Researchers unravel the structure, function of mitochondrial classification and aggregation mechanisms

Mitochondria are essential for the human body as centers of cellular power: They contain over 1,000 different proteins, which are essential for many major metabolic pathways. Deficiency of these leads to serious diseases, especially the nervous system and the heart. To transport proteins and metabolites, there is a special group of beta-barrel membrane proteins called mitochondria, which form transport pores in the outer mitochondrial membrane. Until now, scientists have not been able to define the mode of operation of the classification and aggregation device (SAM) for the biogenesis of these beta-barrel proteins.

A team led by Dr. Dr. Toshiya Endo from Kyoto / Japan University, Prof. Dr. Nils Wiedemann and Prof. Dr. Nikolaus Pfanner from the University of Freiburg and Dr. Dr. Thomas Becker of the University of Bonn has now solved the structure and function of the USA. The researchers have published their findings in the journal Nature.

There are usually two beta-barrel subunits called Sam50, which contains the two additional subunits Sam35 and Sam37, outside the SAM. The researchers found that while the SAM complex creates a new beta-barrel protein, there is only one Sam50. The second beta-barrel subunit acts as a flexible substitute: it leaves the SAM complex for a short time, freeing up space to create the new beta-barrel protein. This dynamic approach suggests how a new beta-barrel protein can mature to full size in a SAM complex and be released as a fully complex protein.

This allowed us to identify a new principle for the formation of limb proteins that perform vital functions in our cells. “

Prof. Dr. Nils Wiedemann, University of Freiburg

Nils Wiedemann and Nikolaus Pfanner are group leaders at the Institute of Biochemistry and Molecular Biology and project leaders in the collections of excellence in BIOSS and CIBSS biological signage as well as the Spemann Graduate School of Biology and Medicine at the University of Freiburg.