Plasmodium falciparum cytochrome bc1 complex (Pfbc1)

The Plasmodium falciparum cytochrome bc1 complex is a multi-subunit enzyme embedded in the inner mitochondrial membrane of the malaria parasite P. falciparum. It catalyzes the transfer of electrons from ubiquinol to cytochrome c, coupled with the translocation of protons across the membrane, thus establishing the proton gradient essential for ATP production. This complex is essential for parasite survival and proliferation and has two key inhibitor binding sites (Qo and Qi), both of which are exploited by various classes of antimalarial drugs. Atovaquone, a widely used antimalarial, and other inhibitors bind to these sites to block parasite respiration, ultimately resulting in parasite death. Clinical resistance can arise rapidly due to mutations in the cytochrome b subunit, which motivates ongoing drug development targeting this complex with new chemotypes to overcome resistance and safety challenges.

Other names

Cytochrome bc1 complex (in P. falciparum)Complex III (mitochondrial electron transport chain, P. falciparum)Mitochondrial respiratory chain complex III (P. falciparum)Pfbc1 (abbreviation in literature)

Inhibition of electron transfer at the Qo or Qi site of the cytochrome bc1 complex, blocking mitochondrial respiration, leading to ATP depletion and parasite death.