Transcriptomics DNAJC15 and DNAJC19 knockdown in HeLa cells
To better understand how OMA1 affects mitochondrial proteostasis and stress responses, we performed a proteomic survey of OMA1-deficient cells for proteolytic substrates. We demonstrate that OMA1 cleaves the mitochondrial chaperone DNAJC15 facilitating its degradation by the mitochondrial m-AAA protease. The loss of DNAJC15 alters protein import by TIM23 protein translocases in the IM and limits the accumulation of OXPHOS-related mitochondrial matrix and IM proteins. Non-imported mitochondrial preproteins accumulate at the endoplasmic reticulum (ER) and trigger an ATF6-related unfolded protein response. These results demonstrate that OMA1 allows to adapt mitochondrial protein biogenesis to stress and reveal an intricate network of cellular stress responses to proteostasis disturbances. Overall design: RNA-seq profile of scrambled control HeLa cell versus DNAJC15 and DNAJC19 knock down.