Tim50 maintains the permeability barrier of the mitochondrial inner membrane.
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.
Meinecke
Michael
M
Biophysik, Universität Osnabrück, FB Biologie/Chemie, D-49034 Osnabrück, Germany.
Wagner
Richard
R
Kovermann
Peter
P
Guiard
Bernard
B
Mick
David U
DU
Hutu
Dana P
DP
Voos
Wolfgang
W
Truscott
Kaye N
KN
Chacinska
Agnieszka
A
Pfanner
Nikolaus
N
Rehling
Peter
P
D002463:Cell Membrane Permeability; D008081:Liposomes; D026901:Membrane Transport Proteins / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D008081:Liposomes; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D029701:Saccharomyces cerevisiae Proteins; C083081:TIM23 protein, S cerevisiae; C469615:TIM50 protein, S cerevisiae