Plasmodium mitochondrial electron transport chain and dihydroorotate dehydrogenase (mETC-DHODH)

The Plasmodium mitochondrial electron transport chain (mETC) and its associated dihydroorotate dehydrogenase (DHODH) enzyme constitute a vital metabolic pathway for malaria parasites (Vaidya & Mather, 2009). Unlike their human hosts, Plasmodium parasites are unable to salvage pyrimidines and must rely entirely on de novo synthesis for nucleic acid production (Painter et al., 2007). The mETC's primary role in the parasite's blood stage is to provide an electron sink for DHODH by regenerating the ubiquinone pool (Painter et al., 2007). This regeneration is essential for the conversion of dihydroorotate to orotate, a rate-limiting step in pyrimidine biosynthesis. When drugs like atovaquone inhibit the cytochrome bc1 complex or when DSM265 inhibits DHODH directly, the parasite loses its ability to synthesize DNA and RNA (Phillips et al., 2015). This disruption leads to metabolic collapse, growth arrest, and eventual parasite death. This pathway is a validated target for both the treatment and prophylaxis of malaria across various life stages (Goodman et al., 2017). However, the clinical utility of targeting this system is often challenged by the rapid emergence of resistance mutations, particularly in the cytochrome b gene (Vaidya & Mather, 2009). Modern drug discovery efforts focus on high-potency inhibitors with improved selectivity to minimize host toxicity.

Other names

Plasmodium mitochondrial electron transport chainPlasmodium pyrimidine biosynthesis pathwayDHODH-mETC axisMitochondrial respiratory chain of Plasmodium

Inhibition of the Cytochrome bc1 complex (Complex III) or Dihydroorotate dehydrogenase (DHODH) to disrupt the regeneration of ubiquinone, thereby halting de novo pyrimidine biosynthesis and parasite replication (Painter et al., 2007; Phillips et al., 2015).