ROLE OF LIPOPEROXIDATION ON THE INHIBITION OF THE MITOCHONDRIAL ENERGETIC METABOLISM IN S. cerevisiae

Mitochondrial lipoperoxidation increase the sensitivity of the electron transport chain (ETC) to oxidative stress by limiting electron flux and increasing ROS production. However, the role of lipoperoxidation on other functions that depends on ETC function like mitochondrial membrane potential ( mt ΔΨ) or ATPase activity has not been fully elucidated. To address this problem, we evaluated the effects of oxidative stress on mt ΔΨ and mitochondrial ATPase activity in native yeast (−C18:3), which is resistant to lipoperoxidation, and lipoperoxidation‐sensitive yeast (+C18:3) obtained by the manipulation of its fatty acid content with linolenic acid (C18:3). It was observed in +C18:3 cells that the mt ΔΨ was lost at lower concentrations of ferrous iron (Fe 2+ ) than those required to collapse mt ΔΨ in −C18:3 cells. The sensitivity of mitochondrial ATPase activity to Fe 2+ was several fold higher in +C18:3 mitochondria than in −C18:3 mitochondria and a role was attributed to lipoperoxidation, as the anti‐lipoperoxidative agent β‐butylated hydroxytoluene (BHT) was able to protect this activity only in +C18:3 mitochondria. These results indicate that lipoperoxidation also affects mitochondrial functions involved in energy generation that are dependent of ETC.