51
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 175] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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52
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Schumann-Gillett A, Blyth MT, O’Mara ML. Is protein structure enough? A review of the role of lipids in SLC6 transporter function. Neurosci Lett 2019; 700:64-69. [DOI: 10.1016/j.neulet.2018.05.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 05/09/2018] [Accepted: 05/11/2018] [Indexed: 12/17/2022]
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53
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Bolla JR, Agasid MT, Mehmood S, Robinson CV. Membrane Protein-Lipid Interactions Probed Using Mass Spectrometry. Annu Rev Biochem 2019; 88:85-111. [PMID: 30901263 DOI: 10.1146/annurev-biochem-013118-111508] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Membrane proteins that exist in lipid bilayers are not isolated molecular entities. The lipid molecules that surround them play crucial roles in maintaining their full structural and functional integrity. Research directed at investigating these critical lipid-protein interactions is developing rapidly. Advancements in both instrumentation and software, as well as in key biophysical and biochemical techniques, are accelerating the field. In this review, we provide a brief outline of structural techniques used to probe protein-lipid interactions and focus on the molecular aspects of these interactions obtained from native mass spectrometry (native MS). We highlight examples in which lipids have been shown to modulate membrane protein structure and show how native MS has emerged as a complementary technique to X-ray crystallography and cryo-electron microscopy. We conclude with a short perspective on future developments that aim to better understand protein-lipid interactions in the native environment.
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Affiliation(s)
- Jani Reddy Bolla
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom;
| | - Mark T Agasid
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom;
| | - Shahid Mehmood
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom;
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom;
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54
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Angladon MA, Fossépré M, Leherte L, Vercauteren DP. Interaction of POPC, DPPC, and POPE with the μ opioid receptor: A coarse-grained molecular dynamics study. PLoS One 2019; 14:e0213646. [PMID: 30870466 PMCID: PMC6417715 DOI: 10.1371/journal.pone.0213646] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 02/26/2019] [Indexed: 11/18/2022] Open
Abstract
The μ opioid receptor (μOR), which is part of the G protein-coupled receptors family, is a membrane protein that is modulated by its lipid environment. In the present work, we model μOR in three different membrane systems: POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine), POPE (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine), and DPPC (1, 2-dipalmitoyl-sn-glycero-3-phosphocholine) through 45 μs molecular dynamics (MD) simulations at the coarse-grained level. Our theoretical studies provide new insights to the lipid-induced modulation of the receptor. Particularly, to characterize how μOR interacts with each lipid, we analyze the tilt of the protein, the number of contacts occurring between the lipids and each amino acid of the receptor, and the μOR-lipid interface described as a network graph. We also analyze the variations in the number and the nature of the protein contacts that are induced by the lipid structure. We show that POPC interacts preferentially with helix 1 (H1) and helices H5-H6, POPE, with H5-H6 and H6-H7, and DPPC, with H4 and H6. We demonstrate how each of the three lipids shape the structure of the μOR.
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Affiliation(s)
- Marie-Ange Angladon
- Laboratoire de Physico-Chimie Informatique, Unité de Chimie Physique Théorique et Structurale, Namur Medecine and Drug Innovation Center (NAMEDIC), Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), Namur, Belgium
- * E-mail:
| | - Mathieu Fossépré
- Laboratoire de Physico-Chimie Informatique, Unité de Chimie Physique Théorique et Structurale, Namur Medecine and Drug Innovation Center (NAMEDIC), Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), Namur, Belgium
| | - Laurence Leherte
- Laboratoire de Physico-Chimie Informatique, Unité de Chimie Physique Théorique et Structurale, Namur Medecine and Drug Innovation Center (NAMEDIC), Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), Namur, Belgium
| | - Daniel P. Vercauteren
- Laboratoire de Physico-Chimie Informatique, Unité de Chimie Physique Théorique et Structurale, Namur Medecine and Drug Innovation Center (NAMEDIC), Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), Namur, Belgium
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55
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Hedger G, Koldsø H, Chavent M, Siebold C, Rohatgi R, Sansom MSP. Cholesterol Interaction Sites on the Transmembrane Domain of the Hedgehog Signal Transducer and Class F G Protein-Coupled Receptor Smoothened. Structure 2019; 27:549-559.e2. [PMID: 30595453 PMCID: PMC6408332 DOI: 10.1016/j.str.2018.11.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/28/2018] [Accepted: 11/02/2018] [Indexed: 12/12/2022]
Abstract
Transduction of Hedgehog signals across the plasma membrane is facilitated by the class F G-protein-coupled-receptor (GPCR) Smoothened (SMO). Recent studies suggest that SMO is modulated via interactions of its transmembrane (TM) domain with cholesterol. We apply molecular dynamics simulations of SMO embedded in cholesterol containing lipid bilayers, revealing a direct interaction of cholesterol with the TM domain at regions distinct from those observed in class A GPCRs. In particular the extracellular tips of helices TM2 and TM3 form a well-defined cholesterol interaction site. Potential of mean force calculations yield a free energy landscape for cholesterol binding. Alongside analysis of equilibrium cholesterol occupancy, this reveals the existence of a dynamic "greasy patch" interaction with the TM domain of SMO, which may be compared with previously identified lipid interaction sites on other membrane proteins. These predictions provide molecular-level insights into cholesterol interactions with a class F GPCR, suggesting potential druggable sites.
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Affiliation(s)
- George Hedger
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Heidi Koldsø
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Matthieu Chavent
- Institut de Pharmacologie et de Biologie Structurale IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Rajat Rohatgi
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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56
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Inada M, Kinoshita M, Sumino A, Oiki S, Matsumori N. A concise method for quantitative analysis of interactions between lipids and membrane proteins. Anal Chim Acta 2019; 1059:103-112. [PMID: 30876624 DOI: 10.1016/j.aca.2019.01.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 01/17/2019] [Accepted: 01/18/2019] [Indexed: 01/31/2023]
Abstract
Although interactions between lipids and membrane proteins (MPs) have been considered crucially important for understanding the functions of lipids, lack of useful and convincing experimental methods has hampered the analysis of the interactions. Here, we developed a surface plasmon resonance (SPR)-based concise method for quantitative analysis of lipid-MP interactions, coating the sensor chip surface with self-assembled monolayer (SAM) with C6-chain. To develop this method, we used bacteriorhodopsin (bR) as an MP, and examined its interaction with various types of lipids. The merits of using C6-SAM-modified sensor chip are as follows: (1) alkyl-chains of SAM confer a better immobilization of MPs because of the efficient preconcentration due to hydrophobic contacts; (2) SAM provides immobilized MPs with a partial membranous environment, which is important for the stabilization of MPs; and (3) a thinner C6-SAM layer (1 nm) compared with MP size forces the MP to bulge outward from the SAM surface, allowing extraneously injected lipids to be accessible to the hydrophobic transmembrane regions. Actually, the amount of bR immobilized on C6-SAM is 10 times higher than that on a hydrophilic CM5 sensor chip, and AFM observations confirmed that bR molecules are exposed on the SAM surface. Of the lipids tested, S-TGA-1, a halobacterium-derived glycolipid, had the highest specificity to bR with a nanomolar dissociation constant. This is consistent with the reported co-crystal structure that indicates the formation of several intermolecular hydrogen bonds. Therefore, we not only reproduced the specific lipid-bR recognition, but also succeeded in its quantitative evaluation, demonstrating the validity and utility of this method.
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Affiliation(s)
- Masataka Inada
- Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Masanao Kinoshita
- Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Ayumi Sumino
- Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan; High-speed AFM for Biological Application Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, 920-1192, Japan; Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa, 920-1192, Japan
| | - Shigetoshi Oiki
- Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan
| | - Nobuaki Matsumori
- Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
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57
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Chung HW, Petersen EN, Cabanos C, Murphy KR, Pavel MA, Hansen AS, Ja WW, Hansen SB. A Molecular Target for an Alcohol Chain-Length Cutoff. J Mol Biol 2019; 431:196-209. [PMID: 30529033 PMCID: PMC6360937 DOI: 10.1016/j.jmb.2018.11.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/30/2018] [Accepted: 11/30/2018] [Indexed: 11/23/2022]
Abstract
Despite the widespread consumption of ethanol, mechanisms underlying its anesthetic effects remain uncertain. n-Alcohols induce anesthesia up to a specific chain length and then lose potency-an observation known as the "chain-length cutoff effect." This cutoff effect is thought to be mediated by alcohol binding sites on proteins such as ion channels, but where these sites are for long-chain alcohols and how they mediate a cutoff remain poorly defined. In animals, the enzyme phospholipase D (PLD) has been shown to generate alcohol metabolites (e.g., phosphatidylethanol) with a cutoff, but no phenotype has been shown connecting PLD to an anesthetic effect. Here we show loss of PLD blocks ethanol-mediated hyperactivity in Drosophila melanogaster (fruit fly), demonstrating that PLD mediates behavioral responses to alcohol in vivo. Furthermore, the metabolite phosphatidylethanol directly competes for the endogenous PLD product phosphatidic acid at lipid-binding sites within potassium channels [e.g., TWIK-related K+ channel type 1 (K2P2.1, TREK-1)]. This gives rise to a PLD-dependent cutoff in TREK-1. We propose an alcohol pathway where PLD produces lipid-alcohol metabolites that bind to and regulate downstream effector molecules including lipid-regulated potassium channels.
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Affiliation(s)
- Hae-Won Chung
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - E Nicholas Petersen
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Cerrone Cabanos
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Keith R Murphy
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA; Center on Aging, The Scripps Research Institute, Jupiter, FL 33458, USA; Program in Integrative Biology and Neuroscience, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Mahmud Arif Pavel
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Andrew S Hansen
- HBBiotech, BioInnovations Gateway, Salt Lake City, UT 84115, USA
| | - William W Ja
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA; Center on Aging, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Scott B Hansen
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
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58
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Newport TD, Sansom MS, Stansfeld PJ. The MemProtMD database: a resource for membrane-embedded protein structures and their lipid interactions. Nucleic Acids Res 2019; 47:D390-D397. [PMID: 30418645 PMCID: PMC6324062 DOI: 10.1093/nar/gky1047] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 10/05/2018] [Accepted: 10/16/2018] [Indexed: 12/19/2022] Open
Abstract
Integral membrane proteins fulfil important roles in many crucial biological processes, including cell signalling, molecular transport and bioenergetic processes. Advancements in experimental techniques are revealing high resolution structures for an increasing number of membrane proteins. Yet, these structures are rarely resolved in complex with membrane lipids. In 2015, the MemProtMD pipeline was developed to allow the automated lipid bilayer assembly around new membrane protein structures, released from the Protein Data Bank (PDB). To make these data available to the scientific community, a web database (http://memprotmd.bioch.ox.ac.uk) has been developed. Simulations and the results of subsequent analysis can be viewed using a web browser, including interactive 3D visualizations of the assembled bilayer and 2D visualizations of lipid contact data and membrane protein topology. In addition, ensemble analyses are performed to detail conserved lipid interaction information across proteins, families and for the entire database of 3506 PDB entries. Proteins may be searched using keywords, PDB or Uniprot identifier, or browsed using classification systems, such as Pfam, Gene Ontology annotation, mpstruc or the Transporter Classification Database. All files required to run further molecular simulations of proteins in the database are provided.
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Affiliation(s)
- Thomas D Newport
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
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59
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Rosenhouse-Dantsker A. Cholesterol Binding Sites in Inwardly Rectifying Potassium Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1135:119-138. [DOI: 10.1007/978-3-030-14265-0_7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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60
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Jeckelmann JM, Erni B. Carbohydrate Transport by Group Translocation: The Bacterial Phosphoenolpyruvate: Sugar Phosphotransferase System. Subcell Biochem 2019; 92:223-274. [PMID: 31214989 DOI: 10.1007/978-3-030-18768-2_8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Bacterial Phosphoenolpyruvate (PEP) : Sugar Phosphotransferase System (PTS) mediates the uptake and phosphorylation of carbohydrates, and controls the carbon- and nitrogen metabolism in response to the availability of sugars. PTS occur in eubacteria and in a few archaebacteria but not in animals and plants. All PTS comprise two cytoplasmic phosphotransferase proteins (EI and HPr) and a species-dependent, variable number of sugar-specific enzyme II complexes (IIA, IIB, IIC, IID). EI and HPr transfer phosphorylgroups from PEP to the IIA units. Cytoplasmic IIA and IIB units sequentially transfer phosphates to the sugar, which is transported by the IIC and IICIID integral membrane protein complexes. Phosphorylation by IIB and translocation by IIC(IID) are tightly coupled. The IIC(IID) sugar transporters of the PTS are in the focus of this review. There are four structurally different PTS transporter superfamilies (glucose, glucitol, ascorbate, mannose) . Crystal structures are available for transporters of two superfamilies: bcIICmal (MalT, 5IWS, 6BVG) and bcIICchb (ChbC, 3QNQ) of B. subtilis from the glucose family, and IICasc (UlaA, 4RP9, 5ZOV) of E. coli from the ascorbate superfamily . They are homodimers and each protomer has an independent transport pathway which functions by an elevator-type alternating-access mechanism. bcIICmal and bcIICchb have the same fold, IICasc has a completely different fold. Biochemical and biophysical data accumulated in the past with the transporters for mannitol (IICBAmtl) and glucose (IICBglc) are reviewed and discussed in the context of the bcIICmal crystal structures. The transporters of the mannose superfamily are dimers of protomers consisting of a IIC and a IID protein chain. The crystal structure is not known and the topology difficult to predict. Biochemical data indicate that the IICIID complex employs a different transport mechanism . Species specific IICIID serve as a gateway for the penetration of bacteriophage lambda DNA across, and insertion of class IIa bacteriocins into the inner membrane. PTS transporters are inserted into the membrane by SecYEG translocon and have specific lipid requirements. Immunoelectron- and fluorescence microscopy indicate a non-random distribution and supramolecular complexes of PTS proteins.
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Affiliation(s)
- Jean-Marc Jeckelmann
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012, Bern, Switzerland.
| | - Bernhard Erni
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012, Bern, Switzerland
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61
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Physical states and thermodynamic properties of model gram-negative bacterial inner membranes. Chem Phys Lipids 2019; 218:57-64. [DOI: 10.1016/j.chemphyslip.2018.12.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 11/16/2018] [Accepted: 12/05/2018] [Indexed: 01/27/2023]
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62
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Hoogerheide DP, Noskov SY, Kuszak AJ, Buchanan SK, Rostovtseva TK, Nanda H. Structure of voltage-dependent anion channel-tethered bilayer lipid membranes determined using neutron reflectivity. Acta Crystallogr D Struct Biol 2018; 74:1219-1232. [PMID: 30605136 PMCID: PMC6317592 DOI: 10.1107/s2059798318011749] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 08/20/2018] [Indexed: 01/05/2023] Open
Abstract
Neutron reflectivity (NR) has emerged as a powerful technique to study the structure and behavior of membrane proteins at planar lipid interfaces. Integral membrane proteins (IMPs) remain a significant challenge for NR owing to the difficulty of forming complete bilayers with sufficient protein density for scattering techniques. One strategy to achieve high protein density on a solid substrate is the capture of detergent-stabilized, affinity-tagged IMPs on a nitrilotriacetic acid (NTA)-functionalized self-assembled monolayer (SAM), followed by reconstitution into the lipids of interest. Such protein-tethered bilayer lipid membranes (ptBLMs) have the notable advantage of a uniform IMP orientation on the substrate. Here, NR is used to provide a structural characterization of the ptBLM process from formation of the SAM to capture of the detergent-stabilized IMP and lipid reconstitution. The mitochondrial outer-membrane voltage-dependent anion channel (VDAC), which controls the exchange of bioenergetic metabolites between mitochondria and the cytosol, was used as a model β-barrel IMP. Molecular dynamics simulations were used for comparison with the experimental results and to inform the parameters of the physical models describing the NR data. The detailed structure of the SAM is shown to depend on the density of the NTA chelating groups. The relative content of detergent and protein in surface-immobilized, detergent-stabilized VDAC is measured, while the reconstituted lipid bilayer is shown to be complete to within a few percent, using the known atomic structure of VDAC. Finally, excess lipid above the reconstituted bilayer, which is of consequence for more indirect structural and functional studies, is shown to be present.
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Affiliation(s)
- David P. Hoogerheide
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20878, USA
| | - Sergei Yu. Noskov
- Centre for Molecular Simulations and Department of Biological Sciences, University of Calgary, Calgary T2N 1N4, Canada
| | - Adam J. Kuszak
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Susan K. Buchanan
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tatiana K. Rostovtseva
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hirsh Nanda
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20878, USA
- Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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63
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Pichler H, Emmerstorfer-Augustin A. Modification of membrane lipid compositions in single-celled organisms – From basics to applications. Methods 2018; 147:50-65. [DOI: 10.1016/j.ymeth.2018.06.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/18/2018] [Accepted: 06/16/2018] [Indexed: 12/12/2022] Open
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64
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Jaipuria G, Ukmar-Godec T, Zweckstetter M. Challenges and approaches to understand cholesterol-binding impact on membrane protein function: an NMR view. Cell Mol Life Sci 2018; 75:2137-2151. [PMID: 29520423 PMCID: PMC11105689 DOI: 10.1007/s00018-018-2789-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 02/16/2018] [Accepted: 02/27/2018] [Indexed: 01/27/2023]
Abstract
Experimental evidence for a direct role of lipids in determining the structure, dynamics, and function of membrane proteins leads to the term 'functional lipids'. In particular, the sterol molecule cholesterol modulates the activity of many membrane proteins. The precise nature of cholesterol-binding sites and the consequences of modulation of local membrane micro-viscosity by cholesterol, however, is often unknown. Here, we review the current knowledge of the interaction of cholesterol with transmembrane proteins, with a special focus on structural aspects of the interaction derived from nuclear magnetic resonance approaches. We highlight examples of the importance of cholesterol modulation of membrane protein function, discuss the specificity of cholesterol binding, and review the proposed binding motifs from a molecular perspective. We conclude with a short perspective on what could be future trends in research efforts targeted towards a better understanding of cholesterol/membrane protein interactions.
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Affiliation(s)
- Garima Jaipuria
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075, Göttingen, Germany
| | - Tina Ukmar-Godec
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075, Göttingen, Germany
- Department of Neurology, University Medical Center Göttingen, University of Göttingen, Waldweg 33, 37073, Göttingen, Germany
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075, Göttingen, Germany.
- Department of Neurology, University Medical Center Göttingen, University of Göttingen, Waldweg 33, 37073, Göttingen, Germany.
- Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.
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65
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Membrane properties that shape the evolution of membrane enzymes. Curr Opin Struct Biol 2018; 51:80-91. [PMID: 29597094 DOI: 10.1016/j.sbi.2018.03.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 02/07/2023]
Abstract
Spectacular recent progress in structural biology has led to determination of the structures of many integral membrane enzymes that catalyze reactions in which at least one substrate also is membrane bound. A pattern of results seems to be emerging in which the active site chemistry of these enzymes is usually found to be analogous to what is observed for water soluble enzymes catalyzing the same reaction types. However, in light of the chemical, structural, and physical complexity of cellular membranes plus the presence of transmembrane gradients and potentials, these enzymes may be subject to membrane-specific regulatory mechanisms that are only now beginning to be uncovered. We review the membrane-specific environmental traits that shape the evolution of membrane-embedded biocatalysts.
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66
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Fuhs T, Klausen LH, Sønderskov SM, Han X, Dong M. Direct measurement of surface charge distribution in phase separating supported lipid bilayers. NANOSCALE 2018; 10:4538-4544. [PMID: 29461548 DOI: 10.1039/c7nr09522h] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The local surface charge density of the cell membrane influences regulation and localization of membrane proteins. The local surface charge density could, until recently, not be measured directly under physiological conditions, and it was largely a hypothetical yet very important parameter. Here we use unsaturated lipids of a distinct charge (DOTAP, DOPC, and DOPG) and a neutral fully saturated lipid (DPPC) to create model membranes with phase separating domains of a defined charge. We then apply quantitative surface charge microscopy (QSCM) to investigate the local surface charge density; this is a technique based on a scanning ion conductance microscope (SICM) capable of measuring surface charge density with nanoscale lateral resolution. We are able to clearly distinguish lipid domains from charge and topography in all three model membranes. The measured surface charge densities furthermore reveal that disordered domains formed by charged lipids are in fact not only impure, but also incorporate uncharged saturated lipids. We estimate that at least 30% of disordered domains in DOPG : DPPC and DOTAP : DPPC will be DPPC. These ratios could present a limit for the formation of charged domains in lipid membranes.
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Affiliation(s)
- Thomas Fuhs
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 92 West Da-Zhi Street, Harbin, 150001, China.
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67
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Ferraro NA, Cascio M. Cross-Linking-Mass Spectrometry Studies of Cholesterol Interactions with Human α1 Glycine Receptor. Anal Chem 2018; 90:2508-2516. [DOI: 10.1021/acs.analchem.7b03639] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Nicholas A. Ferraro
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Michael Cascio
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
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68
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Van Eerden FJ, Melo MN, Frederix PWJM, Marrink SJ. Prediction of Thylakoid Lipid Binding Sites on Photosystem II. Biophys J 2018; 113:2669-2681. [PMID: 29262360 PMCID: PMC5770566 DOI: 10.1016/j.bpj.2017.09.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 09/11/2017] [Accepted: 09/29/2017] [Indexed: 11/20/2022] Open
Abstract
The thylakoid membrane has a unique lipid composition, consisting mostly of galactolipids. These thylakoid lipids have important roles in photosynthesis. Here, we investigate to what extent these lipids bind specifically to the Photosystem II complex. To this end, we performed coarse-grain MD simulations of the Photosystem II complex embedded in a thylakoid membrane with realistic composition. Based on >85 μs simulation time, we find that monogalactosyldiacylglycerol and sulfoquinovosyldiacylglycerol lipids are enriched in the annular shell around the protein, and form distinct binding sites. From the analysis of residue contacts, we conclude that electrostatic interactions play an important role in stabilizing these binding sites. Furthermore, we find that chlorophyll a has a prevalent role in the coordination of the lipids. In addition, we observe lipids to diffuse in and out of the plastoquinone exchange cavities, allowing exchange of cocrystallized lipids with the bulk membrane and suggesting a more open nature of the plastoquinone exchange cavity. Together, our data provide a wealth of information on protein-lipid interactions for a key protein in photosynthesis.
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Affiliation(s)
- Floris J Van Eerden
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands.
| | - Manuel N Melo
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands; Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Pim W J M Frederix
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands
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69
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Schmidt V, Sturgis JN. Modifying styrene-maleic acid co-polymer for studying lipid nanodiscs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:777-783. [PMID: 29273333 DOI: 10.1016/j.bbamem.2017.12.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 12/12/2017] [Accepted: 12/14/2017] [Indexed: 01/09/2023]
Abstract
Recently, styrene-maleic acid copolymer lipid nanodiscs have become an increasingly popular tool for the study of membrane proteins. In the work we report here, we have developed a novel method for the efficient preparation of labeled nanodiscs, under chemically mild conditions, by modification of the hydrolyzed styrene-maleic acid copolymer. This protocol is designed to be easily accessible to biochemistry laboratories. We use this procedure to prepare various fluorescent nanodiscs labeled with different fluorophores. By studying the development of Förster resonance energy transfer, we demonstrate the rapid exchange of co-polymer between nanodiscs. This demonstration, in conjunction of previous work, indicates that the lipid nanodiscs prepared using this polymer are very dynamic structures with rapid exchange of the different components.
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Affiliation(s)
- Victoria Schmidt
- LISM UMR 7255, CNRS and Aix-Marseille University, 31 Chemin Joseph Aiguier, Marseille cedex 20 13402, France
| | - James N Sturgis
- LISM UMR 7255, CNRS and Aix-Marseille University, 31 Chemin Joseph Aiguier, Marseille cedex 20 13402, France.
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70
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Duncan AL, Reddy T, Koldsø H, Hélie J, Fowler PW, Chavent M, Sansom MSP. Protein crowding and lipid complexity influence the nanoscale dynamic organization of ion channels in cell membranes. Sci Rep 2017; 7:16647. [PMID: 29192147 PMCID: PMC5709381 DOI: 10.1038/s41598-017-16865-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 11/15/2017] [Indexed: 01/07/2023] Open
Abstract
Cell membranes are crowded and complex environments. To investigate the effect of protein-lipid interactions on dynamic organization in mammalian cell membranes, we have performed coarse-grained molecular dynamics simulations containing >100 copies of an inwardly rectifying potassium (Kir) channel which forms specific interactions with the regulatory lipid phosphatidylinositol 4,5-bisphosphate (PIP2). The tendency of protein molecules to cluster has the effect of organizing the membrane into dynamic compartments. At the same time, the diversity of lipids present has a marked effect on the clustering behavior of ion channels. Sub-diffusion of proteins and lipids is observed. Protein crowding alters the sub-diffusive behavior of proteins and lipids such as PIP2 which interact tightly with Kir channels. Protein crowding also affects bilayer properties, such as membrane undulations and bending rigidity, in a PIP2-dependent manner. This interplay between the diffusion and the dynamic organization of Kir channels may have important implications for channel function.
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Affiliation(s)
- Anna L Duncan
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Tyler Reddy
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- T-6, MS K710, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Heidi Koldsø
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- D. E. Shaw Research, 120 W 45th St., New York, NY, 10036, USA
| | - Jean Hélie
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- Semmle, Blue Boar Court, 9 Alfred St, Oxford, OX1 4EH, UK
| | - Philip W Fowler
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Matthieu Chavent
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- IPBS-CNRS, Toulouse, Midi-Pyrénées, France
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
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71
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Reidenbach AG, Kemmerer ZA, Aydin D, Jochem A, McDevitt MT, Hutchins PD, Stark JL, Stefely JA, Reddy T, Hebert AS, Wilkerson EM, Johnson IE, Bingman CA, Markley JL, Coon JJ, Dal Peraro M, Pagliarini DJ. Conserved Lipid and Small-Molecule Modulation of COQ8 Reveals Regulation of the Ancient Kinase-like UbiB Family. Cell Chem Biol 2017; 25:154-165.e11. [PMID: 29198567 DOI: 10.1016/j.chembiol.2017.11.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 09/10/2017] [Accepted: 11/01/2017] [Indexed: 12/14/2022]
Abstract
Human COQ8A (ADCK3) and Saccharomyces cerevisiae Coq8p (collectively COQ8) are UbiB family proteins essential for mitochondrial coenzyme Q (CoQ) biosynthesis. However, the biochemical activity of COQ8 and its direct role in CoQ production remain unclear, in part due to lack of known endogenous regulators of COQ8 function and of effective small molecules for probing its activity in vivo. Here, we demonstrate that COQ8 possesses evolutionarily conserved ATPase activity that is activated by binding to membranes containing cardiolipin and by phenolic compounds that resemble CoQ pathway intermediates. We further create an analog-sensitive version of Coq8p and reveal that acute chemical inhibition of its endogenous activity in yeast is sufficient to cause respiratory deficiency concomitant with CoQ depletion. Collectively, this work defines lipid and small-molecule modulators of an ancient family of atypical kinase-like proteins and establishes a chemical genetic system for further exploring the mechanistic role of COQ8 in CoQ biosynthesis.
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Affiliation(s)
- Andrew G Reidenbach
- Morgridge Institute for Research, Madison, WI 53715, USA; Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Zachary A Kemmerer
- Morgridge Institute for Research, Madison, WI 53715, USA; Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Deniz Aydin
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Adam Jochem
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - Molly T McDevitt
- Morgridge Institute for Research, Madison, WI 53715, USA; Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Paul D Hutchins
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jaime L Stark
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jonathan A Stefely
- Morgridge Institute for Research, Madison, WI 53715, USA; Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Thiru Reddy
- Morgridge Institute for Research, Madison, WI 53715, USA
| | | | - Emily M Wilkerson
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Isabel E Johnson
- Morgridge Institute for Research, Madison, WI 53715, USA; Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Craig A Bingman
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - John L Markley
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Joshua J Coon
- Morgridge Institute for Research, Madison, WI 53715, USA; Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA; Genome Center of Wisconsin, Madison, WI 53706, USA; Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Matteo Dal Peraro
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - David J Pagliarini
- Morgridge Institute for Research, Madison, WI 53715, USA; Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
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72
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Poppe S, Poppe M, Ebert H, Prehm M, Chen C, Liu F, Werner S, Bacia K, Tschierske C. Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene) Cores on Self-Assembly Behaviour. Part 1: Transition between Amphiphilic and Polyphilic Self-Assembly in the Bulk. Polymers (Basel) 2017; 9:E471. [PMID: 30965775 PMCID: PMC6418615 DOI: 10.3390/polym9100471] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 09/21/2017] [Accepted: 09/22/2017] [Indexed: 02/06/2023] Open
Abstract
Polyphilic self-assembly leads to compartmentalization of space and development of complex structures in soft matter on different length scales, reaching from the morphologies of block copolymers to the liquid crystalline (LC) phases of small molecules. Whereas block copolymers are known to form membranes and interact with phospholipid bilayers, liquid crystals have been less investigated in this respect. Here, series of bolapolyphilic X-shaped molecules were synthesized and investigated with respect to the effect of molecular structural parameters on the formation of LC phases (part 1), and on domain formation in phospholipid bilayer membranes (part 2). The investigated bolapolyphiles are based on a rod-like π-conjugated oligo(phenylene ethynylene) (OPE) core with two glycerol groups being either directly attached or separated by additional ethylene oxide (EO) units to both ends. The X-shape is provided by two lateral alkyl chains attached at opposite sides of the OPE core, being either linear, branched, or semiperfluorinated. In this report, the focus is on the transition from polyphilic (triphilic or tetraphilic) to binary amphiphilic self-assembly. Polyphilic self-assembly, i.e., segregation of all three or four incorporated units into separate nano-compartments, leads to the formation of hexagonal columnar LC phases, representing triangular honeycombs. A continuous transition from the well-defined triangular honeycomb structures to simple hexagonal columnar phases, dominated by the arrangement of polar columns on a hexagonal lattice in a mixed continuum formed by the lipophilic chains and the OPE rods, i.e., to amphiphilic self-assembly, was observed by reducing the length and volume of the lateral alkyl chains. A similar transition was found upon increasing the length of the EO units involved in the polar groups. If the lateral alkyl chains are enlarged or replaced by semiperfluorinated chains, then the segregation of lateral chains and rod-like cores is retained, even for enlarged polar groups, i.e., the transition from polyphilic to amphiphilic self-assembly is suppressed.
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Affiliation(s)
- Silvio Poppe
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle, Germany.
| | - Marco Poppe
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle, Germany.
| | - Helgard Ebert
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle, Germany.
| | - Marko Prehm
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle, Germany.
| | - Changlong Chen
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Feng Liu
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Stefan Werner
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 3, 06120 Halle, Germany.
| | - Kirsten Bacia
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 3, 06120 Halle, Germany.
| | - Carsten Tschierske
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle, Germany.
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73
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Rouse SL, Hawthorne WJ, Berry JL, Chorev DS, Ionescu SA, Lambert S, Stylianou F, Ewert W, Mackie U, Morgan RML, Otzen D, Herbst FA, Nielsen PH, Dueholm M, Bayley H, Robinson CV, Hare S, Matthews S. A new class of hybrid secretion system is employed in Pseudomonas amyloid biogenesis. Nat Commun 2017; 8:263. [PMID: 28811582 PMCID: PMC5557850 DOI: 10.1038/s41467-017-00361-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 06/23/2017] [Indexed: 11/25/2022] Open
Abstract
Gram-negative bacteria possess specialised biogenesis machineries that facilitate the export of amyloid subunits for construction of a biofilm matrix. The secretion of bacterial functional amyloid requires a bespoke outer-membrane protein channel through which unfolded amyloid substrates are translocated. Here, we combine X-ray crystallography, native mass spectrometry, single-channel electrical recording, molecular simulations and circular dichroism measurements to provide high-resolution structural insight into the functional amyloid transporter from Pseudomonas, FapF. FapF forms a trimer of gated β-barrel channels in which opening is regulated by a helical plug connected to an extended coil-coiled platform spanning the bacterial periplasm. Although FapF represents a unique type of secretion system, it shares mechanistic features with a diverse range of peptide translocation systems. Our findings highlight alternative strategies for handling and export of amyloid protein sequences. Gram-negative bacteria assemble biofilms from amyloid fibres, which translocate across the outer membrane as unfolded amyloid precursors through a secretion system. Here, the authors characterise the structural details of the amyloid transporter FapF in Pseudomonas.
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Affiliation(s)
- Sarah L Rouse
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW72AZ, UK
| | - William J Hawthorne
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW72AZ, UK
| | - Jamie-Lee Berry
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW72AZ, UK
| | - Dror S Chorev
- Chemistry Research Laboratory, University of Oxford, Oxford, OX1 3TA, UK
| | - Sandra A Ionescu
- Chemistry Research Laboratory, University of Oxford, Oxford, OX1 3TA, UK
| | - Sebastian Lambert
- Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Fisentzos Stylianou
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW72AZ, UK
| | - Wiebke Ewert
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW72AZ, UK
| | - Uma Mackie
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW72AZ, UK.,Walthamstow School for Girls, London, E17 9RZ, UK
| | - R Marc L Morgan
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW72AZ, UK
| | - Daniel Otzen
- Interdisciplinary Nanoscience Center (iNANO), Centre for Insoluble Protein Structures (inSPIN), Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Florian-Alexander Herbst
- Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Per H Nielsen
- Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Morten Dueholm
- Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Hagan Bayley
- Chemistry Research Laboratory, University of Oxford, Oxford, OX1 3TA, UK
| | - Carol V Robinson
- Chemistry Research Laboratory, University of Oxford, Oxford, OX1 3TA, UK
| | - Stephen Hare
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW72AZ, UK
| | - Stephen Matthews
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW72AZ, UK.
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74
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Computational studies of membrane proteins: from sequence to structure to simulation. Curr Opin Struct Biol 2017; 45:133-141. [DOI: 10.1016/j.sbi.2017.04.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 04/07/2017] [Accepted: 04/07/2017] [Indexed: 11/19/2022]
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75
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Rosenhouse-Dantsker A. Insights Into the Molecular Requirements for Cholesterol Binding to Ion Channels. CURRENT TOPICS IN MEMBRANES 2017; 80:187-208. [PMID: 28863816 DOI: 10.1016/bs.ctm.2017.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The concept that cholesterol binds to proteins via specific binding motifs, and thereby modulates their function, has emerged two decades ago. When we recently embarked on studies to uncover the putative binding region(s) of cholesterol in the Kir2.1 channel, we carried out an unbiased approach that combines computational and experimental methods. This approach resulted in the identification of novel cholesterol-binding regions distinct from known cholesterol-binding motifs. In recent years, a plethora of structures of proteins complexed with cholesterol have been determined revealing variegated cholesterol-binding regions that can provide invaluable insights into the prerequisites for cholesterol binding. Thus, using this database of structures, the goal of this chapter is to present a comprehensive analysis of representative cholesterol-binding regions, and thereby determine the molecular requirements for cholesterol binding. The analysis demonstrates that the primary requirement for cholesterol binding is a highly hydrophobic environment, and that the interaction with the cholesterol molecule can be stabilized by stacking interactions between its ring structure and hydrophobic aromatic residues, and by hydrogen bonding between its hydroxyl group and a variety of protein residues. This general requirement suggests that the known cholesterol-binding motifs describe a subset of cholesterol-binding regions, and provides a framework for expanding the search for novel cholesterol-binding regions in ion channels.
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76
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Lee J, Patel DS, Kucharska I, Tamm LK, Im W. Refinement of OprH-LPS Interactions by Molecular Simulations. Biophys J 2017; 112:346-355. [PMID: 28122220 DOI: 10.1016/j.bpj.2016.12.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 11/27/2016] [Accepted: 12/05/2016] [Indexed: 12/16/2022] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria is composed of lipopolysaccharide (LPS) in the outer leaflet and phospholipids in the inner leaflet. The outer membrane protein H (OprH) of Pseudomonas aeruginosa provides an increased stability to the OMs by directly interacting with LPS. Here we report the influence of various P. aeruginosa and, for comparison, Escherichia coli LPS environments on the physical properties of the OMs and OprH using all-atom molecular dynamics simulations. The simulations reveal that although the P. aeruginosa OMs are thinner hydrophobic bilayers than the E. coli OMs, which is expected from the difference in the acyl chain length of their lipid A, this effect is almost imperceptible around OprH due to a dynamically adjusted hydrophobic match between OprH and the OM. The structure and dynamics of the extracellular loops of OprH show distinct behaviors in different LPS environments. Including the O-antigen greatly reduces the flexibility of the OprH loops and increases the interactions between these loops and LPS. Furthermore, our study shows that the interactions between OprH and LPS mainly depend on the secondary structure of OprH and the chemical structure of LPS, resulting in distinctive patterns in different LPS environments.
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Affiliation(s)
- Joonseong Lee
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania; Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania
| | - Dhilon S Patel
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania; Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania
| | - Iga Kucharska
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Wonpil Im
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania; Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania.
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77
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Govaerts C. Lipids Can Make Them Stick Together. Trends Biochem Sci 2017; 42:329-330. [DOI: 10.1016/j.tibs.2017.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 03/07/2017] [Indexed: 10/19/2022]
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78
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Vermaas JV, Pogorelov TV, Tajkhorshid E. Extension of the Highly Mobile Membrane Mimetic to Transmembrane Systems through Customized in Silico Solvents. J Phys Chem B 2017; 121:3764-3776. [PMID: 28241729 PMCID: PMC5558153 DOI: 10.1021/acs.jpcb.6b11378] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanics of the protein-lipid interactions of transmembrane proteins are difficult to capture with conventional atomic molecular dynamics, due to the slow lateral diffusion of lipids restricting sampling to states near the initial membrane configuration. The highly mobile membrane mimetic (HMMM) model accelerates lipid dynamics by modeling the acyl tails nearest to the membrane center as a fluid organic solvent while maintaining an atomic description of the lipid headgroups and short acyl tails. The HMMM has been applied to many peripheral protein systems; however, the organic solvent used to date caused deformations in transmembrane proteins by intercalating into the protein and disrupting interactions between individual side chains. We ameliorate the effect of the solvent on transmembrane protein structure through the development of two new in silico Lennard-Jones solvents. The parameters for the new solvents were determined through an extensive parameter search in order to match the bulk properties of alkanes in a highly simplified model. Using these new solvents, we substantially improve the insertion free energy profiles of 10 protein side chain analogues across the entire bilayer. In addition, we reduce the intercalation of solvent into transmembrane systems, resulting in native-like transmembrane protein structures from five different topological classes within a HMMM bilayer. The parametrization of the solvents, in addition to their computed physical properties, is discussed. By combining high lipid lateral diffusion with intact transmembrane proteins, we foresee the developed solvents being useful to efficiently identify membrane composition inhomogeneities and lipid binding caused by the presence of membrane proteins.
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Affiliation(s)
- Josh V Vermaas
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Taras V Pogorelov
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Department of Chemistry, School of Chemical Sciences, National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Department of Biochemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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79
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80
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The role of interfacial lipids in stabilizing membrane protein oligomers. Nature 2017; 541:421-424. [PMID: 28077870 DOI: 10.1038/nature20820] [Citation(s) in RCA: 288] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 11/23/2016] [Indexed: 12/20/2022]
Abstract
Oligomerization of membrane proteins in response to lipid binding has a critical role in many cell-signalling pathways but is often difficult to define or predict. Here we report the development of a mass spectrometry platform to determine simultaneously the presence of interfacial lipids and oligomeric stability and to uncover how lipids act as key regulators of membrane-protein association. Evaluation of oligomeric strength for a dataset of 125 α-helical oligomeric membrane proteins reveals an absence of interfacial lipids in the mass spectra of 12 membrane proteins with high oligomeric stability. For the bacterial homologue of the eukaryotic biogenic transporters (LeuT, one of the proteins with the lowest oligomeric stability), we found a precise cohort of lipids within the dimer interface. Delipidation, mutation of lipid-binding sites or expression in cardiolipin-deficient Escherichia coli abrogated dimer formation. Molecular dynamics simulation revealed that cardiolipin acts as a bidentate ligand, bridging across subunits. Subsequently, we show that for the Vibrio splendidus sugar transporter SemiSWEET, another protein with low oligomeric stability, cardiolipin shifts the equilibrium from monomer to functional dimer. We hypothesized that lipids are essential for dimerization of the Na+/H+ antiporter NhaA from E. coli, which has the lowest oligomeric strength, but not for the substantially more stable homologous Thermus thermophilus protein NapA. We found that lipid binding is obligatory for dimerization of NhaA, whereas NapA has adapted to form an interface that is stable without lipids. Overall, by correlating interfacial strength with the presence of interfacial lipids, we provide a rationale for understanding the role of lipids in both transient and stable interactions within a range of α-helical membrane proteins, including G-protein-coupled receptors.
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81
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Efremov RG, Gatsogiannis C, Raunser S. Lipid Nanodiscs as a Tool for High-Resolution Structure Determination of Membrane Proteins by Single-Particle Cryo-EM. Methods Enzymol 2017; 594:1-30. [DOI: 10.1016/bs.mie.2017.05.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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82
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Periole X. Interplay of G Protein-Coupled Receptors with the Membrane: Insights from Supra-Atomic Coarse Grain Molecular Dynamics Simulations. Chem Rev 2016; 117:156-185. [PMID: 28073248 DOI: 10.1021/acs.chemrev.6b00344] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
G protein-coupled receptors (GPCRs) are central to many fundamental cellular signaling pathways. They transduce signals from the outside to the inside of cells in physiological processes ranging from vision to immune response. It is extremely challenging to look at them individually using conventional experimental techniques. Recently, a pseudo atomistic molecular model has emerged as a valuable tool to access information on GPCRs, more specifically on their interactions with their environment in their native cell membrane and the consequences on their supramolecular organization. This approach uses the Martini coarse grain (CG) model to describe the receptors, lipids, and solvent in molecular dynamics (MD) simulations and in enough detail to allow conserving the chemical specificity of the different molecules. The elimination of unnecessary degrees of freedom has opened up large-scale simulations of the lipid-mediated supramolecular organization of GPCRs. Here, after introducing the Martini CGMD method, we review these studies carried out on various members of the GPCR family, including rhodopsin (visual receptor), opioid receptors, adrenergic receptors, adenosine receptors, dopamine receptor, and sphingosine 1-phosphate receptor. These studies have brought to light an interesting set of novel biophysical principles. The insights range from revealing localized and heterogeneous deformations of the membrane bilayer at the surface of the protein, specific interactions of lipid molecules with individual GPCRs, to the effect of the membrane matrix on global GPCR self-assembly. The review ends with an overview of the lessons learned from the use of the CGMD method, the biophysical-chemical findings on lipid-protein interplay.
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Affiliation(s)
- Xavier Periole
- Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 7, 9747AG Groningen, The Netherlands
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83
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Taylor KC, Sanders CR. Regulation of KCNQ/Kv7 family voltage-gated K + channels by lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:586-597. [PMID: 27818172 DOI: 10.1016/j.bbamem.2016.10.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/24/2016] [Accepted: 10/31/2016] [Indexed: 12/19/2022]
Abstract
Many years of studies have established that lipids can impact membrane protein structure and function through bulk membrane effects, by direct but transient annular interactions with the bilayer-exposed surface of protein transmembrane domains, and by specific binding to protein sites. Here, we focus on how phosphatidylinositol 4,5-bisphosphate (PIP2) and polyunsaturated fatty acids (PUFAs) impact ion channel function and how the structural details of the interactions of these lipids with ion channels are beginning to emerge. We focus on the Kv7 (KCNQ) subfamily of voltage-gated K+ channels, which are regulated by both PIP2 and PUFAs and play a variety of important roles in human health and disease. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Keenan C Taylor
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
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84
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Duneau JP, Khao J, Sturgis JN. Lipid perturbation by membrane proteins and the lipophobic effect. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:126-134. [PMID: 27794424 DOI: 10.1016/j.bbamem.2016.10.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 10/21/2016] [Accepted: 10/25/2016] [Indexed: 11/26/2022]
Abstract
Understanding how membrane proteins interact with their environment is fundamental to the understanding of their structure, function and interactions. We have performed coarse-grained molecular dynamics simulations on a series of membrane proteins in a membrane environment to examine the perturbations of the lipids by the presence of protein. We analyze these perturbations in terms of elastic membrane deformations and local lipid protein interactions. However these two factors are insufficient to describe the variety of effects that we observe and the changes caused by membranes proteins to the structure and dynamics of their lipid environment. Other factors that change the conformation available to lipid molecules are evident and are able to modify lipid structure far from the protein surface, and thus mediate long-range interactions between membrane proteins. We suggest that these multiple modifications to lipid behavior are responsible, at the molecular level, for the lipophobic effect we have proposed to account for our observations of membrane protein organization.
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Affiliation(s)
- Jean-Pierre Duneau
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, CNRS and Aix-Marseille Univ, Marseille 13402 cedex 20, France.
| | - Jonathan Khao
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, CNRS and Aix-Marseille Univ, Marseille 13402 cedex 20, France
| | - James N Sturgis
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, CNRS and Aix-Marseille Univ, Marseille 13402 cedex 20, France.
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85
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Bernardino de la Serna J, Schütz GJ, Eggeling C, Cebecauer M. There Is No Simple Model of the Plasma Membrane Organization. Front Cell Dev Biol 2016; 4:106. [PMID: 27747212 PMCID: PMC5040727 DOI: 10.3389/fcell.2016.00106] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/14/2016] [Indexed: 12/29/2022] Open
Abstract
Ever since technologies enabled the characterization of eukaryotic plasma membranes, heterogeneities in the distributions of its constituents were observed. Over the years this led to the proposal of various models describing the plasma membrane organization such as lipid shells, picket-and-fences, lipid rafts, or protein islands, as addressed in numerous publications and reviews. Instead of emphasizing on one model we in this review give a brief overview over current models and highlight how current experimental work in one or the other way do not support the existence of a single overarching model. Instead, we highlight the vast variety of membrane properties and components, their influences and impacts. We believe that highlighting such controversial discoveries will stimulate unbiased research on plasma membrane organization and functionality, leading to a better understanding of this essential cellular structure.
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Affiliation(s)
- Jorge Bernardino de la Serna
- Science and Technology Facilities Council, Rutherford Appleton Laboratory, Central Laser Facility, Research Complex at Harwell Harwell, UK
| | - Gerhard J Schütz
- Institute of Applied Physics, Technische Universität Wien Wien, Austria
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford Headley Way, UK
| | - Marek Cebecauer
- Department of Biophysical Chemistry, J.Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences Prague, Czech Republic
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86
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Zhao L, Wang S, Run C, OuYang B, Chou JJ. Specific Lipid Binding of Membrane Proteins in Detergent Micelles Characterized by NMR and Molecular Dynamics. Biochemistry 2016; 55:5317-20. [PMID: 27625145 DOI: 10.1021/acs.biochem.6b00836] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Many membrane proteins bind specifically to lipids as an integral component of their structures. The ability of detergents to support lipid binding is thus an important consideration when solubilizing membrane proteins for structural studies. In particular, the zwitterionic phosphocholine (PC)-based detergents, which have been widely used in solution NMR studies of channels and transporters, are controversial because of their strong solubilization power and thus perceived as more denaturing than nonionic detergents such as the maltosides. Here, we investigate the ability of the mitochondrial ADP/ATP carrier (AAC) to specifically bind cardiolipin, a mitochondrial lipid important for the carrier function, in dodecylphosphocholine (DPC) micelles. We found that in DPC, the AAC specifically binds cardiolipin in a manner consistent with the bound cardiolipins found in the crystal structures of the AAC determined in n-decyl β-d-maltoside. Our results suggest that PC detergent is compatible with specific lipid binding and that PC detergent mixed with the relevant lipid represents a viable solubilization system for NMR studies of membrane proteins.
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Affiliation(s)
- Linlin Zhao
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Institute of Biochemistry and Cell Biology, Shanghai Science Research Center, Chinese Academy of Sciences , Shanghai 200031, China
| | - Shuqing Wang
- School of Pharmacy, Tianjin Medical University , Tianjin 300070, China
| | - Changqing Run
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Institute of Biochemistry and Cell Biology, Shanghai Science Research Center, Chinese Academy of Sciences , Shanghai 200031, China
| | - Bo OuYang
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Institute of Biochemistry and Cell Biology, Shanghai Science Research Center, Chinese Academy of Sciences , Shanghai 200031, China
| | - James J Chou
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Institute of Biochemistry and Cell Biology, Shanghai Science Research Center, Chinese Academy of Sciences , Shanghai 200031, China.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School , Boston, Massachusetts 02115, United States
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87
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Evaluation of diacylphospholipids as boundary lipids for bacteriorhodopsin from structural and functional aspects. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2106-2115. [DOI: 10.1016/j.bbamem.2016.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 06/08/2016] [Accepted: 06/10/2016] [Indexed: 11/18/2022]
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88
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Kucharska I, Liang B, Ursini N, Tamm LK. Molecular Interactions of Lipopolysaccharide with an Outer Membrane Protein from Pseudomonas aeruginosa Probed by Solution NMR. Biochemistry 2016; 55:5061-72. [PMID: 27532487 DOI: 10.1021/acs.biochem.6b00630] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen causing pneumonias that are particularly severe in cystic fibrosis and immunocompromised patients. The outer membrane (OM) of P. aeruginosa is much less permeable to nutrients and other chemical compounds than that of Escherichia coli. The low permeability of the OM, which also contributes to Pseudomonas' significant antibiotic resistance, is augmented by the presence of the outer membrane protein H (OprH). OprH directly interacts with lipopolysaccharides (LPS) that constitute the outer leaflet of the OM and thus contributes to the structural stability of the OM. In this study, we used solution NMR spectroscopy to characterize the interactions between LPS and OprH in molecular detail. NMR chemical shift perturbations observed upon the addition of LPS to OprH in DHPC micelles indicate that this interaction is predominantly electrostatic and localized to the extracellular loops 2 and 3 and a number of highly conserved basic residues near the extracellular barrel rim of OprH. Single-site mutations of these residues were not enough to completely abolish binding, but OprH with cumulative mutations of Lys70, Arg72, and Lys103 no longer binds LPS. The dissociation constant (∼200 μM) measured by NMR is sufficient to efficiently bind LPS to OprH in the OM. This work highlights that solution NMR is suitable to study specific interactions of lipids with integral membrane proteins and provides a detailed molecular model for the interaction of LPS with OprH; i.e., an interaction that contributes to the integrity of the OM of P. aeruginosa under low divalent cation and antibiotic stress conditions. These methods should thus be useful for screening antibiotics that might disrupt OprH-LPS interactions and thereby increase the permeability of the OM of P. aeruginosa.
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Affiliation(s)
- Iga Kucharska
- Center for Membrane and Cell Physiology and Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Charlottesville, Virginia 22908, United States
| | - Binyong Liang
- Center for Membrane and Cell Physiology and Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Charlottesville, Virginia 22908, United States
| | - Nicholas Ursini
- Center for Membrane and Cell Physiology and Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Charlottesville, Virginia 22908, United States
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology and Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Charlottesville, Virginia 22908, United States
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89
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Landreh M, Marty MT, Gault J, Robinson CV. A sliding selectivity scale for lipid binding to membrane proteins. Curr Opin Struct Biol 2016; 39:54-60. [PMID: 27155089 PMCID: PMC5287393 DOI: 10.1016/j.sbi.2016.04.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/11/2016] [Accepted: 04/20/2016] [Indexed: 01/24/2023]
Abstract
Biological membranes form barriers that are essential for cellular integrity and compartmentalisation. Proteins in the membrane have co-evolved with their hydrophobic lipid environment, which serves as a solvent for proteins with very diverse requirements. As a result, their interactions range from non-selective to highly discriminating. Mass spectrometry enables us to monitor how lipids interact with membrane proteins and assess their effects on structure and dynamics. Recent studies illustrate the ability to differentiate specific lipid binding, preferential interactions with lipid subsets, and nonselective annular contacts. Here, we consider the biological implications of different lipid-binding scenarios and propose that binding occurs on a sliding selectivity scale, in line with the view of biological membranes as facilitators of dynamic protein and lipid organization.
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Affiliation(s)
- Michael Landreh
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3QZ, United Kingdom
| | - Michael T Marty
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3QZ, United Kingdom
| | - Joseph Gault
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3QZ, United Kingdom
| | - Carol V Robinson
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3QZ, United Kingdom.
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90
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Unusual Butane- and Pentanetriol-Based Tetraether Lipids in Methanomassiliicoccus luminyensis, a Representative of the Seventh Order of Methanogens. Appl Environ Microbiol 2016; 82:4505-4516. [PMID: 27208108 DOI: 10.1128/aem.00772-16] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 05/10/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED A new clade of archaea has recently been proposed to constitute the seventh methanogenic order, the Methanomassiliicoccales, which is related to the Thermoplasmatales and the uncultivated archaeal clades deep-sea hydrothermal vent Euryarchaeota group 2 and marine group II Euryarchaeota but only distantly related to other methanogens. In this study, we investigated the membrane lipid composition of Methanomassiliicoccus luminyensis, the sole cultured representative of this seventh order. The lipid inventory of M. luminyensis comprises a unique assemblage of novel lipids as well as lipids otherwise typical for thermophilic, methanogenic, or halophilic archaea. For instance, glycerol sesterpanyl-phytanyl diether core lipids found mainly in halophilic archaea were detected, and so were compounds bearing either heptose or methoxylated glycosidic head groups, neither of which have been reported so far for other archaea. The absence of quinones or methanophenazines is consistent with a biochemistry of methanogenesis different from that of the methanophenazine-containing methylotrophic methanogens. The most distinctive characteristic of the membrane lipid composition of M. luminyensis, however, is the presence of tetraether lipids in which one glycerol backbone is replaced by either butane- or pentanetriol, i.e., lipids recently discovered in marine sediments. Butanetriol dibiphytanyl glycerol tetraether (BDGT) constitutes the most abundant core lipid type (>50% relative abundance) in M. luminyensis We have thus identified a source for these unusual orphan lipids. The complementary analysis of diverse marine sediment samples showed that BDGTs are widespread in anoxic layers, suggesting an environmental significance of Methanomassiliicoccales and/or related BDGT producers beyond gastrointestinal tracts. IMPORTANCE Cellular membranes of members of all three domains of life, Archaea, Bacteria, and Eukarya, are largely formed by lipids in which glycerol serves as backbone for the hydrophobic alkyl chains. Recently, however, archaeal tetraether lipids with either butanetriol or pentanetriol as a backbone were identified in marine sediments and attributed to uncultured sediment-dwelling archaea. Here we show that the butanetriol-based dibiphytanyl tetraethers constitute the major lipids in Methanomassiliicoccus luminyensis, currently the only isolate of the novel seventh order of methanogens. Given the absence of these lipids in a large set of archaeal isolates, these compounds may be diagnostic for the Methanomassiliicoccales and/or closely related archaea.
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91
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Hresko RC, Kraft TE, Quigley A, Carpenter EP, Hruz PW. Mammalian Glucose Transporter Activity Is Dependent upon Anionic and Conical Phospholipids. J Biol Chem 2016; 291:17271-82. [PMID: 27302065 PMCID: PMC5016126 DOI: 10.1074/jbc.m116.730168] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Indexed: 01/05/2023] Open
Abstract
The regulated movement of glucose across mammalian cell membranes is mediated by facilitative glucose transporters (GLUTs) embedded in lipid bilayers. Despite the known importance of phospholipids in regulating protein structure and activity, the lipid-induced effects on the GLUTs remain poorly understood. We systematically examined the effects of physiologically relevant phospholipids on glucose transport in liposomes containing purified GLUT4 and GLUT3. The anionic phospholipids, phosphatidic acid, phosphatidylserine, phosphatidylglycerol, and phosphatidylinositol, were found to be essential for transporter function by activating it and stabilizing its structure. Conical lipids, phosphatidylethanolamine and diacylglycerol, enhanced transporter activity up to 3-fold in the presence of anionic phospholipids but did not stabilize protein structure. Kinetic analyses revealed that both lipids increase the kcat of transport without changing the Km values. These results allowed us to elucidate the activation of GLUT by plasma membrane phospholipids and to extend the field of membrane protein-lipid interactions to the family of structurally and functionally related human solute carriers.
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Affiliation(s)
| | | | - Andrew Quigley
- the Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Elisabeth P Carpenter
- the Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Paul W Hruz
- From the Departments of Pediatrics and Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110 and
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92
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Hedger G, Shorthouse D, Koldsø H, Sansom MSP. Free Energy Landscape of Lipid Interactions with Regulatory Binding Sites on the Transmembrane Domain of the EGF Receptor. J Phys Chem B 2016; 120:8154-63. [PMID: 27109430 PMCID: PMC5002933 DOI: 10.1021/acs.jpcb.6b01387] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
![]()
Lipid molecules can
bind to specific sites on integral membrane
proteins, modulating their structure and function. We have undertaken
coarse-grained simulations to calculate free energy profiles for glycolipids
and phospholipids interacting with modulatory sites on the transmembrane
helix dimer of the EGF receptor within a lipid bilayer environment.
We identify lipid interaction sites at each end of the transmembrane
domain and compute interaction free energy profiles for lipids with
these sites. Interaction free energies ranged from ca. −40
to −4 kJ/mol for different lipid species. Those lipids (glycolipid
GM3 and phosphoinositide PIP2) known to modulate EGFR function
exhibit the strongest binding to interaction sites on the EGFR, and
we are able to reproduce the preference for interaction with GM3 over
other glycolipids suggested by experiment. Mutation of amino acid
residues essential for EGFR function reduce the binding free energy
of these key lipid species. The residues interacting with the lipids
in the simulations are in agreement with those suggested by experimental
(mutational) studies. This approach provides a generalizable tool
for characterizing the interactions of lipids that bind to specific
sites on integral membrane proteins.
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Affiliation(s)
- George Hedger
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
| | - David Shorthouse
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom.,MRC Cancer Unit, University of Cambridge , MRC Research Centre, Box 197, Cambridge CB2 0X1, United Kingdom
| | - Heidi Koldsø
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom.,D. E. Shaw Research , 120 West 45th Street, 39th floor, New York, New York 10036, United States
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
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93
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Wessels HJCT, de Almeida NM, Kartal B, Keltjens JT. Bacterial Electron Transfer Chains Primed by Proteomics. Adv Microb Physiol 2016; 68:219-352. [PMID: 27134025 DOI: 10.1016/bs.ampbs.2016.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Electron transport phosphorylation is the central mechanism for most prokaryotic species to harvest energy released in the respiration of their substrates as ATP. Microorganisms have evolved incredible variations on this principle, most of these we perhaps do not know, considering that only a fraction of the microbial richness is known. Besides these variations, microbial species may show substantial versatility in using respiratory systems. In connection herewith, regulatory mechanisms control the expression of these respiratory enzyme systems and their assembly at the translational and posttranslational levels, to optimally accommodate changes in the supply of their energy substrates. Here, we present an overview of methods and techniques from the field of proteomics to explore bacterial electron transfer chains and their regulation at levels ranging from the whole organism down to the Ångstrom scales of protein structures. From the survey of the literature on this subject, it is concluded that proteomics, indeed, has substantially contributed to our comprehending of bacterial respiratory mechanisms, often in elegant combinations with genetic and biochemical approaches. However, we also note that advanced proteomics offers a wealth of opportunities, which have not been exploited at all, or at best underexploited in hypothesis-driving and hypothesis-driven research on bacterial bioenergetics. Examples obtained from the related area of mitochondrial oxidative phosphorylation research, where the application of advanced proteomics is more common, may illustrate these opportunities.
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Affiliation(s)
- H J C T Wessels
- Nijmegen Center for Mitochondrial Disorders, Radboud Proteomics Centre, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands
| | - N M de Almeida
- Institute of Water and Wetland Research, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - B Kartal
- Institute of Water and Wetland Research, Radboud University Nijmegen, Nijmegen, The Netherlands; Laboratory of Microbiology, Ghent University, Ghent, Belgium
| | - J T Keltjens
- Institute of Water and Wetland Research, Radboud University Nijmegen, Nijmegen, The Netherlands.
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94
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Lindhoud S, Carvalho V, Pronk JW, Aubin-Tam ME. SMA-SH: Modified Styrene–Maleic Acid Copolymer for Functionalization of Lipid Nanodiscs. Biomacromolecules 2016; 17:1516-22. [DOI: 10.1021/acs.biomac.6b00140] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Simon Lindhoud
- Department of Bionanoscience,
Kavli Institute of Nanoscience, Delft University of Technology. Lorentzweg
1, Delft 2628 CJ, The Netherlands
| | - Vanessa Carvalho
- Department of Bionanoscience,
Kavli Institute of Nanoscience, Delft University of Technology. Lorentzweg
1, Delft 2628 CJ, The Netherlands
| | - Joachim W. Pronk
- Department of Bionanoscience,
Kavli Institute of Nanoscience, Delft University of Technology. Lorentzweg
1, Delft 2628 CJ, The Netherlands
| | - Marie-Eve Aubin-Tam
- Department of Bionanoscience,
Kavli Institute of Nanoscience, Delft University of Technology. Lorentzweg
1, Delft 2628 CJ, The Netherlands
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95
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Lipid interaction sites on channels, transporters and receptors: Recent insights from molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2390-2400. [PMID: 26946244 DOI: 10.1016/j.bbamem.2016.02.037] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 02/25/2016] [Accepted: 02/28/2016] [Indexed: 11/22/2022]
Abstract
Lipid molecules are able to selectively interact with specific sites on integral membrane proteins, and modulate their structure and function. Identification and characterization of these sites are of importance for our understanding of the molecular basis of membrane protein function and stability, and may facilitate the design of lipid-like drug molecules. Molecular dynamics simulations provide a powerful tool for the identification of these sites, complementing advances in membrane protein structural biology and biophysics. We describe recent notable biomolecular simulation studies which have identified lipid interaction sites on a range of different membrane proteins. The sites identified in these simulation studies agree well with those identified by complementary experimental techniques. This demonstrates the power of the molecular dynamics approach in the prediction and characterization of lipid interaction sites on integral membrane proteins. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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96
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Köberlin MS, Heinz LX, Superti-Furga G. Functional crosstalk between membrane lipids and TLR biology. Curr Opin Cell Biol 2016; 39:28-36. [PMID: 26895312 DOI: 10.1016/j.ceb.2016.01.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 01/20/2016] [Accepted: 01/27/2016] [Indexed: 12/16/2022]
Abstract
Toll-like receptors (TLRs) are important transmembrane proteins of the innate immune system that detect invading pathogens and subsequently orchestrate an immune response. The ensuing inflammatory processes are connected to lipid metabolism at multiple levels. Here, we describe different aspects of how membrane lipids can shape the response of TLRs. Recent reports have uncovered the role of individual lipid species on membrane protein function and mouse models have contributed to the understanding of how changes in lipid metabolism alter TLR signaling, endocytosis, and cytokine secretion. Finally, we discuss the importance of systematic approaches to identify the function of individual lipid species or the composition of membrane lipids in TLR-related processes.
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Affiliation(s)
- Marielle S Köberlin
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Leonhard X Heinz
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria; Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria.
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97
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Stimulation of Na(+),K(+)-ATPase Activity as a Possible Driving Force in Cholesterol Evolution. J Membr Biol 2015; 249:251-9. [PMID: 26715509 DOI: 10.1007/s00232-015-9864-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 12/09/2015] [Indexed: 12/19/2022]
Abstract
Cholesterol is exclusively produced by animals and is present in the plasma membrane of all animal cells. In contrast, the membranes of fungi and plants contain other sterols. To explain the exclusive preference of animal cells for cholesterol, we propose that cholesterol may have evolved to optimize the activity of a crucial protein found in the plasma membrane of all multicellular animals, namely the Na(+),K(+)-ATPase. To test this hypothesis, mirror tree and phylogenetic distribution analyses have been conducted of the Na(+),K(+)-ATPase and 3β-hydroxysterol Δ(24)-reductase (DHCR24), the last enzyme in the Bloch cholesterol biosynthetic pathway. The results obtained support the hypothesis of a co-evolution of the Na(+),K(+)-ATPase and DHCR24. The evolutionary correlation between DHCR24 and the Na(+),K(+)-ATPase was found to be stronger than between DHCR24 and any other membrane protein investigated. The results obtained, thus, also support the hypothesis that cholesterol evolved together with the Na(+),K(+)-ATPase in multicellular animals to support Na(+),K(+)-ATPase activity.
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98
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Abstract
Which properties of the membrane environment are essential for the folding and oligomerization of transmembrane proteins? Because the lipids that surround membrane proteins in situ spontaneously organize into bilayers, it may seem intuitive that interactions with the bilayer provide both hydrophobic and topological constraints that help the protein to achieve a stable and functional three-dimensional structure. However, one may wonder whether folding is actually driven by the membrane environment or whether the folded state just reflects an adaptation of integral proteins to the medium in which they function. Also, apart from the overall transmembrane orientation, might the asymmetry inherent in biosynthesis processes cause proteins to fold to out-of-equilibrium, metastable topologies? Which of the features of a bilayer are essential for membrane protein folding, and which are not? To which extent do translocons dictate transmembrane topologies? Recent data show that many membrane proteins fold and oligomerize very efficiently in media that bear little similarity to a membrane, casting doubt on the essentiality of many bilayer constraints. In the following discussion, we argue that some of the features of bilayers may contribute to protein folding, stability and regulation, but they are not required for the basic three-dimensional structure to be achieved. This idea, if correct, would imply that evolution has steered membrane proteins toward an accommodation to biosynthetic pathways and a good fit into their environment, but that their folding is not driven by the latter or dictated by insertion apparatuses. In other words, the three-dimensional structure of membrane proteins is essentially determined by intramolecular interactions and not by bilayer constraints and insertion pathways. Implications are discussed.
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Affiliation(s)
- Jean-Luc Popot
- Centre National de la Recherche Scientifique/Université Paris-7 UMR 7099 , Institut de Biologie Physico-Chimique (FRC 550), 13, rue Pierre-et-Marie-Curie, F-75005 Paris, France
| | - Donald M Engelman
- Department of Molecular Biophysics and Biochemistry, Yale University , Box 208114, New Haven, Connecticut 06520-8114, United States
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99
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Aryal P, Abd-Wahab F, Bucci G, Sansom MSP, Tucker SJ. Influence of lipids on the hydrophobic barrier within the pore of the TWIK-1 K2P channel. Channels (Austin) 2015; 9:44-9. [PMID: 25487004 PMCID: PMC4594343 DOI: 10.4161/19336950.2014.981987] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Several recent ion channel structures have revealed large side portals, or ‘fenestrations’ at the interface between their transmembrane helices that potentially expose the ion conduction pathway to the lipid core of the bilayer. In a recent study we demonstrated that functional activity of the TWIK-1 K2P channel is influenced by the presence of hydrophobic residues deep within the inner pore. These residues are located near the fenestrations in the TWIK-1 structure and promote dewetting of the pore by forming a hydrophobic barrier to ion conduction. During our previous MD simulations, lipid tails were observed to enter these fenestrations. In this addendum to that study, we investigate lipid contribution to the dewetting process. Our results demonstrate that lipid tails from both the upper and lower leaflets can occupy the fenestrations and partially penetrate into the pore. The lipid tails do not sterically occlude the pore, but there is an inverse correlation between the presence of water within the hydrophobic barrier and the number of lipids tails within the lining of the pore. However, dewetting still occurs in the absence of lipids tails, and pore hydration appears to be determined primarily by those side-chains lining the narrowest part of the pore cavity.
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Affiliation(s)
- Prafulla Aryal
- a Clarendon Laboratory, Department of Physics; University of Oxford ; Oxford , UK
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100
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Moriyama A, Katagiri N, Nishimura S, Takahashi N, Kakeya H. In Vivo Linking of Membrane Lipids and the Anion Transporter Band 3 with Thiourea-modified Amphiphilic Lipid Probes. Sci Rep 2015; 5:17427. [PMID: 26616474 PMCID: PMC4663539 DOI: 10.1038/srep17427] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/29/2015] [Indexed: 12/23/2022] Open
Abstract
Membrane proteins interact with membrane lipids for their structural stability and proper function. However, lipid–protein interactions are poorly understood at a molecular level especially in the live cell membrane, due to current limitations in methodology. Here, we report that amphiphilic lipid probes can be used to link membrane lipids and membrane proteins in vivo. Cholesterol and a phospholipid were both conjugated to a fluorescent tag through a linker containing thiourea. In the erythrocyte, the cholesterol probe fluorescently tagged the anion transporter band 3 via thiourea. Tagging by the cholesterol probe, but not by the phospholipid probe, was competitive with an anion transporter inhibitor, implying the presence of a specific binding pocket for cholesterol in this ~100 kDa protein. This method could prove an effective strategy for analyzing lipid–protein interactions in vivo in the live cell membrane.
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Affiliation(s)
- Akihiro Moriyama
- Department of System Chemotherapy and Molecular Sciences, Division of Bioinformatics and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Naohiro Katagiri
- Department of System Chemotherapy and Molecular Sciences, Division of Bioinformatics and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shinichi Nishimura
- Department of System Chemotherapy and Molecular Sciences, Division of Bioinformatics and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Nobuaki Takahashi
- Department of System Chemotherapy and Molecular Sciences, Division of Bioinformatics and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hideaki Kakeya
- Department of System Chemotherapy and Molecular Sciences, Division of Bioinformatics and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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