References of "Lins, Laurence"
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See detailHow different serols contribute to cytotoxic action of sea cucumber saponins
Claereboudt, Emily ULiege; Eeckhaut, Igor; Lins, Laurence ULiege et al

in Scientific Reports (in press)

Sea cucumbers produce saponins as a chemical defense mechanism, however their cells can tolerate the cytotoxic nature of these chemicals. To elucidate the molecular mechanisms behind this tolerance a ... [more ▼]

Sea cucumbers produce saponins as a chemical defense mechanism, however their cells can tolerate the cytotoxic nature of these chemicals. To elucidate the molecular mechanisms behind this tolerance a suite of complementary biophysical tools was used, firstly using liposomes for in vitro techniques then using in silico approaches for a molecular-level insight. The holothuroid saponin Frondoside A, caused significantly less permeabilization in liposomes containing a Δ7 holothuroid sterol than those containing cholesterol and resulted in endothermic interactions versus exothermic interactions with cholesterol containing liposomes. Lipid phases simulations revealed that Frondoside A has an agglomerating effect on cholesterol domains, however, induced small irregular Δ7 sterol clusters. Our results suggest that the structural peculiarities of holothuroid sterols provide sea cucumbers with a mechanism to mitigate the sterol-agglomerating effect of saponins, and therefore to protect their cells from the cytotoxicity of the saponins they produce. [less ▲]

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See detailHow different serols contribute to cytotoxic action of sea cucumber saponins
Claereboudt, Emily ULiege; Eeckhaut, Igor; Deleu, Magali ULiege et al

Poster (2018, May 24)

Saponins form a diverse class of secondary metabolites found in both plants and some marine invertebrates. Holothuroids, or sea cucumbers, produce these molecules as a chemical defense against predators ... [more ▼]

Saponins form a diverse class of secondary metabolites found in both plants and some marine invertebrates. Holothuroids, or sea cucumbers, produce these molecules as a chemical defense against predators and parasites, but interestingly, tolerate the cytotoxic nature of these chemicals. This tolerance is poorly understood. The aim of this study was therefore to elucidate the mechanisms behind the tolerance of holothuroid cells to the cytotoxic saponins (e.g. Frondoside A) they produce. This investigation was conducted using a suite of complementary biophysical tools, firstly using in vitro techniques such as Isothermal Titration Calorimetry (ITC) and calcein leakage experiments, for measuring interactions between lipid models of various compositions and the saponin Frondoside A, then using in silico approaches such as docking methods and insertion into implicit lipid bilayers, to provide a molecular point of view on our observations. Interactions between Frondoside A and cholesterol were more favorable than those with the holothuroid Δ7 and Δ9(11) sterols. Liposomes containing cholesterol resulted in exothermic interactions with the holothuroid saponin Frondoside A whereas liposomes containing the Δ7 sterol resulted in endothermic interactions. Lipid phase simulations using settings previously developed for plant saponins revealed that the holothuroid saponin Frondoside A has an agglomerating effect on cholesterol domains, similar to that previously observed for the plant saponin α-Hederin. However, when interacting with the Δ7 sterols, the sterol domains were fragmented into small clusters. A significantly lower leakage was observed with liposomes containing the Δ7 holothuroid sterol than that with liposomes containing cholesterol. Our results suggest that the structural peculiarities of holothuroid sterols provide the organisms with a mechanism to mitigate the sterol-agglomerating effect of saponins on the cell membranes, and therefore to protect sea cucumber cells from the cytotoxicity of the saponins they produce. [less ▲]

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See detailInteractions of allelochemicals with plant plasma membrane: a case study with alkaloids from barley
Lebecque, Simon ULiege; Crowet, Jean-Marc; du Jardin, Patrick ULiege et al

Poster (2018, April)

Allelopathy is defined as “any direct or indirect harmful effect by one plant on another through production of chemical compounds that escape into the environment” (Rice, 1974).This phenomenon is seen as ... [more ▼]

Allelopathy is defined as “any direct or indirect harmful effect by one plant on another through production of chemical compounds that escape into the environment” (Rice, 1974).This phenomenon is seen as a potential tool for weeds management within the framework of sustainable agriculture. While many studies investigated the mode of action of various allelochemicals (molecules emitted by allelopathic plants), little attention was given to their initial contact with the plant plasma membrane. In our work, this key step is explored for two alkaloids, gramine and hordenine, that are allelochemicals produced by barley. [less ▲]

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See detailHow different sterols contribute to saponin tolerant plasma membranes in sea cucumbers
Claereboudt, Emily ULiege; Deleu, Magali ULiege; Lins, Laurence ULiege et al

Scientific conference (2018, March 07)

ABSTRACT. Sea cucumbers produce saponins as a chemical defense mechanism, however their cells can tolerate the cytotoxic nature of these chemicals. To elucidate the molecular mechanisms behind this ... [more ▼]

ABSTRACT. Sea cucumbers produce saponins as a chemical defense mechanism, however their cells can tolerate the cytotoxic nature of these chemicals. To elucidate the molecular mechanisms behind this tolerance a suite of complementary biophysical tools was used, firstly using liposomes for in vitro techniques then using in silico approaches for a molecular-level insight. The holothuroid saponin Frondoside A, caused significantly less permeabilization in liposomes containing a Δ7 holothuroid sterol than those containing cholesterol and resulted in endothermic interactions versus exothermic interactions with cholesterol containing liposomes. Lipid phases simulations revealed that Frondoside A has an agglomerating effect on cholesterol domains, however, induced small irregular Δ7 sterol clusters. Our results suggest that the structural peculiarities of holothuroid sterols provide sea cucumbers with a mechanism to mitigate the sterol-agglomerating effect of saponins, and therefore to protect their cells from the cytotoxicity of the saponins they produce. [less ▲]

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See detailUse of molecular dynamics simulations to study the interactions between barley allelochemicals and plant plasma membrane
Lebecque, Simon ULiege; Crowet, Jean-Marc; du Jardin, Patrick ULiege et al

Poster (2018, March)

Gramine and hordenine, two alkaloids produced by barley, were shown to inhibit the growth of a common weed (Matricaria recutita L.). This feature could be useful in order to reach a more sustainable weeds ... [more ▼]

Gramine and hordenine, two alkaloids produced by barley, were shown to inhibit the growth of a common weed (Matricaria recutita L.). This feature could be useful in order to reach a more sustainable weeds management. In vitro experiments have proven that both molecules do interact with lipid bilayers (made of a phosphatidylglycerol (PG) lipid) mimicking plant plasma membranes and are able to modify some of their properties. Moreover, gramine was shown to be more effective than hordenine in both inhibiting weeds growth and altering lipid bilayers properties, suggesting that interactions with membranes could be linked to their mode of action. Molecular dynamics (MD) simulations are carried out in order to get an insight into the molecular mechanisms that underlie these interactions with model membranes and to discriminate between gramine behavior and hordenine behavior. [less ▲]

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See detailAnalyse de séquence et dynamique moléculaire pour révéler le rôle des domaines C2 des protéines MCTPs impliquées dans la connexion membranaire des plasmodesmes chez les plantes
Petit, Jules ULiege; Crowet, Jean-Marc; Deleu, Magali ULiege et al

Conference (2018, January 19)

Chez les organismes multicellulaires, la communication de cellule à cellule est essentielle à la coordination des activités cellulaires pour le fonctionnement de l’organisme dans son entièreté. Les ... [more ▼]

Chez les organismes multicellulaires, la communication de cellule à cellule est essentielle à la coordination des activités cellulaires pour le fonctionnement de l’organisme dans son entièreté. Les plantes terrestres ont développé des systèmes tout à fait particuliers, les plasmodesmes (PD), qui traversent la paroi et permettent le transfert contrôlé de molécules. La structure et l’organisation membranaire au sein des PD est unique : la membrane plasmique forme un manchon contre la paroi, établissant une continuité cytosolique et permettant le passage du desmotubule, qui est une continuité du réticulum endoplasmique. Les deux membranes traversant le PD sont très intimement accolées (~10nm d’espacement) et connectées par des liens moléculaires protéiques. Les PD sont donc des sites de contacts membranaires spécialisés qui initient et relaient de nombreuses voies de signalisation. Les mécanismes moléculaires associés à ces contacts et à la régulation des PD restent néanmoins largement sous-étudiés. Cependant, leur spécificité d’action et de structure ainsi que leur composition lipidique particulière supportent la présence d’une population protéique propre. Très récemment, le groupe de recherche de E. Bayer a découvert une importante famille de protéine, les MCTPs (Multiple C2 domains and Transmembrane region Proteins), dont les membres sont localisés et enrichis aux PD. Les protéines MCTPs ont une topologie similaire à des protéines "tether" connues qui lient la membrane plasmique et le réticulum endoplasmique chez les animaux et chez les plantes (Extended-Synaptotagmins, Synaptotagmins) : plusieurs domaines C2, connus pour interagir avec des lipides membranaires, du côté N-terminal, et une région transmembranaire ancrée dans le réticulum endoplasmique, du côté C-terminal. Ils sont donc des candidats intéressants dans cette connexion entre les membranes. Notre travail est axé sur la prédiction du docking de ces domaines C2 individuels avec la membrane plasmique des plantes et la compréhension de leurs interactions spécifiques avec les lipides. Dans un premier temps, une analyse de la séquence a permis une délimitation fine de chaque domaine C2 des protéines MCTP afin de pouvoir construire des modèles 3D par homologie de structure. Ensuite, des simulations de dynamique moléculaire ont permis de prédire la capacité d’interaction de chaque domaine et d’obtenir des informations, à l’échelle atomique, sur les interactions. Les résultats semblent indiquer une affinité de certains domaines pour les lipides anioniques de la membrane plasmique des plantes (phosphatidylsérine, phosphatidylinositol-4-phosphate). De plus, des résultats préliminaires concernant la possibilité de coordination d’ions calciums par certains domaines – une autre caractéristique connue des domaines C2 – suggèrent que les différents domaines C2 des MCTPs ont des fonctions différentes et spécifiques, compatible avec l’idée de haute plasticité des sites de contact membranaire PD. [less ▲]

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See detailEvaluation des interactions entre les arabidopsides et les lipides de la membrane plasmique des plantes
Genva, Manon ULiege; Deleu, Magali ULiege; Andersson, Mats X. et al

Poster (2018, January 19)

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See detailSynthetic rhamnolipid bolaforms trigger an innate immune response in Arabidopsis thaliana
Luzuriaga-Loaiza, Patricio; Schellenberger, Romain; De Gaetano, Yannick et al

in Scientific Reports (2018), 8

Stimulation of plant innate immunity by natural and synthetic elicitors is a promising alternative to conventional pesticides for a more sustainable agriculture. Sugar-based bolaamphiphiles are known for ... [more ▼]

Stimulation of plant innate immunity by natural and synthetic elicitors is a promising alternative to conventional pesticides for a more sustainable agriculture. Sugar-based bolaamphiphiles are known for their biocompatibility, biodegradability and low toxicity. In this work, we show that Synthetic Rhamnolipid Bolaforms (SRBs) that have been synthesized by green chemistry trigger Arabidopsis innate immunity. Using structure-function analysis, we demonstrate that SRBs, depending on the acyl chain length, differentially activate early and late immunity-related plant defense responses and provide local increase in resistance to plant pathogenic bacteria. Our biophysical data suggest that SRBs can interact with plant biomimetic plasma membrane and open the possibility of a lipid driven process for plant-triggered immunity by SRBs. [less ▲]

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See detailEvaluation of interactions between arabidopsides and plant plasma membrane lipids
Genva, Manon ULiege; Deleu, Magali ULiege; Andersson, Mats X. et al

Poster (2018)

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See detailSequence analysis & molecular dynamics to decipher the role of C2 domains from plant plasmodesmata MCTP proteins for membrane tethering
Petit, Jules ULiege; Crowet, Jean-Marc; Deleu, Magali ULiege et al

Poster (2017, November)

Intercellular communication is critical for multicellularity. It coordinates the activities within individual cells to support the function of an organism as a whole. Plants have developed remarkable ... [more ▼]

Intercellular communication is critical for multicellularity. It coordinates the activities within individual cells to support the function of an organism as a whole. Plants have developed remarkable cellular machines –the plasmodesmata (PD) pores- which interconnect every single cell within the plant body, establishing direct membrane and cytoplasmic continuity, a situation unique to plants. A striking feature of PD organisation, setting them apart from animal cell junctions, is a strand of tightly constricted ER called the desmotubule forming the center of plasmodesmata and connected to the PM by tethering elements which appear like spokes by electron microscopy and are assumed to be proteinaceous 1,2 . The close proximity (~10 nm) of the PM and ER within the pores, and the presence of tethers qualifies plasmodesmata as a specialized type of ER-to-PM membrane contact sites (MCS) 3,4 . Due to their importance for plant intercellular transport, and their emerging role as sensing and signalling ‘hubs’, a better understanding of the structure-function relationship of plasmodesmata is crucial for plant biology. Based on the biophysical properties of the plasmodesmata membranes and their distinct composition in lipid species, it can be assumed that both the ER and PM domains within PD differ from their surrounding bulk membranes and have a unique protein population. Very recently, it was shown by the team of E. Bayer that highly plasmodesmata-enriched proteins, members of the Multiple C2 domains and Transmembrane region Proteins (MCTPs) were significantly more abundant in PD with tight membrane connections, and exhibit the domain architecture expected of membrane tethering proteins 5,6 , with multiple lipid-binding C2 domains in the N-terminal, and an ER-anchored transmembrane region in the C-terminal region. Our work is focused on investigating the potential docking of C2 domains of MCTPs on the plant plasma membrane at a molecular level. We first performed sequence analysis to accurately define the C2 domains from the MCTP and to obtain good 3D models by homology modelling. Then, molecular dynamics is carried out to predict the docking of the different C2 domains onto biomimetic plant plasma membrane and eventually lipid specificity. Based on those results and sequence analysis, specific binding sites in the C2 domains could be predicted. Our preliminary results suggest that the different C2 domains of MCTP proteins could have different roles in lipid tethering, depending or not of calcium. [less ▲]

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See detailFunctional and structural characterisation of the Arabidopsis thaliana HMA4 protein
Lekeux, Gilles ULiege; Laurent, Clémentine; Xiao, Zhiguang et al

Poster (2017, July 24)

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See detailStructural Basis for Plant Plasma Membrane Protein Dynamics and Organization into Functional Nanodomains
Gronnier, Julien; Crowet, Jean-Marc ULiege; Habenstein, Birgit et al

in eLife (2017), 6

Plasma Membrane is the primary structure for adjusting to ever changing conditions. PM sub-compartmentalization in domains is thought to orchestrate signalling cascades. Yet, mechanisms governing membrane ... [more ▼]

Plasma Membrane is the primary structure for adjusting to ever changing conditions. PM sub-compartmentalization in domains is thought to orchestrate signalling cascades. Yet, mechanisms governing membrane organization are mostly uncharacterized. The plant-specific proteins REMORINs are factors regulating hormonal crosstalk and host invasion. REMs are the best-characterized PM nanodomain markers targeted to the PM via an uncharacterized moiety called REMORIN C-terminal Anchor. By coupling biophysical methods, super-resolution microscopy and physiology, we decipher an original mechanism regulating the dynamic and organization of nanodomains. We showed that PM targeting is independent of the COP II-dependent secretory pathway and mediated by PI4P and sterol. REM-CA is an unconventional lipid-binding motif that confers nanodomain organization. Analyses of REM-CA mutants by single particle tracking demonstrate that mobility and supramolecular organization are critical for immunity. This study provides a unique mechanistic insight into how the tight control of spatial segregation is critical in the definition of PM domain necessary to support biological function. [less ▲]

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See detailSynthetic Rhamnolipid Bolaforms (SRBs) as inducers of plant innate immunity
Luzuriaga-Loaiza, Patricio ULiege; Schellenberger, Romain; Touchard, Matthieu et al

Conference (2017, June 28)

Natural and synthetic elicitors have demonstrated a high potential for a more sustainable agriculture and the control of plant diseases via the induction of plant defense responses. Microbial ... [more ▼]

Natural and synthetic elicitors have demonstrated a high potential for a more sustainable agriculture and the control of plant diseases via the induction of plant defense responses. Microbial biosurfactants like surfactin (Bacillus spp.) and rhamnolipids (Pseudomonas spp.) have recently been shown to stimulate the plant innate immune system. Unlike canonical elicitors exemplified by bacterial flagellin, some data suggest that surfactin and rhamnolipid perception do not depend on the presence of specific receptors in the plant cell but rather on the direct interaction of the molecules with the lipid phase of the plant plasma membrane. Moreover, surfactin and rhamnolipid interactions with plant cells are thought to depend on their amphipathicity and the length of their acyl chain. In an attempt to mimic the efficacy of these natural biosurfactants, we have synthesized via green chemistry new bio-inspired amphiphilic elicitors. In this work, we present the characterization of Arabidopsis innate immunity in response to synthetic rhamnolipid bolaforms (SRBs) with variable acyl chain lengths. Using an original pluridisciplinary approach that covers biophysical and biological assays, we assessed the capacity of SRBs to interact with plasma membranes and to stimulate defense responses in Arabidopsis thaliana. Our results show that SRBs, depending on the acyl chain length, differentially activated early and late immunityrelated signaling events, defense gene expression and cell death. Moreover, we have demonstrated that an unsaturated SRB containing a C14 acyl chain is effective to induce local resistance against the hemibiotrophic bacteria Pseudomonas syringae pv. tomato. The biophysical studies suggest that a direct interaction of the SRB C14 with the plasma membrane lipids would be involved in the plant perception and induction of plant immunity. [less ▲]

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See detailPlant oxylipins: structure-function relationship
Genva, Manon ULiege; Andersson, Mats X.; Nasir, Mehmet Nail ULiege et al

Conference (2017, May 09)

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