title: Mutations affecting substrate specificity of the Bacillus subtilis multidrug transporter Bmr.
abstract: The Bacillus subtilis multidrug transporter Bmr, a member of the major facilitator superfamily of transporters, causes the efflux of a number of structurally unrelated toxic compounds from cells. We have shown previously that the activity of Bmr can be inhibited by the plant alkaloid reserpine. Here we demonstrate that various substitutions of residues Phe143 and Phe306 of Bmr not only reduce its sensitivity to reserpine inhibition but also significantly change its substrate specificity. Cross-resistance profiles of bacteria expressing mutant forms of the transporter differ from each other and from the cross-resistance profile of cells expressing wild-type Bmr. This result strongly suggests that Bmr interacts with its transported drugs directly, with residues Phe143 and Phe306 likely to be involved in substrate recognition.
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago 60607, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Klyachko
authors.forename: S
authors.initials: S
authors.lastname: Schuldiner
authors.forename: A A
authors.initials: AA
authors.lastname: Neyfakh
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D026901:Membrane Transport Proteins; D016297:Mutagenesis, Site-Directed; D012110:Reserpine / Q000378:metabolism / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; C075041:Bmr protein, Bacillus subtilis; D012110:Reserpine