Decoding ROS signaling in plasma membrane nanodomains

• Applicant: Professor Dr. Andreas Meyer
• Subject Area: Plant Physiology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 545516367

Multiple stress responses and developmental processes are associated with the generation of reactive oxygen species (ROS). Hydrogen peroxide (H2O2) causes oxidation of protein thiols, either directly or indirectly through transmitter proteins. The reversible protein oxidation constitutes an important post-translational modification that regulates protein function during cell signaling. Recently, we demonstrated that the GTPase ROP6 after osmotic challenge forms nanodomains in the plasma membrane (PM) where it then clusters with the NADPH oxidases RBOHD/F. The formation of ROP6 nanodomains is necessary and sufficient for the production of ROS and ultimately acts on root cell growth. Further preliminary data show that superoxide produced by RBOH is quickly converted to H2O2, which at least in part enters the cytosol through aquaporins. By ratiometric TIRF imaging with the H2O2 biosensor HyPer7, we describe H2O2 hotspots in the cytoplasm just below PM nanodomains. Based on this locally increased H2O2 concentrations, it can be envisaged that specific thiol-containing proteins are oxidized and thus switched to either active or inactive forms or are modified in their conformation. This may be key to distinct protein-protein interactions. Yet, to be specific, there may be a need for highly sensitive redox transmitters that transfer the primary oxidation to target proteins and thereby overcome possible kinetic barriers. In this context, our observation that the PM-associated glutathione peroxidase-like proteins GPXL4 and 5 also assemble in nanodomains after osmotic challenge, together with the fact that GPXLs can act as protein thiol oxidases is highly intriguing. It suggests that the formation of H2O2 hotspots at the PM together with suitable redox transmitters may constitute a functional decoding hub for redox signals involving H2O2. The objectives of the NanoROS project encompasses unraveling the molecular composition of osmotically induced nanodomains, elucidating the roles of GPXL4 and GPXL5, and understanding the interplay between H2O2 signaling, cytosolic redox regulation, and cytoskeletal dynamics during cell growth. To achieve these goals, we will implement an interdisciplinary approach integrating molecular biology, advanced live cell imaging and biochemical analyses. The anticipated outcomes include a deeper understanding of the molecular composition of PM nanodomains, their influence on local cytosolic redox dynamics, and their functional role in coordinating cellular responses to external stimuli.

• DFG Programme: Research Grants
• International Connection: France
• Partner Organisation: Agence Nationale de la Recherche / The French National Research Agency
• Cooperation Partner: Dr. Alexandre Martinière