Reduction of Clofazimine by Mycobacterial Type 2 NADH:Quinone Oxidoreductase

The mechanism of action of clofazimine (CFZ), an antimycobacterial drug with a long history, is not well understood. The present study describes a redox cycling pathway that involves the enzymatic reduction of CFZ by NDH-2, the primary respiratory chain NADH:quinone oxidoreductase of mycobacteria an...

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Bibliographic Details
Published in:	The Journal of biological chemistry 2011-03, Vol.286 (12), p.10276-10287
Main Authors:	Yano, Takahiro, Kassovska-Bratinova, Sacha, Teh, J. Shin, Winkler, Jeffrey, Sullivan, Kevin, Isaacs, Andre, Schechter, Norman M., Rubin, Harvey
Format:	Article
Language:	eng
Subjects:	Amyloid Blood Brain RNA Binding Protein RNA Folding Translation Control
Online Access:	Get full text
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Summary:	The mechanism of action of clofazimine (CFZ), an antimycobacterial drug with a long history, is not well understood. The present study describes a redox cycling pathway that involves the enzymatic reduction of CFZ by NDH-2, the primary respiratory chain NADH:quinone oxidoreductase of mycobacteria and nonenzymatic oxidation of reduced CFZ by O2 yielding CFZ and reactive oxygen species (ROS). This pathway was demonstrated using isolated membranes and purified recombinant NDH-2. The reduction and oxidation of CFZ was measured spectrally, and the production of ROS was measured using a coupled assay system with Amplex Red. Supporting the ROS-based killing mechanism, bacteria grown in the presence of antioxidants are more resistant to CFZ. CFZ-mediated increase in NADH oxidation and ROS production were not observed in membranes from three different Gram-negative bacteria but was observed in Staphylococcus aureus and Saccharomyces cerevisiae, which is consistent with the known antimicrobial specificity of CFZ. A more soluble analog of CFZ, KS6, was synthesized and was shown to have the same activities as CFZ. These studies describe a pathway for a continuous and high rate of reactive oxygen species production in Mycobacterium smegmatis treated with CFZ and a CFZ analog as well as evidence that cell death produced by these agents are related to the production of these radical species.
ISSN:	0021-9258 1083-351X