* To whom correspondence should be addressed.
Received November 5, 2009
The effect of fatty acids and mitochondria-targeted lipophilic cations (SkQ1, SkQ3, MitoQ, and C12TPP) on tightly-coupled mitochondria from yeasts Dipodascus (Endomyces) magnusii and Yarrowia lipolytica was investigated. Micromolar concentrations of saturated and unsaturated fatty acids were found to decrease the membrane potential, which was recovered almost totally by ATP and BSA. At low, micromolar concentrations, mitochondria-targeted lipophilic cations are “relatively weak, mild uncouplers”, at higher concentrations they inhibit respiration in state 3, and at much higher concentrations they induce swelling of mitochondria, possibly due to their prooxidant and detergent action. At very low, not uncoupling concentrations, mitochondria-targeted lipophilic cations profoundly promote (potentiate) the uncoupling effect of fatty acids. It is conceivable that the observed uncoupling effect of lipophilic cations can be, at least partially, due to their interactions with the endogenous pool of fatty acids.
KEY WORDS: yeast, Yarrowia lipolytica, Dipodascus (Endomyces) magnusii, mitochondria, fatty acids, SkQ1, SkQ3, MitoQ, C12TPP, respiration, transmembrane potential, swelling