Plasmodium mitochondrial electron transport chain (mtETC) (mtETC)

The Plasmodium mitochondrial electron transport chain (mtETC) is a vital metabolic pathway in malaria-causing parasites, distinct from its human counterpart in both structure and primary function. While human mitochondria primarily use the ETC for ATP production via oxidative phosphorylation, blood-stage Plasmodium parasites rely on it mainly as an electron sink for dihydroorotate dehydrogenase (DHODH), an essential enzyme in the de novo pyrimidine biosynthesis pathway (Painter et al., 2007, Nature). Because Plasmodium cannot salvage preformed pyrimidines, inhibition of the mtETC—specifically the cytochrome bc1 complex (Complex III)—effectively halts DNA and RNA synthesis, leading to parasite death (Fry & Pudney, 1992, Biochem Pharmacol). The chain also includes a unique single-subunit NADH dehydrogenase (NDH2) that is absent in humans, making it an attractive target for selective toxicity (Fisher et al., 2007, J Biol Chem). This pathway is the target of the clinical antimalarial atovaquone and several next-generation candidates like ELQ-300. However, the high rate of resistance mutations in the mitochondrial-encoded cytochrome b gene remains a significant therapeutic challenge (Kessl et al., 2007, J Biol Chem).

Other names

Plasmodium mitochondrial respiratory chainMalaria parasite electron transport chainPlasmodium falciparum mitochondrial electron transport chainApicomplexan mitochondrial electron transport chain

Inhibition of the cytochrome bc1 complex (Complex III) prevents the turnover of ubiquinol to ubiquinone, which is a necessary cofactor for dihydroorotate dehydrogenase (DHODH), thereby halting de novo pyrimidine biosynthesis and disrupting the mitochondrial membrane potential (Mather et al., 2007, Molecular and Biochemical Parasitology; Painter et al., 2007, Nature).