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See detailLinolenic fatty acid hydroperoxide acts as biocide on plant pathogenic bacteria: biophysical investigation of the mode of action
Deboever, Estelle ULiege; Lins, Laurence ULiege; Ongena, Marc ULiege et al

in Bioorganic Chemistry (2020)

Fatty acid hydroperoxides (HPO) are free phyto-oxylipins known for their crucial role as signalling molecules during plant defense mechanisms. They were also demonstrated to have direct biocidal ... [more ▼]

Fatty acid hydroperoxides (HPO) are free phyto-oxylipins known for their crucial role as signalling molecules during plant defense mechanisms. They were also demonstrated to have direct biocidal activities against plant pathogens including gram negative bacteria. In the present work, the biocidal effect of one linolenic fatty acid hydroperoxide, namely 13-HPOT has been investigated on three plant pathogen gram negative bacteria: Pectobacterium carotovorum, Pseudomonas syringae and Xanthomonas translucens. We showed that 13-HPOT has a strong dose response effect on those phytopathogens. In a second part, the molecular mechanism behind the antibacterial effect of 13-HPOT was investigated at a molecular level using an integrative biophysical approach combining in vitro and in silico methods. Since other antimicrobial amphiphilic molecules have been shown to target the lipid membrane of the organisms they act on, we focused our study on the interaction of 13-HPOT with biomimetic membranes. In a first step, we hypothesized that the inner membrane of the bacteria was the main site of action of 13-HPOT and hence we used lipids representative of this membrane to form our models. Our results indicated that 13-HPOT can interact with the lipid representative of the inner bacterial plasma membrane. A strong membrane insertion is suggested but no major permeabilization of the membrane is observed. Phosphatidylethanolamine (PE) and cardiolipin (CL), present in the bacterial plasma membrane, appear to play important roles in this interaction. We suggest that the mode of action of 13-HPOT should involve either subtle changes in membrane properties, such as its lateral organization and distribution, and/or interactions with membrane proteins. [less ▲]

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See detailMolecular biophysics as a tool to investigate the bioherbicide effect of essential oils related to their interaction with plant plasma membrane
Lins, Laurence ULiege; De Clerck, Caroline ULiege; Fauconnier, Marie-Laure ULiege et al

Conference (2020, February)

Essential oils (EOs) are used in an increasingly number of sectors like medicine, cosmetics, food industry and more recently in agronomy. In agronomy, EOs are used as bio-pesticides for their insecticidal ... [more ▼]

Essential oils (EOs) are used in an increasingly number of sectors like medicine, cosmetics, food industry and more recently in agronomy. In agronomy, EOs are used as bio-pesticides for their insecticidal, antifungal or bactericidal effects but also as bio-herbicides. Owing to the current attraction for natural products, a better understanding of their mode of biological action for new and optimal applications is of importance. It has been shown that EOs antimicrobial activity, quite well described in the literature, is at least partly due to their interaction with the plasma membrane. They notably change the lipid composition, altering fluidity, leading to various effects which can induce cell lysis, apoptosis or necrosis. Citronellol, a major compound of lemongrass EO was notably shown to have antifungal activities by changing the membrane composition and inhibiting cell growth. Cinnamaldehyde (cinnamon EO) has been reported to have a broad spectrum of antibacterial activity, notably by affecting cell morphology, membrane integrity, permeability and composition. We are currently working on the development of a bioherbicide made from Cinnamomum zeylanicum Blume (cinnamon) and Cymbogognon winterianus Jowitt (citronella) EOs. We have shown that the application of the whole EOs and their major individual compounds on the leaves and cotyledons of A. thaliana appears to be promising: when applied on cotyledons or leaves, EOs induce damages that are as important as those observed for commercial herbicides. Since EOs are small amphiphilic molecules, they can cross the mesh of cell wall and interact directly with the plant plasma membrane (PPM). Modifying the lipid organization could lead to crucial cellular effects, notably on protein function. We used a unique and original combination of in silico (molecular dynamics simulations) and in vitro (Langmuir monolayers, isothermal calorimetry, fluorescence and infrared spectroscopies) biophysical approaches, previously developed to study structure-function relationships of molecules of biological interest (pharmacological drugs , proteins, peptides, surfactants…) to investigate the interaction of EOs or their individual compounds with bio-mimetic plant plasma membranes to better understand the structure- activity relationships in the context of their bioherbicide activity. [less ▲]

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See detailCynara cardunculus crude extract as a powerful natural herbicide and insight into the mode of action of its bioactive molecules
Ben Kaab, Sofiène ULiege; Lins, Laurence ULiege; Hanafi, Marwa ULiege et al

in Biomolecules (2020)

The use of chemical herbicides could not only potentially induce negative impacts on the environment, animals, and human health, but also increase the weed resistance to herbicides. In this context, the ... [more ▼]

The use of chemical herbicides could not only potentially induce negative impacts on the environment, animals, and human health, but also increase the weed resistance to herbicides. In this context, the use of plant extracts could be an interesting and natural alternative to chemical products. It is important to understand the mode of action of their bioactive compounds. This is why we have studied the herbicidal effect of Cynara cardunculus crude extract in terms of inhibition of weeds’ seedling growth and its impact on physiological parameters of treated plantlets, like conductivity, dry weight, and fluorescence, and biochemical parameters linked to oxidative stress. We have observed that C. cardunculus crude extract induces oxidative stress in the treated plants and consequently disturbs the physiological and biochemical functions of the plant cells. We have investigated the herbicidal activity of three bioactive compounds, naringenin, myricitrin, and quercetin, from the C. cardunculus crude extract. In both pre- and post-emergence trials, naringenin and myricitrin were significantly more phytotoxic than quercetin. We suggest that their differential initial interaction with the plant’s plasma membrane could be one of the main signals for electrolyte leakage and production of high levels of phenoxyl radicals. [less ▲]

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See detailEnhancing the Membranolytic Activity of Chenopodium quinoa Saponins by Fast Microwave Hydrolysis
Colson, Emmanuel; Savarino, Philippe; Claereboudt, Emily ULiege et al

in Molecules (2020), 25(7), 1731

Saponins are plant secondary metabolites. There are associated with defensive roles due to their cytotoxicity and are active against microorganisms. Saponins are frequently targeted to develop efficient ... [more ▼]

Saponins are plant secondary metabolites. There are associated with defensive roles due to their cytotoxicity and are active against microorganisms. Saponins are frequently targeted to develop efficient drugs. Plant biomass containing saponins deserves sustained interest to develop high-added value applications. A key issue when considering the use of saponins for human healthcare is their toxicity that must be modulated before envisaging any biomedical application. This can only go through understanding the saponin-membrane interactions. Quinoa is abundantly consumed worldwide, but the quinoa husk is discarded due to its astringent taste associated with its saponin content. Here, we focus on the saponins of the quinoa husk extract (QE). We qualitatively and quantitively characterized the QE saponins using mass spectrometry. They are bidesmosidic molecules, with two oligosaccharidic chains appended on the aglycone with two different linkages; a glycosidic bond and an ester function. The latter can be hydrolyzed to prepare monodesmosidic molecules. The microwave-assisted hydrolysis reaction was optimized to produce monodesmosidic saponins. The membranolytic activity of the saponins was assayed based on their hemolytic activity that was shown to be drastically increased upon hydrolysis. In silico investigations confirmed that the monodesmosidic saponins interact preferentially with a model phospholipid bilayer, explaining the measured increased hemolytic activity. [less ▲]

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See detailAmphiphilic azobenzenes: Antibacterial activities and biophysical investigation of their interaction with bacterial membrane lipids
Franche, Antoine; Fayeulle, Antoine; Lins, Laurence ULiege et al

in Bioorganic Chemistry (2020), 94

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See detailContributions and Limitations of Biophysical Approaches to Study of the Interactions between Amphiphilic Molecules and the Plant Plasma Membrane
Furlan, Aurélien ULiege; Laurin, Yoann ULiege; Botcazon, Camille et al

in Plants (2020), 9(5), 648

Some amphiphilic molecules are able to interact with the lipid matrix of plant plasma membranes and trigger the immune response in plants. This original mode of perception is not yet fully understood and ... [more ▼]

Some amphiphilic molecules are able to interact with the lipid matrix of plant plasma membranes and trigger the immune response in plants. This original mode of perception is not yet fully understood and biophysical approaches could help to obtain molecular insights. In this review, we focus on such membrane-interacting molecules, and present biophysically grounded methods that are used and are particularly interesting in the investigation of this mode of perception. Rather than going into overly technical details, the aim of this review was to provide to readers with a plant biochemistry background a good overview of how biophysics can help to study molecular interactions between bioactive amphiphilic molecules and plant lipid membranes. In particular, we present the biomimetic membrane models typically used, solid-state nuclear magnetic resonance, molecular modeling, and fluorescence approaches, because they are especially suitable for this field of research. For each technique, we provide a brief description, a few case studies, and the inherent limitations, so non-specialists can gain a good grasp on how they could extend their toolbox and/or could apply new techniques to study amphiphilic bioactive compound and lipid interactions [less ▲]

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See detailStress-related accumulation of arabidopsides: impact on plant chloroplasts - Flash presentation
Genva, Manon ULiege; Deleu, Magali ULiege; Andersson, Mats X et al

Conference (2020)

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See detailStress-related accumulation of arabidopsides: impact on plant chloroplasts
Genva, Manon ULiege; Deleu, Magali ULiege; Andersson, Mats X et al

Poster (2020)

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See detailPlant-pathogen interactions: underestimated roles of phyto-oxylipins
Deboever, Estelle ULiege; Deleu, Magali ULiege; Mongrand, Sébastien et al

in Trends in Plant Science (2020), 25(1), 22-34

Plant oxylipins are produced under a wide range of stress conditions, and even though they are well known to activate stress-related signalling pathways, the non-signalling roles of phyto-oxylipins are ... [more ▼]

Plant oxylipins are produced under a wide range of stress conditions, and even though they are well known to activate stress-related signalling pathways, the non-signalling roles of phyto-oxylipins are poorly understood. We describe oxylipins as direct biocidal agents and propose that structure-function relationships play here a pivotal role. Indeed, based on their chemical configuration, plant oxylipins, such as reactive oxygen and electrophile species, activate defence-related genes expression. We also propose that their ability to interact with pathogen membranes is important, but still misunderstood, and that they are involved in cross-kingdom communication. Taken as a whole, the current literature suggests that plant oxylipins have a high potential as biocontrol agents. However, the mechanisms underlying these multi-faceted compounds remain largely unknown. [less ▲]

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See detail« SAR out of the box » : insights into the relations between molecular structure, membrane interaction and activity of biomolecules using complementary biophysical tools
Lins, Laurence ULiege; Deleu, Magali ULiege

Conference (2019, December 02)

Classically, structure-Activity Relationship (SAR) is an approach designed to find relationships between chemical structure (or structural-related properties), 3D structure and biological activity of ... [more ▼]

Classically, structure-Activity Relationship (SAR) is an approach designed to find relationships between chemical structure (or structural-related properties), 3D structure and biological activity of compounds of interest, as defined by Crum-Brown and Fraser in 1865. This is because similar compounds should have similar physico-chemical and biological properties. If this notion is almost always associated to pharmacological drug design and assessment of side effects of existing compounds in the human health field, it can actually be extended to a large number of bioactive molecules exerting a number of cellular activities. For instance, interactions between plant or bacterial secondary metabolites as well as proteins belonging to the same structural family could have differential activities, notably at the level of the cellular membrane. In this talk, I propose to overview some complementary “in vitro” and “in silico” biophysical approaches such as those described in ref [1–3] that can give information about the relation between chemical structure (or structural-related properties), 3D structure and membrane activity of bioactive molecules. [less ▲]

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See detailNew insight into free-oxylipins roles, a potential for biocontrol agents
Deboever, Estelle ULiege; Deleu, Magali ULiege; Fauconnier, Marie-Laure ULiege et al

Conference (2019, November 19)

Nowadays, biopesticides have emerged as a main alternative to conventional agriculture. In this context, plant oxylipins, a vast and diverse family of secondary metabolites originated from polyunsaturated ... [more ▼]

Nowadays, biopesticides have emerged as a main alternative to conventional agriculture. In this context, plant oxylipins, a vast and diverse family of secondary metabolites originated from polyunsaturated fatty acids (PUFAs), appear to be crucial agents in plant defence mechanisms. Actually, it is highly known that plant oxylipins are produced under a wide range of stress conditions. While those molecules are well known to activate several signalling pathways and to induce adaptations in plant exposed to (a)biotic stresses, non-signalling roles of phyto-oxylipins are poorly understood. Among plant oxylipins, the 13-hydroperoxy oxylipins (13-HPO) constitute key intermediate oxylipins (KIOs) as they can be converted into jasmonic acid, OPDA, dn-OPDA or traumatic acid, well-characterized components involved in plant resistance mechanisms. Their presumed functions include direct antimicrobial effect, stimulation of plant defence gene expression, and/or regulation of plant cell death. However, the precise contribution of each of those molecules in plant defence remains unknown. In this study, 13-HPO properties as direct biocidal agents are investigated. In vitro assays have showed that KIOs can hinder growth of some plant microbial pathogens, with differences between strains and KIOs forms. Further investigation are needed to know if they maintain this power while being exogenously applied on plants, before or after infection. Afterwards, this study aims to understand the oxylipins action mechanisms and especially their membrane activities. As KIOs are found to be potential biocontrol agents and also to interact with plant plasma membranes, their interactions with plants and pathogens plasma membranes were studied using biomimetic membranes via a complementary in silico informatics and in vitro biophysical approaches. Finally, in analogy with other amphiphilic molecules (e.g. surfactins), KIOs may act as elicitors. This hypothesis is reinforced by preliminary results showing the production of reactive oxygen species (priming agents of eliciting reaction) when tobacco roots were in presence of KIOs. Further investigation are needed to confirm this property. [less ▲]

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See detailComplementary biophysical tools to investigate the membrane activities of essential oils
Lins, Laurence ULiege; Deleu, Magali ULiege

Scientific conference (2019, October 18)

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See detailInsights into the Relationships Between Herbicide Activities, Molecular Structure and Membrane Interaction of Cinnamon and Citronella Essential Oils Components
Lins, Laurence ULiege; Dal Maso, Simon ULiege; Foncoux, Bérénice ULiege et al

in International Journal of Molecular Sciences (2019), 20

Since the 50’s, the massive and “environmental naïve” use of synthetic chemistry has revolutionized the farming community facing the dramatic growth of demography. However, nowadays, the controversy grows ... [more ▼]

Since the 50’s, the massive and “environmental naïve” use of synthetic chemistry has revolutionized the farming community facing the dramatic growth of demography. However, nowadays, the controversy grows regarding the long-term harmful effects of these products on human health and the environment. In this context, the use of essential oils (EOs) could be an alternative to chemical products and a better understanding of theirmode of biological action for new and optimal applications is of importance. Indeed, if the biocidal effects of some EOs or their components have been at least partly elucidated at the molecular level, very little is currently known regarding their mechanism of action as herbicides at themolecular level. Here, we showed that cinnamon and Java citronella essential oils and some of their main components, i.e., cinnamaldehyde (CIN), citronellal (CitA), and citronellol (CitO) could act as efficient herbicides when spread on A. thaliana leaves. The individual EO molecules are small amphiphiles, allowing for them to cross the mesh of cell wall and directly interact with the plant plasma membrane (PPM), which is one of the potential cellular targets of EOs. Hence, we investigated and characterized their interaction with biomimetic PPMwhile using an integrative biophysical approach. If CitO and CitA, maintaining a similar chemical structure, are able to interact with the model membranes without permeabilizing effect, CIN belonging to the phenylpropanoid family, is not. We suggested that different mechanisms of action for the two types of molecules can occur: while the monoterpenes could disturb the lipid organization and/or domain formation, the phenylpropanoid CIN could interact with membrane receptors. [less ▲]

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See detailMolecular biophysics: An integrative approach to investigate the bioherbicide effect of essential oils related to their interaction with plant plasma membrane
Lins, Laurence ULiege; De Clerck, Caroline ULiege; Foncoux, Bérénice et al

Conference (2019, July)

Essential oils (EOs) are used in an increasingly number of sectors like medicine, cosmetics, food industry and more recently in agronomy. In agronomy, EOs are used as bio-pesticides for their insecticidal ... [more ▼]

Essential oils (EOs) are used in an increasingly number of sectors like medicine, cosmetics, food industry and more recently in agronomy. In agronomy, EOs are used as bio-pesticides for their insecticidal, antifungal or bactericidal effects but also as bio-herbicides. Owing to the current attraction for natural products, a better understanding of their mode of biological action for new and optimal applications is of importance. It has been shown that EOs antimicrobial activity, quite well described in the literature, is at least partly due to their interaction with the plasma membrane. They notably change the lipid composition, altering fluidity, leading to various effects which can induce cell lysis, apoptosis or necrosis. Citronellol, a major compound of lemongrass EO was notably shown to have antifungal activities by changing the membrane composition and inhibiting cell growth. Cinnamaldehyde (cinnamon EO) has been reported to have a broad spectrum of antibacterial activity, notably by affecting cell morphology, membrane integrity, permeability and composition. We are currently working on the development of a bioherbicide made from Cinnamomum zeylanicum Blume (cinnamon) and Cymbogognon winterianus Jowitt (lemongrass) EOs. We have shown that the application of the whole EOs and their major individual compounds on the leaves and cotyledons of A. thaliana appears to be promising: when applied on cotyledons or leaves, EOs induce damages that are as important as those observed for commercial herbicides. Since EOs are small amphiphilic molecules, they can cross the mesh of cell wall and interact directly with the plant plasma membrane (PPM). Modifying the lipid organization could lead to crucial cellular effects, notably on protein function. We used a unique and original combination of in silico (molecular dynamics simulations) and in vitro (Langmuir monolayers, isothermal calorimetry, fluorescence and infrared spectroscopies) biophysical approaches, previously developed to study structure-function relationships of molecules of biological interest (pharmacological drugs , proteins, peptides, surfactants…) to investigate the interaction of EOs or their individual compounds with bio-mimetic plant plasma membranes to better understand the structure- activity relationships in the context of their bioherbicide activity. [less ▲]

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See detailSearching for interactions at the membrane interface that confer antagonistic activities on floral regulators FT and TFL1
Pottier, Mathieu ULiege; Orman-Ligeza, Beata; Redouté, Gaëlle et al

Poster (2019, July)

In plants, the switch from leaf- to flower-producing meristems is controlled by the FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1) proteins. FT is a major component of the so-called "florigen", a ... [more ▼]

In plants, the switch from leaf- to flower-producing meristems is controlled by the FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1) proteins. FT is a major component of the so-called "florigen", a systemic signal that moves from leaves to shoot meristems and triggers the floral transition. By contrast, TFL1 is expressed in the shoot meristems and represses flowering, antagonising FT. Despite their opposite functions, FT and TFL1 are both members of the same family, showing homology to PHOSPHATIDYLETHANOLAMINE BINDING PROTEINs (PEBPs). They are unable to bind phosphatidylethanolamines though, but bind phosphatidylcholines that are major phospholipids of plant membranes and whose concentration impacts flowering time (Nakamura et al., 2014). The mechanisms by which FT and TFL1 regulate floral transition have been focused on their ability to complex with the transcription factor FD, which itself regulates floral identity genes. However, the loss of FD function does not abolish flowering and hence other interactors remain to be identified. We are therefore investigating in further detail the ability of Arabidopsis FT and TFL1 proteins to interact with membrane lipids and proteins. Langmuir method and molecular dynamics are currently being undertaken to characterize FT and TFL1 interactions with different phospholipids and to simulate their behaviors in contact with membranes, respectively. In parallel, FT and TFL1 protein interactomes are being investigated. We are performing in vitro pulldown assays using His-FT and His-TFL1 as baits and solubilized membranes proteins from cauliflower meristem as preys, taking advantage of the conservation of flowering genes among Brassicaceae. In parallel, complementation of Arabidopsis ft and tfl1 mutants with FT-GS and TFL1-GS constructs allowed us to perform in vivo co-purification analyses. This work will provide us with a better understanding of FT and TFL1 actions and highlight missing checkpoints of the floral transition. [less ▲]

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See detailIs it possible to predict the odor of a molecule on the basis of its structure?
Genva, Manon ULiege; Kenne Kemene, Tierry ULiege; Deleu, Magali ULiege et al

in International Journal of Molecular Sciences (2019), 20(12), 3018

The olfactory sense is the dominant sensory perception for many animals. When Richard Axel and Linda Buck received in 2004 the Nobel Prize for discovering the G-protein coupled receptors role in olfactory ... [more ▼]

The olfactory sense is the dominant sensory perception for many animals. When Richard Axel and Linda Buck received in 2004 the Nobel Prize for discovering the G-protein coupled receptors role in olfactory cells, it highlighted the importance of olfaction to scientific community. Several theories tried to explain how cells are able to distinguish such a wide variety of odorant molecules in a complex context in which enantiomers can result in completely different perceptions and structurally different molecules in the same one. Moreover, sex, age, cultural origin and individual differences contribute to odor perception variations that complicate the picture. Recent advances in olfaction theory will be presented and future trends in human olfaction like structure-based odor prediction or artificial sniffing will be discussed at the frontiers of chemistry, physiology, neurobiology and machine learning. [less ▲]

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