title: Active efflux of chloramphenicol in susceptible Escherichia coli strains and in multiple-antibiotic-resistant (Mar) mutants.
abstract: The multiple-antibiotic resistance (mar) locus (min 34) regulates a resistance to chloramphenicol in Escherichia coli that does not involve acetyltransferase. Transport studies showed that wild-type cells had an apparent endogenous active efflux of chloramphenicol which depended on the proton motive force. This efflux was not altered by a 39-kb chromosomal deletion which included the mar locus. Nevertheless, mutations at the mar locus led to a stronger net chloramphenicol efflux. Therefore, a gene encoding the putative efflux system cannot be at the mar locus but may be positively influenced by that locus.
authors.affiliation: Center for Adaptation Genetics and Drug Resistance, Tufts University School of Medicine, Boston, Massachusetts 02111.
authors.forename: L M
authors.initials: LM
authors.lastname: McMurry
authors.forename: A M
authors.initials: AM
authors.lastname: George
authors.forename: S B
authors.initials: SB
authors.lastname: Levy
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002701:Chloramphenicol / Q000378:metabolism* / Q000494:pharmacology; D002702:Chloramphenicol Resistance / Q000235:genetics; D002876:Chromosomes, Bacterial; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
chemical_list: D002701:Chloramphenicol