The role of respiratory chain in paraquat toxicity in yeast.

Yeast respiratory deficient mutants are resistant to paraquat. Similar resistance is caused by lowering the respiration by physiological mechanisms, as well as by some inhibitors of electron transfer chain of mitochondria. Presented results suggest that the major contribution of mitochondria to overall toxicity of paraquat in yeast is a consequence of very low level of cytochrome P-450, and presumably its presumably its reductase in aerobic yeast cells. In mammalian cells this enzyme is considered as the most important factor involved in paraquat toxicity. Mitochondrial cytochromes seem to be the first targets of damaging effects of paraquat.