Local control of intracellular microtubule dynamics by EB1 photodissociation

End-binding proteins (EBs) are adaptors that recruit functionally diverse microtubule plus-end-tracking proteins (+TIPs) to growing microtubule plus ends. To test with high spatial and temporal accuracy how, when and where + TIP complexes contribute to dynamic cell biology, we developed a photo-inactivated EB1 variant (pi-EB1) by inserting a blue-light-sensitive protein-protein interaction module between the microtubule-binding and + TIP-binding domains of EB1 pi-EB1 replaces endogenous EB1 function in the absence of blue light. By contrast, blue-light-mediated pi-EB1 photodissociation results in rapid + TIP complex disassembly, and acutely and reversibly attenuates microtubule growth independent of microtubule end association of the microtubule polymerase CKAP5 (also known as ch-TOG and XMAP215). Local pi-EB1 photodissociation allows subcellular control of microtubule dynamics at the second and micrometre scale, and elicits aversive turning of migrating cancer cells. Importantly, light-mediated domain splitting can serve as a template to optically control other intracellular protein activities.