Biology subjects

Simon-Plas, F.

Publications and source records attributed to Simon-Plas, F..

3 recordsLinked to original sources

bioRxiv2025

Sphingolipid-driven interleaflet coupling orchestrates Rho-GTPase recruitment to nanodomains for signal activation in plants

Biological membranes are both laterally heterogeneous and asymmetrical across leaflets, yet how this asymmetry contributes to signal transduction remains unclear. Here we show that sphingolipid-driven interleaflet coupling coordinates nanodomain organization and Rho-GTPase activation in plants. Using molecular dynamics simulations, super-resolution and single-molecule imaging, quantitative genetics, and biochemistry, we find that very long acyl chain (VLCFA)-containing sphingolipids in the outer leaflet interdigitate with phosphatidylserine (PS) in the inner leaflet, forming a vertical molecular bridge that organizes PS into nanodomains. This coupling promotes recruitment and activation of the Rho-GTPase ROP6 in response to auxin, whereas disruption of VLCFA synthesis or sphingolipid composition disperses PS and ROP6 nanodomains, impairing cytoskeletal reorganization and directional growth. Our findings reveal interleaflet coupling as a fundamental organizing principle linking membrane asymmetry to signaling, providing a conceptual framework for spatial and temporal control of signal transduction across eukaryotic membranes.

plant biology↗

bioRxiv2023

Revealing the lipidome and proteome of Arabidopsis thaliana plasma membrane

The plant plasma membrane (PM) plays a key role in nutrition, cell homeostasis, perception of environmental signals, and set-up of appropriate adaptive responses. An exhaustive and quantitative description of the whole set of lipids and proteins constituting the PM is thus necessary to understand how the way these components, are organized and interact together, allow to fulfill such essential physiological functions. Here we provide by state-of-the-art approaches the first combined reference of the plant PM lipidome and proteome from Arabidopsis thaliana suspension cell culture. We identified a reproducible core set of 2,165 proteins (406 of which had not been shown associated to PM previously), which is by far the largest set of available data concerning the plant PM proteome. Using the same samples, we combined lipidomic approaches, allowing the identification and quantification of an unprecedented repertoire of 405 molecular species of lipids. We showed that the different classes of lipids (sterols, phospholipids, and sphingolipids) are present in similar proportions in the plant PM. Within each lipid class, the precise amount of each lipid family and the relative proportion of each molecular species were further determined, allowing us to establish the complete lipidome of Arabidopsis PM, and highlighting specific characteristics of the different molecular species of lipids (for instance fatty acyl chain length and saturation according to the polar head). Results obtained are consistent with the plant PM being an ordered mosaic of domains and point to a finely tuned adjustment of the molecular characteristics of lipids and proteins. More than a hundred proteins related to lipid metabolism, transport or signaling have been identified and put in perspective of the lipids with which they are associated. All these results provide an overall view of both the organization and the functioning of the PM.

plant biology↗

bioRxiv2020

Purification, characterization and influence on membrane properties of the plant-specific sphingolipids GIPC

The plant plasma membrane (PM) is an essential barrier between the cell and the external environment. The PM is crucial for signal perception and transmission. It consists of an asymmetrical lipid bilayer made up of three different lipid classes: sphingolipids, sterols and phospholipids. The most abundant sphingolipids in the plant PM are the Glycosyl Inositol Phosphoryl Ceramides (GIPCs), representing up to 40% of total sphingolipids, assumed to be almost exclusively in the outer leaflet of the PM. In this study, we investigated the structure of GIPCs and their role in membrane organization. Since GIPCs are not commercially available, we developed a protocol to extract and isolate GIPC-enriched fractions from eudicots (cauliflower and tobacco) and monocots (leek and rice). Lipidomic analysis confirmed the presence of different long chain bases and fatty acids. The glycan head groups of the different GIPC series from monocots and dicots were analysed by GC-MS showing different sugar moieties. Multiple biophysics tools namely Langmuir monolayer, {zeta}-Potential, light scattering, neutron reflectivity, solid state 2H-NMR and molecular modelling were used to investigate the physical properties of the GIPCs, as well as their interaction with free and conjugated phytosterols. We showed that GIPCs increase the thickness and electronegativity of model membranes, interact differentially with the phytosterols species and regulate the gel-to-fluid phase transition during temperature variations.

plant biology↗