Identification of a mitochondrial superoxide dismutase with an unusual targeting sequence in Plasmodium falciparum.
Abstract
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.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe- info:eu-repo/semantics/article
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- Biologie
- Adaptation, Psychological
- Amino Acid Sequence
- Animals
- Cytoplasm -- enzymology
- DNA, Complementary
- DNA, Protozoan -- chemistry
- Erythrocytes -- parasitology
- Fluorescent Antibody Technique, Indirect
- Gene Duplication
- Gene Expression Regulation
- Introns -- genetics
- Mitochondria -- enzymology
- Models, Molecular
- Molecular Sequence Data
- Oxidative Stress
- Phylogeny
- Plasmodium falciparum -- enzymology -- genetics -- growth & development
- Protein Sorting Signals
- Protein Transport
- RNA, Messenger -- analysis
- RNA, Protozoan -- analysis
- Recombinant Fusion Proteins -- metabolism
- Sequence Analysis, DNA
- Sequence Homology
- Superoxide Dismutase -- chemistry -- genetics -- metabolism
- Biologie structurale