0000000000484282
AUTHOR
Patricia Gerbeau-pissot
La membrane plasmique des plantes : une clé dans la détection des agresseurs et le processus de défensefra
SPE IPM; Le développement d’une méthode d’imagerie innovante a permis de montrer que la membrane plasmique des cellules végétales est une mosaïque de territoires présentant des propriétés biophysiques variées. Cette organisation est modifiée de façon très rapide en réponse à certaines molécules provenant de microorganismes, établissant un lien fonctionnel entre cette organisation et la mise en place des mécanismes de défense.
Influence of phytosterols on the structural and dynamic properties of plant plasma membrane
National audience; The complex mixture of sterols, namely phytosterols, found in the plasma membrane (PM) of plant cells is an intriguing characteristic. In the present work, we characterized the sterol composition of tobacco BY-2 cell PM, and we adapted a sterol manipulation method to this plant material. Methyl-b-cyclodextrin was found to induce a drastic reduction of the PM total free sterol content, with a low specificity for the different phytosterols, and without effect on steryl-conjugates. The consequences of phytosterols depletion were investigated by means of fluorescence spectroscopy and biochemical detergent resistant membrane (DRM) fraction purification methods. Data obtained w…
Modification of Plasma Membrane Organization in Tobacco Cells Elicited by Cryptogein
Abstract Lipid mixtures within artificial membranes undergo a separation into liquid-disordered and liquid-ordered phases. However, the existence of this segregation into microscopic liquid-ordered phases has been difficult to prove in living cells, and the precise organization of the plasma membrane into such phases has not been elucidated in plant cells. We developed a multispectral confocal microscopy approach to generate ratiometric images of the plasma membrane surface of Bright Yellow 2 tobacco (Nicotiana tabacum) suspension cells labeled with an environment sensitive fluorescent probe. This allowed the in vivo characterization of the global level of order of this membrane, by which w…
Liquid ordered domains of tobacco cell plasma membrane : in vivo visualization, spatial distribution and modulation upon elicitation
SPE IPM; International audience; The ability of lipids in complex mixtures to form liquid-ordered, sterol-rich phases, together with the association of specific proteins with sterol-enriched biochemical fractions extracted from biological membranes, gave raise to the "lipid rafts" hypothesis. This suggests the presence within biological membranes of small-sized, ordered domains, of particular lipid and protein composition, which could serve as signal transduction platforms, particularly during plant-microorganisms interactions. However, the precise organization of living cell plasma membrane is still poorly described and the spatial distribution of segregating liquid-disordered and liquid-o…
Plasma membrane sterol complexation, generated by filipin, triggers signaling responses in tobacco cells
International audience; The effects of changes in plasma membrane (PM) sterol lateral organization and availability on the control of signaling pathways have been reported in various animal systems, but rarely assessed in plant cells. In the present study, the pentaene macrolide antibiotic filipin III, commonly used in animal systems as a sterol sequestrating agent, was applied to tobacco cells. We show that filipin can be used at a non-lethal concentration that still allows an homogeneous labeling of the plasma membrane and the formation of filipin-sterol complexes at the ultrastructural level. This filipin concentration triggers a rapid and transient NADPH oxidase-dependent production of …
Antioxidant Properties of Ergosterol and Its Role in Yeast Resistance to Oxidation
International audience; Although the functions and structural roles of sterols have been the subject of numerous studies, the reasons for the diversity of sterols in the different eukaryotic kingdoms remain unclear. It is thought that the specificity of sterols is linked to unidentified supplementary functions that could enable organisms to be better adapted to their environment. Ergosterol is accumulated by late branching fungi that encounter oxidative perturbations in their interfacial habitats. Here, we investigated the antioxidant properties of ergosterol using in vivo, in vitro, and in silico approaches. The results showed that ergosterol is involved in yeast resistance to tert-butyl h…
Ratiometric fluorescence live imaging analysis of membrane lipid order in Arabidopsis mitotic cells using a lipid order-sensitive probe
SPE Pôle IPM; International audience; Eukaryotic cells contain membranes exhibiting different levels of lipid order mostly related to their relative amount of sterol-rich domains, thought to mediate temporal and spatial organization of cellular processes. We previously provided evidence in Arabidopsis thaliana that sterols are crucial for execution of cytokinesis, the last stage of cell division. Recently, we used di-4-ANEPPDHQ, a fluorescent probe sensitive to order of lipid phases, to quantify the level of membrane order of the cell plate, the membrane structure separating daughter cells during somatic cytokinesis of higher plant cells. By employing quantitative, ratiometric fluorescence …
Study of lipidic membrane component effect on the membrane order level by using GUVs
National audience
Plant lipids: Key players of plasma membrane organization and function
International audience; The Plasma Membrane (PM) is a key structure protecting the cell, regulating nutrient exchanges and acting as a control tower allowing the cell to perceive signals. Plasma comes from the greek πλάσμα meaning "which molds", meaning that the PM takes the shape of the cell by delimitating it. The PM harbors the appropriate signaling cascades allowing adaptive responses ensuring proper cell functions in a continuously fluctuating environment, crucial for cell survival. To address this challenge, the PM needs to be both stable and robust yet incredibly fluid and adaptable. This amazing combination of long-term stability and short-term dynamics in order to adapt to signals …
Rôle des microdomaines du plasmalemme dans la réponse de la cellule végétale au stress biotique
National audience
Exocytosis and endocytosis act together to modify the plasma membrane order in cryptogein-elicited tobacco cells
SPEIPMUBINRA; Exocytosis and endocytosis act together to modify the plasma membrane order in cryptogein-elicited tobacco cells. 19. European Network for Plant Endomembrane Research meeting
Characterization of membrane structure modifications induced during plant defense signaling
SPEIPMUBINRADOCT; Plasma membrane was long considered as a simple separation between internal and external cellular environment. But more, it is a dynamic interface, an exchange platform. Now, recent researches highlight its role in plant defense responses to biotic and abiotic stresses. We use the tobaccocryptogein model to study the early steps of plant cell responses to pathogen detection. The signaling cascade includes an oxidative burst triggering an increase of plasma membrane order. The level of membrane order informs us about both packing and arrangement of membrane components, this parameter being evaluated by spectrofluorimetric approaches using a lipidic environment-sensitive pro…
Differential Effect of Plant Lipids on Membrane Organization
SPE IPM; International audience; The high diversity of the plant lipid mixture raises the question of their respective involvement in the definition of membrane organization. This is particularly the case for plant plasma membrane, which is enriched in specific lipids, such as free and conjugated forms of phytosterols and typical phytosphingolipids, such as glycosylinositolphosphoceramides. This question was here addressed extensively by characterizing the order level of membrane from vesicles prepared using various plant lipid mixtures and labeled with an environment-sensitive probe. Fluorescence spectroscopy experiments showed that among major phytosterols, campesterol exhibits a stronger…
Les radeaux membranaires et la signalisation végétale
Face à une fluctuation des paramètres de son milieu ambiant ou à une agression biotique, la cellule végétale met en place une réponse adaptative dont les étapes les plus précoces sont la reconnaissance précise et rapide du stress, capable d’induire le développement d’une cascade de signalisation appropriée. Certains des acteurs de ces voies sont localisés sur la membrane plasmique (MP). En fonction de l’espèce, l’état physiologique… d’une cellule, on trouve au sein de sa MP des lipides, des protéines et des oses de structures et en concentrations variables. Chez les cellules de tabac, par exemple, on compte environ 50 lipides pour une protéine.Bien que moins nombreuses, les protéines ont po…
La membrane plasmique des plantes : une clé dans la détection des agresseurs et le processus de défense
SPE IPM; Le développement d’une méthode d’imagerie innovante a permis de montrer que la membrane plasmique des cellules végétales est une mosaïque de territoires présentant des propriétés biophysiques variées. Cette organisation est modifiée de façon très rapide en réponse à certaines molécules provenant de microorganismes, établissant un lien fonctionnel entre cette organisation et la mise en place des mécanismes de défense.
Plant lipid rafts : from proteic composition to physiological roles
International audience; A large body of evidence supports the existence, in membrane from animal and yeast cells, of functional microdomains playing important roles in protein sorting, signal transduction, or infection by pathogens (1). We demonstrated the presence, in plants, of detergent resistant fractions isolated from plasma membrane, with a lipidic composition similar to animal microdomains (2). Electrophoresis experiments indicated that these fractions were able to recruit a specific set of plasma membrane proteins and exclude others. We used mass spectrometry to give an extensive description of a tobacco plasma membrane microdomains. This led to the identification of 145 proteins wh…
Behavior of plant plasma membranes under hydrostatic pressure as monitored by fluorescent environment-sensitive probes.
International audience; We monitored the behavior of plasma membrane (PM) isolated from tobacco cells (BY-2) under hydrostatic pressures up to 3.5 kbar at 30 °C, by steady-state fluorescence spectroscopy using the newly introduced environment-sensitive probe F2N12S and also Laurdan and di-4-ANEPPDHQ. The consequences of sterol depletion by methyl-β-cyclodextrin were also studied. We found that application of hydrostatic pressure led to a marked decrease of hydration as probed by F2N12S and to an increase of the generalized polarization excitation (GPex) of Laurdan. We observed that the hydration effect of sterol depletion was maximal between 1 and 1.5 kbar but was much less important at hig…
Asymétrie de la membrane plasmique végétale : caractérisation et rôle dans la signalisation immunitaire des plantes
National audience; La membrane plasmique (MP) forme une barrière sélective entre la cellule et le milieu extérieur.C’est un senseur des modifications environnementales et une plateforme orchestrant latransduction du signal permettant de déployer une réponse adaptée. Elle joue donc un rôleessentiel dans la physiologie cellulaire. Décrypter les bases moléculaires de l’organisation dela MP apparaît donc nécessaire pour comprendre comment les plantes s’adaptent auxmodifications environnementales. La MP est une bicouche de lipides à laquelle des protéinessont associées, et les données accumulées sur ce modèle ont révélé son organisation complexeet dynamique et le rôle essentiel joué par les lipi…
Rôle de la membrane plasmique dans les mécanismes de défense des plantes 2013
National audience; Le développement d’une méthode d’imagerie innovante a permis de montrer que la membrane qui entoure les cellules végétales est composée d’une multitude de petits territoires présentant des états physiques variés. L’organisation globale et locale de cette membrane est modifiée de façon très rapide lorsque la cellule détecte des microorganismes, établissant un lien fonctionnel entre cette organisation et la mise en place de mécanismes de défense. 13 10 ans de recherche SPE Les plantes sont confrontées en permanence à des attaques de champignons, bactéries ou autres parasites, et développent des réponses adaptatives qui conditionnent leur survie. Certaines molécules produite…
Revisiting Plant Plasma Membrane Lipids in Tobacco: A Focus on Sphingolipids
International audience; The lipid composition of plasma membrane (PM) and the corresponding detergent-insoluble membrane (DIM) fraction were analyzed with a specific focus on highly polar sphingolipids, so-called glycosyl inositol phosphorylceramides (GIPCs). Using tobacco (Nicotiana tabacum) 'Bright Yellow 2' cell suspension and leaves, evidence is provided that GIPCs represent up to 40 mol % of the PM lipids. Comparative analysis of DIMs with the PM showed an enrichment of 2-hydroxylated very-long-chain fatty acid-containing GIPCs and polyglycosylated GIPCs in the DIMs. Purified antibodies raised against these GIPCs were further used for immunogold-electron microscopy strategy, revealing …