Dysfunctional mitochondria trap proteins in the intermembrane space
Mitochondrial dysfunction and accumulation of mitochondrial precursor proteins are characteristics of various diseases but why non-imported precursors are toxic and how eukaryotic cells prevent their accumulation in the cytosol is still poorly understood.
The authors demonstrate that dysfunctional mitochondria can trap import intermediates in the intermembrane space (IMS) and mitoribosomal proteins are enriched among the IMS-trapped proteins. They also demonstrate that the trapping does not require ATP and the mitochondrial import motor.
Trapping of mitochondrial ribosomal proteins prevents their mistargeting to the nucleus and potentially averting interference with assembly of cytosolic ribosomes.
MitoTraP thus represents a novel, so far unknown mechanism of the eukaryotic quality control system that protects the cellular proteome against the toxic effects of non-imported mitochondrial precursor proteins.
https://www.embopress.org/doi/full/10.1038/s44318-025-00486-1
