Project

Discipline

LRR-extensins; LRX proteins; Arabidopsis thaliana; cell wall; development; Ca2+ and ROS

Lead
Ein spezifisches Charakteristikum von Pflanzen ist die Zellwand, welche jede einzelne Zelle umgibt. Diese schützt die Zelle, gibt ihr eine definierte Form und ist eine wichtige regulatorische Komponente im Zellwachstum. Letzteres deshalb, weil Pflanzenzellen nur wachsen können, wenn die Zellwand sich ausdehnt. Um dies zu ermöglichen, muss ein Informationsaustausch zwischen dem Zellinnern und der Zellwand bestehen.
Lay summary
Inhalt des Forschungsprojektes LRR-Extensine sind in der Zellwand lokalisierte Proteine, welche in den Zellwandaufbau involviert sind. Dieses Projekt untersucht die Funktion(en) dieser Proteine im Detail. Indizien sprechen für eine Funktion an der äusseren Schicht der Zelle, der Plasmamembran, wo die LRX Proteine möglicherweise die Aktivität von Proteinen beeinflussen. Da LRX Proteine mit der Zellwand verbunden sind, könnten sie die Funktion haben, die Plasmamembran mit der Zellwand zu verbinden. Diese Hypothese soll in diesem Projekt untersucht werden. Zudem ist es das Ziel, die Art der Interaktion zwischen LRX Proteinen und der Plasmamembran zu charakterisieren, und die biologische Relevanz dieser Bindung zu definieren.    Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojektes Das Projekt befasst sich mit der molekularen Kommunikation zwischen verschiedenen Zonen von pflanzlichen Zellen. Dies ist aus dem Blickwinkel der Grundlagenforschung relevant. Allerdings ist das bessere Verständnis des Zellwandaufbaus auch deshalb interessant, weil die Zellwandmaterialien von grossem industriellen Interesse sind, z.B. in der Prouktion von Geliermitteln, Papier oder Biobrennstoffen.

Direct link to Lay Summary

Last update: 06.04.2016

Communication	Title	Media	Place	Year

Number	Title	Start	Funding scheme

Plant cells are surrounded by cell walls provide protection against pathogens, wounding, and abiotic stresses. Typically, they are composed of cellulose, hemicellulose, pectins, and structural proteins. Plant cell growth is driven by the internal turgor pressure of the cell but is limited by the cell wall, which has to expand for successful yielding of the cell. Expansion of the cell wall requires metabolic activity in the cell to supply new wall material and the integration of this material into the expanding cell wall. Hence, a network of proteins establishing the cytoplasm - cell wall continuum is necessary to survey, control, and regulate these complex processes in a temporally and spatially coordinated fashion.Leucine-rich repeat-extensin (LRX) proteins are extracellular proteins that are anchored to the cell wall through the extensin (hydroxyproline-rich glycoprotein) domain and bind, via their LRR domain, a so far unknown interaction partner. Of the eleven LRX proteins encoded by the genome of Arabidopsis thaliana, several have been shown to influence cell wall formation. We have mutants of different Arabidopsis LRX genes that are affected in the root, the shoot, or pollen tubes, giving a choice of cellular systems to be used for the different analyses. In addition, a number of rol (repressor of lrx1) mutants were isolated that suppress the root hair growth defect of the lrx1 mutant. Whole genome sequencing of five of these mutants revealed candidate genes for the mutated rol loci, providing an insight into genes and processes that can suppress lrx1. We recently have obtained results indicating that the LRR domain of several LRX proteins associates with the plasma membrane, while the extensin domain has been shown to interact with the cell wall. We propose to investigate this observation in detail as it provides evidence for LRX proteins being plasma membrane. In parallel, we aim to identify the interaction partner(s) of the LRR domain of LRXs, which are likely to localize in or at the plasma membrane. Finally, several of the isolated rol mutants are affected in the homeostasis of reactive oxygen species (ROS). The biological relevance of this observation will be investigated in the rol mutants, while a detailed molecular analysis of the mutated genes will be limited to one or two of these lines.The proposed project will determine the contribution of LRX proteins to the regulation of Ca2+- and possibly ROS- related processes. If LRX proteins indeed represent cell-wall attached linker proteins, this should be substantiated by the planned experiments. Cytological experiments and genetic analyses should also shed light on the potential function of LRXs and their possible interaction partner(s). Together, these experiments should provide a better insight into the poorly understood function of LRX proteins.