Optogenetic control of mitochondrial metabolism and Ca2+ signaling by mitochondria-targeted opsins

Key mitochondrial functions such as ATP production, Ca2+ uptake and release, and substrate accumulation depend on the proton electrochemical gradient (Delta mu H+) across the inner membrane. Although several drugs can modulate Delta mu H+, their effects are hardly reversible, and lack cellular specificity and spatial resolution. Although channelrhodopsins are widely used to modulate the plasma membrane potential of excitable cells, mitochondria have thus far eluded optogenetic control. Here we describe a toolkit of optometabolic constructs based on selective targeting of channelrhodopsins with distinct functional properties to the inner mitochondrial membrane of intact cells. We show that our strategy enables a light-dependent control of the mitochondrial membrane potential (Delta Psi(m)) and coupled mitochondrial functions such as ATP synthesis by oxidative phosphorylation, Ca2+ dynamics, and respiratory metabolism. By directly modulating Delta Psi(m), the mitochondriatargeted opsinswere used to control complex physiological processes such as spontaneous beats in cardiac myocytes and glucose-dependent ATP increase in pancreatic beta-cells. Furthermore, our optometabolic tools allow modulation of mitochondrial functions in single cells and defined cell regions.