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Identification of a mitochondrial superoxide dismutase with an unusual targeting sequence in Plasmodium falciparum.

par Sienkiewicz, Natasha;Daher, Wassim;Dive, Daniel;Wrenger, Carsten;Viscogliosi, Eric;Wintjens, René ;Jouin, Helène;Capron, Monique;Müller, Sylke;Khalife, Jamal
Référence Molecular and biochemical parasitology, 137, 1, page (121-132)
Publication Publié, 2004-09

Article révisé par les pairs

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Résumé :

The intraerythrocytic stages of Plasmodium falciparum are exposed to oxidative stress and require functional anti-oxidant systems to survive. In addition to the parasite's known iron-dependent superoxide dismutase PfSOD1, a second SOD gene (PfSOD2) interrupted by 8 introns was identified on chromosome 6. Molecular modelling shows that the structure of PfSOD2 is similar to other iron-dependent SODs and phylogenetic analysis suggests PfSOD1 and PfSOD2 are the result of an ancestral gene duplication. The deduced amino acid sequence of PfSOD2 is similar to PfSOD1 but has a long N-terminal extension. Immunofluorescence studies show that PfSOD1 is cytosolic, whereas the N-terminal extension of PfSOD2 targets a green fluorescent protein fusion into the parasite's mitochondrion. Both SOD genes are transcribed during the erythrocytic cycle with PfSOD1 mRNA levels up to 35-fold higher than those of PfSOD2. Northern blots demonstrated that the mRNA levels of both SOD genes are up-regulated upon exposure to oxidative stress.