The crystal structure of superoxide dismutase from Plasmodium falciparum.
BACKGROUND
Superoxide dismutases (SODs) are important enzymes in defence against oxidative stress. In Plasmodium falciparum, they may be expected to have special significance since part of the parasite life cycle is spent in red blood cells where the formation of reactive oxygen species is likely to be promoted by the products of haemoglobin breakdown. Thus, inhibitors of P. falciparum SODs have potential as anti-malarial compounds. As a step towards their development we have determined the crystal structure of the parasite's cytosolic iron superoxide dismutase.


RESULTS
The cytosolic iron superoxide dismutase from P. falciparum (PfFeSOD) has been overexpressed in E. coli in a catalytically active form. Its crystal structure has been solved by molecular replacement and refined against data extending to 2.5 A resolution. The structure reveals a two-domain organisation and an iron centre in which the metal is coordinated by three histidines, an aspartate and a solvent molecule. Consistent with ultracentrifugation analysis the enzyme is a dimer in which a hydrogen bonding lattice links the two active centres.


CONCLUSIONS
The tertiary structure of PfFeSOD is very similar to those of a number of other iron-and manganese-dependent superoxide dismutases, moreover the active site residues are conserved suggesting a common mechanism of action. Comparison of the dimer interfaces of PfFeSOD with the human manganese-dependent superoxide dismutase reveals a number of differences, which may underpin the design of parasite-selective superoxide dismutase inhibitors.
Boucher
Ian W
IW
Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, UK. boucher@ysbl.york.ac.uk
Brzozowski
Andrzej M
AM
Brannigan
James A
JA
Schnick
Claudia
C
Smith
Derek J
DJ
Kyes
Sue A
SA
Wilkinson
Anthony J
AJ
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000201:enzymology*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000235:genetics
D011994:Recombinant Proteins; D013482:Superoxide Dismutase