Description du projet
Structure et fonction du complexe de signalisation minimal des récepteurs kinases dans les plantes
Les récepteurs kinases (RK) localisés dans les membranes plasmiques fonctionnent dans les voies de signalisation des plantes pendant le développement, la reproduction et en réaction aux stress environnementaux. Ils ont différentes fonctions biochimiques et, outre la fixation des ligands, certains jouent un rôle de régulation au sein des complexes RK. Le projet MINIREX, financé par l’UE, se propose de chercher les composants minimaux qui lient la fixation des ligands à l’activation des récepteurs et à l’initiation des processus cellulaires, ainsi que les mécanismes structurels de l’activation des complexes de récepteurs. Son objectif consiste à analyser les changements structurels induits par les ligands par microscopie cryoélectronique des complexes RK incorporés dans les membranes en utilisant le récepteur immunitaire végétal FLS2 (qui perçoit la flagelline bactérienne) comme système modèle.
Objectif
Plasma membrane-localized receptor kinases (RKs) perceive diverse extracellular ligands, allowing plants to react to various stimuli. They function in signaling processes during all aspects of plants’ life, including development, biotic and abiotic stress responses as well as reproduction. In the last decade, a major paradigm has emerged that individual RKs have different biochemical functions. There are e.g. ligand-binding RKs, which require the formation of stable complexes with RK co-receptors in order to initiate signaling. In addition to this common mode of activation, it has been revealed that additional RKs can have regulatory functions within RK complexes, and that in planta several other proteins are part of these complexes to regulate – either positively or negatively – complex formation and initiation of downstream signaling.
The proposed project aims to understand what the minimal components linking ligand binding to receptor activation and to the initiation of cellular outputs are. Furthermore, it has the goal to elucidate the structural mechanisms of receptor complex activation. To achieve this, two interconnected approaches will be pursued. The first will utilize protein expression in cell-culture to reconstitute the signaling pathway from ligand perception to activation of downstream targets. The second approach will use a cell-free in vitro expression system to reconstitute the complete RK complex in synthetic, membrane-mimicking nanodiscs. This will ultimately allow the analysis of ligand induced structural changes by cryo-electron microscopy within full length, membrane embedded RK complexes.
The well-characterized RK FLAGELLIN SENSING 2 (FLS2) and its co-receptor RK BRI1-ASSOCIATED KINASE 1 (BAK1), which are core elements of the receptor complex mediating the perception of bacterial Flagellin and function in the induction of antibacterial immune responses, will be to this end employed as a model for the proposed project.
Champ scientifique
Programme(s)
Régime de financement
MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)Coordinateur
8006 Zurich
Suisse