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The role of respiratory chain in paraquat toxicity in yeast
Abstract:
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.
Insights
Yeast cells lacking respiration are resistant to paraquat. This suggests that mitochondria, not cytochrome P-450, are the primary targets of paraquat toxicity in yeast.
Area of Science:
- Biochemistry
- Cell Biology
- Toxicology
Background:
- Paraquat is a herbicide known for its toxicity.
- Cytochrome P-450 is implicated in paraquat toxicity in mammalian cells.
- Mitochondrial function plays a role in cellular response to toxins.
Purpose of the Study:
- To investigate the role of mitochondria in paraquat toxicity in yeast.
- To compare the mechanisms of paraquat toxicity in yeast and mammalian cells.
- To identify the primary targets of paraquat in yeast cells.
Main Methods:
- Utilized yeast respiratory deficient mutants.
- Examined resistance mechanisms through physiological and inhibitor-based approaches.
- Assessed the role of cytochrome P-450 and its reductase.
Main Results:
- Yeast respiratory deficient mutants exhibited resistance to paraquat.
- Reduced respiration, via physiological means or electron transport chain inhibitors, conferred similar resistance.
- Mitochondria, specifically mitochondrial cytochromes, appear to be the initial targets of paraquat damage in yeast.
Conclusions:
- Mitochondrial damage is a significant contributor to paraquat toxicity in yeast.
- The low levels of cytochrome P-450 in aerobic yeast cells explain the difference in toxicity mechanisms compared to mammalian cells.
- Mitochondrial cytochromes are the primary targets of paraquat in yeast.