ATP synthase subunits e and g are essential for Ca2+ homeostasis and development in Drosophila melanogaster independent of oxidative phosphorylation

Abstract Beyond its roles in ATP production and shaping cristae architecture, mitochondrial ATP synthase has been implicated in generating the permeability transition pore (PTP), a Ca 2+ -activated, high-conductance channel that leads to matrix swelling and cell death in mammalian cells. In Drosophila melanogaster, the PTP homolog rather forms a selective Ca 2+ -induced Ca 2+ -release (CICR) channel whose physiological relevance at the organism level remains poorly understood. Here, we down-regulated Drosophila subunits e and g, which are essential for PTP formation in yeast and mammalian cells. Ubiquitous down-regulation of either subunit caused larval developmental arrest, whereas tissue-specific suppression in muscle or neurons led to severe locomotor impairment. Dimerization was markedly reduced, altering mitochondrial ultrastructure while leaving respiratory capacity largely preserved. Strikingly, mitochondria from both knockdown animals accumulated larger Ca 2+ loads, consistent with an impaired CICR. This was accompanied by near-complete loss of ecdysone, the Ca 2+ -dependent master hormone of metamorphosis. Neuron-specific knockdown flies displayed defective mitochondrial Ca 2+ efflux and altered synaptic organization at the neuromuscular junction. Altogether, our findings establish that ATP synthase functions as a CICR channel controlling Ca 2+ homeostasis, endocrine signaling and development in Drosophila .