The voltage sensor of the mitochondrial permeability transition pore is tuned by the oxidation-reduction state of vicinal thiols. Increase of the gating potential by oxidants and its reversal by reducing agents.
Reaction of isolated mitochondria with a variety of agents that lead to oxidation or cross-linking of sulfhydryl groups leads to an increased "open" probability of the permeability transition pore, a cyclosporin A-sensitive channel. We have investigated the mechanism by which the pore is induced by menadione, diamide, arsenite, and tert-butylhydroperoxide. We find that these inducers increase the probability of pore opening by shifting its gating potential to higher values. Furthermore, the induced shift was prevented by treatment with N-ethylmaleimide or dithiothreitol. At moderate levels of depolarization an apparent I50 for N-ethylmaleimide of bout 5 microM can be defined, while the N-ethylmaleimide or dithiothreitol effects are overcome by maximal depolarization. We conclude that the oxidation-reduction state of vicinal thiols in cysteinyl residues plays a critical role in tuning the voltage sensor of the transition pore, with an increase of gating potential (i.e. an increase in the probability of pore opening despite a high transmembrane potential difference) as the couple is poised to a more oxidized state. These findings may have implications for the mechanism of cell damage under oxidative stress.
Petronilli
V
V
Department of Biomedical Sciences, University of Padova Medical School, Italy.
Costantini
P
P
Scorrano
L
L
Colonna
R
R
Passamonti
S
S
Bernardi
P
P
D000818:Animals; D018053:Arsenites / Q000494:pharmacology; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D003958:Diamide / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology*; D005033:Ethylmaleimide / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology*; D015640:Ion Channel Gating / Q000187:drug effects; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects* / Q000502:physiology; D008565:Membrane Proteins / Q000187:drug effects / Q000502:physiology*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000502:physiology*; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010545:Peroxides / Q000494:pharmacology; D018272:Porins; D011336:Probability; D051381:Rats; D014812:Vitamin K / Q000494:pharmacology; D050994:Voltage-Dependent Anion Channels; D020122:tert-Butylhydroperoxide
D018053:Arsenites; D007473:Ion Channels; D008565:Membrane Proteins; D016877:Oxidants; D010545:Peroxides; D018272:Porins; D050994:Voltage-Dependent Anion Channels; D003958:Diamide; D014812:Vitamin K; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D020122:tert-Butylhydroperoxide; C015001:arsenite; D005033:Ethylmaleimide; D004229:Dithiothreitol