Optogenetic inhibition and activation of Rac and Rap1 using a modified iLID system

Abstract

The small GTPases Rac1 and Rap1 can fulfill multiple cellular functions because their activation kinetics and localization are precisely controlled. To probe the role of their spatio-temporal dynamics, we generated optogenetic tools that activate or inhibit endogenous Rac and Rap1 in living cells. An improved version of the light-induced dimerization (iLID) system was used to control plasma membrane localization of protein domains that specifically activate or inactivate Rap1 and Rac (Tiam1 and Chimerin for Rac, RasGRP2 and Rap1GAP for Rap1). Irradiation yielded a 50-230% increase in the concentration of these domains at the membrane, leading to effects on cell morphodynamics consistent with the known roles of Rac1 and Rap1.