Biology subjects

Crowet, J.-M.

Publications and source records attributed to Crowet, J.-M..

4 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

Mechanosensing and Sphingolipid-Docking Mediate Lipopetide-Induced Immunity in Arabidopsis

Bacteria-derived lipopeptides are immunogenic triggers of host defenses in metazoans and plants. Root-associated rhizobacteria produce cyclic lipopeptides that activate systemically induced resistance (IR) against microbial infection in various plants. How these molecules are perceived by plant cells remains elusive. Here, we reveal that immunity activation in Arabidopsis thaliana by the lipopeptide elicitor surfactin is mediated by docking into specific sphingolipid-enriched domains and relies on host membrane deformation and subsequent activation of mechanosensitive ion channels. This mechanism leads to host defense potentiation and resistance to the necrotroph B. cinerea but is distinct from host pattern recognition receptor-mediated immune activation and reminiscent of damage-induced plant immunity.

plant biology↗

bioRxiv2019

Structural analysis of nonapeptides derived from elastin

Elastin-derived peptides are released from the extracellular matrix remodeling by numerous proteases and seem to regulate many biological processes, notably cancer progression. The canonical elastin peptide is VGVAPG which harbors the XGXXPG consensus pattern allowing interaction with the elastin receptor complex located at the surface of cells. Besides these elastokines, another class of peptides has been identified. This group of bioactive elastin peptides presents the XGXPGXGXG consensus sequence but the reason for their bioactivity remains unexplained. In order to better understand their nature and structure-function relationships, herein we searched the current databases for this nonapeptide motif and observed that the XGXPGXGXG elastin peptides define a specific group of tandemly repeated patterns. Further, we focused on four tandemly repeated human elastin nonapeptides, i.e. AGIPGLGVG, VGVPGLGVG, AGVPGLGVG and AGVPGFGAG. These peptides were analysed by means of optical spectroscopies and molecular dynamics. UV-circular dichroism and Raman spectra are consistent with a conformational equilibrium between {beta}-turn, {beta}-strand and random chain secondary elements in aqueous media. This equilibrium was found to be concentration-independent. Quantitative analysis of their conformations suggested that turns corresponded to half of the total population of structural elements while the remaining half was equally distributed between {beta}-strand and unordered chains. These distributions were confirmed by molecular dynamics simulations. Altogether, our data suggest that these peptides harbor a type II {beta}-turn located in their central part. We hypothesize that this structural element could explain their specific bioactivity. Statement of SignificanceElastin fragmentation products, the so-called elastin peptides, may exhibit a bioactivity towards normal and tumor cells. This phenomenon depends on the sequence motif they harbor. While XGXXPG sequences bioactivity is explained by the presence of a type VIII {beta}-turn allowing interaction with the elastin receptor complex, the structural reasons for XGXPGXGXG specific activity remain unexplained. Using data mining, we show that elastin nonapeptides define a specific class of tandemly repeated features. Further, spectroscopic and numerical simulations methods suggest the presence of a type II {beta}-turn in their conformation. This structural element could explain their bioactivity.

biochemistry↗

bioRxiv2018

Multiple C2 domains and Transmembrane region Proteins (MCTPs) tether membranes at plasmodesmata

AO_SCPLOWBSTRACTC_SCPLOWIn eukaryotes, membrane contact sites (MCS) allow direct communication between organelles. Plants have evolved unique MCS, the plasmodesmata intercellular pores, which combine endoplasmic reticulum (ER) - plasma membrane (PM) contacts with regulation of cell-to-cell signalling. The molecular mechanism and function of membrane tethering within plasmodesmata remains unknown.\n\nHere we show that the Multiple C2 domains and Transmembrane region Protein (MCTP) family, key regulators of cell-to-cell signalling in plants, act as ER - PM tethers specifically at plasmodesmata. We report that MCTPs are core plasmodesmata proteins that insert into the ER via their transmembrane region whilst their C2 domains dock to the PM through interaction with anionic phospholipids. A mctp3/4 loss-of-function mutant induces plant developmental defects while MCTP4 expression in a yeast {Delta}tether mutant partially restores ER-PM tethering. Our data suggest that MCTPs are unique membrane tethers controlling both ER-PM contacts and cell-cell signalling.

plant biology↗