and Genetic Medicine, Stanford, California 94305-5117, USA.
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