Novel mitochondrial import pathway discovered
Mitochondria are organelles that fulfill the function of the powerhouse of the cell. Their evolution started more than a billion years ago when a primitive bacterium was incorporated by an early cell resulting in an endosymbiotic relationship. During the evolutionary process the genome of the ancient bacterium was almost completely transferred to the nucleus of the host cell. Therefore, the vast majority of mitochondrial proteins is synthesized in the cytosol and has to be imported. Another striking feature of mitochondria are two distinct biological membranes (outer and inner membrane), hence various proteins follow different import routes to reach their correct destination.
Scientists from the Interfaculty Institute of Biochemistry (IFIB) of the University of Tübingen characterized a novel import pathway of proteins into mitochondria. The team including Monika Sinzel, Doron Rapaport and Kai Stefan Dimmer employed a wide variety of biochemical and genetic methods in their experiments. In a genetic screen to find new proteins involved in organelle contact sites they identified a new mitochondrial outer membrane protein. Among other approaches they used radioactively labelled precursor proteins to study the import pathway in isolated genetically modified mitochondria. They discovered an unknown import route taken by the novel protein that is the first protein shown to be processed by an inner membrane protease during its assembly into the outer membrane. These findings are reported in the renowned scientific journal EMBO Reports.
The findings increase our understanding of the formation and cellular maintenance of the organelle. This is of special interest as mitochondrial defects play an important role in many human diseases like cancer and neurodegeneration.
Dr. Kai Stefan Dimmer
Interfakultäres Institut für Biochemie (IFIB)
Hoppe-Seyler-Str. 4 · 72076 Tübingen
Telefon: +49 7071 29-74174
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