EmmdR, a new member of the MATE family of multidrug transporters, extrudes quinolones from Enterobacter cloacae
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EmmdR, a new member of the MATE family of multidrug transporters, extrudes quinolones from Enterobacter cloacae Gui-Xin He • Conner Thorpe • Dennis Walsh • Robert Crow • Huizhong Chen • Sanath Kumar Manuel F. Varela
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Received: 10 April 2011 / Revised: 5 June 2011 / Accepted: 20 July 2011 / Published online: 7 August 2011 Ó Springer-Verlag 2011
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 (EcDemmdR) 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.
Communicated by Jorge Membrillo-Herna´ndez. G.-X. He (&) C. Thorpe D. Walsh Department of Clinical Laboratory and Nutritional Sciences, University of Massachusetts Lowell, Lowell, MA 01854, USA e-mail: [email protected] R. Crow S. Kumar M. F. Varela Department of Biology, Eastern New Mexico University, Portales, NM 88130, USA H. Chen Division of Microbiology, National Center for Toxicological Research, US FDA, Jefferson, AR 72079, USA
Keywords Multidrug transporter Enterobacter cloacae Resistance MATE Family
Introduction Enterobacter cloacae is an important nosocomial pathogen that causes a variety of infections, including bacteremia, lower respiratory tract infections, skin and soft-tissue infections, urinary tract infections (UTIs), endocarditis, intra-abdominal infections, septic arthritis, osteomyelitis, and ophthalmic infections (Fraser et al. 2010; Leversteinvan Hall et al. 2006; Paterson 2006). E. cloacae has a global presence in both adult and neonatal intensive care units (ICUs). Recently, multidrug-resistant E. cloacae has been reported with increasing frequency in clinical and environmental settings (Hidron et al. 2008; Rossi et al. 2006). Also, antimicrobial resistance has been shown to be conferred by several E. cloacae determinants, such as ampC, gyrA, murA, qnrA, acrAB, and ramA (Corkill et al. 2005; Diaz et al. 2006; Eschenburg et al. 2005; Giakkoupi et al. 2000; Kaneko et al. 2005; Keeney et al. 2007; Pe´rez et al. 2007; and Weigel et al. 1998). These resistance genes, however, are not sufficient to account for the reported spectra of multidrug resistances, such as resistances to aminoglycosides, q
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