Previous Article | Next Article ![]()
J. Bacteriol., 07 1996, 3791-3795, Vol 178, No. 13
J Liu, HE Takiff and H Nikaido
The lfrA gene cloned from chromosomal DNA of quinolone-resistant
Mycobacterium smegmatis mc2-552 conferred low-level resistance to
fluoroquinolones when present on multicopy plasmids. Sequence analysis
suggested that lfrA encodes a membrane efflux pump of the major facilitator
family (H. E. Takiff, M. Cimino, M. C. Musso, T. Weisbrod, R. Martinez, M.
B. Delgado, L Salazar, B. R. Bloom, and W. R. Jacbos, Jr., Proc. Natl.
Acad. Sci. USA 93:362-366, 1996). In this work, we studied the role of LfrA
in the accumulation of fluoroquinolones by M. smegmatis. The steady-state
accumulation level of a hydrophilic quinolone, norfloxacin, by M. smegmatis
harboring a plasmid carrying the lfrA gene was about 50% of that by the
parent strain but was increased to the same level as that of the parent
strain by addition of a proton conductor, carbonyl cyanide
m-chorophenylhydrazone. Norfloxacin efflux mediated by LfrA was competed
for strongly by ciprofloxacin but not by nalidixic acid. Furthermore, we
showed that portions of norfloxacin accumulated by starved cells were
pumped out upon reenergization of the cells, and the rates of this efflux
showed evidence of saturation at higher intracellular concentrations of the
drug. These results suggest that the LfrA polypeptide catalyzes the active
efflux of several quinolones.
Copyright © 1996, American Society for Microbiology
Active efflux of fluoroquinolones in Mycobacterium smegmatis mediated by LfrA, a multidrug efflux pump
Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3206, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»