Dr Alexandre MARTINIÈRE, Laboratoire de Biochimie et Physiologie Moléculaire des Plantes (BPMP), Montpellier, France, invité par M.-E. Chabouté
Plant membrane nano-organization and cell signaling
Far from been a homogenous environment, biological membranes are highly structured with lipids and proteins segregating in domains of different sizes and dwell times. This nanoscale organization of the membrane creates emergent properties that determine cellular signaling. Taking plant osmotic signaling pathway as an example, we have found that Rho of Plant 6 (ROP6) is necessary and sufficient to transduce downstream signals in Arabidopsis root cell, especially the accumulation of reactive oxygen species (ROS). At the plasma membrane and only upon cell stimulation, this protein forms domain of a few 10th of nanometers. This specific organization of the protein at the PM is needed to recruit effector protein like the NADPH oxidase, a major actor of ROS signaling in plant. Our observations suggest also that depending of the upstream signal, ROP6 clustering lead to recruitment of specific effector proteins that might encode for a part of the signal specificity. Finally, we have found that the quantity of certain charged lipids in ROP6 nanodomaines appeared to control signal amplitudes. Furthermore, I will discuss an hypothetical model for ROP membrane targeting and discuss how there organization could determine signaling parameters like signal specificity, amplification and integration.