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Mitochondrial activity of 2,6-diaminopurine in Saccharomyces cerevisiae
Abstract:
2,6-diaminpurine (DAP) selectively inhibited mitochondrial protein synthesis in yeast cells with concomitant failure of cells to grow in non-fermentable (yeast extract, glycerol) medium. The selectivity was pronounced in all strains tested (15) nearly all of which were able to grow in yeast extract, glucose medium containing 5 mg/ml DAP (maximum solubility) whereas growth was arrested in all strains at 250-500 microgram/ml DAP in the glycerol medium. The inhibition was reversed by further addition of adenine to the culture medium. RNA synthesis in rat liver mitochondria was depressed by DAP suggesting that the analogue affected RNA polymerase activity. There was no evidence of nuclear mutagenicity by DAP but resistance to the antibiotics chloramphenicol and oligomycin was induced by the drug. Genetic evidence, although limited, indicated that the resistance mutations were cytoplasmic. The mitochondrial petite mutation was also induced by DAP but only at comparatively high concentrations. The mutagenic effects were seen only in the glycerol medium.
Insights
2,6-diaminopurine (DAP) selectively inhibits yeast mitochondrial protein synthesis, halting growth in glycerol medium but not glucose. This effect is reversible by adenine and suggests DAP impacts mitochondrial RNA polymerase.
Area of Science:
- Biochemistry
- Molecular Biology
- Yeast Genetics
Background:
- Mitochondrial protein synthesis is crucial for cellular respiration.
- Selective inhibitors of mitochondrial processes are valuable research tools.
- Understanding drug interactions with mitochondrial function is important.
Purpose of the Study:
- To investigate the effects of 2,6-diaminopurine (DAP) on yeast mitochondrial protein synthesis.
- To determine the selectivity of DAP's inhibitory action.
- To explore the potential mechanisms and consequences of DAP exposure.
Main Methods:
- Yeast cell culture in various media (glucose, glycerol).
- Growth inhibition assays with different DAP concentrations.
- Assessment of adenine's effect on DAP inhibition.
- Measurement of RNA synthesis in isolated rat liver mitochondria.
- Induction of antibiotic resistance and petite mutations.
Main Results:
- DAP selectively inhibited mitochondrial protein synthesis and growth in glycerol medium, but not glucose medium.
- Inhibition was reversed by adenine, suggesting a link to purine metabolism.
- DAP depressed RNA synthesis in isolated mitochondria, indicating potential RNA polymerase inhibition.
- DAP induced resistance to chloramphenicol and oligomycin, with cytoplasmic inheritance.
- DAP induced mitochondrial petite mutations at higher concentrations, specifically in glycerol medium.
Conclusions:
- DAP is a selective inhibitor of yeast mitochondrial protein synthesis.
- The drug likely targets mitochondrial RNA polymerase activity.
- DAP can induce cytoplasmic mutations conferring antibiotic resistance and the petite phenotype.
- These findings highlight DAP's utility in studying mitochondrial genetics and function.