Chemical modification of arginines by 2,3-butanedione and phenylglyoxal causes closure of the mitochondrial permeability transition pore.
We have investigated the role of arginine residues in the regulation of the mitochondrial permeability transition pore, a cyclosporin A-sensitive inner membrane channel. Isolated rat liver mitochondria were treated with the arginine-specific chemical reagent 2, 3-butanedione or phenylglyoxal, followed by removal of excess free reagent. After this treatment, mitochondria accumulated Ca2+ normally, but did not undergo permeability transition following depolarization, a condition that normally triggers opening of the permeability transition pore. Inhibition by 2,3-butanedione and phenylglyoxal correlated with matrix pH, suggesting that the relevant arginine(s) are exposed to the matrix aqueous phase. Inhibition by 2,3-butanedione was potentiated by borate and was reversed upon its removal, whereas inhibition by phenylglyoxal was irreversible. Treatment with 2,3-butanedione or phenylglyoxal after induction of the permeability transition by Ca2+ overload resulted in pore closure despite the presence of 0.5 mM Ca2+. At concentrations that were fully effective at inhibiting the permeability transition, these arginine reagents (i) had no effect on the isomerase activity of cyclophilin D and (ii) did not affect the rate of ATP translocation and hydrolysis, as measured by the production of a membrane potential upon ATP addition in the presence of rotenone. We conclude that reaction with 2,3-butanedione and phenylglyoxal results in a stable chemical modification of critical arginine residue(s) located on the matrix side of the inner membrane, which, in turn, strongly favors a closed state of the pore.
Eriksson
O
O
Consiglio Nazionale delle Ricerche Unit for the Study of Biomembranes and the Laboratory of Biophysics and Membrane Biology, Department of Biomedical Sciences, University of Padova Medical School, Viale Giuseppe Colombo 3, I-35121 Padova, Italy.
Fontaine
E
E
Bernardi
P
P
D000818:Animals; D001120:Arginine / Q000187:drug effects* / Q000378:metabolism; D003931:Diacetyl / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000378:metabolism*; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D010539:Permeability / Q000187:drug effects; D010658:Phenylglyoxal / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D001120:Arginine; D003931:Diacetyl; D010658:Phenylglyoxal