title: Role of an energized inner membrane in mitochondrial protein import. Delta psi drives the movement of presequences.
abstract: The transport of precursor proteins into mitochondria requires an energized inner membrane. We report here that the import of various precursor proteins showed a differential sensitivity to treatment of the mitochondria with the uncoupler carbonyl cyanide m-chlorophenylhydrazone. The differential inhibition by carbonyl cyanide m-chlorophenylhydrazone was not influenced by the length of the precursor, the presence of mature protein parts, or the folding state of the precursor but was specific for the presequence. Moreover, only the membrane potential delta psi and not the total proton motive force was required for the transport of precursors, indicating that protein translocation across the inner membrane is not driven by a movement of protons. We conclude that delta psi (negative inside) is needed for the translocation of the positively charged presequences, possibly via an electrophoretic effect.
authors.affiliation: Institut für Physiologische Chemie, Universität München, Federal Republic of Germany.
authors.forename: J
authors.initials: J
authors.lastname: Martin
authors.forename: K
authors.initials: K
authors.lastname: Mahlke
authors.forename: N
authors.initials: N
authors.lastname: Pfanner
mesh_terms: D001692:Biological Transport; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000378:metabolism*; D007202:Indicators and Reagents; D008928:Mitochondria / Q000378:metabolism*; D009492:Neurospora crassa; D011188:Potassium / Q000378:metabolism; D011487:Protein Conformation; D011498:Protein Precursors / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D007202:Indicators and Reagents; D011498:Protein Precursors; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; C058965:carbonyl cyanide 2-nitrophenylhydrazone; D011188:Potassium