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Smith AE, Zhang Z, Pielak GJ, Li C. NMR studies of protein folding and binding in cells and cell-like environments. Curr Opin Struct Biol 2014; 30:7-16. [PMID: 25479354 DOI: 10.1016/j.sbi.2014.10.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Revised: 10/20/2014] [Accepted: 10/24/2014] [Indexed: 11/18/2022]
Abstract
Proteins function in cells where the concentration of macromolecules can exceed 300g/L. The ways in which this crowded environment affects the physical properties of proteins remain poorly understood. We summarize recent NMR-based studies of protein folding and binding conducted in cells and in vitro under crowded conditions. Many of the observations can be understood in terms of interactions between proteins and the rest of the intracellular environment (i.e. quinary interactions). Nevertheless, NMR studies of folding and binding in cells and cell-like environments remain in their infancy. The frontier involves investigations of larger proteins and further efforts in higher eukaryotic cells.
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Affiliation(s)
- Austin E Smith
- Department of Chemistry, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599-3290, USA
| | - Zeting Zhang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Gary J Pielak
- Department of Chemistry, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599-3290, USA; Department of Biochemistry and Biophysics, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599-3290, USA.
| | - Conggang Li
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China.
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52
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In-cell NMR reveals potential precursor of toxic species from SOD1 fALS mutants. Nat Commun 2014; 5:5502. [PMID: 25429517 DOI: 10.1038/ncomms6502] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 10/07/2014] [Indexed: 12/20/2022] Open
Abstract
Mutations in the superoxide dismutase 1 (SOD1) gene are related to familial cases of amyotrophic lateral sclerosis (fALS). Here we exploit in-cell NMR to characterize the protein folding and maturation of a series of fALS-linked SOD1 mutants in human cells and to obtain insight into their behaviour in the cellular context, at the molecular level. The effect of various mutations on SOD1 maturation are investigated by changing the availability of metal ions in the cells, and by coexpressing the copper chaperone for SOD1, hCCS. We observe for most of the mutants the occurrence of an unstructured SOD1 species, unable to bind zinc. This species may be a common precursor of potentially toxic oligomeric species, that are associated with fALS. Coexpression of hCCS in the presence of copper restores the correct maturation of the SOD1 mutants and prevents the formation of the unstructured species, confirming that hCCS also acts as a molecular chaperone.
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53
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Barbieri L, Luchinat E, Banci L. Structural insights of proteins in sub-cellular compartments: In-mitochondria NMR. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2492-6. [DOI: 10.1016/j.bbamcr.2014.06.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 06/12/2014] [Accepted: 06/16/2014] [Indexed: 10/25/2022]
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54
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Martorana A, Bellapadrona G, Feintuch A, Di Gregorio E, Aime S, Goldfarb D. Probing protein conformation in cells by EPR distance measurements using Gd3+ spin labeling. J Am Chem Soc 2014; 136:13458-65. [PMID: 25163412 DOI: 10.1021/ja5079392] [Citation(s) in RCA: 166] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Protein structure investigations are usually carried out in vitro under conditions far from their native environment in the cell. Differences between in-cell and in vitro structures of proteins can be generated by crowding effects, local pH changes, specific and nonspecific protein and ligand binding events, and chemical modifications. Double electron-electron resonance (DEER), in conjunction with site-directed spin-labeling, has emerged in the past decade as a powerful technique for exploring protein conformations in frozen solutions. The major challenges facing the application of this methodology to in-cell measurements are the instabilities of the standard nitroxide spin labels in the cell environment and the limited sensitivity at conventional X-band frequencies. We present a new approach for in-cell DEER distance measurement in human cells, based on the use of: (i) reduction resistant Gd(3+) chelates as spin labels, (ii) high frequency (94.9 GHz) for sensitivity enhancement, and (iii) hypo-osmotic shock for efficient delivery of the labeled protein into the cell. The proof of concept is demonstrated on doubly labeled ubiquitin in HeLa cells.
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Affiliation(s)
- Andrea Martorana
- Department of Chemical Physics and ‡Department of Materials and Interfaces, Weizmann Institute of Science , Rehovot, Israel 7610001
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55
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Abstract
Ever since scientists realized that cells are the basic building blocks of all life, they have been developing tools to look inside them to reveal the architectures and mechanisms that define their biological functions. Whereas "looking into cells" is typically said in reference to optical microscopy, high-resolution in-cell and on-cell nuclear magnetic resonance (NMR) spectroscopy is a powerful method that offers exciting new possibilities for structural and functional studies in and on live cells. In contrast to conventional imaging techniques, in- and on-cell NMR methods do not provide spatial information on cellular biomolecules. Instead, they enable atomic-resolution insights into the native cell states of proteins, nucleic acids, glycans, and lipids. Here we review recent advances and developments in both fields and discuss emerging concepts that have been delineated with these methods.
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Affiliation(s)
- Darón I Freedberg
- Laboratory of Bacterial Polysaccharides, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Rockville, Maryland 20852-1448;
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56
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Felli IC, Gonnelli L, Pierattelli R. In-cell ¹³C NMR spectroscopy for the study of intrinsically disordered proteins. Nat Protoc 2014; 9:2005-16. [PMID: 25079425 DOI: 10.1038/nprot.2014.124] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A large number of proteins carry out their function in highly flexible and disordered states, lacking a well-defined 3D structure. These proteins, referred to as intrinsically disordered proteins (IDPs), are now in the spotlight of modern structural biology. Nuclear magnetic resonance (NMR) spectroscopy represents a unique tool for accessing atomic resolution information on IDPs in complex environments as whole cells, provided that the methods are optimized to their peculiar properties and to the characteristics of in-cell experiments. We describe procedures for the preparation of in-cell NMR samples, as well as for the setup of NMR experiments and their application to in-cell studies, using human α-synuclein overexpressed in Escherichia coli as an example. The expressed protein is labeled with (13)C and (15)N stable isotopes to enable the direct recording of (13)C-detected NMR experiments optimized for the properties of IDPs. The entire procedure covers 24 h, including cell transformation, cell growth overnight, setup of the spectrometer and NMR experiment recording.
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Affiliation(s)
- Isabella C Felli
- Magnetic Resonance Center (CERM), Department of Chemistry 'Ugo Schiff', University of Florence, Sesto Fiorentino, Italy
| | - Leonardo Gonnelli
- Magnetic Resonance Center (CERM), Department of Chemistry 'Ugo Schiff', University of Florence, Sesto Fiorentino, Italy
| | - Roberta Pierattelli
- Magnetic Resonance Center (CERM), Department of Chemistry 'Ugo Schiff', University of Florence, Sesto Fiorentino, Italy
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57
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Hänsel R, Luh LM, Corbeski I, Trantirek L, Dötsch V. Intrazelluläre NMR- und EPR-Spektroskopie von biologischen Makromolekülen. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201311320] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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58
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Hänsel R, Luh LM, Corbeski I, Trantirek L, Dötsch V. In-cell NMR and EPR spectroscopy of biomacromolecules. Angew Chem Int Ed Engl 2014; 53:10300-14. [PMID: 25070284 DOI: 10.1002/anie.201311320] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Indexed: 12/21/2022]
Abstract
The dream of cell biologists is to be able to watch biological macromolecules perform their duties in the intracellular environment of live cells. Ideally, the observation of both the location and the conformation of these macromolecules with biophysical techniques is desired. The development of many fluorescence techniques, including superresolution fluorescence microscopy, has significantly enhanced our ability to spot proteins and other molecules in the crowded cellular environment. However, the observation of their structure and conformational changes while they attend their business is still very challenging. In principle, NMR and EPR spectroscopy can be used to investigate the conformation and dynamics of biological macromolecules in living cells. The development of in-cell magnetic resonance techniques has demonstrated the feasibility of this approach. Herein we review the different techniques with a focus on liquid-state in-cell NMR spectroscopy, provide an overview of applications, and discuss the challenges that lie ahead.
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Affiliation(s)
- Robert Hänsel
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt (Germany)
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59
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Theillet FX, Binolfi A, Frembgen-Kesner T, Hingorani K, Sarkar M, Kyne C, Li C, Crowley PB, Gierasch L, Pielak GJ, Elcock AH, Gershenson A, Selenko P. Physicochemical properties of cells and their effects on intrinsically disordered proteins (IDPs). Chem Rev 2014; 114:6661-714. [PMID: 24901537 PMCID: PMC4095937 DOI: 10.1021/cr400695p] [Citation(s) in RCA: 338] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Indexed: 02/07/2023]
Affiliation(s)
- Francois-Xavier Theillet
- Department
of NMR-supported Structural Biology, In-cell NMR Laboratory, Leibniz Institute of Molecular Pharmacology (FMP Berlin), Robert-Roessle Strasse 10, 13125 Berlin, Germany
| | - Andres Binolfi
- Department
of NMR-supported Structural Biology, In-cell NMR Laboratory, Leibniz Institute of Molecular Pharmacology (FMP Berlin), Robert-Roessle Strasse 10, 13125 Berlin, Germany
| | - Tamara Frembgen-Kesner
- Department
of Biochemistry, University of Iowa, Bowen Science Building, 51 Newton
Road, Iowa City, Iowa 52242, United States
| | - Karan Hingorani
- Departments
of Biochemistry & Molecular Biology and Chemistry, Program in
Molecular & Cellular Biology, University
of Massachusetts, Amherst, 240 Thatcher Way, Amherst, Massachusetts 01003, United States
| | - Mohona Sarkar
- Department
of Chemistry, Department of Biochemistry and Biophysics and Lineberger
Comprehensive Cancer Center, University
of North Carolina, Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Ciara Kyne
- School
of Chemistry, National University of Ireland,
Galway, University Road, Galway, Ireland
| | - Conggang Li
- 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
| | - Peter B. Crowley
- School
of Chemistry, National University of Ireland,
Galway, University Road, Galway, Ireland
| | - Lila Gierasch
- Departments
of Biochemistry & Molecular Biology and Chemistry, Program in
Molecular & Cellular Biology, University
of Massachusetts, Amherst, 240 Thatcher Way, Amherst, Massachusetts 01003, United States
| | - Gary J. Pielak
- Department
of Chemistry, Department of Biochemistry and Biophysics and Lineberger
Comprehensive Cancer Center, University
of North Carolina, Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Adrian H. Elcock
- Department
of Biochemistry, University of Iowa, Bowen Science Building, 51 Newton
Road, Iowa City, Iowa 52242, United States
| | - Anne Gershenson
- Departments
of Biochemistry & Molecular Biology and Chemistry, Program in
Molecular & Cellular Biology, University
of Massachusetts, Amherst, 240 Thatcher Way, Amherst, Massachusetts 01003, United States
| | - Philipp Selenko
- Department
of NMR-supported Structural Biology, In-cell NMR Laboratory, Leibniz Institute of Molecular Pharmacology (FMP Berlin), Robert-Roessle Strasse 10, 13125 Berlin, Germany
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60
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Majumder S, DeMott CM, Burz DS, Shekhtman A. Using singular value decomposition to characterize protein-protein interactions by in-cell NMR spectroscopy. Chembiochem 2014; 15:929-33. [PMID: 24692227 PMCID: PMC4041589 DOI: 10.1002/cbic.201400030] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Indexed: 11/10/2022]
Abstract
Distinct differences between how model proteins interact in-cell and in vitro suggest that the cytosol might have a profound effect in modulating protein-protein and/or protein-ligand interactions that are not observed in vitro. Analyses of in-cell NMR spectra of target proteins interacting with physiological partners are further complicated by low signal-to-noise ratios, and the long overexpression times used in protein-protein interaction studies may lead to changes in the in-cell spectra over the course of the experiment. To unambiguously resolve the principal binding mode between two interacting species against the dynamic cellular background, we analyzed in-cell spectral data of a target protein over the time course of overexpression of its interacting partner by using single-value decomposition (SVD). SVD differentiates between concentration-dependent and concentration-independent events and identifies the principal binding mode between the two species. The analysis implicates a set of amino acids involved in the specific interaction that differs from previous NMR analyses but is in good agreement with crystallographic data.
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Affiliation(s)
- Subhabrata Majumder
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave., Albany, NY 12222 (USA)
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61
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Xu G, Ye Y, Liu X, Cao S, Wu Q, Cheng K, Liu M, Pielak GJ, Li C. Strategies for Protein NMR in Escherichia coli. Biochemistry 2014; 53:1971-81. [DOI: 10.1021/bi500079u] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Guohua Xu
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Yansheng Ye
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
- Graduate University of Chinese Academy of Sciences, Beijing 100029, P. R. China
| | - Xiaoli Liu
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Shufen Cao
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Qiong Wu
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Kai Cheng
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
- Graduate University of Chinese Academy of Sciences, Beijing 100029, P. R. China
| | - Maili Liu
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Gary J. Pielak
- Department
of Chemistry and Department of Biochemistry and Biophysics, University of North Carolina−Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Conggang Li
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
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62
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Li H, Sun H. In-cell NMR: an emerging approach for monitoring metal-related events in living cells. Metallomics 2014; 6:69-76. [DOI: 10.1039/c3mt00224a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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63
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Luh LM, Hänsel R, Löhr F, Kirchner DK, Krauskopf K, Pitzius S, Schäfer B, Tufar P, Corbeski I, Güntert P, Dötsch V. Molecular crowding drives active Pin1 into nonspecific complexes with endogenous proteins prior to substrate recognition. J Am Chem Soc 2013; 135:13796-803. [PMID: 23968199 DOI: 10.1021/ja405244v] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Proteins and nucleic acids maintain the crowded interior of a living cell and can reach concentrations in the order of 200-400 g/L which affects the physicochemical parameters of the environment, such as viscosity and hydrodynamic as well as nonspecific strong repulsive and weak attractive interactions. Dynamics, structure, and activity of macromolecules were demonstrated to be affected by these parameters. However, it remains controversially debated, which of these factors are the dominant cause for the observed alterations in vivo. In this study we investigated the globular folded peptidyl-prolyl isomerase Pin1 in Xenopus laevis oocytes and in native-like crowded oocyte extract by in-cell NMR spectroscopy. We show that active Pin1 is driven into nonspecific weak attractive interactions with intracellular proteins prior to substrate recognition. The substrate recognition site of Pin1 performs specific and nonspecific attractive interactions. Phosphorylation of the WW domain at Ser16 by PKA abrogates both substrate recognition and the nonspecific interactions with the endogenous proteins. Our results validate the hypothesis formulated by McConkey that the majority of globular folded proteins with surface charge properties close to neutral under physiological conditions reside in macromolecular complexes with other sticky proteins due to molecular crowding. In addition, we demonstrate that commonly used synthetic crowding agents like Ficoll 70 are not suitable to mimic the intracellular environment due to their incapability to simulate biologically important weak attractive interactions.
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Affiliation(s)
- Laura M Luh
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University , Frankfurt, 60438, Germany
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64
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Kosol S, Contreras-Martos S, Cedeño C, Tompa P. Structural characterization of intrinsically disordered proteins by NMR spectroscopy. Molecules 2013; 18:10802-28. [PMID: 24008243 PMCID: PMC6269831 DOI: 10.3390/molecules180910802] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/19/2013] [Accepted: 08/30/2013] [Indexed: 01/25/2023] Open
Abstract
Recent advances in NMR methodology and techniques allow the structural investigation of biomolecules of increasing size with atomic resolution. NMR spectroscopy is especially well-suited for the study of intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs) which are in general highly flexible and do not have a well-defined secondary or tertiary structure under functional conditions. In the last decade, the important role of IDPs in many essential cellular processes has become more evident as the lack of a stable tertiary structure of many protagonists in signal transduction, transcription regulation and cell-cycle regulation has been discovered. The growing demand for structural data of IDPs required the development and adaption of methods such as 13C-direct detected experiments, paramagnetic relaxation enhancements (PREs) or residual dipolar couplings (RDCs) for the study of ‘unstructured’ molecules in vitro and in-cell. The information obtained by NMR can be processed with novel computational tools to generate conformational ensembles that visualize the conformations IDPs sample under functional conditions. Here, we address NMR experiments and strategies that enable the generation of detailed structural models of IDPs.
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Affiliation(s)
- Simone Kosol
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels 1050, Belgium; E-Mails: (S.C.M.); (C.C.)
- Authors to whom correspondence should be addressed; E-Mails: (S.K.); (P.T.)
| | - Sara Contreras-Martos
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels 1050, Belgium; E-Mails: (S.C.M.); (C.C.)
| | - Cesyen Cedeño
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels 1050, Belgium; E-Mails: (S.C.M.); (C.C.)
| | - Peter Tompa
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels 1050, Belgium; E-Mails: (S.C.M.); (C.C.)
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest 1518, Hungary
- Authors to whom correspondence should be addressed; E-Mails: (S.K.); (P.T.)
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65
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An in-cell NMR study of monitoring stress-induced increase of cytosolic Ca2+ concentration in HeLa cells. Biochem Biophys Res Commun 2013; 438:653-9. [PMID: 23933251 DOI: 10.1016/j.bbrc.2013.07.127] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 07/31/2013] [Indexed: 11/21/2022]
Abstract
Recent developments in in-cell NMR techniques have allowed us to study proteins in detail inside living eukaryotic cells. The lifetime of in-cell NMR samples is however much shorter than that in culture media, presumably because of various stresses as well as the nutrient depletion in the anaerobic environment within the NMR tube. It is well known that Ca(2+)-bursts occur in HeLa cells under various stresses, hence the cytosolic Ca(2+) concentration can be regarded as a good indicator of the healthiness of cells in NMR tubes. In this study, aiming at monitoring the states of proteins resulting from the change of cytosolic Ca(2+) concentration during experiments, human calbindin D9k (P47M+C80) was used as the model protein and cultured HeLa cells as host cells. Time-resolved measurements of 2D (1)H-(15)N SOFAST-HMQC experiments of calbindin D9k (P47M+C80) in HeLa cells showed time-dependent changes in the cross-peak patterns in the spectra. Comparison with in vitro assignments revealed that calbindin D9k (P47M+C80) is initially in the Mg(2+)-bound state, and then gradually converted to the Ca(2+)-bound state. This conversion process initiates after NMR sample preparation. These results showed, for the first time, that cells inside the NMR tube were stressed, presumably because of cell precipitation, the lack of oxygen and nutrients, etc., thereby releasing Ca(2+) into cytosol during the measurements. The results demonstrated that in-cell NMR can monitor the state transitions of stimulated cells through the observation of proteins involved in the intracellular signalling systems. Our method provides a very useful tool for in situ monitoring of the "healthiness" of the cells in various in-cell NMR studies.
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66
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Barrett PJ, Chen J, Cho MK, Kim JH, Lu Z, Mathew S, Peng D, Song Y, Van Horn WD, Zhuang T, Sönnichsen FD, Sanders CR. The quiet renaissance of protein nuclear magnetic resonance. Biochemistry 2013; 52:1303-20. [PMID: 23368985 DOI: 10.1021/bi4000436] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
From roughly 1985 through the start of the new millennium, the cutting edge of solution protein nuclear magnetic resonance (NMR) spectroscopy was to a significant extent driven by the aspiration to determine structures. Here we survey recent advances in protein NMR that herald a renaissance in which a number of its most important applications reflect the broad problem-solving capability displayed by this method during its classical era during the 1970s and early 1980s.
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Affiliation(s)
- Paul J Barrett
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232-8725, United States
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67
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Hamatsu J, O'Donovan D, Tanaka T, Shirai T, Hourai Y, Mikawa T, Ikeya T, Mishima M, Boucher W, Smith BO, Laue ED, Shirakawa M, Ito Y. High-resolution heteronuclear multidimensional NMR of proteins in living insect cells using a baculovirus protein expression system. J Am Chem Soc 2013; 135:1688-91. [PMID: 23327446 DOI: 10.1021/ja310928u] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Recent developments in in-cell NMR techniques have allowed us to study proteins in detail inside living eukaryotic cells. In order to complement the existing protocols, and to extend the range of possible applications, we introduce a novel approach for observing in-cell NMR spectra using the sf9 cell/baculovirus system. High-resolution 2D (1)H-(15)N correlation spectra were observed for four model proteins expressed in sf9 cells. Furthermore, 3D triple-resonance NMR spectra of the Streptococcus protein G B1 domain were observed in sf9 cells by using nonlinear sampling to overcome the short lifetime of the samples and the low abundance of the labeled protein. The data were processed with a quantitative maximum entropy algorithm. These were assigned ab initio, yielding approximately 80% of the expected backbone NMR resonances. Well-resolved NOE cross peaks could be identified in the 3D (15)N-separated NOESY spectrum, suggesting that structural analysis of this size of protein will be feasible in sf9 cells.
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Affiliation(s)
- Jumpei Hamatsu
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0373, Japan
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68
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Abstract
Isotope-assisted multi-dimensional NMR spectroscopy can now be applied to proteins inside living cells. The technique, called in-cell NMR, aims to investigate the structures, interactions and dynamics of proteins under their native conditions, ideally at an atomic resolution. The application has begun with bacterial cells but has now expanded to mammalian cultured cells, such as HeLa cells. The importance of the realization of such 'in-mammalian cell' NMR should be stressed, as these are the cells most often employed in cell biology. Hence, a substantially wide range of application would be possible in the near future once the technique has been well developed.
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Affiliation(s)
- Hidehito Tochio
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
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