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Mutations affecting substrate specificity of the Bacillus subtilis multidrug transporter Bmr
K A Klyachko1, S Schuldiner, A A Neyfakh
1Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago 60607, USA.
Journal of Bacteriology
|April 1, 1997
Summary
Mutations in the Bacillus subtilis multidrug transporter Bmr alter drug specificity and reserpine inhibition. These findings suggest key residues are involved in how Bmr recognizes and transports toxic compounds.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Bacillus subtilis multidrug transporter (Bmr) is a major facilitator superfamily transporter.
- Bmr extrudes various toxic compounds from cells.
- Reserpine, a plant alkaloid, previously shown to inhibit Bmr activity.
Purpose of the Study:
- Investigate the role of Phe143 and Phe306 residues in Bmr function.
- Determine how substitutions at these residues affect reserpine inhibition and substrate specificity.
- Elucidate the interaction mechanism between Bmr and its transported drugs.
Main Methods:
- Site-directed mutagenesis of Bmr at Phe143 and Phe306.
- Assessing reserpine sensitivity of mutant Bmr transporters.
- Analyzing cross-resistance profiles of bacteria expressing wild-type and mutant Bmr.
Main Results:
- Mutations at Phe143 and Phe306 reduced reserpine sensitivity.
- Substitutions significantly altered the substrate specificity of Bmr.
- Cross-resistance profiles of mutant transporters differed from wild-type Bmr.
Conclusions:
- Residues Phe143 and Phe306 are critical for Bmr substrate recognition.
- Bmr directly interacts with the drugs it transports.
- Understanding these interactions can inform the development of new antimicrobial strategies.