Activation of the potato plant uncoupling mitochondrial protein inhibits reactive oxygen species generation by the respiratory chain

A variety of plant tissues contain an uncoupling mitochondrial protein (PUMP), recently described and characterized by our group. In this study me show that the inhibition of PUMP activity in potato tuber mitochondria significantly increases mitochondrial H2O2 generation, while PUMP substrates, such as linoleic acid, reduce mitochondrial H2O2 generation. This H2O2 generation occurred mainly by the dismutation of superoxide radicals formed through monoelectronic reduction of O-2 by semiquinone forms of coenzyme Q. The results presented suggest that protection against mitochondrial oxidative stress may be a physiological role of PUMP. (C) 1998 Federation of European Biochemical Societies.