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Structural Biology of Mitochondrial Outer Membrane Proteins

Final Report Summary - MOMP (Structural Biology of Mitochondrial Outer Membrane Proteins)

Proteins in the outer membranes of mitochondria and bacteria are produced by a machinery of helper molecules, so called chaperones. The mitochondrial protein Sam50 from the Omp85 family, part of the Sam complex, is one of these molecules. The structure of the Sam50 homologue TamA provides the first structure of a Omp85 insertase and enables a direct hypothesis for the insertion mechanism. This mechanism presumably uses the formation of an hybrid barrel as intermediate step. Furthermore, we have characterized membrane-protein-chaperone complexes at atomic resolution with NMR spectroscopy. The chaperone Skp denatures unfolded membrane proteins and keeps them in a fluidic state. In the mitochondrial membrane, the membrane protein VDAC enables the transport of ATP across the mitochondrial outer membrane. We could show that VDAC gating is directly linked to dynamics of the N-terminal helical segment alpha2. Finally, we have recorded the first solid-state NMR spectra of the membrane-inserted form of the protein Bax, opening a pathway its structure elucidation.