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Uncovering the Molecular Mode of Action of the Antimalarial Drug Atovaquone Using a Bacterial System
Journal article   Open access   Peer reviewed

Uncovering the Molecular Mode of Action of the Antimalarial Drug Atovaquone Using a Bacterial System

Michael W Mather, Elisabeth Darrouzet, Maria Valkova-Valchanova, Jason W Cooley, Michael T McIntosh, Fevzi Daldal and Akhil B Vaidya
The Journal of biological chemistry, v 280(29), pp 27458-27465
22 Jul 2005
PMID: 15917236
url
https://doi.org/10.1074/jbc.M502319200View
Published, Version of Record (VoR) Open

Abstract

Atovaquone is an antiparasitic drug that selectively inhibits electron transport through the parasite mitochondrial cytochrome bc 1 complex and collapses the mitochondrial membrane potential at concentrations far lower than those at which the mammalian system is affected. Because this molecule represents a new class of antimicrobial agents, we seek a deeper understanding of its mode of action. To that end, we employed site-directed mutagenesis of a bacterial cytochrome b , combined with biophysical and biochemical measurements. A large scale domain movement involving the iron-sulfur protein subunit is required for electron transfer from cytochrome b -bound ubihydroquinone to cytochrome c 1 of the cytochrome bc 1 complex. Here, we show that atovaquone blocks this domain movement by locking the iron-sulfur subunit in its cytochrome b -binding conformation. Based on our malaria atovaquone resistance data, a series of cytochrome b mutants was produced that were predicted to have either enhanced or reduced sensitivity to atovaquone. Mutations altering the bacterial cytochrome b at its ef loop to more closely resemble Plasmodium cytochrome b increased the sensitivity of the cytochrome bc 1 complex to atovaquone, whereas a mutation within the ef loop that is associated with resistance in malaria parasites rendered it resistant to atovaquone. Interestingly, the atovaquone resistance-associated mutation led to a 10-fold reduction in the efficiency of the cytochrome bc 1 complex, suggesting that it may exert a cost on efficiency of the cytochrome bc 1 complex, without compromising seriously the growth of the organism.

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Collaboration types
Domestic collaboration
Web of Science research areas
Biochemistry & Molecular Biology
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