172 - Novel optogenetic control of mitochondrial energetics rescues electron transport chain inhibition

Abstract

Mitochondria use an electrochemical proton gradient to produce ATP, the main cellular energy source. This gradient, called the protonmotive force (PMF), also controls substrate uptake, calcium signaling, and reactive oxygen species (ROS) production and signaling. Despite the central role of the PMF in mitochondrial bioenergetics, current tools to modulate the PMF lack spatial and temporal control in vivo. For example, protonophores are used to irreversibly decrease the PMF, but this pharmacologic approach lacks tissue and mitochondria-selectivity. Importantly, there are no means to increase the PMF. Here, we characterize an optogenetic approach to selectively increase the PMF and affect mitochondrial function in vivo with light. Using a novel mitochondria-targeting strategy we expressed a light-activated proton pump in mitochondria of Caenorhabditis elegans. In response to light, the mitochondria-targeted light-activated proton pump (mtLAPP) increased the PMF in isolated mitochondria and whole animals, observed through tetramethylrhodamine ethyl ester fluorescence. Additionally, optogenetic stimulation of bioenergetics by mtLAPP can overcome toxicity from inhibition of proton-pumping complexes of the mitochondrial electron transport chain. Our results provide a novel method to enhance mitochondrial bioenergetics in whole organisms, and may be used to affect physiologic outputs downstream of the PMF, such as ROS signaling and metabolism.