51
|
Cation-π Interactions and their Functional Roles in Membrane Proteins. J Mol Biol 2021; 433:167035. [PMID: 33957146 PMCID: PMC8338773 DOI: 10.1016/j.jmb.2021.167035] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/27/2021] [Accepted: 04/27/2021] [Indexed: 01/25/2023]
Abstract
Cation-π interactions arise as a result of strong attractive forces between positively charged entities and the π-electron cloud of aromatic groups. The physicochemical characteristics of cation-π interactions are particularly well-suited to the dual hydrophobic/hydrophilic environment of membrane proteins. As high-resolution structural data of membrane proteins bring molecular features into increasingly sharper view, cation-π interactions are gaining traction as essential contributors to membrane protein chemistry, function, and pharmacology. Here we review the physicochemical properties of cation-π interactions and present several prominent examples which demonstrate significant roles for this specialized biological chemistry.
Collapse
|
52
|
Villemure E, Terrett JA, Larouche-Gauthier R, Déry M, Chen H, Reese RM, Shields SD, Chen J, Magnuson S, Volgraf M. A Retrospective Look at the Impact of Binding Site Environment on the Optimization of TRPA1 Antagonists. ACS Med Chem Lett 2021; 12:1230-1237. [PMID: 34413952 DOI: 10.1021/acsmedchemlett.1c00305] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 07/02/2021] [Indexed: 12/27/2022] Open
Abstract
Transient receptor potential ankyrin 1 (TRPA1) antagonists have generated broad interest in the pharmaceutical industry for the treatment of both pain and asthma. Over the past decade, multiple antagonist classes have been reported in the literature with a wide range of structural diversity. Our own work has focused on the development of proline sulfonamide and hypoxanthine-based antagonists, two antagonist classes with distinct physicochemical properties and pharmacokinetic (PK) trends. Late in our discovery program, cryogenic electron microscopy (cryoEM) studies revealed two different antagonist binding sites: a membrane-exposed proline sulfonamide transmembrane site and an intracellular hypoxanthine site near the membrane interface. A retrospective look at the discovery program reveals how the different binding sites, and their location relative to the cell membrane, influenced the optimization trajectories and overall drug profiles of each antagonist class.
Collapse
Affiliation(s)
- Elisia Villemure
- Department of Discovery Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Jack A. Terrett
- Department of Discovery Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | | | - Martin Déry
- Paraza Pharma, Inc. 2525 Avenue Marie-Curie, Montréal, Québec H4S 2E1, Canada
| | - Huifen Chen
- Department of Discovery Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Rebecca M. Reese
- Department of Neuroscience, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Shannon D. Shields
- Department of Neuroscience, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Jun Chen
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Steven Magnuson
- Department of Discovery Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Matthew Volgraf
- Department of Discovery Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| |
Collapse
|
53
|
Campuzano IDG, Sandoval W. Denaturing and Native Mass Spectrometric Analytics for Biotherapeutic Drug Discovery Research: Historical, Current, and Future Personal Perspectives. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1861-1885. [PMID: 33886297 DOI: 10.1021/jasms.1c00036] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Mass spectrometry (MS) plays a key role throughout all stages of drug development and is now as ubiquitous as other analytical techniques such as surface plasmon resonance, nuclear magnetic resonance, and supercritical fluid chromatography, among others. Herein, we aim to discuss the history of MS, both electrospray and matrix-assisted laser desorption ionization, specifically for the analysis of antibodies, evolving through to denaturing and native-MS analysis of newer biologic moieties such as antibody-drug conjugates, multispecific antibodies, and interfering nucleic acid-based therapies. We discuss challenging therapeutic target characterization such as membrane protein receptors. Importantly, we compare and contrast the MS and hyphenated analytical chromatographic methods used to characterize these therapeutic modalities and targets within biopharmaceutical research and highlight the importance of appropriate MS deconvolution software and its essential contribution to project progression. Finally, we describe emerging applications and MS technologies that are still predominantly within either a development or academic stage of use but are poised to have significant impact on future drug development within the biopharmaceutic industry once matured. The views reflected herein are personal and are not meant to be an exhaustive list of all relevant MS performed within biopharmaceutical research but are what we feel have been historically, are currently, and will be in the future the most impactful for the drug development process.
Collapse
MESH Headings
- Antibodies, Monoclonal/analysis
- Automation, Laboratory
- Biopharmaceutics/methods
- Chromatography, Liquid
- Drug Discovery/methods
- Drug Industry/history
- History, 20th Century
- History, 21st Century
- Humans
- Immunoconjugates/analysis
- Immunoconjugates/chemistry
- Protein Denaturation
- Protein Processing, Post-Translational
- Proteins/analysis
- Spectrometry, Mass, Electrospray Ionization/history
- Spectrometry, Mass, Electrospray Ionization/instrumentation
- Spectrometry, Mass, Electrospray Ionization/methods
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/history
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/instrumentation
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
Collapse
Affiliation(s)
- Iain D G Campuzano
- Discovery Attribute Sciences, Amgen Research, 1 Amgen Center Drive, Thousand Oaks, California 92130, United States
| | - Wendy Sandoval
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| |
Collapse
|
54
|
Bansia H, Catalano C, Melville Z, Guo Y, Marks AR, des Georges A. Investigating gating mechanisms of ion channels using temperature-resolved cryoEM. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2021; 27:1690-1694. [PMID: 37644957 PMCID: PMC10464605 DOI: 10.1017/s1431927621006206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Affiliation(s)
- Harsh Bansia
- CUNY Advanced Science Research Center, New York, United States
| | - Claudio Catalano
- Virginia Commonwealth University, Richmond, Virginia, United States
| | - Zephan Melville
- Columbia University Vagelos College of Physicians and Surgeons, New York, New York, United States
| | - Youzhong Guo
- Virginia Commonwealth University, Richmond, Virginia, United States
| | - Andrew R Marks
- Columbia University Vagelos College of Physicians and Surgeons, New York, New York, United States
| | | |
Collapse
|
55
|
Hu H, Santiveri M, Wadhwa N, Berg HC, Erhardt M, Taylor NMI. Structural basis of torque generation in the bi-directional bacterial flagellar motor. Trends Biochem Sci 2021; 47:160-172. [PMID: 34294545 DOI: 10.1016/j.tibs.2021.06.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 06/16/2021] [Accepted: 06/18/2021] [Indexed: 12/11/2022]
Abstract
The flagellar stator unit is an oligomeric complex of two membrane proteins (MotA5B2) that powers bi-directional rotation of the bacterial flagellum. Harnessing the ion motive force across the cytoplasmic membrane, the stator unit operates as a miniature rotary motor itself to provide torque for rotation of the flagellum. Recent cryo-electron microscopic (cryo-EM) structures of the stator unit provided novel insights into its assembly, function, and subunit stoichiometry, revealing the ion flux pathway and the torque generation mechanism. Furthermore, in situ cryo-electron tomography (cryo-ET) studies revealed unprecedented details of the interactions between stator unit and rotor. In this review, we summarize recent advances in our understanding of the structure and function of the flagellar stator unit, torque generation, and directional switching of the motor.
Collapse
Affiliation(s)
- Haidai Hu
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Mònica Santiveri
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Navish Wadhwa
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA; Rowland Institute at Harvard, Harvard University, 100 Edwin H. Land Blvd, Cambridge, MA 02142, USA
| | - Howard C Berg
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA; Rowland Institute at Harvard, Harvard University, 100 Edwin H. Land Blvd, Cambridge, MA 02142, USA
| | - Marc Erhardt
- Institut für Biologie/Bakterienphysiologie, Humboldt-Universität zu Berlin, Philippstr. 13, 10115 Berlin, Germany
| | - Nicholas M I Taylor
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
| |
Collapse
|
56
|
Abstract
ATP-binding cassette (ABC) transporters constitute one of the largest and most ancient protein superfamilies found in all living organisms. They function as molecular machines by coupling ATP binding, hydrolysis, and phosphate release to translocation of diverse substrates across membranes. The substrates range from vitamins, steroids, lipids, and ions to peptides, proteins, polysaccharides, and xenobiotics. ABC transporters undergo substantial conformational changes during substrate translocation. A comprehensive understanding of their inner workings thus requires linking these structural rearrangements to the different functional state transitions. Recent advances in single-particle cryogenic electron microscopy have not only delivered crucial information on the architecture of several medically relevant ABC transporters and their supramolecular assemblies, including the ATP-sensitive potassium channel and the peptide-loading complex, but also made it possible to explore the entire conformational space of these nanomachines under turnover conditions and thereby gain detailed mechanistic insights into their mode of action.
Collapse
Affiliation(s)
- Christoph Thomas
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany; ,
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany; ,
| |
Collapse
|
57
|
Drew D, North RA, Nagarathinam K, Tanabe M. Structures and General Transport Mechanisms by the Major Facilitator Superfamily (MFS). Chem Rev 2021; 121:5289-5335. [PMID: 33886296 PMCID: PMC8154325 DOI: 10.1021/acs.chemrev.0c00983] [Citation(s) in RCA: 157] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Indexed: 12/12/2022]
Abstract
The major facilitator superfamily (MFS) is the largest known superfamily of secondary active transporters. MFS transporters are responsible for transporting a broad spectrum of substrates, either down their concentration gradient or uphill using the energy stored in the electrochemical gradients. Over the last 10 years, more than a hundred different MFS transporter structures covering close to 40 members have provided an atomic framework for piecing together the molecular basis of their transport cycles. Here, we summarize the remarkable promiscuity of MFS members in terms of substrate recognition and proton coupling as well as the intricate gating mechanisms undergone in achieving substrate translocation. We outline studies that show how residues far from the substrate binding site can be just as important for fine-tuning substrate recognition and specificity as those residues directly coordinating the substrate, and how a number of MFS transporters have evolved to form unique complexes with chaperone and signaling functions. Through a deeper mechanistic description of glucose (GLUT) transporters and multidrug resistance (MDR) antiporters, we outline novel refinements to the rocker-switch alternating-access model, such as a latch mechanism for proton-coupled monosaccharide transport. We emphasize that a full understanding of transport requires an elucidation of MFS transporter dynamics, energy landscapes, and the determination of how rate transitions are modulated by lipids.
Collapse
Affiliation(s)
- David Drew
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Rachel A. North
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Kumar Nagarathinam
- Center
of Structural and Cell Biology in Medicine, Institute of Biochemistry, University of Lübeck, D-23538, Lübeck, Germany
| | - Mikio Tanabe
- Structural
Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan
| |
Collapse
|
58
|
Mohany NAM, Totti A, Naylor KR, Janovjak H. Microbial methionine transporters and biotechnological applications. Appl Microbiol Biotechnol 2021; 105:3919-3929. [PMID: 33929594 PMCID: PMC8140960 DOI: 10.1007/s00253-021-11307-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 04/13/2021] [Accepted: 04/18/2021] [Indexed: 11/07/2022]
Abstract
Methionine (Met) is an essential amino acid with commercial value in animal feed, human nutrition, and as a chemical precursor. Microbial production of Met has seen intensive investigation towards a more sustainable alternative to the chemical synthesis that currently meets the global Met demand. Indeed, efficient Met biosynthesis has been achieved in genetically modified bacteria that harbor engineered enzymes and streamlined metabolic pathways. Very recently, the export of Met as the final step during its fermentative production has been studied and optimized, primarily through identification and expression of microbial Met efflux transporters. In this mini-review, we summarize the current knowledge on four families of Met export and import transporters that have been harnessed for the production of Met and other valuable biomolecules. These families are discussed with respect to their function, gene regulation, and biotechnological applications. We cover methods for identification and characterization of Met transporters as the basis for the further engineering of these proteins and for exploration of other solute carrier families. The available arsenal of Met transporters from different species and protein families provides blueprints not only for fermentative production but also synthetic biology systems, such as molecular sensors and cell-cell communication systems. KEY POINTS: • Sustainable production of methionine (Met) using microbes is actively explored. • Met transporters of four families increase production yield and specificity. • Further applications include other biosynthetic pathways and synthetic biology.
Collapse
Affiliation(s)
- Nurul Amira Mohammad Mohany
- Australian Regenerative Medicine Institute (ARMI), Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Clayton, Australia
- European Molecular Biology Laboratory Australia (EMBL Australia), Monash University, Melbourne, Clayton, Australia
| | - Alessandra Totti
- Department of Pharmacy and Biotechnology FaBiT, University of Bologna, Bologna, Italy
| | - Keith R Naylor
- Australian Regenerative Medicine Institute (ARMI), Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Clayton, Australia
- European Molecular Biology Laboratory Australia (EMBL Australia), Monash University, Melbourne, Clayton, Australia
| | - Harald Janovjak
- Australian Regenerative Medicine Institute (ARMI), Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Clayton, Australia.
- European Molecular Biology Laboratory Australia (EMBL Australia), Monash University, Melbourne, Clayton, Australia.
| |
Collapse
|
59
|
Agasid MT, Robinson CV. Probing membrane protein-lipid interactions. Curr Opin Struct Biol 2021; 69:78-85. [PMID: 33930613 DOI: 10.1016/j.sbi.2021.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/08/2021] [Accepted: 03/21/2021] [Indexed: 12/15/2022]
Abstract
Structure determination of membrane proteins has highlighted the many roles played by lipids in influencing overall protein architecture. It is now widely accepted that lipids surrounding membrane proteins play crucial roles by modulating their conformational, structural, and functional properties. Capturing often transient lipid interactions and defining their chemical identity, however, remains challenging. Recent advances in mass spectrometry have resolved questions concerning lipid interactions by providing the molecular composition of intact complexes in association with lipids. Together with other biophysical tools, a picture is emerging of the dynamic nature of lipid-mediated interactions and their effects on conformation, interactions, and signaling.
Collapse
Affiliation(s)
- Mark T Agasid
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| |
Collapse
|
60
|
Moysa A, Steczkiewicz K, Niedzialek D, Hammerschmid D, Zhukova L, Sobott F, Dadlez M. A model of full-length RAGE in complex with S100B. Structure 2021; 29:989-1002.e6. [PMID: 33887170 DOI: 10.1016/j.str.2021.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 02/03/2021] [Accepted: 04/02/2021] [Indexed: 01/10/2023]
Abstract
The receptor for advanced glycation end products (RAGE) is an immunoglobulin-type multiligand transmembrane protein expressed in numerous cell types, including the central nervous system cells. RAGE interaction with S100B, released during brain tissue damage, leads to RAGE upregulation and initialization of a spiral proinflammatory associated with different neural disorders. Here, we present the structural characterization of the hetero-oligomeric complex of the full-length RAGE with S100B, obtained by a combination of mass spectrometry-based methods and molecular modeling. We predict that RAGE functions as a tightly packed tetramer exposing a positively charged surface formed by V domains for S100B binding. Based on HDX results we demonstrate an allosteric coupling of the distal extracellular V domains and the transmembrane region, indicating a possible mechanism of signal transmission by RAGE across the membrane. Our model provides an insight into RAGE-ligand interactions, providing a basis for the rational design of the therapeutic modifiers of its activity.
Collapse
Affiliation(s)
- Alexander Moysa
- Institute of Biochemistry and Biophysics, PAS, Pawinskiego 5a, 02-109 Warsaw, Poland.
| | - Kamil Steczkiewicz
- Institute of Biochemistry and Biophysics, PAS, Pawinskiego 5a, 02-109 Warsaw, Poland.
| | - Dorota Niedzialek
- Institute of Biochemistry and Biophysics, PAS, Pawinskiego 5a, 02-109 Warsaw, Poland
| | - Dietmar Hammerschmid
- Department of Chemistry, King's College London, 7 Trinity Street, SE1 1DB London, UK; Department of Chemistry, Biomolecular & Analytical Mass Spectrometry Group, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Lilia Zhukova
- Institute of Biochemistry and Biophysics, PAS, Pawinskiego 5a, 02-109 Warsaw, Poland
| | - Frank Sobott
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Woodhouse Lane, LS2 9JT Leeds, UK; Department of Chemistry, Biomolecular & Analytical Mass Spectrometry Group, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Michal Dadlez
- Institute of Biochemistry and Biophysics, PAS, Pawinskiego 5a, 02-109 Warsaw, Poland
| |
Collapse
|
61
|
Cheng M, Guo C, Li W, Gross ML. Free‐Radical Membrane Protein Footprinting by Photolysis of Perfluoroisopropyl Iodide Partitioned to Detergent Micelle by Sonication. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202014096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Ming Cheng
- Department of Chemistry Washington University in St. Louis One Brookings Drive Saint Louis MO 63130 USA
- Current address: Department of Molecular Medicine The Scripps Research Institute La Jolla CA 92037 USA
| | - Chunyang Guo
- Department of Chemistry Washington University in St. Louis One Brookings Drive Saint Louis MO 63130 USA
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics Washington University School of Medicine St. Louis MO 63130 USA
| | - Michael L. Gross
- Department of Chemistry Washington University in St. Louis One Brookings Drive Saint Louis MO 63130 USA
| |
Collapse
|
62
|
Cheng M, Guo C, Li W, Gross ML. Free-Radical Membrane Protein Footprinting by Photolysis of Perfluoroisopropyl Iodide Partitioned to Detergent Micelle by Sonication. Angew Chem Int Ed Engl 2021; 60:8867-8873. [PMID: 33751812 PMCID: PMC8083173 DOI: 10.1002/anie.202014096] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/29/2020] [Indexed: 12/14/2022]
Abstract
A free-radical footprinting approach is described for integral membrane protein (IMP) that extends, significantly, the "fast photochemical oxidation of proteins" (FPOP) platform. This new approach exploits highly hydrophobic perfluoroisopropyl iodide (PFIPI) together with tip sonication to ensure efficient transport into the micelle interior, allowing laser dissociation and footprinting of the transmembrane domains. In contrast to water soluble footprinters, PFIPI footprints both the hydrophobic intramembrane and the hydrophilic extramembrane domains of the IMP vitamin K epoxide reductase (VKOR). The footprinting is fast, giving high coverage for Tyr (100 %) and Trp. The incorporation of the reagent with sonication does not significantly affect VKOR's enzymatic function, and tyrosine iodination does not compromise protease digestion and the subsequent analysis. The locations for the modifications are largely consistent with the corresponding solvent accessibilities, recommending this approach for future membrane protein footprinting.
Collapse
Affiliation(s)
- Ming Cheng
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, Saint Louis, MO, 63130, USA
- Current address: Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Chunyang Guo
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, Saint Louis, MO, 63130, USA
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, 63130, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, Saint Louis, MO, 63130, USA
| |
Collapse
|
63
|
Ekman S, Flower R, Barnard RT, Gould A, Bui XT. Computational modeling - an approach to the development of blood grouping reagents. Expert Rev Hematol 2021; 14:329-334. [PMID: 33759674 DOI: 10.1080/17474086.2021.1908119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Introduction: Blood group antigens are defined by an immune response that generates antibodies against a red blood cell molecule. Antibodies against these antigens can be associated with hemolytic transfusion reactions. However, difficulties can arise when developing antibodies against antigens through the use of peptide sequences alone. Three-dimensional representations (models) of the molecular structure of antigen-bearing proteins can provide valuable insights into tertiary structures and their consequent antigenicity. This can be achieved through predictive computational modeling to produce both structural and molecular dynamics models of blood group proteins.Areas covered: Authors discuss the use of molecular dynamic simulations on existing structures, as well as the use of computational modeling techniques in the development of protein models lacking preexisting data. Finally, the authors discuss specific examples of the use of computationally derived models of the MNS blood group system and its use in attempts to produce antibodies against MNS proteins.Expert opinion: Although in silico techniques have limitations, computer-based predictive models can inform the direction of research into blood group proteins. It is to be expected that as computer-based techniques grow more powerful these contributions will be even more significant.
Collapse
Affiliation(s)
- Serena Ekman
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia.,Clinical Services and Research, Australian Red Cross Lifeblood (Formerly Australian Red Cross Blood Service), Research and Development, Kelvin Grove, Australia
| | - Robert Flower
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia.,Clinical Services and Research, Australian Red Cross Lifeblood (Formerly Australian Red Cross Blood Service), Research and Development, Kelvin Grove, Australia
| | - Ross T Barnard
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia.,School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Australia
| | - Alison Gould
- Australian Red Cross Lifeblood (Formerly Australian Red Cross Blood Service), Research and Development, Alexandria, Australia
| | - Xuan T Bui
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia.,Clinical Services and Research, Australian Red Cross Lifeblood (Formerly Australian Red Cross Blood Service), Research and Development, Kelvin Grove, Australia
| |
Collapse
|
64
|
Missel JW, Salustros N, Becares ER, Steffen JH, Laursen AG, Garcia AS, Garcia-Alai MM, Kolar Č, Gourdon P, Gotfryd K. Cyclohexyl-α maltoside as a highly efficient tool for membrane protein studies. Curr Res Struct Biol 2021; 3:85-94. [PMID: 34235488 PMCID: PMC8244287 DOI: 10.1016/j.crstbi.2021.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/09/2021] [Accepted: 03/05/2021] [Indexed: 01/06/2023] Open
Abstract
Membrane proteins (MPs) constitute a large fraction of the proteome, but exhibit physicochemical characteristics that impose challenges for successful sample production crucial for subsequent biophysical studies. In particular, MPs have to be extracted from the membranes in a stable form. Reconstitution into detergent micelles represents the most common procedure in recovering MPs for subsequent analysis. n-dodecyl-β-D-maltoside (DDM) remains one of the most popular conventional detergents used in production of MPs. Here we characterize the novel DDM analogue 4-trans-(4-trans-propylcyclohexyl)-cyclohexyl α-maltoside (t-PCCαM), possessing a substantially lower critical micelle concentration (CMC) than the parental compound that represents an attractive feature when handling MPs. Using three different types of MPs of human and prokaryotic origin, i.e., a channel, a primary and a secondary active transporter, expressed in yeast and bacterial host systems, respectively, we investigate the performance of t-PCCαM in solubilization and affinity purification together with its capacity to preserve native fold and activity. Strikingly, t-PCCαM displays favorable behavior in extracting and stabilizing the three selected targets. Importantly, t-PCCαM promoted extraction of properly folded protein, enhanced thermostability and provided negatively-stained electron microscopy samples of promising quality. All-in-all, t-PCCαM emerges as competitive surfactant applicable to a broad portfolio of challenging MPs for downstream structure-function analysis.
Collapse
Affiliation(s)
- Julie Winkel Missel
- Department of Biomedical Sciences, Copenhagen University, Maersk Tower 7-9, Nørre Allé 14, DK-2200, Copenhagen N, Denmark
| | - Nina Salustros
- Department of Biomedical Sciences, Copenhagen University, Maersk Tower 7-9, Nørre Allé 14, DK-2200, Copenhagen N, Denmark
| | - Eva Ramos Becares
- Department of Biomedical Sciences, Copenhagen University, Maersk Tower 7-9, Nørre Allé 14, DK-2200, Copenhagen N, Denmark
| | - Jonas Hyld Steffen
- Department of Biomedical Sciences, Copenhagen University, Maersk Tower 7-9, Nørre Allé 14, DK-2200, Copenhagen N, Denmark
| | - Amalie Gerdt Laursen
- Department of Biomedical Sciences, Copenhagen University, Maersk Tower 7-9, Nørre Allé 14, DK-2200, Copenhagen N, Denmark
| | - Angelica Struve Garcia
- European Molecular Biology Laboratory Hamburg, Notkestrasse 85, D-22607, Hamburg, Germany
| | - Maria M Garcia-Alai
- European Molecular Biology Laboratory Hamburg, Notkestrasse 85, D-22607, Hamburg, Germany.,Centre for Structural Systems Biology, Notkestrasse 85, D-22607, Hamburg, Germany
| | - Čeněk Kolar
- Glycon Biochemicals GmbH, Im Biotechnologie Park TGZ 1, D-14943, Luckenwalde, Germany
| | - Pontus Gourdon
- Department of Biomedical Sciences, Copenhagen University, Maersk Tower 7-9, Nørre Allé 14, DK-2200, Copenhagen N, Denmark.,Department of Experimental Medical Science, Lund University, Sölvegatan 19, SE-221 84, Lund, Sweden
| | - Kamil Gotfryd
- Department of Biomedical Sciences, Copenhagen University, Maersk Tower 7-9, Nørre Allé 14, DK-2200, Copenhagen N, Denmark
| |
Collapse
|
65
|
Conn CE, de Campo L, Whitten AE, Garvey CJ, Krause-Heuer AM, van 't Hag L. Membrane Protein Structures in Lipid Bilayers; Small-Angle Neutron Scattering With Contrast-Matched Bicontinuous Cubic Phases. Front Chem 2021; 8:619470. [PMID: 33644002 PMCID: PMC7903247 DOI: 10.3389/fchem.2020.619470] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 12/02/2020] [Indexed: 01/12/2023] Open
Abstract
This perspective describes advances in determining membrane protein structures in lipid bilayers using small-angle neutron scattering (SANS). Differentially labeled detergents with a homogeneous scattering length density facilitate contrast matching of detergent micelles; this has previously been used successfully to obtain the structures of membrane proteins. However, detergent micelles do not mimic the lipid bilayer environment of the cell membrane in vivo. Deuterated vesicles can be used to obtain the radius of gyration of membrane proteins, but protein-protein interference effects within the vesicles severely limits this method such that the protein structure cannot be modeled. We show herein that different membrane protein conformations can be distinguished within the lipid bilayer of the bicontinuous cubic phase using contrast-matching. Time-resolved studies performed using SANS illustrate the complex phase behavior in lyotropic liquid crystalline systems and emphasize the importance of this development. We believe that studying membrane protein structures and phase behavior in contrast-matched lipid bilayers will advance both biological and pharmaceutical applications of membrane-associated proteins, biosensors and food science.
Collapse
Affiliation(s)
- Charlotte E. Conn
- School of Science, STEM College, RMIT University, Melbourne, VIC, Australia
| | - Liliana de Campo
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Andrew E. Whitten
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Christopher J. Garvey
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
- Lund Institute for Advanced Neutron and X-Ray Science, Lund, Sweden
- Biolfim-Research Center for Biointerfaces and Biomedical Science Department, Faculty of Health and Society, Malmö University, Malmö, Sweden
| | - Anwen M. Krause-Heuer
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Leonie van 't Hag
- Department of Chemical Engineering, Monash University, Clayton, VIC, Australia
| |
Collapse
|
66
|
Optogenetic Modulation of Ion Channels by Photoreceptive Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1293:73-88. [PMID: 33398808 DOI: 10.1007/978-981-15-8763-4_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In these 15 years, researches to control cellular responses by light have flourished dramatically to establish "optogenetics" as a research field. In particular, light-dependent excitation/inhibition of neural cells using channelrhodopsins or other microbial rhodopsins is the most powerful and the most widely used optogenetic technique. New channelrhodopsin-based optogenetic tools having favorable characteristics have been identified from a wide variety of organisms or created through mutagenesis. Despite the great efforts, some neuronal activities are still hard to be manipulated by the channelrhodopsin-based tools, indicating that complementary approaches are needed to make optogenetics more comprehensive. One of the feasible and complementary approaches is optical control of ion channels using photoreceptive proteins other than channelrhodopsins. In particular, animal opsins can modulate various ion channels via light-dependent G protein activation. In this chapter, we summarize how such alternative optogenetic tools work and they will be improved.
Collapse
|
67
|
Marty MT. Illuminating Individual Membrane Protein Complexes with Mass Photometry. Chem 2021. [DOI: 10.1016/j.chempr.2020.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
68
|
Cai H, Yao H, Li T, Hutter CAJ, Li Y, Tang Y, Seeger MA, Li D. An improved fluorescent tag and its nanobodies for membrane protein expression, stability assay, and purification. Commun Biol 2020; 3:753. [PMID: 33303987 PMCID: PMC7729955 DOI: 10.1038/s42003-020-01478-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 11/12/2020] [Indexed: 01/08/2023] Open
Abstract
Green fluorescent proteins (GFPs) are widely used to monitor membrane protein expression, purification, and stability. An ideal reporter should be stable itself and provide high sensitivity and yield. Here, we demonstrate that a coral (Galaxea fascicularis) thermostable GFP (TGP) is by such reasons an improved tag compared to the conventional jellyfish GFPs. TGP faithfully reports membrane protein stability at temperatures near 90 °C (20-min heating). By contrast, the limit for the two popular GFPs is 64 °C and 74 °C. Replacing GFPs with TGP increases yield for all four test membrane proteins in four expression systems. To establish TGP as an affinity tag for membrane protein purification, several high-affinity synthetic nanobodies (sybodies), including a non-competing pair, are generated, and the crystal structure of one complex is solved. Given these advantages, we anticipate that TGP becomes a widely used tool for membrane protein structural studies.
Collapse
Affiliation(s)
- Hongmin Cai
- University of Chinese Academy of Sciences, National Center for Protein Science Shanghai, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, 200031, Shanghai, China
| | - Hebang Yao
- University of Chinese Academy of Sciences, National Center for Protein Science Shanghai, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, 200031, Shanghai, China
| | - Tingting Li
- University of Chinese Academy of Sciences, National Center for Protein Science Shanghai, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, 200031, Shanghai, China
| | - Cedric A J Hutter
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Yanfang Li
- University of Chinese Academy of Sciences, National Center for Protein Science Shanghai, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, 200031, Shanghai, China
| | - Yannan Tang
- University of Chinese Academy of Sciences, National Center for Protein Science Shanghai, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, 200031, Shanghai, China
| | - Markus A Seeger
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Dianfan Li
- University of Chinese Academy of Sciences, National Center for Protein Science Shanghai, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, 200031, Shanghai, China.
| |
Collapse
|
69
|
Hydrogen-deuterium exchange mass spectrometry captures distinct dynamics upon substrate and inhibitor binding to a transporter. Nat Commun 2020; 11:6162. [PMID: 33268777 PMCID: PMC7710758 DOI: 10.1038/s41467-020-20032-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 10/15/2020] [Indexed: 11/13/2022] Open
Abstract
Proton-coupled transporters use transmembrane proton gradients to power active transport of nutrients inside the cell. High-resolution structures often fail to capture the coupling between proton and ligand binding, and conformational changes associated with transport. We combine HDX-MS with mutagenesis and MD simulations to dissect the molecular mechanism of the prototypical transporter XylE. We show that protonation of a conserved aspartate triggers conformational transition from outward-facing to inward-facing state. This transition only occurs in the presence of substrate xylose, while the inhibitor glucose locks the transporter in the outward-facing state. MD simulations corroborate the experiments by showing that only the combination of protonation and xylose binding, and not glucose, sets up the transporter for conformational switch. Overall, we demonstrate the unique ability of HDX-MS to distinguish between the conformational dynamics of inhibitor and substrate binding, and show that a specific allosteric coupling between substrate binding and protonation is a key step to initiate transport. XylE is a bacterial xylose transporter and homologue of human glucose transporters GLUTs 1-4. HDX-MS, mutagenesis and MD simulations suggest that protonation of a conserved aspartate triggers conformational transition from outward- to inward facing state only in the presence of substrate xylose. In contrast, inhibitor glucose locks the transporter in the outward facing state.
Collapse
|
70
|
Punjani A, Zhang H, Fleet DJ. Non-uniform refinement: adaptive regularization improves single-particle cryo-EM reconstruction. Nat Methods 2020; 17:1214-1221. [PMID: 33257830 DOI: 10.1038/s41592-020-00990-8] [Citation(s) in RCA: 629] [Impact Index Per Article: 157.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 10/06/2020] [Indexed: 11/09/2022]
Abstract
Cryogenic electron microscopy (cryo-EM) is widely used to study biological macromolecules that comprise regions with disorder, flexibility or partial occupancy. For example, membrane proteins are often kept in solution with detergent micelles and lipid nanodiscs that are locally disordered. Such spatial variability negatively impacts computational three-dimensional (3D) reconstruction with existing iterative refinement algorithms that assume rigidity. We introduce non-uniform refinement, an algorithm based on cross-validation optimization, which automatically regularizes 3D density maps during refinement to account for spatial variability. Unlike common shift-invariant regularizers, non-uniform refinement systematically removes noise from disordered regions, while retaining signal useful for aligning particle images, yielding dramatically improved resolution and 3D map quality in many cases. We obtain high-resolution reconstructions for multiple membrane proteins as small as 100 kDa, demonstrating increased effectiveness of cryo-EM for this class of targets critical in structural biology and drug discovery. Non-uniform refinement is implemented in the cryoSPARC software package.
Collapse
Affiliation(s)
- Ali Punjani
- Department of Computer Sciences, University of Toronto, Toronto, Ontario, Canada. .,Vector Institute, Toronto, Ontario, Canada. .,Structura Biotechnology Inc., Toronto, Ontario, Canada.
| | - Haowei Zhang
- Department of Computer Sciences, University of Toronto, Toronto, Ontario, Canada
| | - David J Fleet
- Department of Computer Sciences, University of Toronto, Toronto, Ontario, Canada. .,Vector Institute, Toronto, Ontario, Canada.
| |
Collapse
|
71
|
Birch J, Cheruvara H, Gamage N, Harrison PJ, Lithgo R, Quigley A. Changes in Membrane Protein Structural Biology. BIOLOGY 2020; 9:E401. [PMID: 33207666 PMCID: PMC7696871 DOI: 10.3390/biology9110401] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 12/21/2022]
Abstract
Membrane proteins are essential components of many biochemical processes and are important pharmaceutical targets. Membrane protein structural biology provides the molecular rationale for these biochemical process as well as being a highly useful tool for drug discovery. Unfortunately, membrane protein structural biology is a difficult area of study due to low protein yields and high levels of instability especially when membrane proteins are removed from their native environments. Despite this instability, membrane protein structural biology has made great leaps over the last fifteen years. Today, the landscape is almost unrecognisable. The numbers of available atomic resolution structures have increased 10-fold though advances in crystallography and more recently by cryo-electron microscopy. These advances in structural biology were achieved through the efforts of many researchers around the world as well as initiatives such as the Membrane Protein Laboratory (MPL) at Diamond Light Source. The MPL has helped, provided access to and contributed to advances in protein production, sample preparation and data collection. Together, these advances have enabled higher resolution structures, from less material, at a greater rate, from a more diverse range of membrane protein targets. Despite this success, significant challenges remain. Here, we review the progress made and highlight current and future challenges that will be overcome.
Collapse
Affiliation(s)
- James Birch
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
| | - Harish Cheruvara
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
| | - Nadisha Gamage
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
| | - Peter J. Harrison
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
| | - Ryan Lithgo
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, Leicestershire, UK
| | - Andrew Quigley
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
| |
Collapse
|
72
|
Cryo-EM as a powerful tool for drug discovery. Bioorg Med Chem Lett 2020; 30:127524. [PMID: 32890683 PMCID: PMC7467112 DOI: 10.1016/j.bmcl.2020.127524] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 12/12/2022]
Abstract
The recent revolution in cryo-EM has produced an explosion of structures at near-atomic or better resolution. This has allowed cryo-EM structures to provide visualization of bound small-molecule ligands in the macromolecules, and these new structures have provided unprecedented insights into the molecular mechanisms of complex biochemical processes. They have also had a profound impact on drug discovery, defining the binding modes and mechanisms of action of well-known drugs as well as driving the design and development of new compounds. This review will summarize and highlight some of these structures. Most excitingly, the latest cryo-EM technology has produced structures at 1.2 Å resolution, further solidifying cryo-EM as a powerful tool for drug discovery. Therefore, cryo-EM will play an ever-increasing role in drug discovery in the coming years.
Collapse
|
73
|
Rapp M, Carragher B. Better, faster, and even cheap. Science 2020; 370:171. [PMID: 33033206 DOI: 10.1126/science.abd8035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Micah Rapp
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10027, USA, and Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Bridget Carragher
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10027, USA, and Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
| |
Collapse
|
74
|
Braun N, Sheikh ZP, Pless SA. The current chemical biology tool box for studying ion channels. J Physiol 2020; 598:4455-4471. [DOI: 10.1113/jp276695] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 07/06/2020] [Indexed: 12/13/2022] Open
Affiliation(s)
- N. Braun
- Department of Drug Design and Pharmacology University of Copenhagen Jagtvej 160 Copenhagen 2100 Denmark
| | - Z. P. Sheikh
- Department of Drug Design and Pharmacology University of Copenhagen Jagtvej 160 Copenhagen 2100 Denmark
| | - S. A. Pless
- Department of Drug Design and Pharmacology University of Copenhagen Jagtvej 160 Copenhagen 2100 Denmark
| |
Collapse
|
75
|
Yao X, Fan X, Yan N. Cryo-EM analysis of a membrane protein embedded in the liposome. Proc Natl Acad Sci U S A 2020; 117:18497-18503. [PMID: 32680969 PMCID: PMC7414195 DOI: 10.1073/pnas.2009385117] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Membrane proteins (MPs) used to be the most difficult targets for structural biology when X-ray crystallography was the mainstream approach. With the resolution revolution of single-particle electron cryo-microscopy (cryo-EM), rapid progress has been made for structural elucidation of isolated MPs. The next challenge is to preserve the electrochemical gradients and membrane curvature for a comprehensive structural elucidation of MPs that rely on these chemical and physical properties for their biological functions. Toward this goal, here we present a convenient workflow for cryo-EM structural analysis of MPs embedded in liposomes, using the well-characterized AcrB as a prototype. Combining optimized proteoliposome isolation, cryo-sample preparation on graphene grids, and an efficient particle selection strategy, the three-dimensional (3D) reconstruction of AcrB embedded in liposomes was obtained at 3.9 Å resolution. The conformation of the homotrimeric AcrB remains the same when the surrounding membranes display different curvatures. Our approach, which can be widely applied to cryo-EM analysis of MPs with distinctive soluble domains, lays out the foundation for cryo-EM analysis of integral or peripheral MPs whose functions are affected by transmembrane electrochemical gradients or/and membrane curvatures.
Collapse
Affiliation(s)
- Xia Yao
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - Xiao Fan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - Nieng Yan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| |
Collapse
|
76
|
Hutchison JM, Shih KC, Scheidt HA, Fantin SM, Parson KF, Pantelopulos GA, Harrington HR, Mittendorf KF, Qian S, Stein RA, Collier SE, Chambers MG, Katsaras J, Voehler MW, Ruotolo BT, Huster D, McFeeters RL, Straub JE, Nieh MP, Sanders CR. Bicelles Rich in both Sphingolipids and Cholesterol and Their Use in Studies of Membrane Proteins. J Am Chem Soc 2020; 142:12715-12729. [PMID: 32575981 DOI: 10.1021/jacs.0c04669] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
How the distinctive lipid composition of mammalian plasma membranes impacts membrane protein structure is largely unexplored, partly because of the dearth of isotropic model membrane systems that contain abundant sphingolipids and cholesterol. This gap is addressed by showing that sphingomyelin and cholesterol-rich (SCOR) lipid mixtures with phosphatidylcholine can be cosolubilized by n-dodecyl-β-melibioside to form bicelles. Small-angle X-ray and neutron scattering, as well as cryo-electron microscopy, demonstrate that these assemblies are stable over a wide range of conditions and exhibit the bilayered-disc morphology of ideal bicelles even at low lipid-to-detergent mole ratios. SCOR bicelles are shown to be compatible with a wide array of experimental techniques, as applied to the transmembrane human amyloid precursor C99 protein in this medium. These studies reveal an equilibrium between low-order oligomer structures that differ significantly from previous experimental structures of C99, providing an example of how ordered membranes alter membrane protein structure.
Collapse
Affiliation(s)
- James M Hutchison
- Chemical and Physical Biology Graduate Program and Center for Structural Biology, Vanderbilt University, Nashville 37240, Tennessee, United States
| | - Kuo-Chih Shih
- Polymer Program, Department of Chemical & Biomolecular Engineering, and Department of Biomedical Engineering, University of Connecticut, Storrs 06269, Connecticut, United States
| | - Holger A Scheidt
- Institute for Medical Physics and Biophysics, Leipzig University, Leipzig 16-18, 04107, Germany
| | - Sarah M Fantin
- Department of Chemistry, University of Michigan, Ann Arbor 48109, Michigan, United States
| | - Kristine F Parson
- Department of Chemistry, University of Michigan, Ann Arbor 48109, Michigan, United States
| | - George A Pantelopulos
- Department of Chemistry, Boston University, Boston 02215, Massachusetts, United States
| | - Haley R Harrington
- Center for Structural Biology and Department of Biochemistry, Vanderbilt University School of Medicine Basic Sciences, Nashville 37240, Tennessee, United States
| | - Kathleen F Mittendorf
- Center for Health Research, Kaiser Permanente, Portland 97227, Oregon, United States
| | - Shuo Qian
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge 37831, Tennessee, United States
| | - Richard A Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville37240, Tennessee, United States
| | - Scott E Collier
- Department of Translational and Applied Genomics, Center for Health Research, Kaiser Permanente Northwest, Portland 97227, Oregon, United States
| | - Melissa G Chambers
- Center for Structural Biology, Vanderbilt University, Nashville 37240, Tennessee, United States
| | - John Katsaras
- Neutron Scattering Division and Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge 37831, Tennessee, United States
| | - Markus W Voehler
- Center for Structural Biology and Department of Chemistry, Vanderbilt University, Nashville 37240, Tennessee, United States
| | - Brandon T Ruotolo
- Department of Chemistry, University of Michigan, Ann Arbor 48109, Michigan, United States
| | - Daniel Huster
- Institute for Medical Physics and Biophysics, Leipzig University, Leipzig 16-18, 04107, Germany
| | - Robert L McFeeters
- Department of Chemistry, University of Alabama, Huntsville 35899, Alabama, United States
| | - John E Straub
- Department of Chemistry, Boston University, Boston 02215, Massachusetts, United States
| | - Mu-Ping Nieh
- Polymer Program, Department of Chemical & Biomolecular Engineering, and Department of Biomedical Engineering, University of Connecticut, Storrs 06269, Connecticut, United States
| | - Charles R Sanders
- Center for Structural Biology, Department of Biochemistry, and Department of Medicine, Vanderbilt University School of Medicine, Nashville 37240, Tennessee, United States
| |
Collapse
|
77
|
Padmanabha Das KM, Shih WM, Wagner G, Nasr ML. Large Nanodiscs: A Potential Game Changer in Structural Biology of Membrane Protein Complexes and Virus Entry. Front Bioeng Biotechnol 2020; 8:539. [PMID: 32596222 PMCID: PMC7304444 DOI: 10.3389/fbioe.2020.00539] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 05/05/2020] [Indexed: 01/22/2023] Open
Abstract
Phospho-lipid bilayer nanodiscs have gathered much scientific interest as a stable and tunable membrane mimetic for the study of membrane proteins. Until recently the size of the nanodiscs that could be produced was limited to ~ 16 nm. Recent advances in nanodisc engineering such as covalently circularized nanodiscs (cND) and DNA corralled nanodiscs (DCND) have opened up the possibility of engineering nanodiscs of size up to 90 nm. This enables widening the application of nanodiscs from single membrane proteins to investigating large protein complexes and biological processes such as virus-membrane fusion and synaptic vesicle fusion. Another aspect of exploiting the large available surface area of these novel nanodiscs could be to engineer more realistic membrane mimetic systems with features such as membrane asymmetry and curvature. In this review, we discuss the recent technical developments in nanodisc technology leading to construction of large nanodiscs and examine some of the implicit applications.
Collapse
Affiliation(s)
- Krishna M Padmanabha Das
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
| | - William M Shih
- Wyss Institute for Biologically Inspired Engineering at Harvard, Boston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States
| | - Mahmoud L Nasr
- Renal Division and Engineering in Medicine Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| |
Collapse
|
78
|
Sahu ID, Lorigan GA. Electron Paramagnetic Resonance as a Tool for Studying Membrane Proteins. Biomolecules 2020; 10:E763. [PMID: 32414134 PMCID: PMC7278021 DOI: 10.3390/biom10050763] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 04/24/2020] [Accepted: 04/24/2020] [Indexed: 12/13/2022] Open
Abstract
Membrane proteins possess a variety of functions essential to the survival of organisms. However, due to their inherent hydrophobic nature, it is extremely difficult to probe the structure and dynamic properties of membrane proteins using traditional biophysical techniques, particularly in their native environments. Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labeling (SDSL) is a very powerful and rapidly growing biophysical technique to study pertinent structural and dynamic properties of membrane proteins with no size restrictions. In this review, we will briefly discuss the most commonly used EPR techniques and their recent applications for answering structure and conformational dynamics related questions of important membrane protein systems.
Collapse
Affiliation(s)
- Indra D. Sahu
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Gary A. Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| |
Collapse
|
79
|
Mukherjee S, Erramilli SK, Ammirati M, Alvarez FJD, Fennell KF, Purdy MD, Skrobek BM, Radziwon K, Coukos J, Kang Y, Dutka P, Gao X, Qiu X, Yeager M, Eric Xu H, Han S, Kossiakoff AA. Synthetic antibodies against BRIL as universal fiducial marks for single-particle cryoEM structure determination of membrane proteins. Nat Commun 2020; 11:1598. [PMID: 32221310 PMCID: PMC7101349 DOI: 10.1038/s41467-020-15363-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 03/03/2020] [Indexed: 12/22/2022] Open
Abstract
We propose the concept of universal fiducials based on a set of pre-made semi-synthetic antibodies (sABs) generated by customized phage display selections against the fusion protein BRIL, an engineered variant of apocytochrome b562a. These sABs can bind to BRIL fused either into the loops or termini of different GPCRs, ion channels, receptors and transporters without disrupting their structure. A crystal structure of BRIL in complex with an affinity-matured sAB (BAG2) that bound to all systems tested delineates the footprint of interaction. Negative stain and cryoEM data of several examples of BRIL-membrane protein chimera highlight the effectiveness of the sABs as universal fiducial marks. Taken together with a cryoEM structure of sAB bound human nicotinic acetylcholine receptor, this work demonstrates that these anti-BRIL sABs can greatly enhance the particle properties leading to improved cryoEM outcomes, especially for challenging membrane proteins.
Collapse
Affiliation(s)
- Somnath Mukherjee
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Mark Ammirati
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Frances J D Alvarez
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Kimberly F Fennell
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Michael D Purdy
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Blazej M Skrobek
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Gene Center and Department of Biochemistry, Ludwig Maximilian University of Munich, Munich, Germany
| | - Katarzyna Radziwon
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry, University of Wisconsin Madison, Madison, WI, USA
| | - John Coukos
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Yanyong Kang
- Center for Cancer and Cell Biology, Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
- Takeda San Diego Inc., San Diego, CA, USA
| | - Przemysław Dutka
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Xiang Gao
- Center for Cancer and Cell Biology, Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
| | - Xiayang Qiu
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - H Eric Xu
- Center for Cancer and Cell Biology, Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
- Key Laboratory of Receptor Research, VARI-SIMM Center, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Seungil Han
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA.
| |
Collapse
|
80
|
Abstract
The advent of the X-ray free electron laser (XFEL) in the last decade created the discipline of serial crystallography but also the challenge of how crystal samples are delivered to X-ray. Early sample delivery methods demonstrated the proof-of-concept for serial crystallography and XFEL but were beset with challenges of high sample consumption, jet clogging and low data collection efficiency. The potential of XFEL and serial crystallography as the next frontier of structural solution by X-ray for small and weakly diffracting crystals and provision of ultra-fast time-resolved structural data spawned a huge amount of scientific interest and innovation. To utilize the full potential of XFEL and broaden its applicability to a larger variety of biological samples, researchers are challenged to develop better sample delivery methods. Thus, sample delivery is one of the key areas of research and development in the serial crystallography scientific community. Sample delivery currently falls into three main systems: jet-based methods, fixed-target chips, and drop-on-demand. Huge strides have since been made in reducing sample consumption and improving data collection efficiency, thus enabling the use of XFEL for many biological systems to provide high-resolution, radiation damage-free structural data as well as time-resolved dynamics studies. This review summarizes the current main strategies in sample delivery and their respective pros and cons, as well as some future direction.
Collapse
|
81
|
Adachi A. Grand Challenge in Human/Animal Virology: Unseen, Smallest Replicative Entities Shape the Whole Globe. Front Microbiol 2020; 11:431. [PMID: 32256480 PMCID: PMC7093566 DOI: 10.3389/fmicb.2020.00431] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 03/02/2020] [Indexed: 12/20/2022] Open
Affiliation(s)
- Akio Adachi
- Department of Microbiology, Kansai Medical University, Osaka, Japan.,Tokushima University, Tokushima, Japan
| |
Collapse
|
82
|
Akbar S, Mozumder S, Sengupta J. Retrospect and Prospect of Single Particle Cryo-Electron Microscopy: The Class of Integral Membrane Proteins as an Example. J Chem Inf Model 2020; 60:2448-2457. [DOI: 10.1021/acs.jcim.9b01015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shirin Akbar
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Sukanya Mozumder
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700032, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Jayati Sengupta
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700032, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| |
Collapse
|
83
|
Spotlight on the Ballet of Proteins: The Structural Dynamic Properties of Proteins Illuminated by Solution NMR. Int J Mol Sci 2020; 21:ijms21051829. [PMID: 32155847 PMCID: PMC7084655 DOI: 10.3390/ijms21051829] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 03/01/2020] [Accepted: 03/04/2020] [Indexed: 12/22/2022] Open
Abstract
Solution NMR spectroscopy is a unique and powerful technique that has the ability to directly connect the structural dynamics of proteins in physiological conditions to their activity and function. Here, we summarize recent studies in which solution NMR contributed to the discovery of relationships between key dynamic properties of proteins and functional mechanisms in important biological systems. The capacity of NMR to quantify the dynamics of proteins over a range of time scales and to detect lowly populated protein conformations plays a critical role in its power to unveil functional protein dynamics. This analysis of dynamics is not only important for the understanding of biological function, but also in the design of specific ligands for pharmacologically important proteins. Thus, the dynamic view of structure provided by NMR is of importance in both basic and applied biology.
Collapse
|
84
|
Membrane Protein Production in Lactococcus lactis for Structural Studies. Methods Mol Biol 2020. [PMID: 32112313 DOI: 10.1007/978-1-0716-0373-4_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The expression and downstream purification of membrane proteins is the prerequisite for biophysical and structural studies of this major source of therapeutic targets. The gram-positive bacterium Lactococcus lactis is an attractive option for heterologous membrane protein expression and purification thanks to advantageous characteristics such as mild proteolytic activity and small genome size. Vectors designed for gene transcription under the control of inducible promoters are readily available. Specifically, the tightly regulated nisin-inducible gene expression system (NICE) allows to fine-tune the overexpression of different gene products. The expressed protein engineered with a suitable tag can be readily detected and purified from crude membrane extracts. The purpose of this protocol chapter is to detail the procedures of cloning, expression, isolation of the membrane vesicles, and affinity purification of a membrane protein of interest in L. lactis.
Collapse
|
85
|
Prospects for membrane protein crystals in NMX. Methods Enzymol 2020. [PMID: 32093842 DOI: 10.1016/bs.mie.2019.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Adding hydrogen atoms and protonation states to structures of membrane proteins requires successful implementation of neutron macromolecular crystallography (NMX). This information would significantly increase our fundamental understanding of the transport processes membrane proteins undertake. To grow the large crystals needed for NMX studies requires significant amounts of stable protein, but once that challenge is overcome there is no intrinsic property of membrane proteins preventing the growth of large crystals per se. The calcium-transporting P-type ATPase (SERCA) has been thoroughly characterized biochemically and structurally over decades. We have extended our crystallization efforts to assess the feasibility of growing SERCA crystals for NMX-exploring microdialysis and capillary counterdiffusion crystallization techniques as alternatives to the traditional vapor diffusion crystallization experiment. Both methods possess crystallization dynamics favorable for maximizing crystal size and we used them to facilitate the growth of large crystals, validating these approaches for membrane protein crystallization for NMX.
Collapse
|
86
|
Abstract
The bacterial cell envelope is essential for viability, the environmental gatekeeper and first line of defense against external stresses. For most bacteria, the envelope biosynthesis is also the site of action of some of the most important groups of antibiotics. It is a complex, often multicomponent structure, able to withstand the internally generated turgor pressure. Thus, elucidating the architecture and dynamics of the cell envelope is important, to unravel not only the complexities of cell morphology and maintenance of integrity but also how interventions such as antibiotics lead to death. To address these questions requires the capacity to visualize the cell envelope in situ via high-spatial resolution approaches. In recent years, atomic force microscopy (AFM) has brought novel molecular insights into the assembly, dynamics, and functions of bacterial cell envelopes. The ultrafine resolution and physical sensitivity of the technique have revealed a wealth of ultrastructural features that are invisible to traditional optical microscopy techniques or imperceptible in their true physiological state by electron microscopy. Here, we discuss recent progress in our use of AFM imaging for understanding the architecture and dynamics of the bacterial envelope. We survey recent studies that demonstrate the power of the technique to observe isolated membranes and live cells at (sub)nanometer resolution and under physiological conditions and to track in vitro structural dynamics in response to growth or to drugs.
Collapse
|
87
|
Rose-Sperling D, Tran MA, Lauth LM, Goretzki B, Hellmich UA. 19F NMR as a versatile tool to study membrane protein structure and dynamics. Biol Chem 2020; 400:1277-1288. [PMID: 31004560 DOI: 10.1515/hsz-2018-0473] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/17/2019] [Indexed: 12/25/2022]
Abstract
To elucidate the structures and dynamics of membrane proteins, highly advanced biophysical methods have been developed that often require significant resources, both for sample preparation and experimental analyses. For very complex systems, such as membrane transporters, ion channels or G-protein coupled receptors (GPCRs), the incorporation of a single reporter at a select site can significantly simplify the observables and the measurement/analysis requirements. Here we present examples using 19F nuclear magnetic resonance (NMR) spectroscopy as a powerful, yet relatively straightforward tool to study (membrane) protein structure, dynamics and ligand interactions. We summarize methods to incorporate 19F labels into proteins and discuss the type of information that can be readily obtained for membrane proteins already from relatively simple NMR spectra with a focus on GPCRs as the membrane protein family most extensively studied by this technique. In the future, these approaches may be of particular interest also for many proteins that undergo complex functional dynamics and/or contain unstructured regions and thus are not amenable to X-ray crystallography or cryo electron microscopy (cryoEM) studies.
Collapse
Affiliation(s)
- Dania Rose-Sperling
- Institute for Pharmacy and Biochemistry, Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, D-55128 Mainz, Germany.,Centre for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Mai Anh Tran
- Institute for Pharmacy and Biochemistry, Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, D-55128 Mainz, Germany.,Centre for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Luca M Lauth
- Institute for Pharmacy and Biochemistry, Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, D-55128 Mainz, Germany
| | - Benedikt Goretzki
- Institute for Pharmacy and Biochemistry, Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, D-55128 Mainz, Germany.,Centre for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Ute A Hellmich
- Institute for Pharmacy and Biochemistry, Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, D-55128 Mainz, Germany.,Centre for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| |
Collapse
|
88
|
Celia H, Noinaj N, Buchanan SK. Structure and Stoichiometry of the Ton Molecular Motor. Int J Mol Sci 2020; 21:E375. [PMID: 31936081 PMCID: PMC7014051 DOI: 10.3390/ijms21020375] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 12/29/2019] [Accepted: 01/03/2020] [Indexed: 12/20/2022] Open
Abstract
The Ton complex is a molecular motor that uses the proton gradient at the inner membrane of Gram-negative bacteria to generate force and movement, which are transmitted to transporters at the outer membrane, allowing the entry of nutrients into the periplasmic space. Despite decades of investigation and the recent flurry of structures being reported by X-ray crystallography and cryoEM, the mode of action of the Ton molecular motor has remained elusive, and the precise stoichiometry of its subunits is still a matter of debate. This review summarizes the latest findings on the Ton system by presenting the recently reported structures and related reports on the stoichiometry of the fully assembled complex.
Collapse
Affiliation(s)
- Herve Celia
- National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA;
| | - Nicholas Noinaj
- Markey Center for Structural Biology, Department of Biological Sciences, and the Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA;
| | - Susan K Buchanan
- National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA;
| |
Collapse
|
89
|
Krainer G, Keller S, Schlierf M. Structural dynamics of membrane-protein folding from single-molecule FRET. Curr Opin Struct Biol 2019; 58:124-137. [DOI: 10.1016/j.sbi.2019.05.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 05/27/2019] [Indexed: 12/15/2022]
|
90
|
Duncan AL, Song W, Sansom MSP. Lipid-Dependent Regulation of Ion Channels and G Protein-Coupled Receptors: Insights from Structures and Simulations. Annu Rev Pharmacol Toxicol 2019; 60:31-50. [PMID: 31506010 DOI: 10.1146/annurev-pharmtox-010919-023411] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ion channels and G protein-coupled receptors (GPCRs) are regulated by lipids in their membrane environment. Structural studies combined with biophysical and molecular simulation investigations reveal interaction sites for specific lipids on membrane protein structures. For K channels, PIP2 plays a key role in regulating Kv and Kir channels. Likewise, several recent cryo-EM structures of TRP channels have revealed bound lipids, including PIP2 and cholesterol. Among the pentameric ligand-gated ion channel family, structural and biophysical studies suggest the M4 TM helix may act as a lipid sensor, e.g., forming part of the binding sites for neurosteroids on the GABAA receptor. Structures of GPCRs have revealed multiple cholesterol sites, which may modulate both receptor dynamics and receptor oligomerization. PIP2 also interacts with GPCRs and may modulate their interactions with G proteins. Overall, it is evident that multiple lipid binding sites exist on channels and receptors that modulate their function allosterically and are potential druggable sites.
Collapse
Affiliation(s)
- Anna L Duncan
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
| | - Wanling Song
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
| |
Collapse
|
91
|
Affiliation(s)
- Jean-Paul Armache
- Department of Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Yifan Cheng
- Howard Hughes Medical Institute, University of California San Francisco, USA.,Department of Biochemistry and Biophysics, University of California San Francisco, USA
| |
Collapse
|
92
|
Rivera-Calzada A, Carroni M. Editorial: Technical Advances in Cryo-Electron Microscopy. Front Mol Biosci 2019; 6:72. [PMID: 31508425 PMCID: PMC6713907 DOI: 10.3389/fmolb.2019.00072] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 08/07/2019] [Indexed: 11/13/2022] Open
|
93
|
Sadaf A, Ramos M, Mortensen JS, Du Y, Bae HE, Munk CF, Hariharan P, Byrne B, Kobilka BK, Loland CJ, Guan L, Chae PS. Conformationally Restricted Monosaccharide-Cored Glycoside Amphiphiles: The Effect of Detergent Headgroup Variation on Membrane Protein Stability. ACS Chem Biol 2019; 14:1717-1726. [PMID: 31305987 DOI: 10.1021/acschembio.9b00166] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Detergents are widely used to isolate membrane proteins from lipid bilayers, but many proteins solubilized in conventional detergents are structurally unstable. Thus, there is major interest in the development of novel amphiphiles to facilitate membrane protein research. In this study, we have designed and synthesized novel amphiphiles with a rigid scyllo-inositol core, designated scyllo-inositol glycosides (SIGs). Varying the headgroup structure allowed the preparation of three sets of SIGs that were evaluated for their effects on membrane protein stability. When tested with a few model membrane proteins, representative SIGs conferred enhanced stability to the membrane proteins compared to a gold standard conventional detergent (DDM). Of the novel amphiphiles, a SIG designated STM-12 was most effective at preserving the stability of the multiple membrane proteins tested here. In addition, a comparative study of the three sets suggests that several factors, including micelle size and alkyl chain length, need to be considered in the development of novel detergents for membrane protein research. Thus, this study not only describes new detergent tools that are potentially useful for membrane protein structural study but also introduces plausible correlations between the chemical properties of detergents and membrane protein stabilization efficacy.
Collapse
Affiliation(s)
- Aiman Sadaf
- Department of Bionanotechnology, Hanyang University, Ansan 155-88, Korea
| | - Manuel Ramos
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States
| | - Jonas S. Mortensen
- Department of Neuroscience, University of Copenhagen, Copenhagen N DK-2200, Denmark
| | - Yang Du
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305, United States
| | - Hyoung Eun Bae
- Department of Bionanotechnology, Hanyang University, Ansan 155-88, Korea
| | - Chastine F. Munk
- Department of Neuroscience, University of Copenhagen, Copenhagen N DK-2200, Denmark
| | - Parameswaran Hariharan
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Brian K. Kobilka
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305, United States
| | - Claus J. Loland
- Department of Neuroscience, University of Copenhagen, Copenhagen N DK-2200, Denmark
| | - Lan Guan
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States
| | - Pil Seok Chae
- Department of Bionanotechnology, Hanyang University, Ansan 155-88, Korea
| |
Collapse
|
94
|
Geng H, Chen F, Ye J, Jiang F. Applications of Molecular Dynamics Simulation in Structure Prediction of Peptides and Proteins. Comput Struct Biotechnol J 2019; 17:1162-1170. [PMID: 31462972 PMCID: PMC6709365 DOI: 10.1016/j.csbj.2019.07.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/07/2019] [Accepted: 07/23/2019] [Indexed: 12/21/2022] Open
Abstract
Compared with rapid accumulation of protein sequences from high-throughput DNA sequencing, obtaining experimental 3D structures of proteins is still much more difficult, making protein structure prediction (PSP) potentially very useful. Currently, a vast majority of PSP efforts are based on data mining of known sequences, structures and their relationships (informatics-based). However, if closely related template is not available, these methods are usually much less reliable than experiments. They may also be problematic in predicting the structures of naturally occurring or designed peptides. On the other hand, physics-based methods including molecular dynamics (MD) can utilize our understanding of detailed atomic interactions determining biomolecular structures. In this mini-review, we show that all-atom MD can predict structures of cyclic peptides and other peptide foldamers with accuracy similar to experiments. Then, some notable successes in reproducing experimental 3D structures of small proteins through MD simulations (some with replica-exchange) of the folding were summarized. We also describe advancements of MD-based refinement of structure models, and the integration of limited experimental or bioinformatics data into MD-based structure modeling.
Collapse
Affiliation(s)
- Hao Geng
- Lab of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Fangfang Chen
- Guangdong and Shenzhen Key Laboratory of Male Reproductive Medicine and Genetics, Peking University Shenzhen Hospital, Shenzhen PKU-HKUST Medical Center, Shenzhen 518036, China
| | - Jing Ye
- Guangdong and Shenzhen Key Laboratory of Male Reproductive Medicine and Genetics, Peking University Shenzhen Hospital, Shenzhen PKU-HKUST Medical Center, Shenzhen 518036, China
| | - Fan Jiang
- Lab of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
- NanoAI Biotech Co.,Ltd., Silicon Valley Compound, Longhua District, Shenzhen 518109, China
- Corresponding author at: Lab of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| |
Collapse
|
95
|
Bai L, Kovach A, You Q, Kenny A, Li H. Structure of the eukaryotic protein O-mannosyltransferase Pmt1-Pmt2 complex. Nat Struct Mol Biol 2019; 26:704-711. [PMID: 31285605 PMCID: PMC6684406 DOI: 10.1038/s41594-019-0262-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 05/29/2019] [Indexed: 12/24/2022]
Abstract
In eukaryotes, a nascent peptide entering the endoplasmic reticulum (ER) is scanned by two Sec61-translocon-associated large membrane machines for protein N-glycosylation and protein O-mannosylation, respectively. While the structure of the eight-protein oligosaccharyltransferase complex has been determined recently, the structures of mannosyltransferases of the PMT family, which are an integral part of ER protein homeostasis, are still unknown. Here we report cryo-EM structures of the S. cerevisiae Pmt1–Pmt2 complex bound to a donor and an acceptor peptide at 3.2-Å resolution, showing that each subunit contains 11 transmembrane helices and a lumenal β-trefoil fold termed the MIR domain. The structures reveal the substrate recognition model and confirm an inverting mannosyl-transferring reaction mechanism by the enzyme complex. Furthermore, we found that the transmembrane domains of Pmt1 and Pmt2 share a structural fold with the catalytic subunits of oligosaccharyltransferases, confirming a previously proposed evolutionary relationship between protein O-mannosylation and protein N-glycosylation.
Collapse
Affiliation(s)
- Lin Bai
- Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
| | - Amanda Kovach
- Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
| | - Qinglong You
- Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
| | - Alanna Kenny
- Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
| | - Huilin Li
- Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA.
| |
Collapse
|
96
|
van der Wijst J, van Goor MK, Schreuder MF, Hoenderop JG. TRPV5 in renal tubular calcium handling and its potential relevance for nephrolithiasis. Kidney Int 2019; 96:1283-1291. [PMID: 31471161 DOI: 10.1016/j.kint.2019.05.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 10/26/2022]
Abstract
Nephrolithiasis or renal stone disease is an increasingly common problem, and its relatively high recurrence rate demands better treatment options. The majority of patients with nephrolithiasis have stones that contain calcium (Ca2+), which develop upon "supersaturation" of the urine with insoluble Ca2+ salts; hence processes that influence the delivery and renal handling of Ca2+ may influence stone formation. Idiopathic hypercalciuria is indeed frequently observed in patients with kidney stones that contain Ca2+. Genetic screens of nephrolithiasis determinants have identified an increasing number of gene candidates, most of which are involved in renal Ca2+ handling. This review provides an outline of the current knowledge regarding genetics of nephrolithiasis and will mainly focus on the epithelial Ca2+ channel transient receptor potential vanilloid 5 (TRPV5), an important player in Ca2+ homeostasis. Being a member of the TRP family of ion channels, TRPV5 is currently part of a revolution in structural biology. Recent technological breakthroughs in the cryo-electron microscopy field, combined with improvements in biochemical sample preparation, have resulted in high-resolution 3-dimensional structural models of integral membrane proteins, including TRPV5. These models currently are being used to explore the proteins' structure-function relationship, elucidate the molecular mechanisms of channel regulation, and study the putative effects of disease variants. Combined with other multidisciplinary approaches, this approach may open an avenue toward better understanding of the pathophysiological mechanisms involved in hypercalciuria and stone formation, and ultimately it may facilitate prevention of stone recurrence through the development of effective drugs.
Collapse
Affiliation(s)
- Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, the Netherlands
| | - Mark K van Goor
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, the Netherlands
| | - Michiel F Schreuder
- Department of Pediatric Nephrology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, the Netherlands
| | - Joost G Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, the Netherlands.
| |
Collapse
|
97
|
Single-particle cryo-EM studies of transmembrane proteins in SMA copolymer nanodiscs. Chem Phys Lipids 2019; 221:114-119. [PMID: 30940443 DOI: 10.1016/j.chemphyslip.2019.03.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 03/14/2019] [Accepted: 03/14/2019] [Indexed: 11/21/2022]
Abstract
Styrene-maleic acid (SMA) copolymers can extract membrane proteins from native membranes along with lipids as nanodiscs. Preparation with SMA is fast, cost-effective, and captures the native protein-lipid interactions. On the other hand, cryo-EM has become increasingly successful and efficient for structural determinations of membrane proteins, with biochemical sample preparation often the bottleneck. Three recent cryo-EM studies on the efflux transporter AcrB and the alternative complex III: cyt c oxidase supercomplex have demonstrated the potential of SMA nanodisc samples to yield high-resolution structure information of membrane proteins.
Collapse
|
98
|
Clairfeuille T, Cloake A, Infield DT, Llongueras JP, Arthur CP, Li ZR, Jian Y, Martin-Eauclaire MF, Bougis PE, Ciferri C, Ahern CA, Bosmans F, Hackos DH, Rohou A, Payandeh J. Structural basis of α-scorpion toxin action on Na v channels. Science 2019; 363:science.aav8573. [PMID: 30733386 DOI: 10.1126/science.aav8573] [Citation(s) in RCA: 111] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/28/2019] [Indexed: 01/25/2023]
Abstract
Fast inactivation of voltage-gated sodium (Nav) channels is essential for electrical signaling, but its mechanism remains poorly understood. Here we determined the structures of a eukaryotic Nav channel alone and in complex with a lethal α-scorpion toxin, AaH2, by electron microscopy, both at 3.5-angstrom resolution. AaH2 wedges into voltage-sensing domain IV (VSD4) to impede fast activation by trapping a deactivated state in which gating charge interactions bridge to the acidic intracellular carboxyl-terminal domain. In the absence of AaH2, the S4 helix of VSD4 undergoes a ~13-angstrom translation to unlatch the intracellular fast-inactivation gating machinery. Highlighting the polypharmacology of α-scorpion toxins, AaH2 also targets an unanticipated receptor site on VSD1 and a pore glycan adjacent to VSD4. Overall, this work provides key insights into fast inactivation, electromechanical coupling, and pathogenic mutations in Nav channels.
Collapse
Affiliation(s)
- Thomas Clairfeuille
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, USA
| | - Alexander Cloake
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, USA.,Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Daniel T Infield
- Department of Molecular Physiology and Biophysics, The University of Iowa, Iowa City, IA, USA
| | - José P Llongueras
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Zhong Rong Li
- Department of Biomolecular Resources, Genentech Inc., South San Francisco, CA, USA
| | - Yuwen Jian
- Department of Neuroscience, Genentech Inc., South San Francisco, CA, USA
| | | | - Pierre E Bougis
- Aix Marseille Université, CNRS, LNC, UMR 7291, 13003 Marseille, France
| | - Claudio Ciferri
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, USA
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, The University of Iowa, Iowa City, IA, USA.
| | - Frank Bosmans
- Department of Basic and Applied Medical Sciences, Ghent University, 9000 Ghent, Belgium.
| | - David H Hackos
- Department of Neuroscience, Genentech Inc., South San Francisco, CA, USA.
| | - Alexis Rohou
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, USA.
| | - Jian Payandeh
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, USA.
| |
Collapse
|
99
|
Heath GR, Scheuring S. Advances in high-speed atomic force microscopy (HS-AFM) reveal dynamics of transmembrane channels and transporters. Curr Opin Struct Biol 2019; 57:93-102. [PMID: 30878714 DOI: 10.1016/j.sbi.2019.02.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 02/12/2019] [Accepted: 02/13/2019] [Indexed: 02/07/2023]
Abstract
Recent advances in high-speed atomic force microscopy (HS-AFM) have made it possible to study the conformational dynamics of single unlabeled transmembrane channels and transporters. Improving environmental control with the integration of a non-disturbing buffer exchange system, which in turn allows the gradual change of conditions during HS-AFM operation, has provided a breakthrough toward the performance of structural titration experiments. Further advancements in temporal resolution with the use of line scanning and height spectroscopy techniques show how high-speed atomic force microscopy can measure millisecond to microsecond dynamics, pushing this method beyond current spatial and temporal limits offered by less direct techniques.
Collapse
Affiliation(s)
- George R Heath
- Weill Cornell Medicine, Department of Anesthesiology, 1300 York Avenue, New York, NY 10065, USA; Weill Cornell Medicine, Department of Physiology and Biophysics, 1300 York Avenue, New York, NY 10065, USA
| | - Simon Scheuring
- Weill Cornell Medicine, Department of Anesthesiology, 1300 York Avenue, New York, NY 10065, USA; Weill Cornell Medicine, Department of Physiology and Biophysics, 1300 York Avenue, New York, NY 10065, USA.
| |
Collapse
|