Biology subjects

Trouillas, P.

Publications and source records attributed to Trouillas, P..

4 recordsLinked to original sources

bioRxiv2025

Predicting non-covalent interactions between antioxidants in biological membranes through molecular dynamics

The synergistic association of different polyphenols has gained much interest in the food industry to develop efficient antioxidant cocktails, reducing the concentration of active agents and subsequently potential toxicity. The theoretical description and prediction of such processes is of central interest in this development. This study aims at benchmarking the performance of molecular dynamics (MD) to predict the formation of non-covalent complexes between {pi}-conjugated antioxidants, including two prototypes (quercetin and vitamin E), in a pure 1,2-dipalmitoylphosphatidylcholine (DOPC) lipid bilayer. To reproduce the experimentally observed quenching of vitamin E fluorescence by quercetin, a sphere-of-action quenching model was applied. The predictive capability of MD simulations at capturing this non-covalent association was evaluated with five other {pi}-conjugated potential partners of vitamin E, namely catechin, caffeic acid, myricetin, kaempferol, and galangin. The observed trend agreed with experimental studies, validating again the use of MD simulations as a tool to measure the potential synergism between natural antioxidants.

bioinformatics↗

bioRxiv2024

Skin hydration by natural moisturizing factors, a story of H-bond networking

Dry skin is a common condition experienced by many. Besides being particularly present during the cold season, various diseases exist all year round, leading to localized xerosis. To prevent it, the skin is provided with natural moisturizing factors (NMFs). They are small amino acids or derivatives found in the outermost layer of the skin, the stratum corneum (SC). They are often claimed to be highly efficient humectants, increasing the water content to maintain the fluidity of the skin. However, alternative mechanisms have been proposed, suggesting that NMFs themselves may act as lipid mobility amplifiers. This work aims at investigating the role of three NMFs, namely urea (URE), glycerol (GLY) and urocanic acid / urocanate (UCA/UCO) in SC in silico models, considering two different levels of humidity. Molecular dynamic simulations showed an increase in the diffusion of different lipid components, mainly free fatty acids (FFAs) and ceramides acyl chain moieties, in the presence of either high water content or NMFs. The membrane properties were modified, as seen by an increased thickness and a greater lateral stiffness. All NMFs exhibited a similar impact, whereas UCA revealed slight differences according to its charged state. By studying NMF-water intermolecular interactions, we highlighted the role of NMF as a regulator of membrane perturbations, while insuring membrane fluidity. This role allows NMFs to prevent destabilization of the skin membrane in the presence of high-water content. This study, performed at an atomistic resolution, highlighted a strong H-bond network between lipids, involving mainly ceramides but also all other components. This network can be modified in the presence of high-water concentration or NMFs, resulting in modifications of membrane properties, rationalizing hydration effects.

bioinformatics↗

bioRxiv2020

The impact of plasma membrane lipid composition on flagella-mediated adhesion of enterohemorrhagic Escherichia coli

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major cause of foodborne gastrointestinal illness. The adhesion of EHEC on host tissues is the first step enabling bacterial colonization. Adhesins like fimbriae and flagella mediate this mechanism. Here, we studied the interaction of the bacterial flagellum with the host cell’s plasma membrane using Giant Unilamellar Vesicles (GUVs) as a biologically relevant model. Cultured cell lines contain many different molecular components including proteins and glycoproteins. In contrast, with GUVs we can characterize the bacterial mode of interaction solely with a defined lipid part of the cell membrane. Bacterial adhesion on GUVs was dependent on the presence of the flagellar filament and its motility. By testing different phospholipid head groups, the nature of the fatty acid chains or the liposome curvature, we found that lipid packing is a key parameter to enable bacterial adhesion. Using HT-29 cells grown in the presence of polyunsaturated fatty acid (α-linolenic acid) or saturated fatty acid (palmitic acid), we found that α-linolenic acid reduced adhesion of wild type EHEC but not of a non-flagellated mutant. Finally, our results reveal that the presence of flagella is advantageous for the bacteria to bind to lipid rafts. We speculate that polyunsaturated fatty acids prevent flagellar adhesion on membrane bilayers and play a clear role for optimal host colonization. Flagella-mediated adhesion to plasma membranes has broad implications to host-pathogen interactions.Importance Bacterial adhesion is a crucial step to allow bacteria to colonize their hosts, invade tissues and form biofilm. Enterohemorrhagic E. coli O157:H7 is a human pathogen and the causative agent of diarrhea and hemorrhagic colitis. Here, we use biomimetic membrane models and cell lines to decipher the impact of lipid content of the plasma membrane on enterohemorrhagic E. coli flagella-mediated adhesion. Our findings provide evidence that polyunsaturated fatty acid (α-linolenic acid) inhibits E. coli flagella adhesion to the plasma membrane in a mechanism separate from its antimicrobial and anti-inflammatory functions. In addition, we confirm that cholesterol-enriched lipid microdomains, often called lipid rafts are important in bacterial adhesion. These findings significantly strengthen plasma membrane adhesion via bacterial flagella in an important human pathogen. This mechanism represents a promising target for the development of novel anti-adhesion therapies.Competing Interest StatementThe authors have declared no competing interest.View Full Text

microbiology↗

bioRxiv2018

Nitrone-Trolox conjugate as an inhibitor of lipid oxidation: Towards synergistic antioxidant effects

1Free radical scavengers like -phenyl-N-tert-butylnitrone (PBN) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) have been widely used as protective agents in various biomimetic and biological models. A series of three amphiphilic Trolox and PBN derivatives have been designed by adding to the parent molecules both a perfluorinated chain and a sugar group in order to render them amphiphilic. In this work, we have studied the interaction of these derivatives with lipid membranes and how it correlates to their antioxidant properties.\n\nThe three derivatives form monolayers at the air/water interface. We next investigated the ability of each derivative to interact with 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLPC) as well as their efficiency to inhibit the AAPH-induced oxidation of DLPC liposomes. The location of these derivatives in the membrane is a key parameter to rationalize their antioxidant efficiency. The derivative bearing both the PBN and the Trolox antioxidant moieties on the same fluorinated carrier exhibited a synergistic antioxidant effect by delaying the oxidation process. Molecular dynamics (MD) simulations supported the understanding of the mechanism of action, highlighting various key physical-chemical descriptors.\n\nGraphical abstract\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=82 SRC=\"FIGDIR/small/323386_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (20K):\norg.highwire.dtl.DTLVardef@15e2ce5org.highwire.dtl.DTLVardef@1d58ee3org.highwire.dtl.DTLVardef@197f9d2org.highwire.dtl.DTLVardef@9279ff_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights- Amphiphilic fluorinated antioxidants efficiently inhibit lipid oxidation\n- The perfluorinated chain allows the insertion into membranes\n- The nature of the antioxidant is a key parameter in the antioxidant efficiency\n- The combination of Trolox and PBN results in a synergistic antioxidant effect\n\n\nCondensed running titleTrolox derivatives limit lipid oxidation

biophysics↗