Redox and antioxidant systems of the malaria parasite Plasmodium falciparum

Abstract

SummaryThe malaria parasite Plasmodium falciparum is highly adapted to cope with the oxidative stress to which it is exposed during the erythrocytic stages of its life cycle. This includes the defence against oxidative insults arising from the parasite's metabolism of haemoglobin which results in the formation of reactive oxygen species and the release of toxic ferriprotoporphyrin IX. Central to the parasite's defences are superoxide dismutases and thioredoxin-dependent peroxidases; however, they lack catalase and glutathione peroxidases. The vital importance of the thioredoxin redox cycle (comprising NADPH, thioredoxin reductase and thioredoxin) is emphasized by the confirmation that thioredoxin reductase is essential for the survival of intraerythrocytic P. falciparum . The parasites also contain a fully functional glutathione redox system and the low-molecular-weight thiol glutathione is not only an important intracellular thiol redox buffer but also a cofactor for several redox active enzymes such as glutathione S-transferase and glutaredoxin. Recent findings have shown that in addition to these cytosolic redox systems the parasite also has an important mitochondrial antioxidant defence system and it is suggested that lipoic acid plays a pivotal part in defending the organelle from oxidative damage.

Structural and Functional Characterization of Falcipain-2, a Hemoglobinase from the Malarial Parasite Plasmodium falciparum

“…Where possible, numbers are given for the first and last amino acid residue of each secondary-structure element. that several factors contribute to the formation of methemoglobin during plasmodial infection, including the acidic pH of the plasmodial food vacuole, oxidative damage within infected erythrocytes (51,52), and the reduced activity of NADH-methemoglobin reductase (53). A significantly increased methemoglobin content in the range of 20 -42% has been detected in the plasmodial food vacuole compared with 0.6 -1.0% in uninfected erythrocytes (51).…”

Inhibitors of Nonhousekeeping Functions of the Apicoplast Defy Delayed Death in Plasmodium falciparum

“…Lipoic acid is an efficient free radical scavenger and plays a pivotal role in proffering protection against oxidative insults (19,36). In fact, Toler suggests that the apicoplast in apicomplexans, by virtue of its ability to synthesize lipoic acid, was retained as an obligate endosymbiont under evolutionary selection pressure to combat the oxidative injury generated by mitochondrial reactive oxygen species during pyrimidine biosynthesis in the schizont stage (30).…”

Proteome changes in the plasma of Papilio xuthus (Lepidoptera: Papilionidae): effect of parasitization by the endoparasitic wasp Pteromalus puparum (Hymenoptera: Pteromalidae)

“…Cellular stress such as phagocytosis and melanotic encapsulation can induce the generation of reactive oxygen species (ROS) such as superoxide anions, hydrogen peroxide, and hydroxyl radicals that damage nucleic acids, proteins, lipids, and membranes (Müller, 2004;de Morais Guedes et al, 2005). In order to counter these deleterious events, cells use several protective systems that either repair the various types of damage (for instance, by using DNA repair enzymes) or inactivate the ROS (de Morais Guedes et al, 2005).…”