Effects of clofazimine on potassium uptake by a Trk-deletion mutant of Mycobacterium tuberculosis.
OBJECTIVES: This study was designed to investigate the effects of the membrane-active, anti-mycobacterial agent, clofazimine, on potassium (K+)-uptake by a mutant of Mycobacterium tuberculosis (MTB), in which the Trk system, the major K+ transporter of this microbial pathogen, had been selectively inactivated. METHODS: The ceoB and ceoC genes of MTB, which encode the TrkA proteins, CeoB and CeoC, were deleted by homologous recombination, and the double-knockout mutant and wild-type strains compared with respect to K+ uptake and growth in the presence and absence of clofazimine (0.015-2.5 mg/L) using radioassay procedures. RESULTS: Surprisingly, the magnitudes of K+ uptake and rate of growth of the ceoBC-knockout mutant were significantly (P < 0.05) greater than those of the wild-type strain, due, presumably, to induction of a back-up transporter. Exposure of both the wild-type strain and ceoBC-knockout mutant of MTB to clofazimine was accompanied by dose-related decreases in K+ uptake, as well as growth, which were of comparable magnitude for both strains. CONCLUSIONS: These observations demonstrate that the major K+ transporter of MTB, Trk, as well as an uncharacterized inducible back-up system, is equally sensitive to the inhibitory actions of clofazimine.[1]References
- Effects of clofazimine on potassium uptake by a Trk-deletion mutant of Mycobacterium tuberculosis. Cholo, M.C., Boshoff, H.I., Steel, H.C., Cockeran, R., Matlola, N.M., Downing, K.J., Mizrahi, V., Anderson, R. J. Antimicrob. Chemother. (2006) [Pubmed]
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