Chemi-Optogenetics: Photoactivatable Probes To Control Protein Proximity And Cellular Processes

Chemi-optogenetics is a hybrid chemical and genetic approach that utilizes light to regulate cellular processes. We combined the chemical versatility of photoremovable protecting groups with the biological specificity of self-labelling proteins (i.e. Halo-tag, SNAP-tag, eDHFR), to develop a series of tools that localize proteins of interest to its target with spatiotemporal precision. The local proximity of a protein and its substrate is sufficient to initiate a desired biological effect, as the probably of an effective collision is a function of proximity. Therefore, chemically induced proximity is a valuable technique for probing cellular processes. The removal of a photocage is irreversible and done with a single pulse of light, which enables us to study submicron targets that move quickly within three-dimensional space. This would be otherwise unfeasible with reversible systems such as photo-switches or optogenetic proteins that typically require constant illumination. However, biological processes are often reversible, therefore we developed reversible and bidirectional tools to probe these processes as well. We demonstrate reversible and bidirectional control of subcellular protein localization using sequential pulses of light and apply it to manipulate dynamic biological events. This work expands the boundaries of chemi-optogenetic control of biological processes and highlight the advantages of a genetic and chemical hybrid approach.