An optogenetic tool to recruit individual PKC isozymes to the cell surface and promote specific phosphorylation of membrane proteins.

The PKC family consists of several closely related kinases. These enzymes regulate the function of proteins through the phosphorylation of hydroxyl groups on serines and/or threonines. The selective activation of individual PKC isozymes has proven challenging because of a lack of specific activator molecules. Here, we developed an optogenetic blue light-activated PKC isozyme that harnesses a plant-based dimerization system between the photosensitive cryptochrome-2 (CRY2) and the N terminus of the transcription factor calcium and integrin-binding protein 1 (CIB1) (N-terminal region of the CRY2-binding domain of CIB1). We show that tagging CRY2 with the catalytic domain of PKC isozymes can efficiently promote its translocation to the cell surface upon blue light exposure. We demonstrate this system using PKCε and show that this leads to robust activation of a K channel (G protein-gated inwardly rectifying K channels 1 and 4), previously shown to be activated by PKCε. We anticipate that this approach can be utilized for other PKC isoforms to provide a reliable and direct stimulus for targeted membrane protein phosphorylation by the relevant PKCs.