Biochemical and electron paramagnetic resonance study of the iron superoxide dismutase from Plasmodium falciparum.
Recombinant iron-containing superoxide dismutase (Fe-SOD) from Plasmodium falciparum was produced in a SOD-deficient strain of Escherichia coli, purified and characterised. The enzyme is a dimer, which contains 1.7 Fe equivalents and is sensitive to hydrogen peroxide (H(2)O(2)). Electron paramagnetic resonance (EPR) analysis showed two different signals, reflecting the presence of two different types of high-spin Fe sites with different symmetries. The role of the W71 residue during inactivation by H(2)O(2) of the P. falciparum Fe-SOD was studied by site-directed mutagenesis. First, the W71V mutation led to a change in the relative proportion of the two Fe-based EPR signals. Second, the mutant protein was almost as active as the wild-type (WT) protein but more sensitive to heat inactivation. Third, resistance to H(2)O(2) was only slightly increased indicating that W71 was marginally responsible for the sensitivity of Fe-SOD to H(2)O(2). A molecular model of the subunit was designed to assist in interpretation of the results. The fact that the parasite SOD does not belong to classes of SOD present in humans may provide a novel approach for the design of antimalarial drugs.
Gratepanche
Sylvie
S
Laboratory of Parasitic Diseases, Growth and Development Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0425, USA.
Ménage
Stéphane
S
Touati
Danièle
D
Wintjens
René
R
Delplace
Patrick
P
Fontecave
Marc
M
Masset
Annick
A
Camus
Daniel
D
Dive
Daniel
D
D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007501:Iron / Q000378:metabolism; D013058:Mass Spectrometry; D008958:Models, Molecular; D008970:Molecular Weight; D009154:Mutation; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D011487:Protein Conformation; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D013696:Temperature; D013997:Time Factors
D006861:Hydrogen Peroxide; D007501:Iron; D013482:Superoxide Dismutase