A structural and functional study of the ion channel SLAC1 and its activating kinase OST1 which mediate drought tolerance in plants

The anion channel SLAC1 is specifically expressed in guard cells of plants. Guard cells surround small pores in the lower leave epidermis called stomata. OST1 kinase-mediated activation of SLAC1 leads to ion efflux which, in turn, causes decrease of turgor pressure in guard cells. Reduced turgor pressure in guard cells ultimately causes stomata to close making SLAC1 and OST1 pivotal elements in the process of stomatal closure. The evolution and global distribution of advanced terrestrial plants is closely related to the acquisition of the aforementioned mechanism as it limits water loss by plants in response to drought. This project is aimed to understand the molecular mechanism that controls this process. To this end, the full length structure of SLAC1 bound to its activating kinase OST1 will be solved and structure-based functional studies will be conducted. This project will help to explain the gating- and OST1 kinase-mediated activation mechanism of the plant ion channel SLAC1. Furthermore, it will set the stage for understanding the molecular basis mediating drought tolerance in plants which is central to engineer improved crops able to efficiently grow under limited supply of water.