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Lateral Segregation of Molecular Components Enhances Functionality of Biological Membranes

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A special issue of Biomolecules (ISSN 2218-273X). This special issue belongs to the section "Molecular Biophysics".

Deadline for manuscript submissions: closed (30 September 2022) | Viewed by 21906

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Dr. Jan Malínský

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Department of Functional Organization of Biomembranes Institute of Experimental Medicine, Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic
Interests: membrane microdomains; membrane biophysics; lipid metabolism; steady-state segregation of cellular components; fluorescence microscopy

Special Issue Information

Dear Colleagues,

The idea of biological membranes being subdivided into lateral microdomains, which are characterized by specific composition, structure and biological function, has become widely accepted among scientists worldwide. Membrane microdomains have been observed in numerous species of all kingdoms of life, in the plasma membrane as well as in various internal membranes of complex eukaryotes. Different mechanisms of membrane microdomain formation have been described. These include spontaneous segregation of membrane lipids based on phase separation or hydrophobic mismatch, directed vesicular and non-vesicular transport of membrane components, fencing and scaffolding by membrane-associated proteins, etc. At the same time, more and more accent is being put on overall membrane dynamics – lateral diffusion and membrane fluidity, exchange of membrane contents at membrane contact sites – and the consequent temporal character of membrane microdomains throughout the whole cellular membrane system. Keeping in mind that a substantial part of biochemical reactions within the cell takes place at cellular and organellar surfaces, i.e., membranes, the membrane microdomain architecture represents an intriguing platform for fast and efficient reprogramming of the cell metabolism.

In this Special Issue, having in focus a wide variety of membrane functions, we expect to shed new light on how the clustering of membrane components (lipids, proteins) into microdomains possessing characteristic biochemical and biophysical traits contributes to triggering, regulation and performance of cellular signaling, metabolic pathways and stress adaptation.

Assoc. Prof. Jan Malínský
Guest Editor

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Keywords

membrane microdomain
lipid order
protein conformation
membrane dynamics
membrane contact sites

Published Papers (7 papers)

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Research

14 pages, 2826 KiB

Open AccessArticle

Examining the Effect of Charged Lipids on Mitochondrial Outer Membrane Dynamics Using Atomistic Simulations

by Aline A. Oliveira, Tomasz Róg, Albérico B. F. da Silva, Rommie E. Amaro, Mark S. Johnson and Pekka A. Postila

Biomolecules 2022, 12(2), 183; https://doi.org/10.3390/biom12020183 - 22 Jan 2022

Cited by 5 | Viewed by 3068

Abstract

The outer mitochondrial membrane (OMM) is involved in multiple cellular functions such as apoptosis, inflammation and signaling via its membrane-associated and -embedded proteins. Despite the central role of the OMM in these vital phenomena, the structure and dynamics of the membrane have regularly been investigated in silico using simple two-component models. Accordingly, the aim was to generate the realistic multi-component model of the OMM and inspect its properties using atomistic molecular dynamics (MD) simulations. All major lipid components, phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS), were included in the probed OMM models. Because increased levels of anionic PS lipids have potential effects on schizophrenia and, more specifically, on monoamine oxidase B enzyme activity, the effect of varying the PS concentration was explored. The MD simulations indicate that the complex membrane lipid composition (MLC) behavior is notably different from the two-component PC-PE model. The MLC changes caused relatively minor effects on the membrane structural properties such as membrane thickness or area per lipid; however, notable effects could be seen with the dynamical parameters at the water-membrane interface. Increase of PS levels appears to slow down lateral diffusion of all lipids and, in general, the presence of anionic lipids reduced hydration and slowed down the PE headgroup rotation. In addition, sodium ions could neutralize the membrane surface, when PI was the main anionic component; however, a similar effect was not seen for high PS levels. Based on these results, it is advisable for future studies on the OMM and its protein or ligand partners, especially when wanting to replicate the correct properties on the water-membrane interface, to use models that are sufficiently complex, containing anionic lipid types, PI in particular. Full article

(This article belongs to the Special Issue Lateral Segregation of Molecular Components Enhances Functionality of Biological Membranes)

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17 pages, 2802 KiB

Open AccessArticle

Sterol Extraction from Isolated Plant Plasma Membrane Vesicles Affects H⁺-ATPase Activity and H⁺-Transport

by Nikita K. Lapshin, Michail S. Piotrovskii and Marina S. Trofimova

Biomolecules 2021, 11(12), 1891; https://doi.org/10.3390/biom11121891 - 16 Dec 2021

Cited by 2 | Viewed by 2281

Abstract

Plasma membrane H⁺-ATPase is known to be detected in detergent-resistant sterol-enriched fractions, also called “raft” domains. Studies on H⁺-ATPase reconstituted in artificial or native membrane vesicles have shown both sterol-mediated stimulations and inhibitions of its activity. Here, using sealed isolated plasma membrane vesicles, we investigated the effects of sterol depletion in the presence of methyl-β-cyclodextrin (MβCD) on H⁺-ATPase activity. The rate of ATP-dependent ∆µH⁺ generation and the kinetic parameters of ATP hydrolysis were evaluated. We show that the relative sterols content in membrane vesicles decreased gradually after treatment with MβCD and reached approximately 40% of their initial level in 30 mM probe solution. However, changes in the hydrolytic and H⁺-transport activities of the enzyme were nonlinear. The extraction of up to 20% of the initial sterols was accompanied by strong stimulation of ATP-dependent H⁺-transport in comparison with the hydrolytic activity of enzymes. Further sterol depletion led to a significant inhibition of active proton transport with an increase in passive H⁺-leakage. The solubilization of control and sterol-depleted vesicles in the presence of dodecyl maltoside negated the differences in the kinetics parameters of ATP hydrolysis, and all samples demonstrated maximal hydrolytic activities. The mechanisms behind the sensitivity of ATP-dependent H⁺-transport to sterols in the lipid environment of plasma membrane H⁺-ATPase are discussed. Full article

(This article belongs to the Special Issue Lateral Segregation of Molecular Components Enhances Functionality of Biological Membranes)

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13 pages, 2336 KiB

Open AccessArticle

Correlative Light-Environmental Scanning Electron Microscopy of Plasma Membrane Efflux Carriers of Plant Hormone Auxin

by Ayoub Stelate, Eva Tihlaříková, Kateřina Schwarzerová, Vilém Neděla and Jan Petrášek

Biomolecules 2021, 11(10), 1407; https://doi.org/10.3390/biom11101407 - 26 Sep 2021

Cited by 10 | Viewed by 2687

Abstract

Fluorescence light microscopy provided convincing evidence for the domain organization of plant plasma membrane (PM) proteins. Both peripheral and integral PM proteins show an inhomogeneous distribution within the PM. However, the size of PM nanodomains and protein clusters is too small to accurately determine their dimensions and nano-organization using routine confocal fluorescence microscopy and super-resolution methods. To overcome this limitation, we have developed a novel correlative light electron microscopy method (CLEM) using total internal reflection fluorescence microscopy (TIRFM) and advanced environmental scanning electron microscopy (A-ESEM). Using this technique, we determined the number of auxin efflux carriers from the PINFORMED (PIN) family (NtPIN3b-GFP) within PM nanodomains of tobacco cell PM ghosts. Protoplasts were attached to coverslips and immunostained with anti-GFP primary antibody and secondary antibody conjugated to fluorochrome and gold nanoparticles. After imaging the nanodomains within the PM with TIRFM, the samples were imaged with A-ESEM without further processing, and quantification of the average number of molecules within the nanodomain was performed. Without requiring any post-fixation and coating procedures, this method allows to study details of the organization of auxin carriers and other plant PM proteins. Full article

(This article belongs to the Special Issue Lateral Segregation of Molecular Components Enhances Functionality of Biological Membranes)

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23 pages, 3943 KiB

Open AccessFeature PaperArticle

TORC2-Dependent Ypk1-Mediated Phosphorylation of Lam2/Ltc4 Disrupts Its Association with the β-Propeller Protein Laf1 at Endoplasmic Reticulum-Plasma Membrane Contact Sites in the Yeast Saccharomyces cerevisiae

by Magdalena Topolska, Françoise M. Roelants, Edward P. Si and Jeremy Thorner

Biomolecules 2020, 10(12), 1598; https://doi.org/10.3390/biom10121598 - 25 Nov 2020

Cited by 7 | Viewed by 2657

Abstract

Membrane-tethered sterol-binding Lam/Ltc proteins localize at junctions between the endoplasmic reticulum (ER) membrane and other organelles. Two of the six family members—Lam2/Ltc4 (initially Ysp2) and paralog Lam4/Ltc3—localize to ER-plasma membrane (PM) contact sites (CSs) and mediate retrograde ergosterol transport from the PM to the ER. Our prior work demonstrated that Lam2 and Lam4 are substrates of TORC2-regulated protein kinase Ypk1, that Ypk1-mediated phosphorylation inhibits their function in retrograde sterol transport, and that PM sterol retention bolsters cell survival under stressful conditions. At ER-PM CSs, Lam2 and Lam4 associate with Laf1/Ymr102c and Dgr2/Ykl121w (paralogous WD40 repeat-containing proteins) that reportedly bind sterol. Using fluorescent tags, we found that Lam2 and Lam4 remain at ER-PM CSs when Laf1 and Dgr2 are absent, whereas neither Laf1 nor Dgr2 remain at ER-PM CSs when Lam2 and Lam4 are absent. Loss of Laf1 (but not Dgr2) impedes retrograde ergosterol transport, and a laf1∆ mutation does not exacerbate the transport defect of lam2∆ lam4∆ cells, indicating a shared function. Lam2 and Lam4 bind Laf1 and Dgr2 in vitro in a pull-down assay, and the PH domain in Lam2 hinders its interaction with Laf1. Lam2 phosphorylated by Ypk1, and Lam2 with phosphomimetic (Glu) replacements at its Ypk1 sites, exhibited a marked reduction in Laf1 binding. Thus, phosphorylation prevents Lam2 interaction with Laf1 at ER-PM CSs, providing a mechanism by which Ypk1 action inhibits retrograde sterol transport. Full article

(This article belongs to the Special Issue Lateral Segregation of Molecular Components Enhances Functionality of Biological Membranes)

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18 pages, 70147 KiB

Open AccessArticle

Plasma Membrane Protein Nce102 Modulates Morphology and Function of the Yeast Vacuole

by Katarina Vaskovicova, Petra Vesela, Jakub Zahumensky, Dagmar Folkova, Maria Balazova and Jan Malinsky

Biomolecules 2020, 10(11), 1476; https://doi.org/10.3390/biom10111476 - 23 Oct 2020

Cited by 6 | Viewed by 3233

Abstract

Membrane proteins are targeted not only to specific membranes in the cell architecture, but also to distinct lateral microdomains within individual membranes to properly execute their biological functions. Yeast tetraspan protein Nce102 has been shown to migrate between such microdomains within the plasma membrane in response to an acute drop in sphingolipid levels. Combining microscopy and biochemistry methods, we show that upon gradual ageing of a yeast culture, when sphingolipid demand increases, Nce102 migrates from the plasma membrane to the vacuole. Instead of being targeted for degradation it localizes to V-ATPase-poor, i.e., ergosterol-enriched, domains of the vacuolar membrane, analogous to its plasma membrane localization. We discovered that, together with its homologue Fhn1, Nce102 modulates vacuolar morphology, dynamics, and physiology. Specifically, the fusing of vacuoles, accompanying a switch of fermenting yeast culture to respiration, is retarded in the strain missing both proteins. Furthermore, the absence of either causes an enlargement of ergosterol-rich vacuolar membrane domains, while the vacuoles themselves become smaller. Our results clearly show decreased stability of the V-ATPase in the absence of either Nce102 or Fhn1, a possible result of the disruption of normal microdomain morphology of the vacuolar membrane. Therefore, the functionality of the vacuole as a whole might be compromised in these cells. Full article

(This article belongs to the Special Issue Lateral Segregation of Molecular Components Enhances Functionality of Biological Membranes)

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24 pages, 6228 KiB

Open AccessArticle

Aberrant Membrane Composition and Biophysical Properties Impair Erythrocyte Morphology and Functionality in Elliptocytosis

by Hélène Pollet, Anne-Sophie Cloos, Amaury Stommen, Juliette Vanderroost, Louise Conrard, Adrien Paquot, Marine Ghodsi, Mélanie Carquin, Catherine Léonard, Manuel Guthmann, Maxime Lingurski, Christiane Vermylen, Theodore Killian, Laurent Gatto, Mark Rider, Sébastien Pyr dit Ruys, Didier Vertommen, Miikka Vikkula, Pascal Brouillard, Patrick Van Der Smissen, Giulio G. Muccioli and Donatienne Tyteca Show full author list Hide full author list

Biomolecules 2020, 10(8), 1120; https://doi.org/10.3390/biom10081120 - 29 Jul 2020

Cited by 10 | Viewed by 3065

Abstract

Red blood cell (RBC) deformability is altered in inherited RBC disorders but the mechanism behind this is poorly understood. Here, we explored the molecular, biophysical, morphological, and functional consequences of α-spectrin mutations in a patient with hereditary elliptocytosis (pEl) almost exclusively expressing the Pro260 variant of SPTA1 and her mother (pElm), heterozygous for this mutation. At the molecular level, the pEI RBC proteome was globally preserved but spectrin density at cell edges was increased. Decreased phosphatidylserine vs. increased lysophosphatidylserine species, and enhanced lipid peroxidation, methemoglobin, and plasma acid sphingomyelinase (aSMase) activity were observed. At the biophysical level, although membrane transversal asymmetry was preserved, curvature at RBC edges and rigidity were increased. Lipid domains were altered for membrane:cytoskeleton anchorage, cholesterol content and response to Ca²⁺ exchange stimulation. At the morphological and functional levels, pEl RBCs exhibited reduced size and circularity, increased fragility and impaired membrane Ca²⁺ exchanges. The contribution of increased membrane curvature to the pEl phenotype was shown by mechanistic experiments in healthy RBCs upon lysophosphatidylserine membrane insertion. The role of lipid domain defects was proved by cholesterol depletion and aSMase inhibition in pEl. The data indicate that aberrant membrane content and biophysical properties alter pEl RBC morphology and functionality. Full article

(This article belongs to the Special Issue Lateral Segregation of Molecular Components Enhances Functionality of Biological Membranes)

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24 pages, 2970 KiB

Open AccessArticle

Yeast Sphingolipid-Enriched Domains and Membrane Compartments in the Absence of Mannosyldiinositolphosphorylceramide

by Andreia Bento-Oliveira, Filipa C. Santos, Joaquim Trigo Marquês, Pedro M. R. Paulo, Thomas Korte, Andreas Herrmann, H. Susana Marinho and Rodrigo F. M. de Almeida

Biomolecules 2020, 10(6), 871; https://doi.org/10.3390/biom10060871 - 6 Jun 2020

Cited by 8 | Viewed by 3488

Abstract

The relevance of mannosyldiinositolphosphorylceramide [M(IP)₂C] synthesis, the terminal complex sphingolipid class in the yeast Saccharomyces cerevisiae, for the lateral organization of the plasma membrane, and in particular for sphingolipid-enriched gel domains, was investigated by fluorescence spectroscopy and microscopy. We also addressed how changing the complex sphingolipid profile in the plasma membrane could influence the membrane compartments (MC) containing either the arginine/ H⁺ symporter Can1p (MCC) or the proton ATPase Pma1p (MCP). To achieve these goals, wild-type (wt) and ipt1Δ cells, which are unable to synthesize M(IP)₂C accumulating mannosylinositolphosphorylceramide (MIPC), were compared. Living cells, isolated plasma membrane and giant unilamellar vesicles reconstituted from plasma membrane lipids were labelled with various fluorescent membrane probes that report the presence and organization of distinct lipid domains, global order, and dielectric properties. Can1p and Pma1p were tagged with GFP and mRFP, respectively, in both yeast strains, to evaluate their lateral organization using confocal fluorescence intensity and fluorescence lifetime imaging. The results show that IPT1 deletion strongly affects the rigidity of gel domains but not their relative abundance, whereas no significant alterations could be perceived in ergosterol-enriched domains. Moreover, in these cells lacking M(IP)₂C, a clear alteration in Pma1p membrane distribution, but no significant changes in Can1p distribution, were observed. Thus, this work reinforces the notion that sphingolipid-enriched domains distinct from ergosterol-enriched regions are present in the S. cerevisiae plasma membrane and suggests that M(IP)₂C is important for a proper hydrophobic chain packing of sphingolipids in the gel domains of wt cells. Furthermore, our results strongly support the involvement of sphingolipid domains in the formation and stability of the MCP, possibly being enriched in this compartment. Full article

(This article belongs to the Special Issue Lateral Segregation of Molecular Components Enhances Functionality of Biological Membranes)

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