Import and assembly of mitochondrial proteins

Import and assembly of mitochondrial proteins

Import and assembly of mitochondrial proteins (#40)

Nikolaus Pfanner ¹

University of Freiburg, Germany

Mitochondria contain more than 1,000 different proteins. Most proteins are synthesized as precursors in the cytosol and are imported by the translocase of the outer mitochondrial membrane (TOM). Biogenesis and function of the TOM complex are regulated by cytosolic protein kinases. After passing through the TOM complex, the precursor proteins follow different intramitochondrial sorting pathways: (i) the presequence pathway to the matrix and inner membrane; (ii) the carrier pathway to the inner membrane; (iii) the MIA (mitochondrial intermembrane space assembly) pathway to the intermembrane space; and (iv) the beta-barrel pathway to the outer membrane via the SAM complex (sorting and assembly machinery). Additionally, (v) several alpha-helical outer membrane proteins bypass the TOM channel and use the MIM complex for insertion into the outer membrane. TOM and SAM of the outer membrane form contact sites with a large protein complex of the inner membrane required for maintenance of the characteristic shape of the membrane, termed the mitochondrial contact site and cristae organizing system (MICOS). The protein translocases are thus coupled to machineries that maintain the shape of mitochondria.

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Pfanner, N

Nikolaus (Klaus) Pfanner studies protein sorting in cells and focuses on the biogenesis and assembly of mitochondria. His research team performed the first comprehensive analysis of the proteome of an entire cell organelle (mitochondria), leading to the discovery of more than 200 new mitochondrial proteins. He identified several novel pathways and machineries for the import of proteins into mitochondria and their assembly into oligomeric complexes. His recent studies show that protein translocases do not act as independent units but are integrated into a network of machineries that function in bioenergetics, membrane morphology, signalling and protein quality control, revealing a higher level of organisation of cell organelles. Klaus studied medicine in Munich and received his training in biochemistry and molecular cell biology in the laboratories of Walter Neupert (Munich) and James E. Rothman (Princeton). Since 1992 he has been Professor of Biochemistry and Chair of the Institute of Biochemistry and Molecular Biology at the University of Freiburg, Germany. He received the Max Planck Research Award, the Leibniz Prize, the Wilhelm Feldberg Prize, and the Stein & Moore Award. From 2009 – 2011, he was President of the German Society for Biochemistry and Molecular Biology.

Import and assembly of mitochondrial proteins (#40)

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