Mitochondria are cellular organelles that serve as cellular powerhouses and host other vital metabolic processes. To perform these tasks mitochondria need more than a thousand proteins that are produced outside and are imported into these organelles. What happens to mitochondrial proteins if they get damaged or are not needed anymore?
Piotr Bragoszewski, Agnieszka Chacinska and colleagues from the International Institute of Molecular and Cell Biology in Warsaw and from the University of Freiburg discovered a process of retrotranslocation of mitochondrial proteins. This study has now been published in prestigious Proceedings of the National Academy of Sciences of the United States of America. The work has been focused on the group of mitochondrial proteins that are destined to the intermembrane space. This mitochondrial compartment is separated from the rest of the cell by the outer mitochondrial membrane rich in barrel-shaped channel proteins. The researchers discovered that structural destabilization allows the release of intermembrane space proteins through outer membrane channels. These proteins are directed to destruction by the protein quality machinery outside mitochondria, the ubiquitin proteasome system.
The ability to release mature mitochondrial proteins adds a novel concept into processes that maintain the mitochondrial proteome and its dynamic regulation in the response to metabolic demands of cells. This in turn is of great importance for understanding numerous pathologies linked to mitochondrial dysfunction and to an imbalance in cellular protein homeostasis.
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Article published by PAP Science in Poland:
http://naukawpolsce.pap.pl/aktualnosci/news,405371,podejrzano-jak-mitochondria-robia-porzadki.html