Optical Control of Protein Activity by Fluorescent Protein Domains

Optogenetic Control Fluorescent proteins are widely used as optical sensors; however, optical control of protein activity remains challenging. Zhou et al. (p. 810) describe an approach that allows both sensing and control. Domains of the fluorescent protein Dronpa were designed to dimerize with one another and were fused to each of the termini of an enzyme domain. In the dark, the domains dimerized and inhibited the enzyme. However, exposure to light induced Dronpa dissociation and activated the enzyme, allowing optogenetic control. Shining light onto an engineered fluorescent protein controls the activity of domains fused to the protein. Fluorescent proteins (FPs) are widely used as optical sensors, whereas other light-absorbing domains have been used for optical control of protein localization or activity. Here, we describe light-dependent dissociation and association in a mutant of the photochromic FP Dronpa, and we used it to control protein activities with light. We created a fluorescent light-inducible protein design in which Dronpa domains are fused to both termini of an enzyme domain. In the dark, the Dronpa domains associate and cage the protein, but light induces Dronpa dissociation and activates the protein. This method enabled optical control over guanine nucleotide exchange factor and protease domains without extensive screening. Our findings extend the applications of FPs from exclusively sensing functions to also encompass optogenetic control.