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Oligomycin-resistant mitochondrial ATPase from mouse fibroblasts
Abstract:
Fourteen oligomycin-resistant LM(TK-) clones were isolated following the mutagenesis of minicells. In the absence of oligomycin, the mutants grew with population doubling times similar to that of the wild type (1 day). In 3 or 5 microgram oligomycin/ml the doubling times of the mutants were 1.2-2.5 days. Both stable and unstable classes were represented among the oligomycin-resistant mutants. Mitochondrial ATPase activities of the mutants were 1.3-1130 times more resistant to oligomycin than the wild type. The mitochondrial ATPase of OLI 14 was found to be bound firmly to the mitochondrial membrane, showed no alteration in the pH optimum compared to wild-type, and exhibited increased resistance to DCCD and venturicidin. These results are consistent with the conclusion that oligomycin resistance in these mutants results from altered mitochondrial ATPase.
Insights
Researchers isolated oligomycin-resistant mutants, finding altered mitochondrial ATPase activity is responsible for resistance. These mutants show varying stability and resistance levels to oligomycin and other inhibitors.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Oligomycin is a potent inhibitor of mitochondrial ATP synthase.
- Understanding drug resistance mechanisms is crucial for developing new therapeutics.
Purpose of the Study:
- To isolate and characterize oligomycin-resistant mutants.
- To investigate the role of mitochondrial ATPase in oligomycin resistance.
Main Methods:
- Mutagenesis of LM(TK-) cells using minicells.
- Isolation and growth of oligomycin-resistant clones.
- Measurement of mitochondrial ATPase activity and resistance to inhibitors (oligomycin, DCCD, venturicidin).
Main Results:
- Fourteen oligomycin-resistant clones were isolated.
- Mutants exhibited varying degrees of oligomycin resistance (1.2-2.5 days doubling time).
- Mitochondrial ATPase from resistant mutants showed significantly increased resistance to oligomycin, DCCD, and venturicidin.
Conclusions:
- Oligomycin resistance in these mutants is primarily due to alterations in mitochondrial ATPase.
- The altered ATPase exhibits stable or unstable resistance phenotypes.
- The findings provide insights into mitochondrial energy metabolism and drug resistance.