Resistance mutations reveal the atovaquone‐binding domain of cytochrome b in malaria parasites

作者：Indresh K. Srivastava, Joanne M. Morrisey, Élisabeth Darrouzet, Fevzi Daldal, Akhil B. Vaidya · 发表于：Molecular Microbiology · 年份：1999 · DOI：10.1046/j.1365-2958.1999.01515.x · 被引用次数：316 · 研究领域：Malaria Research and Control、HIV/AIDS drug development and treatment、Pneumocystis jirovecii pneumonia detection and treatment

Atovaquone represents a class of antimicrobial agents with a broad-spectrum activity against various parasitic infections, including malaria, toxoplasmosis and Pneumocystis pneumonia. In malaria parasites, atovaquone inhibits mitochondrial electron transport at the level of the cytochrome bc1 complex and collapses mitochondrial membrane potential. In addition, this drug is unique in being selectively toxic to parasite mitochondria without affecting the host mitochondrial functions. A better understanding of the structural basis for the selective toxicity of atovaquone could help in designing drugs against infections caused by mitochondria-containing parasites. To that end, we derived nine independent atovaquone-resistant malaria parasite lines by suboptimal treatment of mice infected with Plasmodium yoelii; these mutants exhibited resistance to atovaquone-mediated collapse of mitochondrial membrane potential as well as inhibition of electron transport. The mutants were also resistant to the synergistic effects of atovaquone/ proguanil combination. Sequencing of the mitochondrially encoded cytochrome b gene placed these mutants into four categories, three with single amino acid changes and one with two adjacent amino acid changes. Of the 12 nucleotide changes seen in the nine independently derived mutants 11 replaced A:T basepairs with G:C basepairs, possibly because of reactive oxygen species resulting from atovaquone treatment. Visualization of the resistance-conferring amin...