Control of microtubule dynamics using an optogenetic microtubule plus end–F-actin cross-linker

We developed a novel optogenetic tool, SxIP-iLID, to facilitate the reversible recruitment of factors to microtubule (MT) plus ends in an End Binding (EB) protein-dependent manner using blue light. We show that SxIP-iLID can track MT plus ends and recruit tgRFP-SspB upon blue light activation. We then used this system to investigate the effects of cross-linking MT plus ends and F-actin in Drosophila S2 cells to gain insight into spectraplakin function and mechanism. We show that SxIP-iLID can be used to temporally recruit a F-actin binding domain to MT plus ends and cross-link the MT and F-actin networks. Light-mediated MT-F-actin cross-linking decreases MT growth velocities and generates a MT exclusion zone in the lamella. SxIP-iLID facilitates the general recruitment of specific factors to MT plus ends with temporal control enabling researchers to systematically regulate MT plus end dynamics and probe MT plus end function in many biological processes. Summary SxIP-iLID is a novel optogenetic tool designed to assess the spatiotemporal role of proteins on microtubule dynamics. We establish that optogenetic cross-linking of microtubule and actin networks decreases MT growth velocities and increases the cell area void of microtubules.