Effects of atractyloside on the incorporation of radioactive precursors into DNA in isolated rat liver mitochondria

Abstract

Atractyloside (20 [mu]) has been found to decrease the incorporation of dATP-3H into DNA by 90% in intact mitochondria (at a level of 3 mg of protein) but to have no such effect on sonic extracts of mitochondria nor on the DNA polymerase from Escherichia coli. Inhibition of dATP-3H incorporation by atractyloside can be overcome by increasing the level of ATP present. The incorporation of TTP-3H is not similarly inhibited by atractyloside. TTP-3H incorporation, which is stimulated by added ATP, is inhibited by atractyloside to the extent of 40% in the absence of and 13% in the presence of ATP (2 m). Atractyloside can be used with labeled dATP to ascertain that DNA synthesis is occurring intramitochondrially in intact organelles, in vitro, rather than externally as a result of contaminating nuclear DNA polymerase.