101
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Colvin MT, Andreas LB, Chou JJ, Griffin RG. Proton association constants of His 37 in the Influenza-A M218-60 dimer-of-dimers. Biochemistry 2014; 53:5987-94. [PMID: 25184631 PMCID: PMC4179598 DOI: 10.1021/bi5005393] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
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The membrane protein M2 from influenza-A
forms a single-pass transmembrane
helix that assembles in lipid membrane as homotetramers whose primary
function is to act as a proton transporter for viral acidification.
A single residue, histidine 37 (His 37), is known to be responsible
for selectivity and plays an integral role in the protein’s
function. We report pH-dependent 15N MAS NMR spectra of
His 37 within the influenza-A proton conduction domain of M2, M218–60, which has been previously shown to be a fully
functional construct and was recently determined to adopt a dimer-of-dimers
structure in lipids. By extracting the ratio of [His]/[HisH+] as a function of pH, we obtained two doubly degenerate proton disassociation
constants, 7.63 ± 0.15 and 4.52 ± 0.15, despite a possible
maximum of four. We also report the 1HNε chemical shifts at pH 6.5 recorded at 60 kHz MAS in a CP-based 1H–15N spectrum. We were unable to detect
resonances indicative of direct proton sharing among His 37 side chains
when the tetramer is in the +2 state. In the neutral state, His 37
is exclusively in the τ tautomer, indicating that the δ
nitrogen is protonated solely as a function of pH. We also found that
the plot of [HisH+]/[His] as a function of pH is qualitatively
similar to previously reported proton conduction rates, indicating
that proton conduction rate is proportional to the level of histidine
protonation within the channel. Two-dimensional 13C–13C and 13C–15N correlations suggest
that at low pH multiple conformations are populated as the spectra
broaden and eventually disappear as the acidity is increased. A second
highly resolved state at low pH was not observed.
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Affiliation(s)
- Michael T Colvin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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102
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Zhang Z, Chen Y, Tang X, Li J, Wang L, Yang J. Solid-state NMR shows that dynamically different domains of membrane proteins have different hydration dependence. J Phys Chem B 2014; 118:9553-64. [PMID: 25026099 DOI: 10.1021/jp503032h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydration has a profound influence on the structure, dynamics, and functions of membrane and membrane-embedded proteins. So far the hydration response of molecular dynamics of membrane proteins in lipid bilayers is poorly understood. Here, we reveal different hydration dependence of the dynamics in dynamically different domains of membrane proteins by multidimensional magic angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy using 121-residue integral diacylglycerol kinase (DAGK) in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DMPG) lipid bilayers as a model system. The highly mobile and immobile domains of DAGK and their water accessibilities are identified site-specifically by scalar- and dipolar-coupling based MAS ssNMR experiments, respectively. Our experiments reveal different hydration dependence of the dynamics in highly mobile and immobile domains of membrane proteins. We demonstrate that the fast, large-amplitude motions in highly mobile domains are not triggered until 20% hydration, enhanced at 20-50% hydration and unchanged at above 50% hydration. In contrast, motions on submicrosecond time scale of immobile residues are observed to be independent of the hydration levels in gel phase of lipids, and at the temperature near gel-liquid crystalline phase transition, amplitude of whole-molecule rotations around the bilayer normal is dominated by the fluidity of lipid bilayers, which is strongly hydration dependent. The hydration dependence of the dynamics of DAGK revealed by this study provides new insights into the correlations of hydration to dynamics and function of membrane proteins in lipid bilayers.
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Affiliation(s)
- Zhengfeng Zhang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences , Wuhan 430071, P. R. China
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103
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Abstract
Membrane proteins have always presented technical challenges for structural studies because of their requirement for a lipid environment. Multiple approaches exist including X-ray crystallography and electron microscopy that can give significant insights into their structure and function. However, nuclear magnetic resonance (NMR) is unique in that it offers the possibility of determining the structures of unmodified membrane proteins in their native environment of phospholipid bilayers under physiological conditions. Furthermore, NMR enables the characterization of the structure and dynamics of backbone and side chain sites of the proteins alone and in complexes with both small molecules and other biopolymers. The learning curve has been steep for the field as most initial studies were performed under non-native environments using modified proteins until ultimately progress in both techniques and instrumentation led to the possibility of examining unmodified membrane proteins in phospholipid bilayers under physiological conditions. This review aims to provide an overview of the development and application of NMR to membrane proteins. It highlights some of the most significant structural milestones that have been reached by NMR spectroscopy of membrane proteins, especially those accomplished with the proteins in phospholipid bilayer environments where they function.
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104
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Eddy MT, Yu TY. Membranes, peptides, and disease: unraveling the mechanisms of viral proteins with solid state nuclear magnetic resonance spectroscopy. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2014; 61-62:1-7. [PMID: 24837131 DOI: 10.1016/j.ssnmr.2014.04.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/22/2014] [Accepted: 04/22/2014] [Indexed: 06/03/2023]
Abstract
The interplay between peptides and lipid bilayers drives crucial biological processes. For example, a critical step in the replication cycle of enveloped viruses is the fusion of the viral membrane and host cell endosomal membrane, and these fusion events are controlled by viral fusion peptides. Thus such membrane-interacting peptides are of considerable interest as potential pharmacological targets. Deeper insight is needed into the mechanisms by which fusion peptides and other viral peptides modulate their surrounding membrane environment, and also how the particular membrane environment modulates the structure and activity of these peptides. An important step toward understanding these processes is to characterize the structure of viral peptides in environments that are as biologically relevant as possible. Solid state nuclear magnetic resonance (ssNMR) is uniquely well suited to provide atomic level information on the structure and dynamics of both membrane-associated peptides as well as the lipid bilayer itself; further ssNMR can delineate the contribution of specific membrane components, such as cholesterol, or changing cellular conditions, such as a decrease in pH on membrane-associating peptides. This paper highlights recent advances in the study of three types of membrane associated viral peptides by ssNMR to illustrate the more general power of ssNMR in addressing important biological questions involving membrane proteins.
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Affiliation(s)
- Matthew T Eddy
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037 USA
| | - Tsyr-Yan Yu
- Institute of Atomic and Molecular Sciences, Academia Sinica, No. 1 Sec. 4. Rooservelt Rd., Taipei, 10617, Taiwan.
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105
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Ye HY, Li SH, Zhang Y, Zhou L, Deng F, Xiong RG. Solid State Molecular Dynamic Investigation of An Inclusion Ferroelectric: [(2,6-Diisopropylanilinium)([18]crown-6)]BF4. J Am Chem Soc 2014; 136:10033-40. [DOI: 10.1021/ja503344b] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Heng-Yun Ye
- Ordered
Matter Science Research Center, Southeast University, Nanjing 211189, P. R. China
| | - Shen-Hui Li
- State
Key Laboratory Magnetic Resonance and Atomic and Molecular Physics,
Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences; Wuhan 430071, P. R. China
| | - Yi Zhang
- Ordered
Matter Science Research Center, Southeast University, Nanjing 211189, P. R. China
| | - Lei Zhou
- State
Key Laboratory Magnetic Resonance and Atomic and Molecular Physics,
Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences; Wuhan 430071, P. R. China
| | - Feng Deng
- State
Key Laboratory Magnetic Resonance and Atomic and Molecular Physics,
Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences; Wuhan 430071, P. R. China
| | - Ren-Gen Xiong
- Ordered
Matter Science Research Center, Southeast University, Nanjing 211189, P. R. China
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106
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Kinnun JJ, Mallikarjunaiah KJ, Petrache HI, Brown MF. Elastic deformation and area per lipid of membranes: atomistic view from solid-state deuterium NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:246-59. [PMID: 24946141 DOI: 10.1016/j.bbamem.2014.06.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 06/06/2014] [Indexed: 12/17/2022]
Abstract
This article reviews the application of solid-state ²H nuclear magnetic resonance (NMR) spectroscopy for investigating the deformation of lipid bilayers at the atomistic level. For liquid-crystalline membranes, the average structure is manifested by the segmental order parameters (SCD) of the lipids. Solid-state ²H NMR yields observables directly related to the stress field of the lipid bilayer. The extent to which lipid bilayers are deformed by osmotic pressure is integral to how lipid-protein interactions affect membrane functions. Calculations of the average area per lipid and related structural properties are pertinent to bilayer remodeling and molecular dynamics (MD) simulations of membranes. To establish structural quantities, such as area per lipid and volumetric bilayer thickness, a mean-torque analysis of ²H NMR order parameters is applied. Osmotic stress is introduced by adding polymer solutions or by gravimetric dehydration, which are thermodynamically equivalent. Solid-state NMR studies of lipids under osmotic stress probe membrane interactions involving collective bilayer undulations, order-director fluctuations, and lipid molecular protrusions. Removal of water yields a reduction of the mean area per lipid, with a corresponding increase in volumetric bilayer thickness, by up to 20% in the liquid-crystalline state. Hydrophobic mismatch can shift protein states involving mechanosensation, transport, and molecular recognition by G-protein-coupled receptors. Measurements of the order parameters versus osmotic pressure yield the elastic area compressibility modulus and the corresponding bilayer thickness at an atomistic level. Solid-state ²H NMR thus reveals how membrane deformation can affect protein conformational changes within the stress field of the lipid bilayer.
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Affiliation(s)
- Jacob J Kinnun
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | | | - Horia I Petrache
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Michael F Brown
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; Department of Physics, University of Arizona, Tucson, AZ 85721, USA.
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107
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Shi C, Fasshuber HK, Chevelkov V, Xiang S, Habenstein B, Vasa SK, Becker S, Lange A. BSH-CP based 3D solid-state NMR experiments for protein resonance assignment. JOURNAL OF BIOMOLECULAR NMR 2014; 59:15-22. [PMID: 24584701 DOI: 10.1007/s10858-014-9820-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/20/2014] [Indexed: 05/10/2023]
Abstract
We have recently presented band-selective homonuclear cross-polarization (BSH-CP) as an efficient method for CO-CA transfer in deuterated as well as protonated solid proteins. Here we show how the BSH-CP CO-CA transfer block can be incorporated in a set of three-dimensional (3D) solid-state NMR (ssNMR) pulse schemes tailored for resonance assignment of proteins at high static magnetic fields and moderate magic-angle spinning rates. Due to the achieved excellent transfer efficiency of 33 % for BSH-CP, a complete set of 3D spectra needed for unambiguous resonance assignment could be rapidly recorded within 1 week for the model protein ubiquitin. Thus we expect that BSH-CP could replace the typically used CO-CA transfer schemes in well-established 3D ssNMR approaches for resonance assignment of solid biomolecules.
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Affiliation(s)
- Chaowei Shi
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
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108
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Chen Y, Zhang Z, Tang X, Li J, Glaubitz C, Yang J. Conformation and Topology of Diacylglycerol Kinase inE.coliMembranes Revealed by Solid-state NMR Spectroscopy. Angew Chem Int Ed Engl 2014; 53:5624-8. [DOI: 10.1002/anie.201311203] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Revised: 02/05/2014] [Indexed: 01/04/2023]
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109
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Chen Y, Zhang Z, Tang X, Li J, Glaubitz C, Yang J. Conformation and Topology of Diacylglycerol Kinase inE.coliMembranes Revealed by Solid-state NMR Spectroscopy. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201311203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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110
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Nishida N, Osawa M, Takeuchi K, Imai S, Stampoulis P, Kofuku Y, Ueda T, Shimada I. Functional dynamics of cell surface membrane proteins. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 241:86-96. [PMID: 24331735 DOI: 10.1016/j.jmr.2013.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 11/08/2013] [Accepted: 11/11/2013] [Indexed: 06/03/2023]
Abstract
Cell surface receptors are integral membrane proteins that receive external stimuli, and transmit signals across plasma membranes. In the conventional view of receptor activation, ligand binding to the extracellular side of the receptor induces conformational changes, which convert the structure of the receptor into an active conformation. However, recent NMR studies of cell surface membrane proteins have revealed that their structures are more dynamic than previously envisioned, and they fluctuate between multiple conformations in an equilibrium on various timescales. In addition, NMR analyses, along with biochemical and cell biological experiments indicated that such dynamical properties are critical for the proper functions of the receptors. In this review, we will describe several NMR studies that revealed direct linkage between the structural dynamics and the functions of the cell surface membrane proteins, such as G-protein coupled receptors (GPCRs), ion channels, membrane transporters, and cell adhesion molecules.
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Affiliation(s)
- Noritaka Nishida
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masanori Osawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Koh Takeuchi
- Molecular Profiling Research Center, National Institute of Advanced Industrial Science and Technology, Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Shunsuke Imai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Pavlos Stampoulis
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yutaka Kofuku
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takumi Ueda
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ichio Shimada
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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111
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Mowrey DD, Kinde MN, Xu Y, Tang P. Atomistic insights into human Cys-loop receptors by solution NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:307-14. [PMID: 24680782 DOI: 10.1016/j.bbamem.2014.03.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 03/12/2014] [Accepted: 03/20/2014] [Indexed: 12/13/2022]
Abstract
Cys-loop receptors are pentameric ligand-gated ion channels (pLGICs) mediating fast neurotransmission in the central and peripheral nervous systems. They are important targets for many currently used clinical drugs, such as general anesthetics, and for allosteric modulators with potential therapeutic applications. Here, we provide an overview of advances in the use of solution NMR in structural and dynamic characterization of ion channels, particularly human Cys-loop receptors. We present challenges to overcome and realistic solutions for achieving high-resolution structural information for this family of receptors. We discuss how subtle structural differences among homologous channels define unique channel pharmacological properties and advocate the necessity to determine high-resolution structures for individual receptor subtypes. Finally, we describe drug binding to the TMDs of Cys-loop receptors identified by solution NMR and the associated dynamics changes relevant to channel functions.
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Affiliation(s)
- David D Mowrey
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA; Department of Computational & Systems Biology, University of Pittsburgh School of Medicine, USA
| | - Monica N Kinde
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA
| | - Yan Xu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA; Department of Structural Biology, University of Pittsburgh School of Medicine, USA; Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, USA.
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA; Department of Computational & Systems Biology, University of Pittsburgh School of Medicine, USA; Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, USA.
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112
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Lin B, Gao Y, Li Y, Zhang JZH, Mei Y. Implementing electrostatic polarization cannot fill the gap between experimental and theoretical measurements for the ultrafast fluorescence decay of myoglobin. J Mol Model 2014; 20:2189. [PMID: 24671304 DOI: 10.1007/s00894-014-2189-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 02/24/2014] [Indexed: 10/25/2022]
Abstract
Over the past few years, time-dependent ultrafast fluorescence spectroscopy method has been applied to the study of protein dynamics. However, observations from these experiments are in a controversy with other experimental studies. Participating of theoretical methods in this debate has not reconciled the contradiction, because the predicted initial relaxation from computer simulations is one-order faster than the ultrafast fluorescence spectroscopy experiment. In those simulations, pairwise force fields are employed, which have been shown to underestimate the roughness of the free energy landscape. Therefore, the relaxation rate of protein and water molecules under pairwise force fields is falsely exaggerated. In this work, we compared the relaxations of tryptophan/environment interaction under linear response approximation employing pairwise, polarized, and polarizable force fields. Results show that although the relaxation can be slowed down to a certain extent, the large gap between experiment and theory still cannot be filled.
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Affiliation(s)
- Bingbing Lin
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China
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113
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Yu X, Lorigan GA. Secondary structure, backbone dynamics, and structural topology of phospholamban and its phosphorylated and Arg9Cys-mutated forms in phospholipid bilayers utilizing 13C and 15N solid-state NMR spectroscopy. J Phys Chem B 2014; 118:2124-33. [PMID: 24511878 PMCID: PMC3983341 DOI: 10.1021/jp500316s] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Phospholamban (PLB) is a membrane protein that regulates heart muscle relaxation rates via interactions with the sarcoplasmic reticulum Ca(2+) ATPase (SERCA). When PLB is phosphorylated or Arg9Cys (R9C) is mutated, inhibition of SERCA is relieved. (13)C and (15)N solid-state NMR spectroscopy is utilized to investigate conformational changes of PLB upon phosphorylation and R9C mutation. (13)C═O NMR spectra of the cytoplasmic domain reveal two α-helical structural components with population changes upon phosphorylation and R9C mutation. The appearance of an unstructured component is observed on domain Ib. (15)N NMR spectra indicate an increase in backbone dynamics of the cytoplasmic domain. Wild-type PLB (WT-PLB), Ser16-phosphorylated PLB (P-PLB), and R9C-mutated PLB (R9C-PLB) all have a very dynamic domain Ib, and the transmembrane domain has an immobile component. (15)N NMR spectra indicate that the cytoplasmic domain of R9C-PLB adopts an orientation similar to P-PLB and shifts away from the membrane surface. Domain Ib (Leu28) of P-PLB and R9C-PLB loses the alignment. The R9C-PLB adopts a conformation similar to P-PLB with a population shift to a more extended and disordered state. The NMR data suggest the more extended and disordered forms of PLB may relate to inhibition relief.
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Affiliation(s)
- Xueting Yu
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
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114
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115
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Yao H, Hong M. Conformation and lipid interaction of the fusion peptide of the paramyxovirus PIV5 in anionic and negative-curvature membranes from solid-state NMR. J Am Chem Soc 2014; 136:2611-24. [PMID: 24428385 PMCID: PMC3985871 DOI: 10.1021/ja4121956] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Viral fusion proteins catalyze the merger of the virus envelope and the target cell membrane through multiple steps of protein conformational changes. The fusion peptide domain of these proteins is important for membrane fusion, but how it causes membrane curvature and dehydration is still poorly understood. We now use solid-state NMR spectroscopy to investigate the conformation, topology, and lipid and water interactions of the fusion peptide of the PIV5 virus F protein in three lipid membranes, POPC/POPG, DOPC/DOPG, and DOPE. These membranes allow us to investigate the effects of lipid chain disorder, membrane surface charge, and intrinsic negative curvature on the fusion peptide structure. Chemical shifts and spin diffusion data indicate that the PIV5 fusion peptide is inserted into all three membranes but adopts distinct conformations: it is fully α-helical in the POPC/POPG membrane, adopts a mixed strand/helix conformation in the DOPC/DOPG membrane, and is primarily a β-strand in the DOPE membrane. (31)P NMR spectra show that the peptide retains the lamellar structure and hydration of the two anionic membranes. However, it dehydrates the DOPE membrane, destabilizes its inverted hexagonal phase, and creates an isotropic phase that is most likely a cubic phase. The ability of the β-strand conformation of the fusion peptide to generate negative Gaussian curvature and to dehydrate the membrane may be important for the formation of hemifusion intermediates in the membrane fusion pathway.
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Affiliation(s)
- Hongwei Yao
- Department of Chemistry, Iowa State University , Ames, Iowa 50011 United States
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116
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Do HQ, Wittlich M, Glück JM, Möckel L, Willbold D, Koenig BW, Heise H. Full-length Vpu and human CD4(372-433) in phospholipid bilayers as seen by magic angle spinning NMR. Biol Chem 2014; 394:1453-63. [PMID: 23863698 DOI: 10.1515/hsz-2013-0194] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 07/13/2013] [Indexed: 11/15/2022]
Abstract
HIV-1 Vpu and CD4(372-433), a peptide comprising the transmembrane and cytoplasmic domain of human CD4, were recombinantly expressed in Escherichia coli, uniformly labeled with 13C and 15N isotopes, and separately reconstituted into phospholipid bilayers. Highly resolved dipolar cross-polarization (CP)-based solid-state NMR spectra of the two transmembrane proteins were recorded under magic angle sample spinning. Partial assignment of 13C resonances was achieved. Site-specific assignments were obtained for 13 amino acid residues of CD4(372-433) and two Vpu residues. Additional amino acid type-specific assignments were achieved for 10 amino acid spin systems for both CD4(372-433) and Vpu. Further, structural flexibility was probed with different dipolar recoupling techniques, and the correct insertion of the transmembrane domains into the lipid bilayers was confirmed by proton spin diffusion experiments.
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117
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Opella SJ. The development of solid-state NMR of membrane proteins. BIOMEDICAL SPECTROSCOPY AND IMAGING 2014; 3:81-105. [PMID: 26069880 PMCID: PMC4461144 DOI: 10.3233/bsi-140080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Most biological functions are carried out in supramolecular assemblies. As a result of their slow reorientation in solution, these assemblies have been resistant to the widely employed solution NMR approaches. The development of solid-state NMR to first of all overcome the correlation time problem and then obtain informative high-resolution spectra of proteins in supramolecular assemblies, such as virus particles and membranes, is described here. High resolution solid-state NMR is deeply intertwined with the history of NMR, and the seminal paper was published in 1948. Although the general principles were understood by the end of the 1950s, it has taken more than fifty years for instrumentation and experimental methods to become equal to the technical problems presented by the biological assemblies of greatest interest. It is now possible to obtain atomic resolution structures of viral coat proteins in virus particles and membrane proteins in phospholipid bilayers by oriented sample solid-state NMR methods. The development of this aspect of the field of solid-state NMR is summarized in this review article.
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Affiliation(s)
- Stanley J. Opella
- Address for correspondence: Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive 307,La Jolla, California, 92093-0307 USA.,
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118
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Abstract
Membrane proteins remain challenging targets for structural biologists, despite recent technical developments regarding sample preparation and structure determination. We review recent progress towards a structural understanding of TRP channels and the techniques used to that end. We discuss available low-resolution structures from electron microscopy (EM), X-ray crystallography, and nuclear magnetic resonance (NMR) and review the resulting insights into TRP channel function for various subfamily members. The recent high-resolution structure of TRPV1 is discussed in more detail in Chapter 11. We also consider the opportunities and challenges of using the accumulating structural information on TRPs and homologous proteins for deducing full-length structures of different TRP channel subfamilies, such as building homology models. Finally, we close by summarizing the outlook of the "holy grail" of understanding in atomic detail the diverse functions of TRP channels.
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119
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Ferella L, Luchinat C, Ravera E, Rosato A. SedNMR: a web tool for optimizing sedimentation of macromolecular solutes for SSNMR. JOURNAL OF BIOMOLECULAR NMR 2013; 57:319-26. [PMID: 24243317 DOI: 10.1007/s10858-013-9795-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 11/11/2013] [Indexed: 05/09/2023]
Abstract
We have proposed solid state NMR (SSNMR) of sedimented solutes as a novel approach to sample preparation for biomolecular SSNMR without crystallization or other sample manipulations. The biomolecules are confined by high gravity--obtained by centrifugal forces either directly in a SSNMR rotor or in a ultracentrifugal device--into a hydrated non-crystalline solid suitable for SSNMR investigations. When gravity is removed, the sample reverts to solution and can be treated as any solution NMR sample. We here describe a simple web tool to calculate the relevant parameters for the success of the experiment.
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Affiliation(s)
- Lucio Ferella
- Center for Magnetic Resonance (CERM), University of Florence, Via L. Sacconi 6, 50019, Sesto Fiorentino, FI, Italy
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120
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Yang Y, Fritzsching KJ, Hong M. Resonance assignment of the NMR spectra of disordered proteins using a multi-objective non-dominated sorting genetic algorithm. JOURNAL OF BIOMOLECULAR NMR 2013; 57:281-96. [PMID: 24132778 PMCID: PMC4004382 DOI: 10.1007/s10858-013-9788-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 10/03/2013] [Indexed: 05/05/2023]
Abstract
A multi-objective genetic algorithm is introduced to predict the assignment of protein solid-state NMR (SSNMR) spectra with partial resonance overlap and missing peaks due to broad linewidths, molecular motion, and low sensitivity. This non-dominated sorting genetic algorithm II (NSGA-II) aims to identify all possible assignments that are consistent with the spectra and to compare the relative merit of these assignments. Our approach is modeled after the recently introduced Monte-Carlo simulated-annealing (MC/SA) protocol, with the key difference that NSGA-II simultaneously optimizes multiple assignment objectives instead of searching for possible assignments based on a single composite score. The multiple objectives include maximizing the number of consistently assigned peaks between multiple spectra ("good connections"), maximizing the number of used peaks, minimizing the number of inconsistently assigned peaks between spectra ("bad connections"), and minimizing the number of assigned peaks that have no matching peaks in the other spectra ("edges"). Using six SSNMR protein chemical shift datasets with varying levels of imperfection that was introduced by peak deletion, random chemical shift changes, and manual peak picking of spectra with moderately broad linewidths, we show that the NSGA-II algorithm produces a large number of valid and good assignments rapidly. For high-quality chemical shift peak lists, NSGA-II and MC/SA perform similarly well. However, when the peak lists contain many missing peaks that are uncorrelated between different spectra and have chemical shift deviations between spectra, the modified NSGA-II produces a larger number of valid solutions than MC/SA, and is more effective at distinguishing good from mediocre assignments by avoiding the hazard of suboptimal weighting factors for the various objectives. These two advantages, namely diversity and better evaluation, lead to a higher probability of predicting the correct assignment for a larger number of residues. On the other hand, when there are multiple equally good assignments that are significantly different from each other, the modified NSGA-II is less efficient than MC/SA in finding all the solutions. This problem is solved by a combined NSGA-II/MC algorithm, which appears to have the advantages of both NSGA-II and MC/SA. This combination algorithm is robust for the three most difficult chemical shift datasets examined here and is expected to give the highest-quality de novo assignment of challenging protein NMR spectra.
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Affiliation(s)
- Yu Yang
- Department of Chemistry, Iowa State University, Ames, IA, 50011, USA
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121
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Chaudhuri A, Haldar S, Sun H, Koeppe RE, Chattopadhyay A. Importance of indole N-H hydrogen bonding in the organization and dynamics of gramicidin channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:419-28. [PMID: 24148157 DOI: 10.1016/j.bbamem.2013.10.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/10/2013] [Accepted: 10/14/2013] [Indexed: 01/25/2023]
Abstract
The linear ion channel peptide gramicidin represents an excellent model for exploring the principles underlying membrane protein structure and function, especially with respect to tryptophan residues. The tryptophan residues in gramicidin channels are crucial for the structure and function of the channel. In order to test the importance of indole hydrogen bonding for the biophysical properties of gramicidin channels, we monitored the effect of N-methylation of gramicidin tryptophans, using a combination of steady state and time-resolved fluorescence approaches along with circular dichroism spectroscopy. We show here that in the absence of the hydrogen bonding ability of tryptophans, tetramethyltryptophan gramicidin (TM-gramicidin) is unable to maintain the single stranded, head-to-head dimeric channel conformation in membranes. Our results show that TM-gramicidin displays a red-shifted fluorescence emission maximum, lower red edge excitation shift (REES), and higher fluorescence intensity and lifetime, consistent with its nonchannel conformation. This is in agreement with the measured location (average depth) of the 1-methyltryptophans in TM-gramicidin using the parallax method. These results bring out the usefulness of 1-methyltryptophan as a fluorescent tool to examine the hydrogen bonding ability of tryptophans in proteins and peptides. We conclude that changes in the hydrogen bonding ability of tryptophans, along with coupled changes in peptide backbone structure induce the loss of single stranded β(6.3) helical dimer conformation. These results agree with earlier results from size-exclusion chromatography and single-channel measurements for TM-gramicidin, and confirm the importance of indole hydrogen bonding for the conformation and function of ion channels and membrane proteins.
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Affiliation(s)
- Arunima Chaudhuri
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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122
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Shen M, Liu Q, Trébosc J, Lafon O, Masuda Y, Takegoshi K, Amoureux JP, Hu B, Chen Q. Exploring various modulation-sideband recoupling conditions of SHA+ sequence at fast MAS. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2013; 55-56:42-47. [PMID: 23953427 DOI: 10.1016/j.ssnmr.2013.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 06/08/2013] [Accepted: 07/25/2013] [Indexed: 06/02/2023]
Abstract
We explore modulation-sideband recoupling conditions of the (13)C-(13)C Second-order Hamiltonian among Analogous nuclei plus pulse sequence (SHA+), and found that this sequence can be used in two different recoupling regimes. The first regime, νR>Δνiso(max), is recommended for broad-band recoupling to avoid any rotational resonance broadening. In this regime, the spinning speed should be only slightly larger than Δνiso(max), to obtain the best transfer efficiency. The second regime, νR<Δνiso(max), can be used to observe long-range constraints with lower spinning speed, which increases the transfer efficiency, and may allow using bigger rotors to increase the S/N ratio.
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Affiliation(s)
- Ming Shen
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China; UCCS, Lille North of France University, Villeneuve d'Ascq 59652, France
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123
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Ding Y, Yao Y, Marassi FM. Membrane protein structure determination in membrana. Acc Chem Res 2013; 46:2182-90. [PMID: 24041243 DOI: 10.1021/ar400041a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The two principal components of biological membranes, the lipid bilayer and the proteins integrated within it, have coevolved for specific functions that mediate the interactions of cells with their environment. Molecular structures can provide very significant insights about protein function. In the case of membrane proteins, the physical and chemical properties of lipids and proteins are highly interdependent; therefore structure determination should include the membrane environment. Considering the membrane alongside the protein eliminates the possibility that crystal contacts or detergent molecules could distort protein structure, dynamics, and function and enables ligand binding studies to be performed in a natural setting. Solid-state NMR spectroscopy is compatible with three-dimensional structure determination of membrane proteins in phospholipid bilayer membranes under physiological conditions and has played an important role in elucidating the physical and chemical properties of biological membranes, providing key information about the structure and dynamics of the phospholipid components. Recently, developments in the recombinant expression of membrane proteins, sample preparation, pulse sequences for high-resolution spectroscopy, radio frequency probes, high-field magnets, and computational methods have enabled a number of membrane protein structures to be determined in lipid bilayer membranes. In this Account, we illustrate solid-state NMR methods with examples from two bacterial outer membrane proteins (OmpX and Ail) that form integral membrane β-barrels. The ability to measure orientation-dependent frequencies in the solid-state NMR spectra of membrane-embedded proteins provides the foundation for a powerful approach to structure determination based primarily on orientation restraints. Orientation restraints are particularly useful for NMR structural studies of membrane proteins because they provide information about both three-dimensional structure and the orientation of the protein within the membrane. When combined with dihedral angle restraints derived from analysis of isotropic chemical shifts, molecular fragment replacement, and de novo structure prediction, orientation restraints can yield high-quality three-dimensional structures with few or no distance restraints. Using complementary solid-state NMR methods based on oriented sample (OS) and magic angle spinning (MAS) approaches, one can resolve and assign multiple peaks through the use of (15)N/(13)C labeled samples and measure precise restraints to determine structures.
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Affiliation(s)
- Yi Ding
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Yong Yao
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Francesca M. Marassi
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, United States
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Cukkemane A, Baldus M. Characterization of a cyclic nucleotide-activated K(+) channel and its lipid environment by using solid-state NMR spectroscopy. Chembiochem 2013; 14:1789-98. [PMID: 23956185 DOI: 10.1002/cbic.201300182] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Indexed: 01/31/2023]
Abstract
Voltage-gated ion channels are large tetrameric multidomain membrane proteins that play crucial roles in various cellular transduction pathways. Because of their large size and domain-related mobility, structural characterization has proved challenging. We analyzed high-resolution solid-state NMR data on different isotope-labeled protein constructs of a bacterial cyclic nucleotide-activated K(+) channel (MlCNG) in lipid bilayers. We could identify the different subdomains of the 4×355 residue protein, such as the voltage-sensing domain and the cyclic nucleotide binding domain. Comparison to ssNMR data obtained on isotope-labeled cell membranes suggests a tight association of negatively charged lipids to the channel. We detected spectroscopic polymorphism that extends beyond the ligand binding site, and the corresponding protein segments have been associated with mutant channel types in eukaryotic systems. These findings illustrate the potential of ssNMR for structural investigations on large membrane-embedded proteins, even in the presence of local disorder.
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Affiliation(s)
- Abhishek Cukkemane
- NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 Utrecht (The Netherlands)
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125
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Kubrycht J, Sigler K, Souček P, Hudeček J. Structures composing protein domains. Biochimie 2013; 95:1511-24. [DOI: 10.1016/j.biochi.2013.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 04/02/2013] [Indexed: 12/21/2022]
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126
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Goldbourt A. Biomolecular magic-angle spinning solid-state NMR: recent methods and applications. Curr Opin Biotechnol 2013; 24:705-15. [DOI: 10.1016/j.copbio.2013.02.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 02/06/2013] [Accepted: 02/08/2013] [Indexed: 12/28/2022]
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127
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Structure determination of α-helical membrane proteins by solution-state NMR: emphasis on retinal proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:578-88. [PMID: 23831435 DOI: 10.1016/j.bbabio.2013.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 06/24/2013] [Indexed: 11/27/2022]
Abstract
The biochemical processes of living cells involve a numerous series of reactions that work with exceptional specificity and efficiency. The tight control of this intricate reaction network stems from the architecture of the proteins that drive the chemical reactions and mediate protein-protein interactions. Indeed, the structure of these proteins will determine both their function and interaction partners. A detailed understanding of the proximity and orientation of pivotal functional groups can reveal the molecular mechanistic basis for the activity of a protein. Together with X-ray crystallography and electron microscopy, NMR spectroscopy plays an important role in solving three-dimensional structures of proteins at atomic resolution. In the challenging field of membrane proteins, retinal-binding proteins are often employed as model systems and prototypes to develop biophysical techniques for the study of structural and functional mechanistic aspects. The recent determination of two 3D structures of seven-helical trans-membrane retinal proteins by solution-state NMR spectroscopy highlights the potential of solution NMR techniques in contributing to our understanding of membrane proteins. This review summarizes the multiple strategies available for expression of isotopically labeled membrane proteins. Different environments for mimicking lipid bilayers will be presented, along with the most important NMR methods and labeling schemes used to generate high-quality NMR spectra. The article concludes with an overview of types of conformational restraints used for generation of high-resolution structures of membrane proteins. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.
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128
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Li S, Zhou L, Su Y, Han B, Deng F. 13C and 15N spectral editing inside histidine imidazole ring through solid-state NMR spectroscopy. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2013; 54:13-17. [PMID: 23731549 DOI: 10.1016/j.ssnmr.2013.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 04/16/2013] [Accepted: 05/06/2013] [Indexed: 06/02/2023]
Abstract
Histidine usually exists in three different forms (including biprotonated species, neutral τ and π tautomers) at physiological pH in biological systems. The different protonation and tautomerization states of histidine can be characteristically determined by (13)C and (15)N chemical shifts of imidazole ring. In this work, solid-state NMR techniques were developed for spectral editing of (13)C and (15)N sites in histidine imidazole ring, which provides a benchmark to distinguish the existing forms of histidine. The selections of (13)Cγ, (13)Cδ2, (15)Nδ1, and (15)Nε2 sites were successfully achieved based on one-bond homo- and hetero-nuclear dipole interactions. Moreover, it was demonstrated that (1)H, (13)C, and (15) chemical shifts were roughly linearly correlated with the corresponding atomic charge in histidine imidazole ring by theoretical calculations. Accordingly, the (1)H, (13)C and (15)N chemical shifts variation in different protonation and tautomerization states could be ascribed to the atomic charge change due to proton transfer in biological process.
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Affiliation(s)
- Shenhui Li
- 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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129
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Fritzsching KJ, Yang Y, Schmidt-Rohr K, Hong M. Practical use of chemical shift databases for protein solid-state NMR: 2D chemical shift maps and amino-acid assignment with secondary-structure information. JOURNAL OF BIOMOLECULAR NMR 2013; 56:155-67. [PMID: 23625364 PMCID: PMC4048757 DOI: 10.1007/s10858-013-9732-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Accepted: 04/17/2013] [Indexed: 05/05/2023]
Abstract
We introduce a Python-based program that utilizes the large database of (13)C and (15)N chemical shifts in the Biological Magnetic Resonance Bank to rapidly predict the amino acid type and secondary structure from correlated chemical shifts. The program, called PACSYlite Unified Query (PLUQ), is designed to help assign peaks obtained from 2D (13)C-(13)C, (15)N-(13)C, or 3D (15)N-(13)C-(13)C magic-angle-spinning correlation spectra. We show secondary-structure specific 2D (13)C-(13)C correlation maps of all twenty amino acids, constructed from a chemical shift database of 262,209 residues. The maps reveal interesting conformation-dependent chemical shift distributions and facilitate searching of correlation peaks during amino-acid type assignment. Based on these correlations, PLUQ outputs the most likely amino acid types and the associated secondary structures from inputs of experimental chemical shifts. We test the assignment accuracy using four high-quality protein structures. Based on only the Cα and Cβ chemical shifts, the highest-ranked PLUQ assignments were 40-60 % correct in both the amino-acid type and the secondary structure. For three input chemical shifts (CO-Cα-Cβ or N-Cα-Cβ), the first-ranked assignments were correct for 60 % of the residues, while within the top three predictions, the correct assignments were found for 80 % of the residues. PLUQ and the chemical shift maps are expected to be useful at the first stage of sequential assignment, for combination with automated sequential assignment programs, and for highly disordered proteins for which secondary structure analysis is the main goal of structure determination.
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130
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Wang T, Yao H, Hong M. Determining the depth of insertion of dynamically invisible membrane peptides by gel-phase ¹H spin diffusion heteronuclear correlation NMR. JOURNAL OF BIOMOLECULAR NMR 2013; 56:139-148. [PMID: 23606274 PMCID: PMC3700645 DOI: 10.1007/s10858-013-9730-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Accepted: 04/10/2013] [Indexed: 05/28/2023]
Abstract
Solid-state NMR determination of the depth of insertion of membrane peptides and proteins has so far utilized (1)H spin diffusion and paramagnetic relaxation enhancement experiments, which are typically conducted in the liquid-crystalline phase of the lipid bilayer. For membrane proteins or peptide assemblies that undergo intermediate-timescale motion in the liquid-crystalline membrane, these approaches are no longer applicable because the protein signals are broadened beyond detection. Here we show that the rigid-solid HETCOR experiment, with an additional spin diffusion period, can be used to determine the depth of proteins in gel-phase lipid membranes, where the proteins are immobilized to give high-intensity solid-state NMR spectra. Demonstration on two membrane peptides with known insertion depths shows that well-inserted peptides give rise to high lipid cross peak intensities and low water cross peaks within a modest spin diffusion mixing time, while surface-bound peptides have higher water than lipid cross peaks. Furthermore, well-inserted membrane peptides have nearly identical (1)H cross sections as the lipid chains, indicating equilibration of the peptide and lipid magnetization. Using this approach, we measured the membrane topology of the α-helical fusion peptide of the paramyxovirus, PIV5, in the anionic POPC/POPG membrane, in which the peptide undergoes intermediate-timescale motion at physiological temperature. The gel-phase HETCOR spectra indicate that the α-helical fusion peptide is well inserted into the POPC/POPG bilayer, spanning both leaflets. This insertion motif gives insight into the functional role of the α-helical PIV5 fusion peptide in virus-cell membrane fusion.
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Affiliation(s)
| | | | - M. Hong
- Corresponding author: Mei Hong Tel: 515-294-3521, Fax: 515-294-0105,
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131
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Li J, Pilla KB, Li Q, Zhang Z, Su X, Huber T, Yang J. Magic Angle Spinning NMR Structure Determination of Proteins from Pseudocontact Shifts. J Am Chem Soc 2013; 135:8294-303. [DOI: 10.1021/ja4021149] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jianping Li
- Key Laboratory of Magnetic Resonance
in Biological Systems, State Key Laboratory of Magnetic Resonance
and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance,
Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Kala Bharath Pilla
- Research School
of Chemistry, Australian National University, Canberra, ACT 0200,
Australia
| | - Qingfeng Li
- State Key Laboratory of Elemento-Organic
Chemistry, Nankai University, Tianjin300071,
PR China
| | - Zhengfeng Zhang
- Key Laboratory of Magnetic Resonance
in Biological Systems, State Key Laboratory of Magnetic Resonance
and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance,
Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Xuncheng Su
- State Key Laboratory of Elemento-Organic
Chemistry, Nankai University, Tianjin300071,
PR China
| | - Thomas Huber
- Research School
of Chemistry, Australian National University, Canberra, ACT 0200,
Australia
| | - Jun Yang
- Key Laboratory of Magnetic Resonance
in Biological Systems, State Key Laboratory of Magnetic Resonance
and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance,
Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, PR China
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132
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Marbella LE, Cho HS, Spence MM. Observing the translocation of a mitochondria-penetrating peptide with solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1674-82. [PMID: 23567916 DOI: 10.1016/j.bbamem.2013.03.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 03/25/2013] [Accepted: 03/29/2013] [Indexed: 12/18/2022]
Abstract
A new class of penetrating peptides that can target the mitochondria with high specificity was recently discovered. In this work, we developed a model inner mitochondrial membrane, equipped with a transmembrane gradient, suitable for solid-state NMR experiments. Using solid-state NMR, we observed a mitochondria-penetrating peptide interacting with the model inner mitochondrial membrane to gain insight into the mechanism of translocation. The paramagnetic relaxation effect due to Mn(2+) ions on (13)C magic angle spinning NMR was used to measure the insertion depth of the peptide and its distribution in each monolayer of the membrane. We found that at low peptide concentration the peptide binds to the outer leaflet and at high concentration, it crosses the hydrophobic bilayer core and is distributed in both leaflets. In both concentration regimes, the peptide binds at the C2 position on the lipid acyl chain. The mitochondria-penetrating peptide crossed to the inner leaflet of the model membranes without disrupting the lamellarity. These results provide evidence that supports the electroporation model of translocation. We estimated the energy associated with crossing the inner mitochondrial membrane. We found that the transmembrane potential provides sufficient energy for the peptide to cross the hydrophobic core, which is the most unfavorable step in translocation.
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Affiliation(s)
- Lauren E Marbella
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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133
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Cheng CY, Han S. Dynamic Nuclear Polarization Methods in Solids and Solutions to Explore Membrane Proteins and Membrane Systems. Annu Rev Phys Chem 2013; 64:507-32. [DOI: 10.1146/annurev-physchem-040412-110028] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Membrane proteins regulate vital cellular processes, including signaling, ion transport, and vesicular trafficking. Obtaining experimental access to their structures, conformational fluctuations, orientations, locations, and hydration in membrane environments, as well as the lipid membrane properties, is critical to understanding their functions. Dynamic nuclear polarization (DNP) of frozen solids can dramatically boost the sensitivity of current solid-state nuclear magnetic resonance tools to enhance access to membrane protein structures in native membrane environments. Overhauser DNP in the solution state can map out the local and site-specific hydration dynamics landscape of membrane proteins and lipid membranes, critically complementing the structural and dynamics information obtained by electron paramagnetic resonance spectroscopy. Here, we provide an overview of how DNP methods in solids and solutions can significantly increase our understanding of membrane protein structures, dynamics, functions, and hydration in complex biological membrane environments.
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Affiliation(s)
- Chi-Yuan Cheng
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106
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134
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Banigan JR, Gayen A, Traaseth NJ. Combination of ¹⁵N reverse labeling and afterglow spectroscopy for assigning membrane protein spectra by magic-angle-spinning solid-state NMR: application to the multidrug resistance protein EmrE. JOURNAL OF BIOMOLECULAR NMR 2013; 55:391-9. [PMID: 23539118 PMCID: PMC3747971 DOI: 10.1007/s10858-013-9724-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 03/15/2013] [Indexed: 05/20/2023]
Abstract
Magic-angle-spinning (MAS) solid-state NMR spectroscopy has emerged as a viable method to characterize membrane protein structure and dynamics. Nevertheless, the spectral resolution for uniformly labeled samples is often compromised by redundancy of the primary sequence and the presence of helical secondary structure that results in substantial resonance overlap. The ability to simplify the spectrum in order to obtain unambiguous site-specific assignments is a major bottleneck for structure determination. To address this problem, we used a combination of (15)N reverse labeling, afterglow spectroscopic techniques, and frequency-selective dephasing experiments that dramatically improved the ability to resolve peaks in crowded spectra. This was demonstrated using the polytopic membrane protein EmrE, an efflux pump involved in multidrug resistance. Residues preceding the (15)N reverse labeled amino acid were imaged using a 3D NCOCX afterglow experiment and those following were recorded using a frequency-selective dephasing experiment. Our approach reduced the spectral congestion and provided a sensitive way to obtain chemical shift assignments for a membrane protein where no high-resolution structure is available. This MAS methodology is widely applicable to the study of other polytopic membrane proteins in functional lipid bilayer environments.
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Affiliation(s)
| | | | - Nathaniel J. Traaseth
- Author for correspondence: Nathaniel J. Traaseth 100 Washington Square East New York, NY 10003 Phone: (212) 992-9784
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135
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Demers JP, Sgourakis NG, Gupta R, Loquet A, Giller K, Riedel D, Laube B, Kolbe M, Baker D, Becker S, Lange A. The common structural architecture of Shigella flexneri and Salmonella typhimurium type three secretion needles. PLoS Pathog 2013; 9:e1003245. [PMID: 23555258 PMCID: PMC3605151 DOI: 10.1371/journal.ppat.1003245] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 01/23/2013] [Indexed: 11/25/2022] Open
Abstract
The Type Three Secretion System (T3SS), or injectisome, is a macromolecular infection machinery present in many pathogenic Gram-negative bacteria. It consists of a basal body, anchored in both bacterial membranes, and a hollow needle through which effector proteins are delivered into the target host cell. Two different architectures of the T3SS needle have been previously proposed. First, an atomic model of the Salmonella typhimurium needle was generated from solid-state NMR data. The needle subunit protein, PrgI, comprises a rigid-extended N-terminal segment and a helix-loop-helix motif with the N-terminus located on the outside face of the needle. Second, a model of the Shigella flexneri needle was generated from a high-resolution 7.7-Å cryo-electron microscopy density map. The subunit protein, MxiH, contains an N-terminal α-helix, a loop, another α-helix, a 14-residue-long β-hairpin (Q51–Q64) and a C-terminal α-helix, with the N-terminus facing inward to the lumen of the needle. In the current study, we carried out solid-state NMR measurements of wild-type Shigella flexneri needles polymerized in vitro and identified the following secondary structure elements for MxiH: a rigid-extended N-terminal segment (S2-T11), an α-helix (L12-A38), a loop (E39-P44) and a C-terminal α-helix (Q45-R83). Using immunogold labeling in vitro and in vivo on functional needles, we located the N-terminus of MxiH subunits on the exterior of the assembly, consistent with evolutionary sequence conservation patterns and mutagenesis data. We generated a homology model of Shigella flexneri needles compatible with both experimental data: the MxiH solid-state NMR chemical shifts and the state-of-the-art cryoEM density map. These results corroborate the solid-state NMR structure previously solved for Salmonella typhimurium PrgI needles and establish that Shigella flexneri and Salmonella typhimurium subunit proteins adopt a conserved structure and orientation in their assembled state. Our study reveals a common structural architecture of T3SS needles, essential to understand T3SS-mediated infection and develop treatments. Gram-negative bacteria use a molecular machinery called the Type Three Secretion System (T3SS) to deliver toxic proteins to the host cell. Our research group has recently solved the structure of the extracellular T3SS needle of Salmonella typhimurium. Employing solid-state NMR, we could determine local structure parameters such as dihedral angles and inter-nuclear proximities for this supramolecular assembly. Concurrently, a high-resolution cryo-electron microscopy density map of the T3SS needle of Shigella flexneri was obtained by Fujii et al. Modeling of the Shigella needle subunit protein to fit the EM density produced a model incompatible with the atomic model of the Salmonella needle in terms of secondary structure and subunit orientation. Here, we determined directly the secondary structure of the Shigella needle subunit using solid-state NMR, and its orientation using in vitro and in vivo immunogold labeling in functional needles. We found that Shigella subunits adopt the same secondary structure and orientation as in the atomic model of Salmonella, and we generated a homology model of the Shigella needle consistent with the EM density. Knowing the common T3SS needle architecture is essential for understanding the secretion mechanism and interactions of the needle with other components of the T3SS, and to develop therapeutics.
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Affiliation(s)
- Jean-Philippe Demers
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Nikolaos G. Sgourakis
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Rashmi Gupta
- Department for Cellular Microbiology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Antoine Loquet
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Karin Giller
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dietmar Riedel
- Laboratory for Electron Microscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Britta Laube
- Core Facility Microscopy, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Michael Kolbe
- Department for Cellular Microbiology, Max Planck Institute for Infection Biology, Berlin, Germany
- * E-mail: (MK); (DB); (SB); (AL)
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
- * E-mail: (MK); (DB); (SB); (AL)
| | - Stefan Becker
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- * E-mail: (MK); (DB); (SB); (AL)
| | - Adam Lange
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- * E-mail: (MK); (DB); (SB); (AL)
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136
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Su Y, Li S, Hong M. Cationic membrane peptides: atomic-level insight of structure-activity relationships from solid-state NMR. Amino Acids 2013; 44:821-33. [PMID: 23108593 PMCID: PMC3570695 DOI: 10.1007/s00726-012-1421-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 10/11/2012] [Indexed: 12/24/2022]
Abstract
Many membrane-active peptides, such as cationic cell-penetrating peptides (CPPs) and antimicrobial peptides (AMPs), conduct their biological functions by interacting with the cell membrane. The interactions of charged residues with lipids and water facilitate membrane insertion, translocation or disruption of these highly hydrophobic species. In this review, we will summarize high-resolution structural and dynamic findings towards the understanding of the structure-activity relationship of lipid membrane-bound CPPs and AMPs, as examples of the current development of solid-state NMR (SSNMR) techniques for studying membrane peptides. We will present the most recent atomic-resolution structure of the guanidinium-phosphate complex, as constrained from experimentally measured site-specific distances. These SSNMR results will be valuable specifically for understanding the intracellular translocation pathway of CPPs and antimicrobial mechanism of AMPs, and more generally broaden our insight into how cationic macromolecules interact with and cross the lipid membrane.
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Affiliation(s)
- Yongchao Su
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA.
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137
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G-protein-coupled receptor structure, ligand binding and activation as studied by solid-state NMR spectroscopy. Biochem J 2013; 450:443-57. [DOI: 10.1042/bj20121644] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
GPCRs (G-protein-coupled receptors) are versatile signalling molecules at the cell surface and make up the largest and most diverse family of membrane receptors in the human genome. They convert a large variety of extracellular stimuli into intracellular responses through the activation of heterotrimeric G-proteins, which make them key regulatory elements in a broad range of normal and pathological processes, and are therefore one of the most important targets for pharmaceutical drug discovery. Knowledge of a GPCR structure enables us to gain a mechanistic insight into its function and dynamics, and further aid rational drug design. Despite intensive research carried out over the last three decades, resolving the structural basis of GPCR function is still a major activity. The crystal structures obtained in the last 5 years provide the first opportunity to understand how protein structure dictates the unique functional properties of these complex signalling molecules. However, owing to the intrinsic hydrophobicity, flexibility and instability of membrane proteins, it is still a challenge to crystallize GPCRs, and, when this is possible, it is no longer in its native membrane environment and no longer without modification. Furthermore, the conformational change of the transmembrane α-helices associated with the structure activation increases the difficulty of capturing the activation state of a GPCR to a higher resolution by X-ray crystallography. On the other hand, solid-state NMR may offer a unique opportunity to study membrane protein structure, ligand binding and activation at atomic resolution in the native membrane environment, as well as described functionally significant dynamics. In the present review, we discuss some recent achievements of solid-state NMR for understanding GPCRs, the largest mammalian proteome at ~1% of the total expressed proteins. Structural information, details of determination, details of ligand conformations and the consequences of ligand binding to initiate activation can all be explored with solid-state NMR.
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138
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Emami S, Fan Y, Munro R, Ladizhansky V, Brown LS. Yeast-expressed human membrane protein aquaporin-1 yields excellent resolution of solid-state MAS NMR spectra. JOURNAL OF BIOMOLECULAR NMR 2013; 55:147-155. [PMID: 23344971 DOI: 10.1007/s10858-013-9710-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 01/15/2013] [Indexed: 06/01/2023]
Abstract
One of the biggest challenges in solid-state NMR studies of membrane proteins is to obtain a homogeneous natively folded sample giving high spectral resolution sufficient for structural studies. Eukaryotic membrane proteins are especially difficult and expensive targets in this respect. Methylotrophic yeast Pichia pastoris is a reliable producer of eukaryotic membrane proteins for crystallography and a promising economical source of isotopically labeled proteins for NMR. We show that eukaryotic membrane protein human aquaporin 1 can be doubly ((13)C/(15)N) isotopically labeled in this system and functionally reconstituted into phospholipids, giving excellent resolution of solid-state magic angle spinning NMR spectra.
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Affiliation(s)
- Sanaz Emami
- Departments of Physics, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
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139
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Song C, Rohmer T, Tiersch M, Zaanen J, Hughes J, Matysik J. Solid-State NMR Spectroscopy to Probe Photoactivation in Canonical Phytochromes. Photochem Photobiol 2013; 89:259-73. [DOI: 10.1111/php.12029] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/28/2012] [Indexed: 01/17/2023]
Affiliation(s)
| | - Thierry Rohmer
- Leids Instituut voor Chemisch Onderzoek; Universiteit Leiden; Leiden; The Netherlands
| | | | - Jan Zaanen
- Instituut-Lorentz for Theoretical Physics; Universiteit Leiden; Leiden; The Netherlands
| | - Jon Hughes
- Pflanzenphysiologie; Justus-Liebig-Universität; Giessen; Germany
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140
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Abstract
Solid-state NMR spectroscopy proved to be a versatile tool for characterization of structure and dynamics of complex biochemical systems. In particular, magic angle spinning (MAS) solid-state NMR came to maturity for application towards structural elucidation of biological macromolecules. Current challenges in applying solid-state NMR as well as progress achieved recently will be discussed in the following chapter focusing on conceptual aspects important for structural elucidation of proteins.
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Affiliation(s)
- Henrik Müller
- Institute of Physical Biology, Heinrich-Heine-University of Düsseldorf, 40225, Düsseldorf, Germany
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141
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Wang T, Widanapathirana L, Zhao Y, Hong M. Aggregation and dynamics of oligocholate transporters in phospholipid bilayers revealed by solid-state NMR spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:17071-17078. [PMID: 23153411 DOI: 10.1021/la303661p] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Macrocycles made of cholate building blocks were previously found to transport glucose readily across lipid bilayers. In this study, an (15)N, (13)Cα-labeled glycine was inserted into a cyclic cholate trimer and attached at the end of a linear trimer, respectively. The isotopic labeling allowed us to use solid-state NMR spectroscopy to study the dynamics, aggregation, and depth of insertion of these compounds in lipid membranes. The cyclic compound was found to be mostly immobilized in DLPC, POPC/POPG, and POPC/POPG/cholesterol membranes, whereas the linear trimer displayed large-amplitude motion that depended on the membrane thickness and viscosity. (13)C-detected (1)H spin diffusion experiments revealed the depth of insertion of the compounds in the membranes, as well as their contact with water molecules. The data support a consistent stacking model for the cholate macrocycles in lipid membranes, driven by the hydrophobic interactions of the water molecules in the interior of the macrocycles. The study also shows a strong preference of the linear trimer for the membrane surface, consistent with its lack of transport activity in earlier liposome leakage assays.
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Affiliation(s)
- Tuo Wang
- Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, USA
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142
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Schmidt-Rohr K, Fritzsching KJ, Liao SY, Hong M. Spectral editing of two-dimensional magic-angle-spinning solid-state NMR spectra for protein resonance assignment and structure determination. JOURNAL OF BIOMOLECULAR NMR 2012; 54:343-53. [PMID: 23053913 PMCID: PMC3656487 DOI: 10.1007/s10858-012-9676-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 09/14/2012] [Indexed: 05/05/2023]
Abstract
Several techniques for spectral editing of 2D (13)C-(13)C correlation NMR of proteins are introduced. They greatly reduce the spectral overlap for five common amino acid types, thus simplifying spectral assignment and conformational analysis. The carboxyl (COO) signals of glutamate and aspartate are selected by suppressing the overlapping amide N-CO peaks through (13)C-(15)N dipolar dephasing. The sidechain methine (CH) signals of valine, lecuine, and isoleucine are separated from the overlapping methylene (CH(2)) signals of long-chain amino acids using a multiple-quantum dipolar transfer technique. Both the COO and CH selection methods take advantage of improved dipolar dephasing by asymmetric rotational-echo double resonance (REDOR), where every other π-pulse is shifted from the center of a rotor period t(r) by about 0.15 t(r). This asymmetry produces a deeper minimum in the REDOR dephasing curve and enables complete suppression of the undesired signals of immobile segments. Residual signals of mobile sidechains are positively identified by dynamics editing using recoupled (13)C-(1)H dipolar dephasing. In all three experiments, the signals of carbons within a three-bond distance from the selected carbons are detected in the second spectral dimension via (13)C spin exchange. The efficiencies of these spectral editing techniques range from 60 % for the COO and dynamic selection experiments to 25 % for the CH selection experiment, and are demonstrated on well-characterized model proteins GB1 and ubiquitin.
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Affiliation(s)
- K. Schmidt-Rohr
- Department of Chemistry and Ames Laboratory, Iowa State University, Ames, IA 50011, USA
| | - K. J. Fritzsching
- Department of Chemistry and Ames Laboratory, Iowa State University, Ames, IA 50011, USA
| | - S. Y. Liao
- Department of Chemistry and Ames Laboratory, Iowa State University, Ames, IA 50011, USA
| | - Mei Hong
- Department of Chemistry and Ames Laboratory, Iowa State University, Ames, IA 50011, USA
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143
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Yao H, Hong M. Membrane-dependent conformation, dynamics, and lipid interactions of the fusion peptide of the paramyxovirus PIV5 from solid-state NMR. J Mol Biol 2012. [PMID: 23183373 DOI: 10.1016/j.jmb.2012.11.027] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The entry of enveloped viruses into cells requires protein-catalyzed fusion of the viral and cell membranes. The structure-function relation of a hydrophobic fusion peptide (FP) in viral fusion proteins is still poorly understood. We report magic-angle-spinning solid-state NMR results of the membrane-bound conformation, dynamics, and lipid interactions of the FP of the F protein of the paramyxovirus, parainfluenza virus 5 (PIV5). (13)C chemical shifts indicate that the PIV5 FP structure depends on the composition of the phospholipid membrane: the peptide is α-helical in palmitoyloleoylphosphatidylglycerol-containing anionic membranes but mostly β-sheet in neutral phosphocholine membranes. Other environmental factors, including peptide concentration, cholesterol, membrane reconstitution protocol, and a Lys solubility tag, do not affect the secondary structure. The α-helical and β-sheet states exhibit distinct dynamics and lipid interactions. The β-sheet FP is immobilized, resides on the membrane surface, and causes significant membrane curvature. In contrast, the α-helical FP undergoes intermediate-timescale motion and maintains the lamellar order of the membrane. Two-dimensional (31)P-(1)H correlation spectra show clear (31)P-water cross peaks for anionic membranes containing the α-helical FP but weak or no (31)P-water cross peak for neutral membranes containing the β-sheet FP. These results suggest that the β-sheet FP may be associated with high-curvature dehydrated fusion intermediates, while the α-helical state may be associated with the extended prehairpin state and the post-fusion state. Conformational plasticity is also a pronounced feature of the influenza and human immunodeficiency virus FPs, suggesting that these Gly-rich sequences encode structural plasticity to generate and sense different membrane morphologies.
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Affiliation(s)
- Hongwei Yao
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
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144
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Robertson JWF, Kasianowicz JJ, Banerjee S. Analytical Approaches for Studying Transporters, Channels and Porins. Chem Rev 2012; 112:6227-49. [DOI: 10.1021/cr300317z] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Joseph W. F. Robertson
- Physical Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, Maryland
20899, United States
| | - John J. Kasianowicz
- Physical Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, Maryland
20899, United States
| | - Soojay Banerjee
- National
Institute of Neurological
Disorders and Stroke, Bethesda, Maryland 20824, United States
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145
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Membrane-protein structure determination by solid-state NMR spectroscopy of microcrystals. Nat Methods 2012; 9:1212-7. [DOI: 10.1038/nmeth.2248] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 10/10/2012] [Indexed: 11/08/2022]
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146
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Hong M, DeGrado WF. Structural basis for proton conduction and inhibition by the influenza M2 protein. Protein Sci 2012; 21:1620-33. [PMID: 23001990 DOI: 10.1002/pro.2158] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 09/10/2012] [Accepted: 09/11/2012] [Indexed: 12/20/2022]
Abstract
The influenza M2 protein forms an acid-activated and drug-sensitive proton channel in the virus envelope that is important for the virus lifecycle. The functional properties and high-resolution structures of this proton channel have been extensively studied to understand the mechanisms of proton conduction and drug inhibition. We review biochemical and electrophysiological studies of M2 and discuss how high-resolution structures have transformed our understanding of this proton channel. Comparison of structures obtained in different membrane-mimetic solvents and under different pH using X-ray crystallography, solution NMR, and solid-state NMR spectroscopy revealed how the M2 structure depends on the environment and showed that the pharmacologically relevant drug-binding site lies in the transmembrane (TM) pore. Competing models of proton conduction have been evaluated using biochemical experiments, high-resolution structural methods, and computational modeling. These results are converging to a model in which a histidine residue in the TM domain mediates proton relay with water, aided by microsecond conformational dynamics of the imidazole ring. These mechanistic insights are guiding the design of new inhibitors that target drug-resistant M2 variants and may be relevant for other proton channels.
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Affiliation(s)
- Mei Hong
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
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147
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Shen M, Hu B, Lafon O, Trébosc J, Chen Q, Amoureux JP. Broadband finite-pulse radio-frequency-driven recoupling (fp-RFDR) with (XY8)4(1) super-cycling for homo-nuclear correlations in very high magnetic fields at fast and ultra-fast MAS frequencies. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 223:107-119. [PMID: 22985981 DOI: 10.1016/j.jmr.2012.07.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 07/10/2012] [Accepted: 07/16/2012] [Indexed: 06/01/2023]
Abstract
We demonstrate that inter-residue (13)C-(13)C proximities (of about 380 pm) in uniformly (13)C-labeled proteins can be probed by applying robust first-order recoupling during several milliseconds in single-quantum single-quantum dipolar homo-nuclear correlation (SQ-SQ D-HOMCOR) 2D experiments. We show that the intensity of medium-range homo-nuclear correlations in these experiments is enhanced using broadband first-order finite-pulse radio-frequency-driven recoupling (fp-RFDR) NMR sequence with a nested (XY8)4(1) super-cycling. The robustness and the efficiency of the fp-RFDR-(XY8)4(1) method is demonstrated at high magnetic field (21.1T) and high Magic-Angle Spinning (MAS) speeds (up to 60 kHz). The introduced super-cycling, formed by combining phase inversion and a global four-quantum phase cycle, improves the robustness of fp-RFDR to (i) chemical shift anisotropy (CSA), (ii) spread in isotropic chemical shifts, (iii) rf-inhomogeneity and (iv) hetero-nuclear dipolar couplings for long recoupling times. We show that fp-RFDR-(XY8)4(1) is efficient sans (1)H decoupling, which is beneficial for temperature-sensitive biomolecules. The efficiency and the robustness of fp-RFDR-(XY8)4(1) is investigated by spin dynamics numerical simulations as well as solid-state NMR experiments on [U-(13)C]-L-histidine·HCl, a tetra-peptide (Fmoc-[U-(13)C,(15)N]-Val-[U-(13)C,(15)N]-Ala-[U-(13)C,(15)N]-Phe-Gly-t-Boc) and Al(PO(3))(3).
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Affiliation(s)
- Ming Shen
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
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148
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Hu B, Trébosc J, Lafon O, Chen Q, Masuda Y, Takegoshi K, Amoureux JP. Very-Long-Distance Correlations in Proteins Revealed by Solid-State NMR Spectroscopy. Chemphyschem 2012; 13:3585-8. [DOI: 10.1002/cphc.201200548] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Indexed: 11/11/2022]
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149
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Su Y, Hu F, Hong M. Paramagnetic Cu(II) for probing membrane protein structure and function: inhibition mechanism of the influenza M2 proton channel. J Am Chem Soc 2012; 134:8693-702. [PMID: 22519936 DOI: 10.1021/ja3026328] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Paramagnetic Cu(II) ions enhance nuclear spin relaxation in a distance-dependent fashion and can be used as a structural probe of proteins. Cu(II) can also serve as a functionally important ligand in proteins. Here we investigate the structural basis of Cu(II) inhibition of the influenza M2 proton channel through Cu(II)-induced paramagnetic relaxation enhancement (PRE). (13)C T(1) relaxation rates of the central residues of the transmembrane (TM) domain of M2 are significantly enhanced by Cu(II), and pronounced spectral broadening is observed for the proton-selective residue, His37. These data yielded quantitative distances of (13)C spins to the Cu(II) center and identified the Cu(II) binding site to be Nε2 of His37. This binding site is surrounded by four imidazole rings from the top and four indole rings of Trp41 from the bottom, thus explaining the high affinity of Cu(II) binding. Bound at this location, Cu(II) can inhibit proton currents by perturbing histidine-water proton exchange, preventing histidine conformational dynamics, and interfering with His-Trp cation-π interaction. The Cu(II) binding site is distinct from the binding site of the hydrophobic drug amantadine, which is about 10 Å N-terminal to His37. Consistently, Cu(II) and amantadine induce distinct conformational changes at several key residues, suggesting the possibility of designing new drugs that target the His37 site to inhibit amantadine-resistant mutant M2 proteins. In addition to the high-affinity His37 binding site, we also examined the weaker and nonspecific binding of Cu(II) to membrane-surface lipid phosphates and the extent of the resulting PRE to surface-proximal protein residues. This study demonstrates the feasibility of NMR studies of paramagnetic-ion-complexed membrane proteins, where the ion serves as both a functional ligand and a distance probe.
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Affiliation(s)
- Yongchao Su
- Department of Chemistry, Iowa State University, Ames, 50011, United States
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150
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B-cell-lineage immunogen design in vaccine development with HIV-1 as a case study. Nat Biotechnol 2012; 30:423-33. [PMID: 22565972 DOI: 10.1038/nbt.2197] [Citation(s) in RCA: 380] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Failure of immunization with the HIV-1 envelope to induce broadly neutralizing antibodies against conserved epitopes is a major barrier to producing a preventive HIV-1 vaccine. Broadly neutralizing monoclonal antibodies (BnAbs) from those subjects who do produce them after years of chronic HIV-1 infection have one or more unusual characteristics, including polyreactivity for host antigens, extensive somatic hypermutation and long, variable heavy-chain third complementarity-determining regions, factors that may limit their expression by host immunoregulatory mechanisms. The isolation of BnAbs from HIV-1-infected subjects and the use of computationally derived clonal lineages as templates provide a new path for HIV-1 vaccine immunogen design. This approach, which should be applicable to many infectious agents, holds promise for the construction of vaccines that can drive B cells along rare but desirable maturation pathways.
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