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Drug extrusion in Corynebacterium glutamicum
K Kaidoh1, M Kimura, S Miyauchi
1Laboratory of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
Microbial Drug Resistance (Larchmont, N.Y.)
|January 1, 1997
Summary
A Corynebacterium glutamicum mutant resistant to ethidium bromide (EtBr) was identified. This resistance is mediated by a proton-motive-force driven multidrug efflux system, inhibited by reserpine.
Area of Science:
- Microbiology
- Molecular Biology
Background:
- Multidrug resistance (MDR) is a significant challenge in microbial studies and therapies.
- Ethidium bromide (EtBr) is a cytotoxic agent often used to study DNA and can be effluxed by microbial cells.
Purpose of the Study:
- To investigate the mechanism of ethidium bromide (EtBr) resistance in a selected mutant of Corynebacterium glutamicum.
- To identify potential efflux systems involved in the extrusion of cytotoxic compounds.
Main Methods:
- Selection of an ethidium bromide (EtBr)-resistant mutant (EBR) of Corynebacterium glutamicum.
- Assessing the effect of reserpine, a known inhibitor of efflux pumps, on EtBr resistance and efflux.
- Measuring EtBr efflux rates and correlating them with membrane potential and intracellular ATP levels.
Main Results:
- The EBR mutant exhibited high resistance to 100 microM EtBr, which was reversed by 2 microM reserpine.
- EtBr efflux rate was significantly higher in the mutant and completely inhibited by reserpine.
- Reserpine and other unrelated chemicals (quinidine, trifluorperazine, etc.) inhibited EtBr efflux, indicating a broad substrate specificity of the efflux system.
- Efflux activity correlated with membrane potential but not intracellular ATP.
Conclusions:
- Corynebacterium glutamicum possesses a multidrug efflux system responsible for EtBr resistance.
- This efflux system is likely driven by proton motive force.
- The identified efflux system recognizes a diverse range of chemical compounds.