Tim50 maintains the permeability barrier of the mitochondrial inner membrane.

Michael Meinecke (1) , Richard Wagner (1) , Peter Kovermann (1) , Bernard Guiard (2) , David U Mick (3) , Dana P Hutu (3, 4) , Wolfgang Voos (3) , Kaye N Truscott (3, 5) , Agnieszka Chacinska (3) , Nikolaus Pfanner (3) , Peter Rehling (3)

1 Biophysik, FB Biologie/Chemie,Osnabrück,
2 CGM - Centre de génétique moléculaire
3 Institut für Biochemie und Molekularbiologie, Freiburg
4 Fakultät für Biologie,Freiburg
5 Department of Biochemistry, Melbourne

Transport of metabolites across the mitochondrial inner membrane is highly selective, thereby maintaining the electrochemical proton gradient that functions as the main driving force for cellular adenosine triphosphate synthesis. Mitochondria import many preproteins via the presequence translocase of the inner membrane. However, the reconstituted Tim23 protein constitutes a pore remaining mainly in its open form, a state that would be deleterious in organello. We found that the intermembrane space domain of Tim50 induced the Tim23 channel to close. Presequences overcame this effect and activated the channel for translocation. Thus, the hydrophilic cis domain of Tim50 maintains the permeability barrier of mitochondria by closing the translocation pore in a presequence-regulated manner.

Domaines: Biochimie, Biologie Moléculaire; Biochimie [q-bio.BM]

Michael Meinecke, Richard Wagner, Peter Kovermann, Bernard Guiard, David U Mick, et al.. Tim50 maintains the permeability barrier of the mitochondrial inner membrane.. Science, 2006, 312 (5779), pp.1523-6. ⟨10.1126/science.1127628⟩. ⟨hal-00132755⟩