mitoCPR - a surveillance pathway that protects mitochondria in response to mitochondrial import stress [yeast]

Mitochondrial functions are essential for cell viability and rely on protein import into the organelle. Physiological perturbations and disease conditions can lead to mitochondrial import defect. We find that in budding yeast, mitochondrial import defects result in activation of a surveillance mechanism, which we termed mitoCPR. The mitoCPR is aimed at ameliorating mitochondrial import and protecting mitochondria during import stress. This is mediated by the mitoCPR effector, Cis1, which associates with mitochondria to reduce the accumulation of mitochondrial preproteins at the organelle's surface. Clearance of preproteins depends on the AAA-ATPase Msp1 and the proteasome, suggesting that Cis1 facilitates the degradation of unimported proteins that accumulate at the mitochondrial surface. We further show that mitoCPR is critical for maintaining mitochondrial functions during mitochondrial import stress and provide evidence that it is an ancient, conserved mitochondrial protection mechanism. Overall design: Two replicates each of WT controls, Psd1_oe2 samples (overexpressing Psd1) and Psd1_oe_Pdr3_ko2 samples (overexpressing Psd1 with a Pdr3 deletion) were compared.

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