This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Google Scholar
Right arrow Articles by Lin, S. S.
Right arrow Articles by Bohne, W.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Lin, S. S.
Right arrow Articles by Bohne, W.

 Previous Article  |  Next Article 

Eukaryotic Cell, June 2009, p. 877-887, Vol. 8, No. 6
1535-9778/09/$08.00+0     doi:10.1128/EC.00381-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Type II NADH Dehydrogenase Inhibitor 1-Hydroxy-2-Dodecyl- 4(1H)Quinolone Leads to Collapse of Mitochondrial Inner- Membrane Potential and ATP Depletion in Toxoplasma gondii{triangledown}

San San Lin, Uwe Groß, and Wolfgang Bohne*

Institute of Medical Microbiology, University of Göttingen, Kreuzbergring 57, D-37075 Göttingen, Germany

Received 4 December 2008/ Accepted 2 March 2009

The apicomplexan parasite Toxoplasma gondii expresses type II NADH dehydrogenases (NDH2s) instead of canonical complex I at the inner mitochondrial membrane. These non-proton-pumping enzymes are considered to be promising drug targets due to their absence in mammalian cells. We recently showed by inhibition kinetics that T. gondii NDH2-I is a target of the quinolone-like compound 1-hydroxy-2-dodecyl-4(1H)quinolone (HDQ), which inhibits T. gondii replication in the nanomolar range. In this study, the cationic fluorescent probes Mitotracker and DiOC6(3) (3,3'-dihexyloxacarbocyanine iodine) were used to monitor the influence of HDQ on the mitochondrial inner membrane potential ({Delta}{Psi}m) in T. gondii. Real-time imaging revealed that nanomolar HDQ concentrations led to a {Delta}{Psi}m collapse within minutes, which is followed by severe ATP depletions of 30% after 1 h and 70% after 24 h. {Delta}{Psi}m depolarization was attenuated when substrates for other dehydrogenases that can donate electrons to ubiquinone were added to digitonin-permeabilized cells or when infected cultures were treated with the Fo-ATPase inhibitor oligomycin. A prolonged treatment with sublethal concentrations of HDQ induced differentiation into bradyzoites. This dormant stage is likely to be less dependent on the {Delta}{Psi}m, since {Delta}{Psi}m-positive parasites were found at a significantly lower frequency in alkaline-pH-induced bradyzoites than in tachyzoites. Together, our studies reveal that oxidative phosphorylation is essential for maintaining the ATP level in the fast-growing tachyzoite stage and that HDQ interferes with this pathway by inhibiting the electron transport chain at the level of ubiquinone reduction.

* Corresponding author. Mailing address: Institute of Medical Microbiology, University of Göttingen, Kreuzbergring 57, D-37075 Göttingen, Germany. Phone: 49-551-395869. Fax: 49-551-395861. E-mail: wbohne{at}gwdg.de

{triangledown} Published ahead of print on 13 March 2009.

Eukaryotic Cell, June 2009, p. 877-887, Vol. 8, No. 6
1535-9778/09/$08.00+0     doi:10.1128/EC.00381-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»