Functional analysis of Vibrio vulnificus RND efflux pumps homologous to Vibrio cholerae VexAB and VexCD, and to Escherichia coli AcrAB.
Resistance-nodulation-division (RND) efflux pumps are associated with multidrug resistance in many gram-negative pathogens. The genome of Vibrio vulnificus encodes 11 putative RND pumps homologous to those of Vibrio cholerae and Escherichia coli. In this study, we analyzed three putative RND efflux pumps, showing homology to V. cholerae VexAB and VexCD and to E. coli AcrAB, for their functional roles in multidrug resistance of V. vulnificus. Deletion of the vexAB homolog resulted in increased susceptibility of V. vulnificus to bile acid, acriflavine, ethidium bromide, and erythromycin, whereas deletion of acrAB homologs rendered V. vulnificus more susceptible to acriflavine only. Deletion of vexCD had no effect on susceptibility of V. vulnificus to these chemicals. Upon exposure to these antibacterial chemicals, expression of tolCV1 and tolCV2, which are putative outer membrane factors of RND efflux pumps, was induced, whereas expression levels of vexAB, vexCD, and acrAB homologs were not significantly changed. Our results show that the V. vulnificus homologs of VexAB largely contributed to in vitro antimicrobial resistance with a broad substrate specificity that was partially redundant with the AcrAB pump homologs.
Department of Life Science, Chung-Ang University, Seoul, 156-756, Republic of Korea.
Seunghwa
S
Lee
Ji-Hyun
JH
Yeom
Sojin
S
Seo
Minho
M
Lee
Sarang
S
Kim
Jeehyeon
J
Bae
Kangseok
K
Lee
Jihwan
J
Hwang
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics*; D018432:Drug Resistance, Multiple / Q000235:genetics; D004917:Erythromycin / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics; D008826:Microbial Sensitivity Tests; D020539:Sequence Analysis, Protein; D014734:Vibrio cholerae / Q000235:genetics* / Q000378:metabolism; D041261:Vibrio vulnificus / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
C000596829:AcrAB-TolC protein, E coli; D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D004917:Erythromycin