title: EmmdR, a new member of the MATE family of multidrug transporters, extrudes quinolones from Enterobacter cloacae.
abstract: We cloned a gene, ECL_03329, from the chromosome of Enterobacter cloacae ATCC13047, using a drug-hypersensitive Escherichia coli KAM32 cell as the host. We show here that this gene, designated as emmdR, is responsible for multidrug resistance in E. cloacae. E. coli KAM32 host cells containing the cloned emmdR gene (KAM32/pEMMDR28) showed decreased susceptibilities to benzalkonium chloride, norfloxacin, ciprofloxacin, levofloxacin, ethidium bromide, acriflavine, rhodamine6G, and trimethoprim. emmdR-deficient E. cloacae cells (EcΔemmdR) showed increased susceptibilities to several of the antimicrobial agents tested. EmmdR has twelve predicted transmembrane segments and some shared identity with members of the multidrug and toxic compound extrusion (MATE) family of transporters. Study of the antimicrobial agent efflux activities revealed that EmmdR is an H+-drug antiporter but not a Na+ driven efflux pump. These results indicate that EmmdR is responsible for multidrug resistance and pumps out quinolones from E. cloacae.
authors.affiliation: Department of Clinical Laboratory and Nutritional Sciences, University of Massachusetts Lowell, Lowell, MA 01854, USA. Guixin_He@uml.edu
authors.forename: Gui-Xin
authors.initials: GX
authors.lastname: He
authors.forename: Conner
authors.initials: C
authors.lastname: Thorpe
authors.forename: Dennis
authors.initials: D
authors.lastname: Walsh
authors.forename: Robert
authors.initials: R
authors.lastname: Crow
authors.forename: Huizhong
authors.initials: H
authors.lastname: Chen
authors.forename: Sanath
authors.initials: S
authors.lastname: Kumar
authors.forename: Manuel F
authors.initials: MF
authors.lastname: Varela
mesh_terms: D000890:Anti-Infective Agents / Q000378:metabolism; D017920:Antiporters / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001693:Biological Transport, Active; D003001:Cloning, Molecular; D024901:Drug Resistance, Multiple, Bacterial; D016972:Enterobacter cloacae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics; D008826:Microbial Sensitivity Tests; D015363:Quinolones / Q000378:metabolism*
chemical_list: D000890:Anti-Infective Agents; D017920:Antiporters; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D015363:Quinolones