Molecular cloning and characterization of an ABC multidrug efflux pump, VcaM, in Non-O1 Vibrio cholerae.
A gene responsible for multidrug resistance was cloned from the chromosomal DNA of non-O1 Vibrio cholerae NCTC 4716 by using as a host drug-hypersensitive Escherichia coli strain KAM32, which lacks major multidrug efflux pumps. E. coli cells transformed with the gene showed elevated levels of resistance to a number of structurally dissimilar drugs, such as tetracycline, norfloxacin, ciprofloxacin, doxorubicin, daunomycin, 4',6-diamidino-2-phenylindole, and Hoechst 33342. We determined the nucleotide sequence and found one open reading frame. We designated the gene vcaM. The deduced product, VcaM, seems to be a polypeptide with 619 amino acid residues (69 kDa) that has a putative topology of six transmembrane segments in the N-terminal hydrophobic domain, followed by an ATP binding domain in the C-terminal hydrophilic region. The sequence of VcaM was shown to be similar to those of human multidrug resistance proteins P-glycoprotein MDR1 and lactococcal LmrA, which are driven by ATP. The efflux of Hoechst 33342 and doxorubicin from cells possessing VcaM was detected. The efflux activity was inhibited by reserpine and sodium o-vanadate, which are potent inhibitors of MDR1 and LmrA. Thus, we conclude that VcaM is a member of the family of multidrug efflux pumps of the ATP binding cassette type and the first experimentally proven example of a multidrug efflux pump of this family in gram-negative bacteria.
Huda
Nazmul
N
Department of Microbiology, Faculty of Pharmaceutical Sciences, Okayama University, Tsushima, Okayama 700-8530, Japan.
Lee
Eun-Woo
EW
Chen
Jing
J
Morita
Yuji
Y
Kuroda
Teruo
T
Mizushima
Tohru
T
Tsuchiya
Tomofusa
T
D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000378:metabolism; D001562:Benzimidazoles; D002876:Chromosomes, Bacterial / Q000235:genetics; D003001:Cloning, Molecular; D004317:Doxorubicin / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005456:Fluorescent Dyes; D024841:Fluoroquinolones; D008826:Microbial Sensitivity Tests; D013754:Tetracyclines / Q000378:metabolism; D014734:Vibrio cholerae / Q000235:genetics* / Q000378:metabolism
D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D000903:Antibiotics, Antineoplastic; D001562:Benzimidazoles; D005456:Fluorescent Dyes; D024841:Fluoroquinolones; D013754:Tetracyclines; C477295:VcaM protein, Vibrio cholerae; D004317:Doxorubicin; C017807:bisbenzimide ethoxide trihydrochloride