A role for Tim21 in membrane-potential-dependent preprotein sorting in mitochondria.

Martin van der Laan, Nils Wiedemann, David U Mick, Bernard Guiard, Peter Rehling, Nikolaus Pfanner

Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany.

Current biology : CB 2006 Nov 21

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The mitochondrial inner membrane harbors complexes of the respiratory chain and translocase complexes for preproteins. The membrane potential generated by the respiratory chain is essential for ATP production by the mitochondrial ATP synthase and as a driving force for protein import. It is generally believed that the preprotein translocases just use the membrane potential without getting into physical contact with respiratory-chain complexes. Here, we show that the presequence translocase interacts with the respiratory chain. Tim21, a specific subunit of the sorting-active presequence translocase , recruits proton-pumping respiratory-chain complexes and stimulates preprotein insertion. Thus, the presequence translocase cooperates with the respiratory chain and promotes membrane-potential-dependent protein sorting into the inner mitochondrial membrane. These findings suggest a new coupling mechanism in an energy-transducing membrane.

Citation

Martin van der Laan, Nils Wiedemann, David U Mick, Bernard Guiard, Peter Rehling, Nikolaus Pfanner. A role for Tim21 in membrane-potential-dependent preprotein sorting in mitochondria. Current biology : CB. 2006 Nov 21;16(22):2271-6