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Laurence MJ, Carpenter TS, Laurence TA, Coleman MA, Shelby M, Liu C. Biophysical Characterization of Membrane Proteins Embedded in Nanodiscs Using Fluorescence Correlation Spectroscopy. MEMBRANES 2022; 12:membranes12040392. [PMID: 35448362 PMCID: PMC9028781 DOI: 10.3390/membranes12040392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 02/04/2023]
Abstract
Proteins embedded in biological membranes perform essential functions in all organisms, serving as receptors, transporters, channels, cell adhesion molecules, and other supporting cellular roles. These membrane proteins comprise ~30% of all human proteins and are the targets of ~60% of FDA-approved drugs, yet their extensive characterization using established biochemical and biophysical methods has continued to be elusive due to challenges associated with the purification of these insoluble proteins. In response, the development of nanodisc techniques, such as nanolipoprotein particles (NLPs) and styrene maleic acid polymers (SMALPs), allowed membrane proteins to be expressed and isolated in solution as part of lipid bilayer rafts with defined, consistent nanometer sizes and compositions, thus enabling solution-based measurements. Fluorescence correlation spectroscopy (FCS) is a relatively simple yet powerful optical microscopy-based technique that yields quantitative biophysical information, such as diffusion kinetics and concentrations, about individual or interacting species in solution. Here, we first summarize current nanodisc techniques and FCS fundamentals. We then provide a focused review of studies that employed FCS in combination with nanodisc technology to investigate a handful of membrane proteins, including bacteriorhodopsin, bacterial division protein ZipA, bacterial membrane insertases SecYEG and YidC, Yersinia pestis type III secretion protein YopB, yeast cell wall stress sensor Wsc1, epidermal growth factor receptor (EGFR), ABC transporters, and several G protein-coupled receptors (GPCRs).
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Affiliation(s)
- Matthew J. Laurence
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (M.J.L.); (T.S.C.); (M.A.C.)
| | - Timothy S. Carpenter
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (M.J.L.); (T.S.C.); (M.A.C.)
| | - Ted A. Laurence
- Materials Science Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA;
| | - Matthew A. Coleman
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (M.J.L.); (T.S.C.); (M.A.C.)
- Department of Radiation Oncology, University of California Davis, Sacramento, CA 95616, USA
| | - Megan Shelby
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (M.J.L.); (T.S.C.); (M.A.C.)
- Correspondence: (M.S.); (C.L.)
| | - Chao Liu
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (M.J.L.); (T.S.C.); (M.A.C.)
- Correspondence: (M.S.); (C.L.)
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2
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Majeed S, Ahmad AB, Sehar U, Georgieva ER. Lipid Membrane Mimetics in Functional and Structural Studies of Integral Membrane Proteins. MEMBRANES 2021; 11:685. [PMID: 34564502 PMCID: PMC8470526 DOI: 10.3390/membranes11090685] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/18/2021] [Accepted: 08/30/2021] [Indexed: 12/12/2022]
Abstract
Integral membrane proteins (IMPs) fulfill important physiological functions by providing cell-environment, cell-cell and virus-host communication; nutrients intake; export of toxic compounds out of cells; and more. However, some IMPs have obliterated functions due to polypeptide mutations, modifications in membrane properties and/or other environmental factors-resulting in damaged binding to ligands and the adoption of non-physiological conformations that prevent the protein from returning to its physiological state. Thus, elucidating IMPs' mechanisms of function and malfunction at the molecular level is important for enhancing our understanding of cell and organism physiology. This understanding also helps pharmaceutical developments for restoring or inhibiting protein activity. To this end, in vitro studies provide invaluable information about IMPs' structure and the relation between structural dynamics and function. Typically, these studies are conducted on transferred from native membranes to membrane-mimicking nano-platforms (membrane mimetics) purified IMPs. Here, we review the most widely used membrane mimetics in structural and functional studies of IMPs. These membrane mimetics are detergents, liposomes, bicelles, nanodiscs/Lipodisqs, amphipols, and lipidic cubic phases. We also discuss the protocols for IMPs reconstitution in membrane mimetics as well as the applicability of these membrane mimetic-IMP complexes in studies via a variety of biochemical, biophysical, and structural biology techniques.
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Affiliation(s)
- Saman Majeed
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Akram Bani Ahmad
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Ujala Sehar
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Elka R Georgieva
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Science Center, Lubbock, TX 79409, USA
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3
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Sarkar A, Sharma A, Goswami D, Namboodiri V, Enderlein J, Kumbhakar M. Binding Constant Determined from the Angstrom-Scale Change in Hydrodynamic Radius of Transferrin upon Binding with Europium Using Dual-Focus Fluorescence Correlation Spectroscopy. J Phys Chem Lett 2020; 11:1148-1153. [PMID: 31968931 DOI: 10.1021/acs.jpclett.9b03722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Monitoring the binding of a large fluorescently tagged molecule to a small solute by fluorescence correlation spectroscopy (FCS) is rather uncommon because the binding-related change in diffusion coefficient is very small. Here, we use a high-precision variant of FCS, namely, dual-focus FCS (2fFCS), for measuring the angstrom-scale change of the hydrodynamic radius of the bilobal metal transport protein transferrin (Tf) upon binding europium ions. Applying a sequential 1:2 complexation model, we use these measurements for determining the binding constants (K). Our results show a 0.7 Å change of the protein's hydrodynamic radius upon 1:1 Tf-Eu complex formation and a second change of 1.8 Å upon subsequent binding of a second europium ion. More than one unit variation in logK indicates an intrinsic dissimilarity in metal affinity of the C- and N-lobes of Tf, which agrees well with earlier reported ensemble spectroscopy results.
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Affiliation(s)
- Aranyak Sarkar
- Radiation & Photochemistry Division , Bhabha Atomic Research Center , Mumbai 400085 , India
- Homi Bhabha National Institute , Training School Complex , Anushaktinagar, Mumbai 400094 , India
| | - Arjun Sharma
- Radiation & Photochemistry Division , Bhabha Atomic Research Center , Mumbai 400085 , India
- Homi Bhabha National Institute , Training School Complex , Anushaktinagar, Mumbai 400094 , India
| | - Dibakar Goswami
- Radiation & Photochemistry Division , Bhabha Atomic Research Center , Mumbai 400085 , India
- Bio-oragnic Division , Bhabha Atomic Research Center , Mumbai 400085 , India
| | - Vinu Namboodiri
- Radiation & Photochemistry Division , Bhabha Atomic Research Center , Mumbai 400085 , India
| | - Jörg Enderlein
- III. Institute of Physics - Biophysics , Georg August University , 37077 Göttingen , Germany
| | - Manoj Kumbhakar
- Radiation & Photochemistry Division , Bhabha Atomic Research Center , Mumbai 400085 , India
- Homi Bhabha National Institute , Training School Complex , Anushaktinagar, Mumbai 400094 , India
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Gupta A, Sankaran J, Wohland T. Fluorescence correlation spectroscopy: The technique and its applications in soft matter. PHYSICAL SCIENCES REVIEWS 2019. [DOI: 10.1515/psr-2017-0104] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Abstract
Fluorescence correlation spectroscopy (FCS) is a well-established single-molecule method used for the quantitative spatiotemporal analysis of dynamic processes in a wide range of samples. It possesses single-molecule sensitivity but provides ensemble averaged molecular parameters such as mobility, concentration, chemical reaction kinetics, photophysical properties and interaction properties. These parameters have been utilized to characterize a variety of soft matter systems. This review provides an overview of the basic principles of various FCS modalities, their instrumentation, data analysis, and the applications of FCS to soft matter systems.
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Briddon SJ, Kilpatrick LE, Hill SJ. Studying GPCR Pharmacology in Membrane Microdomains: Fluorescence Correlation Spectroscopy Comes of Age. Trends Pharmacol Sci 2017; 39:158-174. [PMID: 29277246 DOI: 10.1016/j.tips.2017.11.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/13/2017] [Accepted: 11/14/2017] [Indexed: 12/17/2022]
Abstract
G protein-coupled receptors (GPCRs) are organised within the cell membrane into highly ordered macromolecular complexes along with other receptors and signalling proteins. Understanding how heterogeneity in these complexes affects the pharmacology and functional response of these receptors is crucial for developing new and more selective ligands. Fluorescence correlation spectroscopy (FCS) and related techniques such as photon counting histogram (PCH) analysis and image-based FCS can be used to interrogate the properties of GPCRs in these membrane microdomains, as well as their interaction with fluorescent ligands. FCS analyses fluorescence fluctuations within a small-defined excitation volume to yield information about their movement, concentration and molecular brightness (aggregation). These techniques can be used on live cells with single-molecule sensitivity and high spatial resolution. Once the preserve of specialist equipment, FCS techniques can now be applied using standard confocal microscopes. This review describes how FCS and related techniques have revealed novel insights into GPCR biology.
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Affiliation(s)
- Stephen J Briddon
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK; Centre for Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK
| | - Laura E Kilpatrick
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK; Centre for Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK
| | - Stephen J Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK; Centre for Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK.
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Poulcharidis D, Belfor K, Kros A, van Kasteren SI. A flow cytometry assay to quantify intercellular exchange of membrane components. Chem Sci 2017; 8:5585-5590. [PMID: 28970937 PMCID: PMC5618768 DOI: 10.1039/c7sc00260b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 05/20/2017] [Indexed: 12/12/2022] Open
Abstract
Membrane-compound exchange is vital for cell-to-cell communication, yet quantification of this process is difficult. Here we present a method using flow cytometry in combination with bioorthogonal and fluorescent labelling techniques to quantify the amount of exchange of cholesterol and sialylated compounds between cells. We demonstrate that direct cell-cell contact is the likely mechanism of sterol-exchange and show that by manipulating the contact time between cells using complementary coiled-coil peptides results in an enhanced exchange rate of membrane components between cells.
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Affiliation(s)
- Dimitrios Poulcharidis
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
- Division of Supramolecular and Biomaterials Chemistry , Leiden Institute of Chemistry , Leiden University , Einsteinweg 55 , 2333 CC Leiden , The Netherlands .
| | - Kimberley Belfor
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
| | - Alexander Kros
- Division of Supramolecular and Biomaterials Chemistry , Leiden Institute of Chemistry , Leiden University , Einsteinweg 55 , 2333 CC Leiden , The Netherlands .
| | - Sander I van Kasteren
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
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7
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Krüger D, Ebenhan J, Werner S, Bacia K. Measuring Protein Binding to Lipid Vesicles by Fluorescence Cross-Correlation Spectroscopy. Biophys J 2017; 113:1311-1320. [PMID: 28697897 DOI: 10.1016/j.bpj.2017.06.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/21/2017] [Accepted: 06/08/2017] [Indexed: 11/26/2022] Open
Abstract
Fluorescence correlation spectroscopy has been previously used to investigate peptide and protein binding to lipid membranes, as it allows for very low amounts of sample, short measurement times and equilibrium binding conditions. Labeling only one of the binding partners, however, comes with certain drawbacks, as it relies on identifying binding events by a change in diffusion coefficient. Since peptide and protein aggregation can obscure specific binding, and since non-stoichiometric binding necessitates the explicit choice of a statistical distribution for the number of bound ligands, we additionally label the liposomes and perform dual-color fluorescence cross-correlation spectroscopy (dcFCCS). We develop a theoretical framework showing that dcFCCS amplitudes allow calculation of the degree of ligand binding and the concentration of unbound ligand, leading to a model-independent binding curve. As the degree of labeling of the ligands does not factor into the measured quantities, it is permissible to mix labeled and unlabeled ligand, thereby extending the range of usable protein concentrations and accessible dissociation constants, KD. The total protein concentration, but not the fraction of labeled protein, needs to be known. In this work, we apply our dcFCCS analysis scheme to Sar1p, a protein of the COPII complex, which binds "major-minor-mix" liposomes. A Langmuir isotherm model yields KD=(2.1±1.1)μM as the single-site dissociation constant. The dcFCCS framework presented here is highly versatile for biophysical analysis of binding interactions. It may be applied to many types of fluorescently labeled ligands and small diffusing particles, including nanodiscs and liposomes containing membrane protein receptors.
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Affiliation(s)
- Daniela Krüger
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany
| | - Jan Ebenhan
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany
| | - Stefan Werner
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany
| | - Kirsten Bacia
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany.
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8
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Rouck J, Krapf J, Roy J, Huff H, Das A. Recent advances in nanodisc technology for membrane protein studies (2012-2017). FEBS Lett 2017; 591:2057-2088. [PMID: 28581067 PMCID: PMC5751705 DOI: 10.1002/1873-3468.12706] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 05/26/2017] [Accepted: 05/31/2017] [Indexed: 01/01/2023]
Abstract
Historically, the main barrier to membrane protein investigations has been the tendency of membrane proteins to aggregate (due to their hydrophobic nature), in aqueous solution as well as on surfaces. The introduction of biomembrane mimetics has since stimulated momentum in the field. One such mimetic, the nanodisc (ND) system, has proved to be an exceptional system for solubilizing membrane proteins. Herein, we critically evaluate the advantages and imperfections of employing nanodiscs in biophysical and biochemical studies. Specifically, we examine the techniques that have been modified to study membrane proteins in nanodiscs. Techniques discussed here include fluorescence microscopy, solution-state/solid-state nuclear magnetic resonance, electron microscopy, small-angle X-ray scattering, and several mass spectroscopy methods. Newer techniques such as SPR, charge-sensitive optical detection, and scintillation proximity assays are also reviewed. Lastly, we cover how nanodiscs are advancing nanotechnology through nanoplasmonic biosensing, lipoprotein-nanoplatelets, and sortase-mediated labeling of nanodiscs.
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Affiliation(s)
- John Rouck
- Department of Biochemistry, University of Illinois Urbana–Champaign, Urbana IL 61802, USA
| | - John Krapf
- Department of Biochemistry, University of Illinois Urbana–Champaign, Urbana IL 61802, USA
| | - Jahnabi Roy
- Department of Chemistry, University of Illinois Urbana–Champaign, Urbana IL 61802, USA
| | - Hannah Huff
- Department of Chemistry, University of Illinois Urbana–Champaign, Urbana IL 61802, USA
| | - Aditi Das
- Department of Comparative Biosciences, University of Illinois Urbana–Champaign, Urbana IL 61802, USA
- Department of Biochemistry, University of Illinois Urbana–Champaign, Urbana IL 61802, USA
- Beckman Institute for Advanced Science, Division of Nutritional Sciences, Neuroscience Program and Department of Bioengineering, University of Illinois Urbana–Champaign, Urbana IL 61802, USA
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Coleman MA, Cappuccio JA, Blanchette CD, Gao T, Arroyo ES, Hinz AK, Bourguet FA, Segelke B, Hoeprich PD, Huser T, Laurence TA, Motin VL, Chromy BA. Expression and Association of the Yersinia pestis Translocon Proteins, YopB and YopD, Are Facilitated by Nanolipoprotein Particles. PLoS One 2016; 11:e0150166. [PMID: 27015536 PMCID: PMC4807764 DOI: 10.1371/journal.pone.0150166] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 02/10/2016] [Indexed: 12/18/2022] Open
Abstract
Yersinia pestis enters host cells and evades host defenses, in part, through interactions between Yersinia pestis proteins and host membranes. One such interaction is through the type III secretion system, which uses a highly conserved and ordered complex for Yersinia pestis outer membrane effector protein translocation called the injectisome. The portion of the injectisome that interacts directly with host cell membranes is referred to as the translocon. The translocon is believed to form a pore allowing effector molecules to enter host cells. To facilitate mechanistic studies of the translocon, we have developed a cell-free approach for expressing translocon pore proteins as a complex supported in a bilayer membrane mimetic nano-scaffold known as a nanolipoprotein particle (NLP) Initial results show cell-free expression of Yersinia pestis outer membrane proteins YopB and YopD was enhanced in the presence of liposomes. However, these complexes tended to aggregate and precipitate. With the addition of co-expressed (NLP) forming components, the YopB and/or YopD complex was rendered soluble, increasing the yield of protein for biophysical studies. Biophysical methods such as Atomic Force Microscopy and Fluorescence Correlation Spectroscopy were used to confirm that the soluble YopB/D complex was associated with NLPs. An interaction between the YopB/D complex and NLP was validated by immunoprecipitation. The YopB/D translocon complex embedded in a NLP provides a platform for protein interaction studies between pathogen and host proteins. These studies will help elucidate the poorly understood mechanism which enables this pathogen to inject effector proteins into host cells, thus evading host defenses.
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Affiliation(s)
- Matthew A. Coleman
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
- University of California Davis, NSF, Center for Biophotonics, Sacramento, CA, United States of America, 95817
- * E-mail: (MAC); (BAC)
| | - Jenny A. Cappuccio
- Humboldt State University, Department of Chemistry, Arcata, CA, United States of America, 95521
| | - Craig D. Blanchette
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Tingjuan Gao
- University of California Davis, NSF, Center for Biophotonics, Sacramento, CA, United States of America, 95817
| | - Erin S. Arroyo
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Angela K. Hinz
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Feliza A. Bourguet
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Brent Segelke
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Paul D. Hoeprich
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Thomas Huser
- University of California Davis, NSF, Center for Biophotonics, Sacramento, CA, United States of America, 95817
| | - Ted A. Laurence
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Vladimir L. Motin
- University of Texas Medical Branch, Galveston, TX, United States of America, 77555
| | - Brett A. Chromy
- University of California Davis, NSF, Center for Biophotonics, Sacramento, CA, United States of America, 95817
- * E-mail: (MAC); (BAC)
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10
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Benjamin CJ, Wright KJ, Hyun SH, Krynski K, Yu G, Bajaj R, Guo F, Stauffacher CV, Jiang W, Thompson DH. Nonfouling NTA-PEG-Based TEM Grid Coatings for Selective Capture of Histidine-Tagged Protein Targets from Cell Lysates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:551-9. [PMID: 26726866 PMCID: PMC5310270 DOI: 10.1021/acs.langmuir.5b03445] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We report the preparation and performance of TEM grids bearing stabilized nonfouling lipid monolayer coatings. These films contain NTA capture ligands of controllable areal density at the distal end of a flexible poly(ethylene glycol) 2000 (PEG2000) spacer to avoid preferred orientation of surface-bound histidine-tagged (His-tag) protein targets. Langmuir-Schaefer deposition at 30 mN/m of mixed monolayers containing two novel synthetic lipids-1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[(5-amido-1-carboxypentyl)iminodiacetic acid]polyethylene glycolamide 2000) (NTA-PEG2000-DSPE) and 1,2-(tricosa-10',12'-diynoyl)-sn-glycero-3-phosphoethanolamine-N-(methoxypolyethylene glycolamide 350) (mPEG350-DTPE)-in 1:99 and 5:95 molar ratios prior to treatment with a 5 min, 254 nm light exposure was used for grid fabrication. These conditions were designed to limit nonspecific protein adsorption onto the stabilized lipid coating by favoring the formation of a mPEG350 brush layer below a flexible, mushroom conformation of NTA-PEG2000 at low surface density to enable specific immobilization and random orientation of the protein target on the EM grid. These grids were then used to capture His6-T7 bacteriophage and RplL from cell lysates, as well as purified His8-green fluorescent protein (GFP) and nanodisc solubilized maltose transporter, His6-MalFGK2. Our findings indicate that TEM grid supported, polymerized NTA lipid monolayers are capable of capturing His-tag protein targets in a manner that controls their areal densities, while efficiently blocking nonspecific adsorption and limiting film degradation, even upon prolonged detergent exposure.
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Affiliation(s)
- Christopher J Benjamin
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Kyle J Wright
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Seok-Hee Hyun
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Kyle Krynski
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Guimei Yu
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Ruchika Bajaj
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Fei Guo
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Cynthia V Stauffacher
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Wen Jiang
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - David H Thompson
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
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11
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Malhotra K, Alder NN. Advances in the use of nanoscale bilayers to study membrane protein structure and function. Biotechnol Genet Eng Rev 2015; 30:79-93. [PMID: 25023464 DOI: 10.1080/02648725.2014.921502] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Within the last decade, nanoscale lipid bilayers have emerged as powerful experimental systems in the analysis of membrane proteins (MPs) for both basic and applied research. These discoidal lipid lamellae are stabilized by annuli of specially engineered amphipathic polypeptides (nanodiscs) or polymers (SMALPs/Lipodisqs®). As biomembrane mimetics, they are well suited for the reconstitution of MPs within a controlled lipid environment. Moreover, because they are water-soluble, they are amenable to solution-based biochemical and biophysical experimentation. Hence, due to their solubility, size, stability, and monodispersity, nanoscale lipid bilayers offer technical advantages over more traditional MP analytic approaches such as detergent solubilization and reconstitution into lipid vesicles. In this article, we review some of the most recent advances in the synthesis of polypeptide- and polymer-bound nanoscale lipid bilayers and their application in the study of MP structure and function.
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Affiliation(s)
- Ketan Malhotra
- a Department of Molecular and Cell Biology , University of Connecticut , Storrs , CT 06269 , USA
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12
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Fine tuning of sub-millisecond conformational dynamics controls metabotropic glutamate receptors agonist efficacy. Nat Commun 2014; 5:5206. [DOI: 10.1038/ncomms6206] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 09/09/2014] [Indexed: 11/08/2022] Open
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13
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Laurence TA, Ly S, Bourguet F, Fischer NO, Coleman MA. Fluorescence correlation spectroscopy at micromolar concentrations without optical nanoconfinement. J Phys Chem B 2014; 118:9662-7. [PMID: 25060197 DOI: 10.1021/jp505881z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fluorescence correlation spectroscopy (FCS) is an important technique for studying biochemical interactions dynamically that may be used in vitro and in cell-based studies. It is generally claimed that FCS may only be used at nM concentrations. We show that this general consensus is incorrect and that the limitation to nM concentrations is not fundamental but due to detector limits as well as laser fluctuations. With a high count rate detector system and applying laser fluctuation corrections, we demonstrate FCS measurements up to 38 μM with the same signal-to-noise as at lower concentrations. Optical nanoconfinement approaches previously used to increase the concentration range of FCS are not necessary, and further increases above 38 μM may be expected using detectors and detector arrays with higher saturation rates and better laser fluctuation corrections. This approach greatly widens the possibilities of dynamic measurements of biochemical interactions using FCS at physiological concentrations.
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Affiliation(s)
- Ted A Laurence
- Lawrence Livermore National Laboratory , Livermore, California 94550, United States
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14
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Comar W, Schubert SM, Jastrzebska B, Palczewski K, Smith AW. Time-resolved fluorescence spectroscopy measures clustering and mobility of a G protein-coupled receptor opsin in live cell membranes. J Am Chem Soc 2014; 136:8342-9. [PMID: 24831851 PMCID: PMC4063175 DOI: 10.1021/ja501948w] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Indexed: 01/31/2023]
Abstract
Determining membrane protein quaternary structure is extremely challenging, especially in live cell membranes. We measured the oligomerization of opsin, a prototypical G protein-coupled receptor with pulsed-interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS). Individual cell measurements revealed that opsin is predominantly organized into dimeric clusters. At low concentrations, we observed that the population of oligomers increased linearly with the square of the individual monomer populations. This finding supports a monomer-dimer equilibrium and provides an experimental measurement of the equilibrium constant.
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Affiliation(s)
- William
D. Comar
- The
University of Akron Department of Chemistry, 190 Buchtel Common, Akron, Ohio 44303-3601, United States
| | - Sarah M. Schubert
- The
University of Akron Department of Chemistry, 190 Buchtel Common, Akron, Ohio 44303-3601, United States
| | - Beata Jastrzebska
- Department
of Pharmacology, School of Medicine, Case
Western Reserve University, 2109 Adelbert Road, Cleveland, Ohio 44106-4965, United States
| | - Krzysztof Palczewski
- Department
of Pharmacology, School of Medicine, Case
Western Reserve University, 2109 Adelbert Road, Cleveland, Ohio 44106-4965, United States
| | - Adam W. Smith
- The
University of Akron Department of Chemistry, 190 Buchtel Common, Akron, Ohio 44303-3601, United States
| |
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