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Roberts BS, Satpute-Krishnan P. The many hats of transmembrane emp24 domain protein TMED9 in secretory pathway homeostasis. Front Cell Dev Biol 2023; 10:1096899. [PMID: 36733337 PMCID: PMC9888432 DOI: 10.3389/fcell.2022.1096899] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 12/29/2022] [Indexed: 01/18/2023] Open
Abstract
The secretory pathway is an intracellular highway for the vesicular transport of newly synthesized proteins that spans the endoplasmic reticulum (ER), Golgi, lysosomes and the cell surface. A variety of cargo receptors, chaperones, and quality control proteins maintain the smooth flow of cargo along this route. Among these is vesicular transport protein TMED9, which belongs to the p24/transmembrane emp24 domain (TMED) family of proteins, and is expressed across vertebrate species. The TMED family is comprised of structurally-related type I transmembrane proteins with a luminal N-terminal Golgi-dynamics domain, a luminal coiled-coil domain, a transmembrane domain and a short cytosolic C-terminal tail that binds COPI and COPII coat proteins. TMED9, like other members of the TMED family, was first identified as an abundant constituent of the COPI and COPII coated vesicles that mediate traffic between the ER and the Golgi. TMED9 is typically purified in hetero-oligomers together with TMED family members, suggesting that it may function as part of a complex. Recently, TMED family members have been discovered to play various roles in secretory pathway homeostasis including secreted protein processing, quality control and degradation of misfolded proteins, and post-Golgi trafficking. In particular, TMED9 has been implicated in autophagy, lysosomal sorting, viral replication and cancer, which we will discuss in this Mini-Review.
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Scrima S, Tiberti M, Campo A, Corcelle-Termeau E, Judith D, Foged MM, Clemmensen KKB, Tooze SA, Jäättelä M, Maeda K, Lambrughi M, Papaleo E. Unraveling membrane properties at the organelle-level with LipidDyn. Comput Struct Biotechnol J 2022; 20:3604-3614. [PMID: 35860415 PMCID: PMC9283888 DOI: 10.1016/j.csbj.2022.06.054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/23/2022] [Accepted: 06/25/2022] [Indexed: 12/22/2022] Open
Abstract
Lipidomics of organelles could be used to design models for molecular simulations. The bottleneck is the analysis and rationalization of the data from simulations. LipidDyn is an automated pipeline to streamline the analyses of lipid bilayers. LipidDyn allows to collect analysis in a non-time-consuming and reproducible manner. We applied LipidDyn to different case studies to illustrate its potential.
Cellular membranes are formed from different lipids in various amounts and proportions depending on the subcellular localization. The lipid composition of membranes is sensitive to changes in the cellular environment, and its alterations are linked to several diseases. Lipids not only form lipid-lipid interactions but also interact with other biomolecules, including proteins. Molecular dynamics (MD) simulations are a powerful tool to study the properties of cellular membranes and membrane-protein interactions on different timescales and resolutions. Over the last few years, software and hardware for biomolecular simulations have been optimized to routinely run long simulations of large and complex biological systems. On the other hand, high-throughput techniques based on lipidomics provide accurate estimates of the composition of cellular membranes at the level of subcellular compartments. Lipidomic data can be analyzed to design biologically relevant models of membranes for MD simulations. Similar applications easily result in a massive amount of simulation data where the bottleneck becomes the analysis of the data. In this context, we developed LipidDyn, a Python-based pipeline to streamline the analyses of MD simulations of membranes of different compositions. Once the simulations are collected, LipidDyn provides average properties and time series for several membrane properties such as area per lipid, thickness, order parameters, diffusion motions, lipid density, and lipid enrichment/depletion. The calculations exploit parallelization, and the pipeline includes graphical outputs in a publication-ready form. We applied LipidDyn to different case studies to illustrate its potential, including membranes from cellular compartments and transmembrane protein domains. LipidDyn is available free of charge under the GNU General Public License from https://github.com/ELELAB/LipidDyn.
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Affiliation(s)
- Simone Scrima
- Cancer Structural Biology, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, 2100 Copenhagen, Denmark.,Cancer Systems Biology, Section for Bioinformatics, Department of Health and Technology, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Matteo Tiberti
- Cancer Structural Biology, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, 2100 Copenhagen, Denmark
| | - Alessia Campo
- Cancer Structural Biology, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, 2100 Copenhagen, Denmark
| | - Elisabeth Corcelle-Termeau
- Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, 2100 Copenhagen, Denmark
| | - Delphine Judith
- Institut Cochin, Inserm U1016-CNRS, UMR8104, Université de Paris, Paris, France
| | - Mads Møller Foged
- Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, 2100 Copenhagen, Denmark
| | | | - Sharon A Tooze
- Molecular Cell Biology of Autophagy Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Marja Jäättelä
- Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, 2100 Copenhagen, Denmark.,Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Kenji Maeda
- Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, 2100 Copenhagen, Denmark
| | - Matteo Lambrughi
- Cancer Structural Biology, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, 2100 Copenhagen, Denmark
| | - Elena Papaleo
- Cancer Structural Biology, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, 2100 Copenhagen, Denmark.,Cancer Systems Biology, Section for Bioinformatics, Department of Health and Technology, Technical University of Denmark, 2800 Lyngby, Denmark
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Salnikov E, Aisenbrey C, Bechinger B. Lipid saturation and head group composition have a pronounced influence on the membrane insertion equilibrium of amphipathic helical polypeptides. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183844. [PMID: 34954200 DOI: 10.1016/j.bbamem.2021.183844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 10/19/2022]
Abstract
The histidine-rich peptides of the LAH4 family were designed using cationic antimicrobial peptides such as magainin and PGLa as templates. The LAH4 amphipathic helical sequences exhibit a multitude of interesting biological properties such as antimicrobial activity, cell penetration of a large variety of cargo and lentiviral transduction enhancement. The parent peptide associates with lipid bilayers where it changes from an orientation along the membrane interface into a transmembrane configuration in a pH-dependent manner. Here we show that LAH4 adopts a transmembrane configuration in fully saturated DMPC membranes already at pH 3.5, i.e. much below the pKa of the histidines whereas the transition pH in POPC correlates closely with histidine neutralization. In contrast in POPG membranes the in-planar configuration is stabilized by about one pH unit. The differences in pH can be converted into energetic contributions for the in-plane to transmembrane transition equilibrium, where the shift in the transition pH due to lipid saturation corresponds to energies which are otherwise obtained by the exchange of several cationic with hydrophobic residues. A similar dependence on lipid saturation has also been observed when the PGLa and magainin antimicrobial peptides interact within lipid bilayers suggesting that the quantitative evaluation presented in this paper also applies to other membrane polypeptides.
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Affiliation(s)
- Evgeniy Salnikov
- University of Strasbourg/CNRS, UMR7177 Chemistry Institute, Membrane Biophysics and NMR, Strasbourg, France
| | - Christopher Aisenbrey
- University of Strasbourg/CNRS, UMR7177 Chemistry Institute, Membrane Biophysics and NMR, Strasbourg, France
| | - Burkhard Bechinger
- University of Strasbourg/CNRS, UMR7177 Chemistry Institute, Membrane Biophysics and NMR, Strasbourg, France; Institut Universitaire de France, France.
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Aisenbrey C, Rifi O, Bechinger B. Structure, membrane topology and influence of cholesterol of the membrane proximal region: transmembrane helical anchor sequence of gp41 from HIV. Sci Rep 2020; 10:22278. [PMID: 33335248 PMCID: PMC7746737 DOI: 10.1038/s41598-020-79327-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 11/30/2020] [Indexed: 11/13/2022] Open
Abstract
During the first steps of HIV infection the Env subunit gp41 is thought to establish contact between the membranes and to be the main driver of fusion. Here we investigated in liquid crystalline membranes the structure and cholesterol recognition of constructs made of a gp41 external region carrying a cholesterol recognition amino acid consensus (CRAC) motif and a hydrophobic membrane anchoring sequence. CD- und ATR-FTIR spectroscopies indicate that the constructs adopt a high degree of helical secondary structure in membrane environments. Furthermore, 15N and 2H solid-state NMR spectra of gp41 polypeptides reconstituted into uniaxially oriented bilayers agree with the CRAC domain being an extension of the transmembrane helix. Upon addition of cholesterol the CRAC NMR spectra remain largely unaffected when being associated with the native gp41 transmembrane sequence but its topology changes when anchored in the membrane by a hydrophobic model sequence. The 2H solid-state NMR spectra of deuterated cholesterol are indicative of a stronger influence of the model sequence on this lipid when compared to the native gp41 sequence. These observations are suggestive of a strong coupling between the transmembrane and the membrane proximal region of gp41 possibly enforced by oligomerization of the transmembrane helical region.
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Affiliation(s)
- Christopher Aisenbrey
- Institut de chimie de Strasbourg, UMR7177, University of Strasbourg/CNRS, 4, Rue Blaise Pascal, 67070, Strasbourg, France
| | - Omar Rifi
- Institut de chimie de Strasbourg, UMR7177, University of Strasbourg/CNRS, 4, Rue Blaise Pascal, 67070, Strasbourg, France
| | - Burkhard Bechinger
- Institut de chimie de Strasbourg, UMR7177, University of Strasbourg/CNRS, 4, Rue Blaise Pascal, 67070, Strasbourg, France.
- Institut Universitaire de France, Paris, France.
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Weber DK, Veglia G. A theoretical assessment of structure determination of multi-span membrane proteins by oriented sample solid-state NMR spectroscopy. Aust J Chem 2020; 73:246-251. [PMID: 33162560 DOI: 10.1071/ch19307] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Oriented sample solid state NMR (OS-ssNMR) spectroscopy allows direct determination of the structure and topology of membrane proteins reconstituted into aligned lipid bilayers. While OS-ssNMR theoretically has no upper size limit, its application to multi-span membrane proteins has not been established since most studies have been restricted to single or dual span proteins and peptides. Here, we present a critical assessment of the application of this method to multi-span membrane proteins. We used molecular dynamics simulations to back-calculate [15N-1H] separated local field (SLF) spectra from a G protein-coupled receptor (GPCR) and show that fully resolved spectra can be obtained theoretically for a multi-span membrane protein with currently achievable resonance linewidths.
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Affiliation(s)
- Daniel K Weber
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.,Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
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Abstract
Regulated transport through the secretory pathway is essential for embryonic development and homeostasis. Disruptions in this process impact cell fate, differentiation and survival, often resulting in abnormalities in morphogenesis and in disease. Several congenital malformations are caused by mutations in genes coding for proteins that regulate cargo protein transport in the secretory pathway. The severity of mutant phenotypes and the unclear aetiology of transport protein-associated pathologies have motivated research on the regulation and mechanisms through which these proteins contribute to morphogenesis. This review focuses on the role of the p24/transmembrane emp24 domain (TMED) family of cargo receptors in development and disease.
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Salnikov ES, Aisenbrey C, Pokrandt B, Brügger B, Bechinger B. Structure, Topology, and Dynamics of Membrane-Inserted Polypeptides and Lipids by Solid-State NMR Spectroscopy: Investigations of the Transmembrane Domains of the DQ Beta-1 Subunit of the MHC II Receptor and of the COP I Protein p24. Front Mol Biosci 2019; 6:83. [PMID: 31608287 PMCID: PMC6769064 DOI: 10.3389/fmolb.2019.00083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/23/2019] [Indexed: 01/04/2023] Open
Abstract
MHC class II receptors carry important function in adaptive immunity and their malfunctioning is associated with diabetes type I, chronic inflammatory diseases and other autoimmune diseases. The protein assembles from the DQ alpha-1 and DQ beta-1 subunits where the transmembrane domains of these type I membrane proteins have been shown to be involved in homo- and heterodimer formation. Furthermore, the DQ alpha 1 chain carries a sequence motif that has been first identified in the context of p24, a protein involved in the formation of COPI vesicles of the intracellular transport machinery, to specifically interact with sphingomyelin-C18 (SM-C18). Here we investigated the membrane interactions and dynamics of DQ beta-1 in liquid crystalline POPC phospholipid bilayers by oriented 15N solid-state NMR spectroscopy. The 15N resonances are indicative of a helical tilt angle of the membrane anchor sequence around 20°. Two populations can be distinguished by their differential dynamics probably corresponding the DQ beta-1 mono- and homodimer. Whereas, this equilibrium is hardly affected by the addition of 5 mole% SM-C18 a single population is visible in DMPC lipid bilayers suggesting that the lipid saturation is an important parameter. Furthermore, the DQ alpha-1, DQ beta-1 and p24 transmembrane helical domains were reconstituted into POPC or POPC/SM-C18 lipid bilayers where the fatty acyl chain of either the phosphatidylcholine or of the sphingolipid have been deuterated. Interestingly in the presence of both sphingolipid and polypeptide a strong decrease in the innermost membrane order of the POPC palmitoyl chain is observed, an effect that is strongest for DQ beta-1. In contrast, for the first time the polypeptide interactions were monitored by deuteration of the stearoyl chain of SM-C18. The resulting 2H solid-state NMR spectra show an increase in order for p24 and DQ alpha-1 which both carry the SM recognition motif. Thereby the data are suggestive that SM-C18 together with the transmembrane domains form structures imposing positive curvature strain on the surrounding POPC lipids. This effect is attenuated when SM-C18 is recognized by the protein.
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Affiliation(s)
- Evgeniy S Salnikov
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, Strasbourg, France
| | | | - Bianca Pokrandt
- Biochemiezentrum der Universität Heidelberg, Heidelberg, Germany
| | - Britta Brügger
- Biochemiezentrum der Universität Heidelberg, Heidelberg, Germany
| | - Burkhard Bechinger
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, Strasbourg, France
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Aisenbrey C, Salnikov ES, Bechinger B. Solid-State NMR Investigations of the MHC II Transmembrane Domains: Topological Equilibria and Lipid Interactions. J Membr Biol 2019; 252:371-384. [PMID: 31187155 DOI: 10.1007/s00232-019-00071-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 05/25/2019] [Indexed: 10/26/2022]
Abstract
The major histocompatibility complex class II (MHC II) membrane proteins are key players in the adaptive immune response. An aberrant function of these molecules is associated with a large number of autoimmune diseases such as diabetes type I and chronic inflammatory diseases. The MHC class II is assembled from DQ alpha 1 and DQ beta 1 which come together as a heterodimer through GXXXG-mediated protein-protein interactions and a highly specific protein-sphingomyelin-C18 interaction motif located on DQA1. This association can have important consequences in regulating the function of these membrane proteins. Here, we investigated the structure and topology of the DQA1 and DQB1 transmembrane helical domains by CD-, oriented 2H and 15N solid-state NMR spectroscopies. The spectra at peptide-to-lipid ratios of 0.5 to 2 mol% are indicative of a topological equilibrium involving a helix crossing the membrane with a tilt angle of about 20° and another transmembrane topology with around 30° tilt. The latter is probably representing a dimer. Furthermore, at the lowest peptide-to-lipid ratio, a third polypeptide population becomes obvious. Interestingly, the DQB1 and to a lesser extent the DQA1 transmembrane helical domains exhibit a strong fatty acyl chain disordering effect on the inner segments of the 2H-labelled palmitoyl chain of POPC bilayers. This phosphatidylcholine disordering requires the presence of sphingomyelin-C18 suggesting that the ensemble of transmembrane polypeptide and sphingolipid exerts positive curvature strain.
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Affiliation(s)
- Christopher Aisenbrey
- Institut de Chimie, Université de Strasbourg/CNRS, UMR7177, 4, Rue Blaise Pascal, 67070, Strasbourg, France
| | - Evgeniy S Salnikov
- Institut de Chimie, Université de Strasbourg/CNRS, UMR7177, 4, Rue Blaise Pascal, 67070, Strasbourg, France
| | - Burkhard Bechinger
- Institut de Chimie, Université de Strasbourg/CNRS, UMR7177, 4, Rue Blaise Pascal, 67070, Strasbourg, France.
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