GEM2023

Session

Clip Session

14 Mar 2023, 16:30

73. A 13C NMR MAS method to sort between mobile and rigid molecules in biomembranes

Prof. Erick Dufourc (CNRS (CBMN/IECB))

Poster

Understanding the membrane dynamics of complex systems is essential to follow their function. As molecules in membranes can be in a rigid or mobile state depending on external (temperature, pressure) or internal (pH, domains, etc.) conditions, we have developed NMR methods to filter highly mobile molecular parts from others that are in more restricted environments. Cross Polarization (CP),...

89. AFM automation allows high throughput nanomechanical characterization of vesicles

Lorena Redondo Morata (Inserm)

Poster

Extracellular Vesicles (EVs) are unique, heterogeneous lipid bilayer-based nanoparticles secreted by cells. Their subpopulations differ in size, charge, biogenesis and vesicle lamellarity. As potential class of cell-free diagnostic and therapeutic vehicles, their physical chemical characterization, in particular their mechanical properties, are an issue of recent investigations [1,2]. As...

39. AMP mechanism of action on bacterial membranes determined by in vivo solid-state NMR

Laila ZAATOUF (Laboratoire des Biomolécules (LBM))

Poster

Keywords:  Bacteria, membrane, lipid profile, DMS-DA6-NH2, mechanism of action, Nuclear Magnetic Resonance

Abstract:

Staphylococcus aureus is a Gram-positive pathogenic bacterium that is resistant to a wide range of antibiotics. DMS-DA6-NH2 (DA6) is a novel antimicrobial peptide (AMP) that has high efficacy on various bacterial strains (1). In vivo 2H solid-state Nuclear Magnetic Resonance...

77. An Azidolipid Monolayer – Transitions, Miscibility, and UV Reactivity studied by Infrared Reflection Absorption Spectroscopy

Christian Schwieger (Martin Luter University Halle-Wittenberg)

Poster

We developed an azide-modified lipid with the potential to be used in photocrosslinking studies in lipid bilayers [1,2] or monolayers[3] with interaction partners, such as peptides or proteins. The UV-activatable lipid is a phosphatidylcholine (PC) and bears a terminal azide moiety in one of its hydrophobic tails (AzidoPC). Here, we present systematic monolayer studies of pure AzidoPC and its...

51. Arg/Trp cell-penetrating peptides incorporating Trp analogues: internalisation properties and interactions with cell membrane components

Sonia Khemaissa (Laboratoire des Biomolécules (Sorbonne Université))

Poster

Cell Penetrating Peptides (CPPs) are small peptides able to cross cell membranes in a receptor-independent way. They are generally cationic and often amphipathic, which leads them to interact favourably with membrane lipids and glycosaminoglycans (GAGs) of the cell surface. Their internalisation can occur according to two pathways: endocytosis which is energy-dependent and translocation which...

34. ATP hydrolysis, autoinhibition and substrate recognition mechanism of the human lipid flippase ATP8B1/CDC50A revealed by cryo-EM

Dr Thibaud Dieudonné (Aarhus University - University Paris-Saclay)

Poster

Lipid flippases (P4-ATPases) mediate active transport of phospholipids from the exoplasmic leaflet to the cytoplasmic one, in order to establish and maintain phospholipid asymmetry in eukaryotic membranes. This asymmetry is tightly regulated, and important for numerous cellular processes such as membrane trafficking, signaling, apoptosis, cytokinesis and cell fusion. The human genome encodes...

44. AtpF and membrane proliferation: the role of dimerization

Francesca Zito (IBPC, UMR 7099 Laboratoire de Biologie Physico-Chimique des Protéines Membranaires CNRS-Université de Paris, France)

Poster

The overproduction of the b subunit of the FoF1-ATP synthase, AtpF, induces massive intracellular membrane (ICM) proliferation in C43(DE3) 1. We identified shorter AtpF variants that lead either to ICM accumulation or vesicle formation (AtpF 1_42 FlAsH). Partial deletions of the AtpF gene lead to intermediate phenotypes.
Here, we investigate the role of the dimerization of the overexpressed...

55. Characterization of the Viral Membrane Assembly Proteins of Vaccinia virus: A6 and its interaction with lipids

Clara A. Feldmann (Leibniz Institute for Virology / Center for Structural Systems Biology / Hamburg University, Hamburg, Germany)

Poster

Poxviruses are enveloped, large cytoplasmic dsDNA viruses that have epidemic potential. Since its successful use as a live vaccine to eradicate Variola virus, the etiologic agent of smallpox, Vaccinia virus (VACV) has become a model for poxvirus research. Early stages of poxvirus assembly rely on a unique membrane acquisition mechanism that does not involve wrapping or budding at cellular...

59. Deciphering relative contribution of polar lipids in adaptation to extreme environmental conditions

Margot Saracco (UMR5240 MAP)

Poster

Tolerance to the most extreme environmental conditions is almost always observed in the phylum Archaea. The synthesis of membrane-spanning, bipolar lipids has been linked to thermal and low pH tolerance: monolayers are more rigid and thermally more resistant than lipid bilayers. However, the requirement for bipolar lipids has been recently challenged by the existence of hyperthermophilic...

100. Developing advanced models of biological membranes with hydrogenous and deuterated natural glycerophospholipids

Dr Krishna Batchu (ILL)

Poster

Cellular membranes are complex systems including hundreds of different lipid species. Their investigation often relies on simpler model systems including fewer synthetic lipid species. Glycerophospholipids (GPLs) extracted from cells are a valuable resource to produce more advanced models of biological membranes. Here we present the optimization of a method previously reported by our team for...

66. Effect of amphiphilic environment on the solution structure of mouse TSPO translocator protein

Sophie Combet (LLB)

Poster

The translocator protein (TSPO) is a ubiquitous transmembrane protein of great pharmacological interest thanks to its high affinity to many drug ligands. The only high-resolution 3D-structure known for mammalian TSPO was obtained by NMR for the mouse mTSPO in DPC detergent only in presence of the high-affinity PK 11195 ligand. An atomic structure of free-ligand mTSPO is still missing to better...

98. Enhanced Total Internal Reflection Fluorescence Microscopy using resonant dielectric multilayers

Cyril Favard (Institut de Recherche en Infectiologie de Montpellier, CNRS, Univ of Montpellier, France)

Poster

Total Internal Reflection Fluorescence (TIRF) Microscopy is based on the generation of evanescent waves on the surface of a glass coverslips enabling imaging with a depth of focus of about 100-200 nm. This makes TIRF microscopy a key instrument to observe cell – substrates contact region and to provide a detailing understanding of membrane particles dynamics. These 2 last decades, TIRF...

52. Evolutionary significance of the bilayer properties for the disappearance of betaine lipids in seed plants

Juliette Jouhet (Laboratoire de Physiologie Cellulaire et Végétale)

Poster

Betaine lipids are non-phosphorus glycerolipids and can represent up to 40% of the membrane lipid content. There are three basic types of betain lipids: DGTS, DGTA and DGCC distributed in photosynthetic organisms such as ferns, mousses macro- and microalgae. In contrast, it is interesting to notice that there are no betaine lipids in seed plants (angiosperms and gymnosperms). Under phosphate...

61. Functional characterization of TgREMIND, an enigmatic F-BAR containing protein involved in vesicular trafficking in Toxoplasma gondii

Mrs Noha AL-QATABI (Institut de Pharmacologie Moléculaire et Cellulaire, CNRS, Université Côte d’Azur)

Poster

Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular parasite. The ability of this parasite to infect host cells depends on its capacity to release unique factors from special organelles called rhoptries, micronemes, and dense granules. The biogenesis of these organelles relies on vesicular trafficking events whose molecular bases are poorly known. In...

47. Impact of membrane lipid polyunsaturation on dopamine D2 receptor ligand binding and signaling

Isabel Alves (CBMN, U. of Bordeaux)

Poster

G-protein coupled receptors (GPCRs) are an important class of membrane proteins, with almost 1000 different proteins in the human genome, that are target of about 50% of the drugs in the market. Being composed of 7 transmembrane helices these receptors establish important lipid contacts and their structure and function is expected to be impacted by the properties of the surrounding lipids....

60. In vitro reconstitution of transbilayer lipid transport mediated by a yeast flippase complex

Pauline Funke (Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France)

Poster

Membrane bilayers in eukaryotic cells display an asymmetrical transbilayer lipid distribution, i.e. a different lipid concentration in their two leaflets, which is important for fundamental cellular processes like vesicle-mediated trafficking or recruitment of signaling proteins to the membrane. Transbilayer lipid asymmetry is maintained by specific membrane proteins, flippases and floppases,...

79. In vivo effects of glycolipid transfer protein (GLTP) knockout in HeLa cells

Mr Henrik Nurmi

Poster

The glycolipid transfer protein (GLTP) has recently been linked to multiple cellular processes and functions aside from its best-known function as a lipid transport protein. For instance, GLTP has been proposed to act as a sensor and regulator of glycosphingolipid homeostasis in the cell. GLTP may also be involved in facilitating or regulating vesicular transport, through its previously...

86. Interaction of arginine modified SNARE peptides with lipid membranes: A molecular dynamics study

Bence Fehér

Poster

Membrane fusion plays an important role in several biological processes. Thus, it is essential to explore the mechanism of vesicle fusion. Fusion is frequently induced by SNARE proteins attached to the membrane. These highly complicated proteins can be modelled by coiled-coil complexes (CCs). Typically, CCs are constructed of heptad repeating hydrophobic and polar residues.
To indicate...

74. Interactions of toxins from S.aureus toxin-antitoxin systems with membranes

Laurence Fermon (Univ Rennes, INSERM, U1230 BRM / Univ Rennes, CNRS, ISCR UMR6226)

Poster

Toxin-antitoxin systems are genetic modules widely spread in bacterial genomes. They contain a toxin, which stops the bacteria’s growth and an antitoxin, which inhibits toxin’s expression. Under normal conditions, the antitoxin is produced concomitantly with the toxin, so the toxin is not translated. Under a stress, the antitoxin is not produced anymore, so the toxin can be translated, act on...

56. Lamellar neutron diffraction sample environment: vapour atmosphere and temperature control with Raman spectroscopic monitoring of gas phase equilibration

Dr Christopher J. Garvey (1. Forschungs-Neutronenquelle, Heinz Maier-Leibnitz Zentrum (FRM II), Technische Universität München)

Poster

Here we investigate the lipid membrane reorganization caused by sorption of ethanol from the gas phase. The physical effects of the short chain alcohols, e.g. ethanol & butanol, on cell membranes seem to be a fundamental limitation on the amount of alcohol that can be produced by fermentation. This technology is already an important renewable alternative to fossil fuels. We hope that...

65. Lipid homeostasis in yeast membranes: Characterization of Ist2 transmembrane protein, the ER-to-plasma membrane tether involved in the phosphatidylserine transport by Osh6

Heitor Gobbi Sebinelli (Laboratory of Membrane Proteins and Membrane Systems, Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif sur Yvette, France), Christine Jaxel (Laboratory of Membrane Proteins and Membrane Systems, Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif sur Yvette, France)

Poster

Ist2 is a yeast transmembrane protein localized in the endoplasmic reticulum (ER). It is a structural homolog of TMEM16 proteins, a family of transporters described as scramblases, i.e., proteins that catalyze facilitated diffusion of lipids in a non-specific manner, and/or anion channels.
Ist2 is made of a N-terminal transmembrane domain, as well as a long cytosolic C-terminus that binds to...

94. Membrane protein platforms for metal efflux in some bacteria

Patrice Catty (CEA)

Poster

Tuberculosis is caused by the bacterium Mycobacterium tuberculosis (Mtb). Upon infection, the pathogen is phagocyted by macrophages, the sentinel cells of the immune system. In the macrophage, Mtb accumulates in the phagosomes where it must adapt to cope with toxic concentrations of metals such as zinc. In that context, metal poisoning can be seen as a host defence mechanism to...

64. MemCross, a robust computational tool to evaluate membrane permeation coefficients of drug-like molecules

Gabin Fabre (P&T UMR INSERM 1248)

Poster

Membrane crossing events are key in the pharmacokinetics of xenobiotics. Among them, passive permeation is the most ubiquitous. Therefore, an accurate and cost-effective prediction of permeation coefficient (logP_erm) is highly valuable. Among the theoretical methods to predict logP_erm, all-atom molecular dynamics simulations are versatile and can provide an accurate...

67. Nanostructural characterisation of sVE interactions with lipid bilayer membranes: basis for biosensor development

Mrs Beatrice Barletti (Institut Laue-Langevin)

Poster

Vascular endothelial-cadherin (VE-cadherin) is the most important transmembrane component of endothelial adherens junctions. A cytokine-induced phosphorylation of VE-cadherin cytoplasmic domain was reported to trigger cleavage of its extracellular domain, producing the soluble form of the protein – soluble vascular endothelial-cadherin (sVE) [1]. Hence, the presence of sVE in human serum and...

33. ON THE INTERPLAY BETWEEN COMPLEX LIPID BILAYER MEMBRANE AND MULTIDRUG RESISTANCE-ASSOCIATED PROTEIN 1 (MRP1) BY MEANS OF MOLECULAR DYNAMICS

Dr Florent Di Meo (1Inserm U1248 P&T, University of Limoges, CHU Limoges – CBRS, Limoges, France)

Poster

In the context of pharmacology, drug membrane transporters play a central role in local pharmacokinetics, i.e., the intracellular drug concentrations of tissues of interest. Particular attention should be paid to membrane transporters located in liver and kidneys given their importance in drug metabolism and elimination. This is particularly true for multidrug-resistance associated proteins...

43. On the use of micro-physiological systems to improve pharmacologically relevant transcellular transport in the liver-kidney axis

Nicolas Vedrenne (Inserm U1248 Pharmacology & Transplantation, Univ. Limoges,)

Poster

In the frameworks of personalized medicine, deciphering the sources of variability in patient drug responses requires the understanding of underlying processes modulating drug pharmacokinetics (PK). This is particularly true to bridge the gap between systemic and local PK, i.e., drug concentration close to its target. In this context,
drugs membrane transporters play a central role...

78. Rationalizing the molecular role of natural moisturizing factors in the skin hydration through molecular dynamic simulations

Marving MARTIN (INSERM U1248)

Poster

Xerosis or dry skin is a common condition experienced by many. Besides being particularly present during the cold season, various diseases can also lead to localized xerosis. To prevent it, the skin is provided with its own natural moisturizing factors (NMF). NMF are small amino acids or derivatives found in the outermost layer of the skin, the $\it{stratum}$ $\it{corneum}$ (SC). They are...

29. Role of Neuronal Phospholipids on the Aggregation Kinetics of Amyloid-β42 (Aβ42)

Dr Purushottam Dubey (Forschungszentrum Jülich)

Poster

Amyloid β42 (Aβ42) is predominantly found in the form of plaques in the brain tissues of Alzheimer's disease and is mainly responsible for cognitive dysfunctionality in Alzheimer’s. Aβ depending upon aggregation states Aβ42-monomer (M)/β-sheets/oligomer (O)/fibril (F), and amino acid length affects the model membrane mimetic systems [1-4]. The plasma membrane is the first biological structure...

88. Spontaneous nanotube formation of Ohmline lipid on solid supports: Role of surface energy and buffer ionic strength

Dr Martín Eduardo Villanueva (Université Libre de Bruxelles (ULB))

Poster

Among the many assemblies that lipid molecules are able to form, lipid nanotubes (LNTs) are currently one of the most interesting structures in the framework of nanomaterials fundamentals and design. Their high-aspect ratio, tunable diameter size and biocompatibility, enables them for a plethora of biotechnological applications such as drug delivery, protein separation and DNA detection.1,2...

76. Structural characterization of bacterial NAD(P)H oxidase: highlighting the origin and mechanism of eukaryotic NOX

Prof. Franck Fieschi (Université Grenoble Alpes)

Poster

For a long time NOX enzymes have been thought to be a landmark of pluricellular organisms where the production of reactive oxygen species could be associated to physiological function related to the multicellularity (immune defense, vascular tone regulation, hormone synthesis, etc..).
However, our group identified in 2017, a first ancestor to eukaryotic NOX in bacteria with the...

42. Structure and elasticity of mitochondrial membranes from molecular dynamics simulations

Dr THI LY MAI (CNRS, Université de Paris, UPR9080, Laboratoire de Biochimie Théorique, Institut de Biologie Physico-Chimique, Fondation Edmond de Rothschild, 13 rue Pierre et Marie Curie, 75005 Paris, France)

Poster

Mitochondria are crucial for energy metabolism. In living cells, they undergo continuous shape transformations in order to perform various biological functions such as fission and fusion rearrangement. The shape of the membrane is determined by the bulk mechanical parameters of the membrane such as lateral tension, bending modulus and spontaneous curvature. These parameters, in turns, depend...

45. Structure of the vasopressin hormone – V2 receptor – beta-arrestin1 ternary complex

Dr Aurélien Fouillen (CNRS)

Poster

Arrestins interact with G protein–coupled receptors (GPCRs) to stop G protein activation and to initiate key signaling pathways. Recent structural studies shed light on the molecular mechanisms involved in GPCR-arrestin coupling, but whether this process is conserved among GPCRs is poorly understood. We have recently reported the cryo–electron microscopy active structure of the wild-type...

31. Studying model membranes with neutrons

Giovanna Fragneto (Europena Spallation Source ERIC)

Poster

To study the dynamics and function of cellular membranes it is important to understand their structure. This involves experiments on model systems and can profit from a probe that is able to access different scales of size and time: thermal neutrons. Since the pioneering work in the seventies on cell membrane structure by neutron scattering, developments driven by constantly improving neutron...

84. THE MEMBRANE ENVIRONMENT DETERMINES THE FUNCTION OF RHOMBOID INTRAMEMBRANE PROTEASE GLPG

Dr Oskar Engberg (University of Leipzig)

Poster

It has been suggested that the intramembrane rhomboid protease GlpG can thin membranes, possibly explaining the observation that rhomboids diffuse faster than the high viscosity of the lipid membrane would allow. Molecular dynamics simulations have shown membrane thinning by GlpG in both phosphatidylcholine (PC) and phosphatidylethanolamine (PE) membranes. To experimentally test the membrane...

53. The Preference for Membrane Curvature of Neutral Lipids and the Role in Lipid Droplet Formation

Jackson Crowley

Poster

Jackson Crowley ¹, Valeria Zoni ², Stefano Vanni ², Luca Monticelli ^1
1 Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS & University of Lyon, Lyon, France
² Department of Biology, University of Fribourg, Fribourg, Switzerland

Lipid droplets (LDs) are organelles responsible for lipid storage and...