1
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Rouchidane Eyitayo A, Daury L, Priault M, Manon S. The membrane insertion of the pro-apoptotic protein Bax is a Tom22-dependent multi-step process: a study in nanodiscs. Cell Death Discov 2024; 10:335. [PMID: 39043635 PMCID: PMC11266675 DOI: 10.1038/s41420-024-02108-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 07/11/2024] [Accepted: 07/17/2024] [Indexed: 07/25/2024] Open
Abstract
Membrane insertion of the pro-apoptotic protein Bax was investigated by setting up cell-free synthesis of full-length Bax in the presence of pre-formed nanodiscs. While Bax was spontaneously poorly inserted in nanodiscs, co-synthesis with the mitochondrial receptor Tom22 stimulated Bax membrane insertion. The initial interaction of Bax with the lipid bilayer exposed the hydrophobic GALLL motif in Hα1 leading to Bax precipitation through hydrophobic interactions. The same motif was recognized by Tom22, triggering conformational changes leading to the extrusion and the ensuing membrane insertion of the C-terminal hydrophobic Hα9. Tom22 was also required for Bax-membrane insertion after Bax was activated either by BH3-activators or by its release from Bcl-xL by WEHI-539. The effect of Tom22 was impaired by D154Y substitution in Bax-Hα7 and T174P substitution in Bax-Hα9, which are found in several tumors. Conversely, a R9E substitution promoted a spontaneous insertion of Bax in nanodiscs, in the absence of Tom22. Both Tom22-activated Bax and BaxR9E alone permeabilized liposomes to dextran-10kDa and formed ~5-nm-diameter pores in nanodiscs. The concerted regulation of Bax membrane insertion by Tom22 and BH3-activators is discussed.
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Affiliation(s)
| | - Laetitia Daury
- CNRS, Université de Bordeaux, UMR 5248, CBMN, Pessac, France
| | - Muriel Priault
- CNRS, Université de Bordeaux, UMR 5095, IBGC, Bordeaux, France
| | - Stéphen Manon
- CNRS, Université de Bordeaux, UMR 5095, IBGC, Bordeaux, France.
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2
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Zhao C. Limitations in membrane protein structure determination by lipid nanodiscs. Trends Biochem Sci 2024; 49:475-476. [PMID: 38538407 DOI: 10.1016/j.tibs.2024.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 06/09/2024]
Abstract
Lipid nanodiscs are popular mimetics of biological membranes for determining membrane protein structures. However, a recent study revealed that the choice of nanodisc scaffold directly influenced the structure of an ion channel. This finding prompts us to be cautious and calls for improved membrane mimetics for structure determination.
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Affiliation(s)
- Chen Zhao
- Department of Biochemistry and Molecular Biology, University of Florida, College of Medicine, Gainesville, FL 32611, USA.
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3
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Woubshete M, Cioccolo S, Byrne B. Advances in Membrane Mimetic Systems for Manipulation and Analysis of Membrane Proteins: Detergents, Polymers, Lipids and Scaffolds. Chempluschem 2024; 89:e202300678. [PMID: 38315323 DOI: 10.1002/cplu.202300678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/31/2024] [Accepted: 02/05/2024] [Indexed: 02/07/2024]
Abstract
Extracting membrane proteins from the hydrophobic environment of the biological membrane, in a physiologically relevant and stable state, suitable for downstream analysis remains a challenge. The traditional route to membrane protein extraction has been to use detergents and the last 15 years or so have seen a veritable explosion in the development of novel detergents with improved properties, making them more suitable for individual proteins and specific applications. There have also been significant advances in the development of encapsulation of membrane proteins in lipid based nanodiscs, either directly from the native membrane using polymers allowing effective capture of the protein and protein-associated membrane lipids, or via reconstitution of detergent extracted and purified protein into nanodiscs of defined lipid composition. All of these advances have been successfully applied to the study of membrane proteins via a range of techniques and there have been some spectacular membrane protein structures solved. In addition, the first detailed structural and biophysical analyses of membrane proteins retained within a biological membrane have been reported. Here we summarise and review the recent advances with respect to these new agents and systems for membrane protein extraction, reconstitution and analysis.
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Affiliation(s)
- Menebere Woubshete
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Sara Cioccolo
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
- Department of Chemistry, Imperial College London, White City, London, W12 0BZ, United Kingdom
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
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4
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Schaefer KG, Russell CM, Pyron RJ, Conley EA, Barrera FN, King GM. Polymerization mechanism of the Candida albicans virulence factor candidalysin. J Biol Chem 2024; 300:107370. [PMID: 38750794 PMCID: PMC11193009 DOI: 10.1016/j.jbc.2024.107370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/16/2024] [Accepted: 05/06/2024] [Indexed: 06/11/2024] Open
Abstract
Candida albicans is a commensal fungus that can cause epithelial infections and life-threatening invasive candidiasis. The fungus secretes candidalysin (CL), a peptide that causes cell damage and immune activation by permeation of epithelial membranes. The mechanism of CL action involves strong peptide assembly into polymers in solution. The free ends of linear CL polymers can join, forming loops that become pores upon binding to membranes. CL polymers constitute a therapeutic target for candidiasis, but little is known about CL self-assembly in solution. Here, we examine the assembly mechanism of CL in the absence of membranes using complementary biophysical tools, including a new fluorescence polymerization assay, mass photometry, and atomic force microscopy. We observed that CL assembly is slow, as tracked with the fluorescent marker C-laurdan. Single-molecule methods showed that CL polymerization involves a convolution of four processes. Self-assembly begins with the formation of a basic subunit, thought to be a CL octamer that is the polymer seed. Polymerization proceeds via the addition of octamers, and as polymers grow they can curve and form loops. Alternatively, secondary polymerization can occur and cause branching. Interplay between the different rates determines the distribution of CL particle types, indicating a kinetic control mechanism. This work elucidates key physical attributes underlying CL self-assembly which may eventually evoke pharmaceutical development.
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Affiliation(s)
| | - Charles M Russell
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee
| | - Robert J Pyron
- Genome Science and Technology, University of Tennessee, Knoxville, Tennessee
| | - Elizabeth A Conley
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri
| | - Francisco N Barrera
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee.
| | - Gavin M King
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri; Department of Biochemistry, University of Missouri, Columbia, Missouri.
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5
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Unwin N. Influence of lipid bilayer on the structure of the muscle-type nicotinic acetylcholine receptor. Proc Natl Acad Sci U S A 2024; 121:e2319913121. [PMID: 38683987 PMCID: PMC11087746 DOI: 10.1073/pnas.2319913121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 03/22/2024] [Indexed: 05/02/2024] Open
Abstract
The muscle-type nicotinic acetylcholine receptor is a transmitter-gated ion channel residing in the plasma membrane of electrocytes and striated muscle cells. It is present predominantly at synaptic junctions, where it effects rapid depolarization of the postsynaptic membrane in response to acetylcholine released into the synaptic cleft. Previously, cryo-EM of intact membrane from Torpedo revealed that the lipid bilayer surrounding the junctional receptor has a uniquely asymmetric and ordered structure, due to a high concentration of cholesterol. It is now shown that this special lipid environment influences the transmembrane (TM) folding of the protein. All five submembrane MX helices of the membrane-intact junctional receptor align parallel to the surface of the cholesterol-ordered lipids in the inner leaflet of the bilayer; also, the TM helices in the outer leaflet are splayed apart. However in the structure obtained from the same protein after extraction and incorporation in nanodiscs, the MX helices do not align to a planar surface, and the TM helices arrange compactly in the outer leaflet. Realignment of the MX helices of the nanodisc-solved structure to a planar surface converts their adjoining TM helices into an obligatory splayed configuration, characteristic of the junctional receptor. Thus, the form of the receptor sustained by the special lipid environment of the synaptic junction is the one that mediates fast synaptic transmission; whereas, the nanodisc-embedded protein may be like the extrajunctional form, existing in a disordered lipid environment.
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Affiliation(s)
- Nigel Unwin
- Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
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6
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Thakur N, Ray AP, Jin B, Afsharian NP, Lyman E, Gao ZG, Jacobson KA, Eddy MT. Membrane mimetic-dependence of GPCR energy landscapes. Structure 2024; 32:523-535.e5. [PMID: 38401537 PMCID: PMC11069452 DOI: 10.1016/j.str.2024.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 01/03/2024] [Accepted: 01/30/2024] [Indexed: 02/26/2024]
Abstract
We leveraged variable-temperature 19F-NMR spectroscopy to compare the conformational equilibria of the human A2A adenosine receptor (A2AAR), a class A G protein-coupled receptor (GPCR), across a range of temperatures ranging from lower temperatures typically employed in 19F-NMR experiments to physiological temperature. A2AAR complexes with partial agonists and full agonists showed large increases in the population of a fully active conformation with increasing temperature. NMR data measured at physiological temperature were more in line with functional data. This was pronounced for complexes with partial agonists, where the population of active A2AAR was nearly undetectable at lower temperature but became evident at physiological temperature. Temperature-dependent behavior of complexes with either full or partial agonists exhibited a pronounced sensitivity to the specific membrane mimetic employed. Cellular signaling experiments correlated with the temperature-dependent conformational equilibria of A2AAR in lipid nanodiscs but not in some detergents, underscoring the importance of the membrane environment in studies of GPCR function.
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Affiliation(s)
- Naveen Thakur
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA
| | - Arka Prabha Ray
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA
| | - Beining Jin
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA
| | | | - Edward Lyman
- Department of Physics and Astronomy, University of Delaware, Newark, DE, USA
| | - Zhan-Guo Gao
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kenneth A Jacobson
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Matthew T Eddy
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA.
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7
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Ayub H, Murray RJ, Kuyler GC, Napier-Khwaja F, Gunner J, Dafforn TR, Klumperman B, Poyner DR, Wheatley M. GPCRs in the round: SMA-like copolymers and SMALPs as a platform for investigating GPCRs. Arch Biochem Biophys 2024; 754:109946. [PMID: 38395122 DOI: 10.1016/j.abb.2024.109946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/21/2024] [Accepted: 02/20/2024] [Indexed: 02/25/2024]
Abstract
G-protein-coupled receptors (GPCRs) are the largest family of membrane proteins, regulate a plethora of physiological responses and are the therapeutic target for 30-40% of clinically-prescribed drugs. They are integral membrane proteins deeply embedded in the plasma membrane where they activate intracellular signalling via coupling to G-proteins and β-arrestin. GPCRs are in intimate association with the bilayer lipids and that lipid environment regulates the signalling functions of GPCRs. This complex lipid 'landscape' is both heterogeneous and dynamic. GPCR function is modulated by bulk membrane properties including membrane fluidity, microdomains, curvature, thickness and asymmetry but GPCRs are also regulated by specific lipid:GPCR binding, including cholesterol and anionic lipids. Understanding the molecular mechanisms whereby GPCR signalling is regulated by lipids is a very active area of research currently. A major advance in membrane protein research in recent years was the application of poly(styrene-co-maleic acid) (SMA) copolymers. These spontaneously generate SMA lipid particles (SMALPs) encapsulating membrane protein in a nano-scale disc of cell membrane, thereby removing the historical need for detergent and preserving lipid:GPCR interaction. The focus of this review is how GPCR-SMALPs are increasing our understanding of GPCR structure and function at the molecular level. Furthermore, an increasing number of 'second generation' SMA-like copolymers have been reported recently. These are reviewed from the context of increasing our understanding of GPCR molecular mechanisms. Moreover, their potential as a novel platform for downstream biophysical and structural analyses is assessed and looking ahead, the translational application of SMA-like copolymers to GPCR drug discovery programmes in the future is considered.
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Affiliation(s)
- Hoor Ayub
- Centre for Health and Life Sciences, Coventry University, Coventry, CV1 2DS, UK.
| | - Rebecca J Murray
- Centre for Health and Life Sciences, Coventry University, Coventry, CV1 2DS, UK; Department of Chemistry and Polymer Sciences, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Gestél C Kuyler
- Centre for Health and Life Sciences, Coventry University, Coventry, CV1 2DS, UK; Department of Chemistry and Polymer Sciences, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | | | - Joseph Gunner
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Tim R Dafforn
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Bert Klumperman
- Department of Chemistry and Polymer Sciences, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - David R Poyner
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Mark Wheatley
- Centre for Health and Life Sciences, Coventry University, Coventry, CV1 2DS, UK; Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
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8
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Janata M, Gupta S, Čadová E, Angelisová P, Krishnarjuna B, Ramamoorthy A, Hořejší V, Raus V. Sulfonated polystyrenes: pH and Mg 2+-insensitive amphiphilic copolymers for detergent-free membrane protein isolation. Eur Polym J 2023; 198:112412. [PMID: 37780808 PMCID: PMC10538444 DOI: 10.1016/j.eurpolymj.2023.112412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Amphiphilic polymers are increasingly applied in the detergent-free isolation and functional studies of membrane proteins. However, the carboxylate group present in the structure of many popular variants, such as styrene-maleic acid (SMA) copolymers, brings limitations in terms of polymer sensitivity to precipitation at acidic pH or in the presence of divalent metal cations. Herein, we addressed this problem by replacing carboxylate with the more acidic sulfonate groups. To this end, we synthesized a library of amphiphilic poly[styrene-co-(sodium 4-styrene sulfonate)] copolymers (termed SSS), differing in their molecular weight and overall polarity. Using model cell membranes (Jurkat), we identified two copolymer compositions (SSS-L30 and SSS-L36) that solubilized membranes to an extent similar to SMA. Interestingly, the density gradient ultracentrifugation/SDS-PAGE/Western blotting analysis of cell lysates revealed a distribution of studied membrane proteins in the gradient fractions that was different than for SMA-solubilized membranes. Importantly, unlike SMA, the SSS copolymers remained soluble at low pH and in the presence of Mg2+ ions. Additionally, the solubilization of DMPC liposomes by the lead materials was studied by turbidimetry, DLS, SEC, and high-resolution NMR, revealing, for SSS-L36, the formation of stable particles (nanodiscs), facilitated by the direct hydrophobic interaction of the copolymer phenyls with lipid acyl chains.
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Affiliation(s)
- Miroslav Janata
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic
| | - Sachin Gupta
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic
| | - Eva Čadová
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic
| | - Pavla Angelisová
- Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Bankala Krishnarjuna
- Biophysics Program, Department of Chemistry, Macromolecular Science and Engineering, Biomedical Engineering, Michigan Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics Program, Department of Chemistry, Macromolecular Science and Engineering, Biomedical Engineering, Michigan Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Václav Hořejší
- Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Vladimír Raus
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic
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9
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Necelis M, McDermott C, Belcher Dufrisne M, Baryiames C, Columbus L. Solution NMR investigations of integral membrane proteins: Challenges and innovations. Curr Opin Struct Biol 2023; 82:102654. [PMID: 37542910 PMCID: PMC10529709 DOI: 10.1016/j.sbi.2023.102654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/08/2023] [Accepted: 06/20/2023] [Indexed: 08/07/2023]
Abstract
Compared to soluble protein counterparts, the understanding of membrane protein stability, solvent interactions, and function are not as well understood. Recent advancements in labeling, expression, and stabilization of membrane proteins have enabled solution nuclear magnetic resonance spectroscopy to investigate membrane protein conformational states, ligand binding, lipid interactions, stability, and folding. This review highlights these advancements and new understandings and provides examples of recent applications.
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Affiliation(s)
- Matthew Necelis
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Connor McDermott
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | | | | | - Linda Columbus
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA.
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10
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Odenkirk MT, Zhang G, Marty MT. Do Nanodisc Assembly Conditions Affect Natural Lipid Uptake? JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:2006-2015. [PMID: 37524089 PMCID: PMC10528108 DOI: 10.1021/jasms.3c00170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Lipids play critical roles in modulating membrane protein structure, interactions, and activity. Nanodiscs provide a tunable membrane mimetic that can model these endogenous protein-lipid interactions in a nanoscale lipid bilayer. However, most studies of membrane proteins with nanodiscs use simple synthetic lipids that lack the headgroup and fatty acyl diversity of natural extracts. Prior research has successfully used natural lipid extracts in nanodiscs that more accurately mimic natural environments, but it is not clear how nanodisc assembly may bias the incorporated lipid profiles. Here, we applied lipidomics to investigate how nanodisc assembly conditions affect the profile of natural lipids in nanodiscs. Specifically, we tested the effects of assembly temperature, nanodisc size, and lipidome extract complexity. Globally, our analysis demonstrates that the lipids profiles are largely unaffected by nanodisc assembly conditions. However, a few notable changes emerged within individual lipids and lipid classes, such as a differential incorporation of cardiolipin and phosphatidylglycerol lipids from the E. coli polar lipid extract at different temperatures. Conversely, some classes of brain lipids were affected by nanodisc size at higher temperatures. Collectively, these data enable the application of nanodiscs to study protein-lipid interactions in complex lipid environments.
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Affiliation(s)
- Melanie T. Odenkirk
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
- Bio5 Institute, University of Arizona, Tucson, AZ
| | - Guozhi Zhang
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
| | - Michael T. Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
- Bio5 Institute, University of Arizona, Tucson, AZ
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11
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Tripathy M, Srivastava A. Lipid packing in biological membranes governs protein localization and membrane permeability. Biophys J 2023; 122:2727-2743. [PMID: 37254482 PMCID: PMC10397809 DOI: 10.1016/j.bpj.2023.05.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 04/18/2023] [Accepted: 05/25/2023] [Indexed: 06/01/2023] Open
Abstract
Plasma membrane (PM) heterogeneity has long been implicated in various cellular functions. However, mechanistic principles governing functional regulations of lipid environment are not well understood due to the inherent complexities associated with the relevant length and timescales that limit both direct experimental measurements and their interpretation. In this context, computer simulations hold immense potential to investigate molecular-level interactions and mechanisms that lead to PM heterogeneity and its functions. Herein, we investigate spatial and dynamic heterogeneity in model membranes with coexisting liquid ordered and liquid disordered phases and characterize the membrane order in terms of the local topological changes in lipid environment using the nonaffine deformation framework. Furthermore, we probe the packing defects in these membranes, which can be considered as the conjugate of membrane order assessed in terms of the nonaffine parameter. In doing so, we formalize the connection between membrane packing and local membrane order and use that to explore the mechanistic principles behind their functions. Our observations suggest that heterogeneity in mixed phase membranes is a consequence of local lipid topology and its temporal evolution, which give rise to disparate lipid packing in ordered and disordered domains. This in turn governs the distinct nature of packing defects in these domains that can play a crucial role in preferential localization of proteins in mixed phase membranes. Furthermore, we observe that lipid packing also leads to contrasting distribution of free volume in the membrane core region in ordered and disordered membranes, which can lead to distinctive membrane permeability of small molecules. Our results, thus, indicate that heterogeneity in mixed phase membranes closely governs the membrane functions that may emerge from packing-related basic design principles.
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Affiliation(s)
- Madhusmita Tripathy
- Molecular Biophysics Unit, Indian Institute of Science Bangalore, Bangalore, Karnataka, India.
| | - Anand Srivastava
- Molecular Biophysics Unit, Indian Institute of Science Bangalore, Bangalore, Karnataka, India.
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