Lilac: Enhanced actin imaging with an optogenetic Lifeact

We have designed an improved Lifeact variant that binds to actin under the control of light using the LOV2 protein. This photoswitchable imaging reagent has two major advantages over standard actin probes. First, light control enables one to subtract the pre-illumination signal of the unbound label, yielding an enhanced view of F-actin dynamics in cells. Second, because the tool is essentially inert in the dark, it eliminates the common issue of actin network perturbations and cell sickness caused by Lifeact overexpression. We discuss factors to consider when using the probe, including a simple approach to tune the photoexcited-state lifetime in live cells.