Biology subjects

Maneta-Peyret, L.

Publications and source records attributed to Maneta-Peyret, L..

7 recordsLinked to original sources

bioRxiv2025

The phytolongin AtPhyl2.1 is involved in cell plate formation and root development

SNAREs are critical elements of the membrane trafficking machinery with a wide variety of functionality across this family of proteins. Phytolongins are a recently identified subfamily of longins which possess the typical longin domain but lack a SNARE motif. Phytolongins have an ubiquitous tissue expression in Arabidopsis and are distributed throughout the secretory pathway. We focused on Phytolongin 2.1 (PHYL2.1) which localizes to the endoplasmic reticulum, and observed a strong root growth phenotype in the loss-of-function Atphyl2.1-1 mutant. We demonstrate that whilst cell elongation efficiency was not affected in the mutant, cell division was significantly reduced. The resulting decrease in root length in the Atphyl2.1-1 mutant is explained by a smaller number of cells which then elongate to enable root growth. Root apical meristem architecture of Atphyl2.1-1 and another mutant Atphyl2.1-2 was disturbed and distances from the root quiescent center to the transition zone and the first areas of mis-organized cells were affected in both mutants. Investigation of the SNARE AtKNOLLE revealed significant perturbation of Atphyl2.1-1 cell plate formation in the mis-organised areas. Our results provide a first characterization of the phytolongin AtPHYL2.1 which appears involved in root cell plate formation, root cell division and therefore root development. HighlightThe phytolongin AtPHYL2.1 significantly affects the efficiency of cell plate formation and root development in Arabidopsis thaliana.

plant biology↗

bioRxiv2021

Lyso-Phosphatidic Acid Acyl-Transferases: a link with intracellular protein transport in Arabidopsis root cells?

Phosphatidic acid (PA) and Lysophosphatidic acid acyltransferases (LPAATs) might be critical for the secretory pathway. Four extra-plastidial LPAATs (numbered 2,3,4 and 5) were identified in A. thaliana. These AtLPAATs, displaying an enzymatic activity specific for LPA to produce PA, are located in the endomembrane system. We focused on the putative role of the AtLPAATs 3, 4 and 5 in the secretory pathway of root cells through genetical (knock-out mutants), biochemical (activity inhibitor, lipid analyses) and imaging (live and immuno-confocal microscopies) approaches. Treating a lpaat4;lpaat5 double mutant with the LPAAT inhibitor CI976 showed a primary root growth decrease. The transport of the auxin transporter PIN2 was disturbed in this lpaat4;lpaat5 double mutant treated with CI976, but not that of H+-ATPases. The lpaat4;lpaat5 double mutant was sensitive to salt stress and the transport of the aquaporin PIP2;7 to the plasma membrane in the lpaat4;lpaat5 double mutant treated with CI976 was reduced. We measured the amounts of neo-synthesized PA in roots, and found a decrease in PA only in the lpaat4;lpaat5 double mutant treated with CI976, suggesting that the protein transport impairment was due to a critical PA concentration threshold. HighlightPhosphatidic acid produced by Lyso-Phosphatidic Acid Acyl-Transferases has an impact on the efficiency of the intracellular transport of some proteins in Arabidopsis thaliana root cells.

cell biology↗

bioRxiv2021

The enpp4 ectonucleotidase regulates kidney patterning signalling networks in Xenopus embryos

The enpp ectonucleotidases regulate lipidic and purinergic signalling pathways by controlling the extracellular concentrations of purines and bioactive lipids. Although both pathways are key regulators of kidney physiology and linked to human renal pathologies, their roles during nephrogenesis remain poorly understood. We previously showed that the pronephros was a major site of enpp expression and now demonstrate an unsuspected role for the conserved vertebrate enpp4 protein during kidney formation in Xenopus. Enpp4 over-expression results in ectopic renal tissues and, on rare occasion, complete mini-duplication of the entire kidney. Enpp4 is required and sufficient for expression of the pronephric markers and regulates the expression of RA, Notch and Wnt pathway members. Enpp4 is a membrane protein that binds, without hydrolyzing, phosphatidylserine and its effects are mediated by the receptor s1pr5, although not via the generation of S1P. Finally, we propose a novel and surprising non-catalytic mechanism by which lipidic signalling regulates nephrogenesis.

developmental 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↗

bioRxiv2018

In vivo phosphatidylserine variations steer Rho GTPase signaling in a cell-context dependent manner

AbstractRho GTPases are master regulators of cell signaling, but how they are regulated depending on the cellular context is unclear. Here, we show that the phospholipid phosphatidylserine acts as a developmentally-controlled lipid rheostat that tunes Rho GTPase signaling in Arabidopsis. Live super-resolution single molecule imaging revealed that RHO-OF-PLANT6 (ROP6) is stabilized by phosphatidylserine into plasma membrane (PM) nanodomains, which is required for auxin signaling. Furthermore, we uncovered that the PM phosphatidylserine content varies during plant root development and that the level of phosphatidylserine modulates the quantity of ROP6 nanoclusters induced by auxin and hence downstream signaling, including regulation of endocytosis and gravitropism. Our work reveals that variations in phosphatidylserine levels are a physiological process that may be leveraged to regulate small GTPase signaling during development.\n\nOne Sentence SummaryPhosphatidylserine acts as a developmentally-controlled lipid rheostat that regulates cellular auxin sensitivity and plant development.

plant biology↗

bioRxiv2018

A combinatorial lipid code shapes the electrostatic landscape of plant endomembranes

Membrane surface charge is critical for the transient, yet specific recruitment of proteins with polybasic regions to certain organelles. In all eukaryotes, the plasma membrane (PM) is the most electronegative compartment of the cell, which specifies its identity. As such, membrane electrostatics is a central parameter in signaling, intracellular trafficking and polarity. Here, we explore which are the lipids that control membrane electrostatics using plants as a model. We show that phosphatidic acidic (PA), phosphatidylserine (PS) and phosphatidylinositol-4-phosphate (PI4P) are separately required to generate the electrostatic signature of the plant PM. In addition, we reveal the existence of an electrostatic territory that is organized as a gradient along the endocytic pathway and is controlled by PS/PI4P combination. Altogether, we propose that combinatorial lipid composition of the cytosolic leaflet of cellular organelles not only defines the plant electrostatic territory but also distinguishes different compartments within this territory by specifying their varying surface charges.

plant biology↗

bioRxiv2017

The Odd One Out: Aabidopsis Reticulon 20 Has A Role In Lipid Biosynthesis

The family of reticulon proteins has been shown to be involved in a variety of functions in eukaryotic cells including tubulation of the endoplasmic reticulum (ER), formation of cell plates and primary plasmodesmata. Reticulons are integral ER membrane proteins characterised by a reticulon homology domain comprising four transmembrane domains which results in the reticulons sitting in the membrane in a W-topology. Here we report on a subgroup of reticulons with an extended N-terminal domain and in particular on arabidopsis reticulon 20. We show that reticulon 20 is located in a unique punctate pattern on the ER membrane. Its closest homologue reticulon 19 labels the whole ER. We show that mutants in RTN20 or RTN19, respectively, display a significant change in sterol composition in the roots indicating a role in lipid biosynthesis or regulation. A third homologue in this family - 3BETAHSD/D1- is localised to ER exit sites resulting in an intriguing location difference for the three proteins.

plant biology↗