Identification of a mitochondrial superoxide dismutase with an unusual targeting sequence in Plasmodium falciparum.
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.
Division of Biological Chemistry and Molecular Microbiology, School of Life Sciences, University of Dundee, WTB/MSI Complex, DD15EH, UK.
Natasha
N
Sienkiewicz
Wassim
W
Daher
Daniel
D
Dive
Carsten
C
Wrenger
Eric
E
Viscogliosi
René
R
Wintjens
Helène
H
Jouin
Monique
M
Capron
Sylke
S
Müller
Jamal
J
Khalife
D000223:Adaptation, Psychological; D000595:Amino Acid Sequence; D000818:Animals; D003593:Cytoplasm / Q000201:enzymology; D018076:DNA, Complementary; D016054:DNA, Protozoan / Q000737:chemistry; D004912:Erythrocytes / Q000469:parasitology; D019084:Fluorescent Antibody Technique, Indirect; D020440:Gene Duplication; D005786:Gene Expression Regulation; D007438:Introns / Q000235:genetics; D008928:Mitochondria / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010802:Phylogeny; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D021382:Protein Sorting Signals; D021381:Protein Transport; D012333:RNA, Messenger / Q000032:analysis; D016053:RNA, Protozoan / Q000032:analysis; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D000099156:Superoxide Dismutase 2
D018076:DNA, Complementary; D016054:DNA, Protozoan; D021382:Protein Sorting Signals; D012333:RNA, Messenger; D016053:RNA, Protozoan; D011993:Recombinant Fusion Proteins; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000099156:Superoxide Dismutase 2